1 What is the purpose of the neurologic exam?

To localize lesions—that is, to identify the precise site of damage. This is rooted in the eloquence of the nervous system (i.e., the unique property that the brain, spinal cord, and peripheral nerves have of “talking to us”) insofar as each section performs such a discrete function that any loss can be easily traced back to its level. Hence, neuro signs (and symptoms) accurately localize lesions. And this also is why the neuro exam is the bedside tool with the highest sensitivity, specificity, and likelihood ratios. Yet, in contrast to other parts of the exam where inspection or palpation are key, the neurologic exam relies on deductive skills and specific maneuvers. Hence, it is difficult to perform but rewarding. It also is long—at least 1 solid hour.

2 What are the most important components of the neurologic exam?

3 What is dementia?

An acquired and persistent cognitive impairment that compromises multiple domains of intellectual function (such as memory, language, etc.—basically, awareness [i.e., the content of consciousness]) while preserving instead perception and arousal (i.e., the level of consciousness). Hence dementia is not coma. Dementia is not delirium either, since this is instead an acute and often reversible confusional state seen in 20% of elderly patients hospitalized for intercurrent illnesses. Dementia is painfully common, affecting 3–11% of adults older than 65, and its prevalence does increase with aging, so that one third of subjects older than 80 (and one half of those older than 90) will eventually suffer from it—something to look forward to. It can be toxic, metabolic, degenerative, inflammatory, infective, or vascular. The earliest signs are often subtle, usually involving short-term memory but otherwise sparing the bulk of the exam. As the disease progresses, frontal release signs appear.

4 What are frontal release signs?

They are the reemergence of primitive reflexes (i.e., signs that are normally present in infants, but resurface in adults only as a result of diffuse frontal lobe disease). Release signs/reflexes include snouting, rooting, sucking, and grasping. Of these, the most sensitive is grasping. To elicit it, place your index and middle fingers in the patient’s palm, apply some pressure, and then slowly withdraw them between the patient’s thumb and index finger. An abnormal response (involuntary squeezing of the examiner’s fingers—with no habituation after three successive strokes) strongly argues for a lesion in the frontal lobes or the deep nuclei and subcortical white matter. Though not too sensitive (13%), it has specificity close to 100%. Contrary to other primitive reflexes (such as palmomental or glabellar), grasp is never seen in normal subjects.

5 What are the snouting, rooting, and sucking reflexes?

6 What is the palmomental reflex?

A brief and involuntary contraction of the ipsilateral mentalis muscle, wrinkles and pushes-up the chin boss, while at the same time curving the lower lip upward in an inverted “U.” This is elicited by stroking the patient’s palm (thenar eminence) with a blunt object, from proximal to distal. As a release sign, it is often seen in Parkinson’s (where it correlates with degree of akinesia), but also in 3–70% of older normal individuals. Note that the muscle is called “mentalis,” because its voluntary contraction is often associated with thinking or concentration. Its nerve supply is provided by the facialis (CN VII).

7 What is the glabellar reflex?

Another primitive (or “release”) reflex, very much like the grasp and palmomental. It involves V and VII, and is elicited by repetitively tapping on the patient’s glabella (between the eyebrows). The normal response is a brief contraction of the orbicularis, producing a few blinks after the initial taps that stop after subsequent taps—usually fewer than five. In cases of frontal release, there is instead no habituation. Hence, blinking persists as long as tapping continues. This occurs in late extrapyramidal disorders (Parkinson), but also in 3–33% of older normal subjects.

8 How do you separate “normal” primitive reflexes from the pathologic ones?

By judging them like people: by the company they keep. Hence, a “normal” palmomental or glabellar reflex will occur in subjects with otherwise a normal neurologic exam. Thus, they will be isolated. In fact, only fewer than 12% of normal individuals have two primitive reflexes, and fewer than 2% have three. Moreover, normal primitive reflexes tend to fade with repetition (i.e., they are fatigable). Only 1% of “normal” subjects will continue to exhibit a palmomental reflex after five stimulations. In contrast, patients with real pathology have no habituation.

9 How long does it take to do a complete mental status examination?

It can take hours and even days. Yet, for clinical purposes the crucial components can be tested rather quickly. These include (1) level of consciousness, (2) orientation, (3) registration, (4) memory (recall), (5) attention and calculation, (7) intelligence, and (6) language.

10 What are the most important levels of consciousness? How do they deteriorate?

There are four levels of consciousness. In increasing degree of deterioration they are:

11 What is orientation? How do you assess it?

Orientation is the patients’ cognizance of their status in time, place, and person. To assess it, ask them to state the year/date/day/month of interview, their location, and their name (state/county/city/hospital/floor). In organic diseases, the sense of time is the first to be lost, while the sense of person is the last one. Hence, patients who are oriented to time and place but do not know who they are tend to be more psychologic than organic.

12 What is memory? How do you assess it?

Memory is the ability to register and recall prior sensory input. For testing purposes:

Most normal subjects can remember three objects after a brief distraction (recent memory). Acute encephalopathies impair all aspects of memory (both recent and remote). Dementia disrupts instead recent memory and attention span, while preserving remote memory.

13 How do you assess attention and calculation?

By spelling “world” backward or doing serial 7’s (i.e., counting backward from 100, in installments of 7, and ending after five subtractions—that is, at 65).

14 How can one efficiently examine all aspects of mental status?

Through a battery of carefully analyzed and validated questions, such as the Folstein Mini Mental Status Examination (MMSE). This consists of 11 items that can be easily administered in 5–10 minutes and are either sensitive for dementia (but not specific), or specific but not sensitive. They evaluate the most important mental status domains (orientation, registration, attention/calculation, recall, and language), with a final score of 0–30 (<23 being abnormal).

15 How reliable is the MMSE in assessing cognitive function?

Quite reliable. In fact, it has strong likelihood ratios for identifying dementia impairments. It is also valuable for follow-up, even though only significant for large changes (>4    points).

16 What is the clock-drawing test?

Another mental status test. It provides patients with a preprinted circle (4    inches in diameter), asking them to “draw a clock.” No further instruction and unlimited time are given. Normal subjects will draw all 12 numbers, even though not necessarily with proper hands or symmetric spaces between them. Missing one number is still acceptable, but absent figures, irrelevant figures, or unusual arrangements/counterclockwise orientation of figures are not. An abnormal clock-drawing test has high specificity for dementia, but low sensitivity (being positive in only 50% of patients).

17 How do you test for delirium?

By looking for (1) acute and fluctuating change in mental status; (2) difficulty in staying focused or keeping track of what is being said; (3) altered level of consciousness (both in defect and in excess); and (4) disorganized thinking, with flights of ideas, often irrelevant and illogical. Hence, delirious patients exhibit a change in both mental status and the ability to stay focused. They also may have disorganized thinking or altered level of consciousness.

18 What is intelligence? How do you test it?

Intelligence is the ability to problem-solve by applying previous knowledge to a new situation and then using reason. It can be tested through calculations (serial 7 calculations), vocabulary, fund of knowledge, abstraction (use of proverbs), and judgment (like what to do with a found wallet).

19 What are the components of language? How do you assess them?

Language involves not only speech (verbal language), but also comprehension (of what is being spoken to you), reading, and writing. Hence, the ability to use language is one of the most complex functions of the human brain, whose correct assessment must test all of its aspects. Speech impairments include dysphonia, dysarthria, and aphasia.

20 What is dysphonia?

Dysphonia is difficulty in phonation. The voice is usually hoarse, but in the most severe cases, it may be altogether absent (aphonia, mutism). Causes include laryngitis (common cold), hypothyroidism (thickening of the vocal cords from myxedematous deposits), unilateral recurrent laryngeal nerve paralysis, and lesions of the vagus nerve. Reading, writing, and understanding are intact.

21 What is dysarthria?

From the Greek dys (difficulty) and arthros (articulation), this is a speech disturbance characterized by difficulty in articulating sounds and words. Hence, the quality of speech is impaired and typically slurred, but its content remains intact. Dysarthria is a motor impairment with intact cortical/subcortical language capacity. It usually results from paralysis/spasticity of the muscles of phonation (pharyngeal, palatal, lingual, or facial), but also can be observed in cerebellar disease or simple emotional stress. Contrary to most types of aphasia, dysarthria (and mutism) preserves the capacity to read, write, and understand speech.

22 What is cerebellar speech?

Another disorder of articulation of sound, rather than ideation or perception (ataxic speech).

23 Beside cerebellar speech, what are the two most important types of dysarthria?

Table 19-1 Dysarthria and Possible Cranial Nerve Involvement

24 What is aphasia?

From the Greek aphatos (speechless), this is an acquired disturbance of language, including its production and comprehension. Hence, it should not be confused with mutism (the inability to produce sounds) or dysarthria (the weakness/incoordination of speech muscles). In both of these cases, the problem is in the “machinery” of language, not in its ideation or comprehension.

25 What are the most important defects in aphasia?

26 What are the clinical differences between fluent and nonfluent aphasia?

id=”p0300″/>Pearl. Wernicke’s aphasia is fluent, with impaired repetition and impaired comprehension. Broca’s aphasia is instead nonfluent, with impaired repetition and intact comprehension.

27 Summarize the common aphasias

See Table 19-2.

28 Who was Broca?

Pierre P. Broca (1824–1880) was a French surgeon with a prolific career in medicine and neurology. A pioneer in many areas, he described rickets as a nutritional disorder before Virchow, Duchenne’s dystrophy before Duchenne, and even the use of hypnotism as a surgical adjuvant. He also was responsible for introducing to France the use of the microscope for cancer diagnosis. An anthropologist with Darwinian sympathies, Broca founded the first Anthropological Society of France and his own anthropological institute. He married the daughter of Dr. Lugol (of Lugol iodine fame) and died at 56 of myocardial infarction.

29 Who was Wernicke?

Karl Wernicke (1848–1905) was a German physician born in what is now Poland. A graduate of Breslau (now the Polish Wroclaw), he described his aphasia in a book written when he was only 26. His interest in localizing lesions was then summarized (sort of) in a three-volume textbook published in 1881, which also contained the description of an encephalopathy caused by alcoholic thiamine deficiency (ataxia, confusion, nystagmus, ophthalmoplegia, and peripheral neuritis). This was later redubbed Wernicke’s encephalopathy (with Korsakoff describing instead the psychotic manifestations of the disease). A cold and aloof man, Wernicke died also at 56, of injuries reported while biking in the Thuringian forest.

30 What is perserveration?

The difficulty in performing a repeated sequence of actions. Frontal lobe patients, for example, cannot switch easily from one task to the next. Instead, they perseverate. For example, when asked to draw a silhouette pattern of alternating triangles and squares, they get stuck on one shape and draw only triangles or squares. A good test of perseveration is Luria’s manual sequencing task, wherein patients are asked to tap sequentially the table with a fist, then an open palm, and finally the side of the open hand. Frontal lobe patients cannot rapidly repeat the sequence.

31 What is cortical dementia? What is subcortical dementia?

32 What is dyspraxia?

The inability to perform tasks requiring fine motor skills, such as drawing, buttoning, writing, and speaking (verbal dyspraxia). From the Greek dys (difficulty in) and praxis (doing).

33 What is agnosia?

The inability to recognize objects by touch alone (a, lack of; and gnosia, recognition).

34 What is the role of cranial nerve examination?

An important one, since all cranial nerves have discrete functions that permit accurate localization of lesions based only on exam. Yet detailed testing of all cranial nerves is time consuming. Hence, it is unnecessary unless symptoms point toward a specific nerve problem.

35 How do you test CN I (olfactory nerve)?

By asking patients to close their eyes, occlude one nostril, and then smell through the open naris a distinctive scent—like cinnamon, cloves, or peppermint. Transient anosmia is common, usually resulting from simple colds or intercurrent sinus infection. Chronic anosmia (especially if congenital) is instead quite important (see Chapter 6, question 33). Note that anosmia can also be seen in frontal/temporal lobectomies or Parkinson’s disease.

36 How do you test CN II (optic nerve)?

By funduscopy and color recognition (through Ishihara chart or a common and colorful object), but also by two bedside maneuvers, each testing a separate function of the optic nerve:

37 How do you test CN III, IV, and VI?

Together, since oculomotor (III), trochlear (IV), and abducens (VI) work in concert to produce the various eye movements. To test them, ask patients to hold the head stationary while following your finger as it moves through the main directions of gaze: left-up, left-middle, left-down, and right-up, right-middle, and right-down. Normal eyes move symmetrically and smoothly. Any restriction or double vision (from inability of the eyes to move together) suggests damage to III, IV, or VI (see Chapter 4, questions 84–90).

38 What abnormal eye movements result from damage to CN III, IV, or VI?

39 How do you test CN V (trigeminal nerve)?

It depends on whether you are testing a motor or sensory component. The divisions of the trigeminal nerve are shown in Figure 19-1.

Figure 19-1 Divisions of the trigeminal nerve.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–10.)

40 Where are the sensory and motor nuclei of the trigeminal nerve?

They are both in the pons. Yet the sensory also extends into the cervical cord.

41 How do you test the sensory function of CN V?

By pinprick or light touch over the areas of distribution of the trigeminal branches: upper (supplied by V1, or ophthalmic; forehead), mid (V2, or maxillary; cheek), and lower (V3, or mandibular; jaw). Sensory function of the ophthalmic branch is also tested by the corneal reflex (see question 58).

42 How do you test the motor function of CN V?

By feeling the masseters during teeth clinching. Contraction must be strong and symmetric.

43 What are the manifestations of trigeminal motor deficit?

44 What is the significance of unilateral trigeminal motor deficit?

It indicates nerve compression (bony metastases) or an ipsilateral pontine lesion. Since trigeminal motor nuclei receive bilateral cortical innervation, hemispheric strokes will not affect them. Hence, bilateral masseter weakness suggests bilateral hemispheric disease (pseudobulbar palsy).

45 What is the significance of a sensory deficit of the trigeminal nerve?

It depends on whether it involves both the face and body, or only the face:

46 What is Hutchinson’s sign?

It is the presence of herpetic vesicles on the nasal tip of patients with ophthalmic zoster—an ominous sign, since it suggests higher risk of ocular complications (uveitis and keratitis). This is because the nasal tip, the cornea, and the iris all share the nasociliary branch of the trigeminus. Patients with nasal tip involvement have a 75% chance of ocular involvement (tearing, irritation, photophobia). Still, Hutchinson’s is a rather specific (82%), but poorly sensitive (57%), sign.

47 What is the jaw-jerk reflex?

A reflex that tests the integrity of sensory (afferent) and motor (efferent) components of the V. To test for it, place your index finger (or tongue depressor) over the patients’ chin, while asking them to keep their mouth slightly open. Then, gently tap the index finger with your reflex hammer. Abnormal responses include jaw deviation or brisk closure. Exaggerated masseteric contraction, often with clonus, suggests upper motor neuron pathology (i.e., above the trigeminal nucleus in the mid-pons). This occurs in 70% of pseudobulbar palsy patients (see below, question 65).

48 How do you test CN VII (facial nerve)?

Through the muscles of facial expression. Damage to CN VII causes inability to wrinkle the forehead, tightly close the eye (Fig. 19-2), or smile. It also causes facial asymmetry (i.e., ipsilateral widening of the palpebral fissure and sagging of the nasolabial fold).

Figure 19-2 A and B, Testing the strength of eyelid closure.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–15.)

49 What determines the difference between central and peripheral lesions of the VII?

It’s the difference in control of upper versus lower facial muscles: the upper being supplied by brain stem motor neurons (controlled by both sides of the cortex), whereas the lower are supplied by brain stem motor neurons (controlled by only one side of the cortex).

50 What are the signs of central lesions of the facial nerve?

Central lesions (i.e., involving either the cortical/upper motor neuron or its pyramidal tracts) result in contralateral weakness of only the lower half of the face. Thus, patients cannot smile (the face draws to the opposite side as they try to do so) or fully open the mouth, but can still wrinkle the forehead and close the eyes. This lower facial weakness only relates to intentional movements (i.e., those originating in the motor cortex). Emotional movements are typically spared, since they originate in the thalamus and frontal lobe.

51 What are the signs of peripheral lesions of the facial nerve?

Peripheral lesions (i.e., involving either the brain stem/lower motor neuron or the nerve itself) result instead in ipsilateral weakness of the entire hemiface. Thus, patients can neither smile, nor open the mouth, nor wrinkle the forehead. Eye closure also is impaired, and the ipsilateral palpebral fissure is wider. Bell’s phenomenon is present too. Weakness affects both volitional and emotional movements. Separating “central” from “peripheral” facial weakness is clinically very important.

52 Are there any other functions of CN VII that can be affected?

Yes. CN VII also controls the anterior two thirds of the tongue, the stapedius muscle, and the lacrimal gland. Hence, its lesions may impair taste, hearing, and tearing.

53 What about ptosis?

This is actually due to lesions of either CN III (which controls the levator palpebrae) or the sympathetic nerves (which control the Mueller muscle). Do not confuse levator palpebrae with orbicularis, which is instead supplied by the VII. Hence, lesions of VII will compromise corneal or glabellar reflexes, but not ptosis.

54 What is Bell’s palsy?

A peripheral mononeuropathy of CN VII. Since it involves the nerve directly (i.e., peripheral damage), Bell’s causes paralysis of both lower and upper facial muscles. Hence, there is ipsilateral inability to smile, open the mouth wide, or wrinkle the forehead. Bell’s also causes dysfunction in (1) taste (reduced in one half of the cases); (2) hearing (hyperacusis in 20–30%); and (3) tearing (usually increased, due to weakness of the orbicularis, but sometimes reduced as a result of lacrimal gland dysfunction). In 20% of cases, Bell’s also may present with facial hyperesthesia due to concomitant trigeminal involvement.

55 What are the causes of Bell’s palsy?

Peripheral paralysis of the VII has been described in infectious mononucleosis, herpes zoster, Guillain-Barré syndrome, parotid neoplasms, sarcoidosis, diabetes, or, occasionally, a cerebellopontine tumor. Yet, by definition Bell’s is idiopathic, in fact probably viral. This is not an uncommon condition, which even affected heartthrob George Clooney while still in high school.

56 What is Bell’s phenomenon?

It is the upward rotation of the eyeball, triggered by contraction of the ipsilateral orbicularis. This is usually invisible, since contraction of the orbicularis shuts the eye. Note that Bell’s phenomenon is a completely normal event, occurring in anyone as a result of synkinesis (from the Greek syn, together, and kinesis, motion), a fancy term for an involuntary motion that accompanies a voluntary one. Examples of synkinesis include the movement of a closed eye that accompanies that of the contralateral open eye or the movement of the arms as a result of leg motion during walking. What makes Bell’s phenomenon so unusual is that in patients with peripheral facial paralysis, the eyelid on the affected side is unable to close as a result of weakness of the orbicularis. Hence, the physiologic upward rotation of the eyeball becomes suddenly visible.

57 Who was Bell?

Sir Charles Bell (1774–1842) was a Scottish neurophysiologist and surgeon. He was not the same Dr. Bell who taught medicine in Edinburgh and made a big impression on young Conan Doyle (thus becoming the accidental model for Sherlock Holmes). That was Joseph Bell, a mesmerizing teacher who even tried his analytical powers on the mystery of Jack the Ripper, the Whitechapel killer of 1888. Charles Bell was instead the soft-spoken son of an Episcopal minister, who after being denied a position in Edinburgh, left for London in 1801. There, he made a name for himself as an artist, thanks to his “Essays on the Anatomy of Painting.” He also attended the military hospital of Haslar, where he had plenty of opportunities to treat the casualties of Wellington’s peninsular campaign. This triggered a lifelong fascination with war, and what it can do to human body and psyche. In 1815, while operating on Waterloo’s wounded, he made sketches and drawings that can still be viewed at the Royal College of Surgeons in Edinburgh. He eventually moved back to his native Scotland, but only after founding the Middlesex Hospital and Medical School. He is remembered not only for his palsy and phenomenon, but also for Bell’s law, which states that the anterior spinal roots carry motor fibers, whereas the posterior carry sensory fibers, including proprioception. He also named the “sense of position” as the “sixth sense”—eventually renamed proprioception by Sherrington.

58 What is the corneal reflex?

A bedside test of CN V and VII. To elicit it, ask patients to look away (so that they cannot see what the examiner is doing), and then use a cotton wisp to gently touch the edge of their cornea. The normal response is a protective reflexive blinking, which is bilateral (i.e., both eyes blink after stimulation of one) and requires the integrity of both V and VII: the ipsilateral V must be intact to receive sensation from the cornea, whereas both facial nerves must be intact to convey the motor response (hence the blinking of both eyes). This is a risky reflex since it can cause corneal damage.

59 What is the significance of an abnormal corneal reflex?

It depends on the response. If the ipsilateral eye does not blink after corneal stimulation (while the contralateral does), the most likely explanation is unilateral facial nerve dysfunction. Conversely, if both eyes fail to blink, the explanation is unilateral trigeminal nerve dysfunction, typically in the ipsilateral brain stem. An absent corneal reflex is especially helpful in cases of unilateral sensorineural hearing loss, since it suggests a lesion of the cerebellopontine angle—like an acoustic neurinoma. Yet, an abnormal corneal reflex is poorly sensitive, since it requires a tumor >2    cm. It is not specific either, being absent in 10% of normal elderly subjects.

60 How do you test CN VIII (acoustic/vestibular nerve)?

It depends on the function you want to test, vestibular or auditory:

61 How do we maintain balance?

Through a complex circuitry that requires intact positional sense input (vision, vestibular, and proprioceptive receptors/pathways), intact sensorimotor integration (cerebellum), and intact motor output (basal ganglia/corticospinal/pyramidal tract). If there is vestibular or proprioceptive damage, the patient will be able to compensate by relying on vision. Yet, darkness (or closed eyes) will remove this compensatory input and thus cause the patient to sway and possibly fall. Conversely, if there is intrinsic cerebellar disease, the patient will be unable to compensate even with open eyes. Hence, Romberg is not a cerebellar test since patients with cerebellar ataxia will not maintain balance even when they can see. It is instead a test for proprioceptive receptors and pathways. Thus, it will be positive in conditions of sensory ataxia (i.e., affecting [1] the sensory nerves (peripheral neuropathy) and/or [2] the dorsal columns of the spinal cord [tabes dorsalis]).

62 How do you perform the Romberg test?

Ask patients to first stand up with the heels together, eyes open, and arms by the side. Note any swaying. Then ask them to close their eyes. Observe for a full minute. Normal patients may sway a little more with the eyes closed, but will not fall. Vestibular patients will sway a lot more with the eyes closed but will not fall. Sensory ataxia patients will instead sway and fall with the eyes closed.

63 Who was Romberg?

Moritz Heinrich Romberg (1795–1873) was a well-respected Jewish physician who studied and practiced in Berlin, where he distinguished himself as “officer to the indigent” during the cholera epidemics of 1831 and 1837. A popular and beloved teacher, Romberg translated into German the works of Sir Charles Bell, and then wrote a three-volume textbook of neurologic diseases centered on the relation between altered structure and symptoms and signs. He reported his homonymous maneuver in an 1846 description of tabes dorsalis:

64 What is the anatomy of CN IX (glossopharyngeal) and CN X (vagus)? How do you test them?

Axons from several brain stem nuclei mingle together to emerge from the neuraxis through two separate nerves, named by early neuroanatomists as glossopharyngeal (IX) and vagal (X) (the vagus was so termed since, as a vagabond, it wanders long distances in the body). In reality, the origin of the two nerves is essentially identical. Function also is similar: motor control of the palate and pharynx (plus, for the IX, sensory supply to the pharynx and posterior third of the tongue). Hence, their clinical testing is not entirely separable. Since the brain stem nuclei of these two nerves receive bilateral innervation from the cortex, their dysfunction results from one of three possibilities: (1) bilateral damage to the cortex or pyramidal tracts (pseudobulbar palsy), (2) brain stem disease (lateral medullary syndrome), or (3) peripheral nerve lesions (jugular foramen syndrome). You can test IX and X by asking patients to say “ahhh” or “ehhh” (see Chapter 6, questions 53 and 54) while observing whether the velum of the palate rises symmetrically. Alternatively, you can use the gag and palatal reflexes. The latter is elicited by touching the patient’s palate with a cotton swab, which causes elevation of the soft palate and ipsilateral deviation of the uvula. The gag is instead triggered by touching the posterior wall of the pharynx (or alternatively, the tonsillar area or base of the tongue). It causes tongue retraction and elevation/constriction of the pharyngeal musculature. In unilateral CN IX and X paralysis, these reflexes result in deviation of the uvula toward the normal side. Lesions of the IX also will result in loss of taste in the posterior third of the tongue, and loss of pain and touch sensations in the same area plus the soft palate and pharyngeal walls. Conversely, unilateral paralysis of CN X’s recurrent laryngeal nerve will cause hoarseness. Bilateral paralysis will cause stridor (requiring tracheostomy).

65 What is pseudobulbar palsy?

The result of bilateral damage to the pyramidal tracts supplying the nuclei of CN IX and X. This is due to lacunar disease of the internal capsule, and presents with paralysis of both the palate and pharynx (i.e., loss of the gag reflex), but also the tongue, face, and chewing muscles. As a result, patients will be dysarthric, dysphagic, and unable to control facial expression. There also will be spasmodic (and inappropriate) laughing and crying.

66 How do you rule out the possibility of aspiration in patients with bilateral strokes?

By testing for pharyngeal sensation and water swallowing (the latter requires swallowing 50   mL of water in 5-mL aliquots without any choking, gagging, or coughing). Preservation of both functions makes aspiration unlikely; an abnormal water swallow test makes it likely.

67 And what about the gag reflex?

It has very little value in predicting the risk of aspiration because swallowing is controlled by different muscles than gagging. Moreover, gag can be absent in many elderly individuals without necessarily increasing the risk of aspiration.

68 What is the anatomy of CN XI (spinal accessory nerve)?

The accessory nucleus comprises motor neurons from both the brain stem and the upper five or six cervical segments (hence, its name). The spinal axons exit the cord and rise in the neck, where they join axons originating from the brain stem, finally emerging together through the foramen magnum as the spinal accessory nerve. This provides motor control to the trapezius and sternocleidomastoids (SCM). The function of the trapezius is to shrug the shoulders. Its weakness will impair shrugging ipsilaterally. Conversely, the SCM’s function is to thrust the head forward, tilt it toward the same side, and turn it toward the opposite side.

69 How do you test CN XI?

By first looking for asymmetry in the SCMs and trapezii. Then, by asking patients to shrug their shoulders against resistance (which tests the trapezius; Fig 19-3) or by having them first turn the head to one side and then attempt to turn it back against your resistance (which tests the SCM; Fig. 19-4). To test the right SCM, instruct the patient to turn the head toward the left, hold it there, and to not let you push it back. Then place your hand on the patient’s left cheek, and try to force the head toward the midline. When the right SCM is weak, pushing against your resistance will be impaired. Repeat the same for the opposite side. Note that atrophy of these muscles reflects a “lower” lesion (peripheral nerve or brain stem/cervical spine). Weakness, on the other hand, also may reflect cerebral hemispheric disease. The latter weakens the contralateral trapezius and the ipsilateral SCM (hence, the patient will be unable to turn the head toward the hemiparetic side). Disease of the accessory nucleus per se (like syringomyelia) weakens instead (and atrophies) both ipsilateral muscles. Hence, the patient will be unable to shrug ipsilaterally or turn the head toward the same side. This also occurs for peripheral nerve lesions.

Figure 19-3 Evaluating the spinal accessory nerve by testing the trapezius muscle.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–19.)

Figure 19-4 Evaluating the spinal accessory nerve by testing the sternocleidomastoid muscle.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–18.)

70 How do you test CN XII (hypoglossal nerve)?

By testing for movements of the tongue. These are controlled by the genioglossus, which is supplied by CN XII (running just sublingually in the neck—hence, its name). To detect weakness or atrophy, simply ask the patient to stick out the tongue. Hypoglossal weakness will deviate the tongue toward the weak side (because the intact genioglossus muscle pushes the tongue contralaterally without meeting any resistance by the weakened muscle). Weakness may result from (1) a contralateral hemispheric cerebral lesion (causing deviation of the tongue toward the hemiparetic side), (2) an ipsilateral brain stem lesion (such as the medial medullary syndrome), or (3) an ipsilateral peripheral nerve lesion. Noncerebral lesions (i.e., lower motor neuron disease) produce also tongue atrophy and fasciculations.

71 Which CNS areas participate in the creation/coordination of muscle movement?

72 What is the motor system made of?

Both pyramidal and extrapyramidal levels converge on the “final common pathway”: the lower motor neurons of the brain stem (cranial nerves) and spinal cord, whose axons go directly out to skeletal muscles. Cord neurons are clustered in nuclei or longitudinal segments of the anterior gray matter, extending one to four spinal segments (anterior horn cells).

73 What is the function of upper motor neurons?

To exert direct or indirect supranuclear control over the lower (and more caudal) motor neurons. Upper motor neurons reside mostly in the motor cortex, but also in the brain stem.

74 What are the manifestations of upper motor neuron dysfunction?

Given their function as modulator of lower motor neurons, disease of upper motor neurons (or their axons) results in muscles that are initially weak and flaccid, but eventually become spastic, hypertonic, and hyperreflexive. This is associated with pathologic reflexes (such as Babinski’s and Hoffmann) and induced clonus of ankle or wrist. Spasticity is especially prominent in the antigravity muscles (flexors of the upper extremities and extensors of the lower), with a clasp-knife character due to a variable degree of resistance to passive movements.

75 What are the manifestations of damage to lower motor neurons or their axons?

Weakness or paralysis of the involved muscles, with flaccidity, hypotonia, diminished or absent stretch reflexes, and eventually atrophy. There also are fasciculations (i.e., visible twitches of small groups of muscle fibers), but no pathologic reflexes (Babinski).

76 What are the main components of examination of the motor system?

(1) Atrophy, Hypertrophy, and Fasciculations

(2) Muscle Strength and Tone

(3) Muscle Percussion

(4) Reflexes

106 What is the Jendrassik maneuver?

A reinforcement technique that can help elicit deep tendon reflexes in apprehensive and tense patients, who, either voluntarily or unconsciously, may be bracing their muscles (Fig. 19-5). During the patellar reflex, have the patient hook together the flexed fingers of the two hands and then pull them apart at the moment the reflex is being elicited. Other re-enforcement maneuvers include having the patient look up at the ceiling, count numbers, read, or cough—all aimed at redirecting the patient’s attention, thus relaxing the tested muscles.

Figure 19-5 Jendrassik’s maneuver.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–38.)

113 What is the plantar reflex?

A cutaneous reflex (i.e., one triggered by skin stimulation) (Fig. 19-6). In normal subjects, a noxious stimulation of the sole leads to a plantar flexion of the toes, including the big toe. Conversely, in organic neurologic disease, there will be an extensor response (i.e., an upward movement of the great toe). Babinski used this finding to exclude hysterical weakness, which typically lacks “Babinski,” as this reflex soon came to be known. Note that when stroking the lateral aspect of the sole of the foot, the big toe may display one of the responses shown in Table 19-3 below.

Figure 19-6 A and B, Plantar reflex.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–46.)

130 What are the two components of the sensory system?

The noncortical and the cortical sensory systems. The first comprises peripheral nerves and their central pathways to the thalamus; the second one adds to these fibers the thalamic-cortical projections and the somatosensory cortex.

131 What are the simple sensations conveyed by the noncortical sensory system?

They are pain, temperature, touch, and vibration. Except for the latter, all originate in skin receptors. And, except for touch, all have well-defined pathways: either nociceptive or proprioceptive.

132 How are nociceptive sensations carried by the nervous system?

By slow and unmyelinated fibers. Nociceptive input (which includes pain, but also temperature and rough touch) synapses in the posterolateral columns of the spinal cord, crosses anteriorly to the opposite side of the cord, ascends in the spinothalamic tract, synapses in the thalamus, and finally reaches the sensory cortex. Loss of one nociceptive mode (such as temperature) is associated with loss of all other modalities conducted by the same tract (pain and rough touch).

133 How are proprioceptive sensations carried by the nervous system?

By fast and myelinated fibers. Proprioceptive input (which includes vibration, but also fine touch and joint position) travels in the posterior columns of the spinal cord, synapses in the gracile and cuneate nuclei of the upper cord, crosses to the opposite side in the medial lemniscus, synapses in the thalamus, and finally ends in the sensory cortex (part of the input also goes to the cerebellum). Loss of one proprioceptive modality (like joint position) is associated with loss of all other modalities conducted by the same tract (vibration and fine touch).

134 How do you describe excess of, or lack of, sensation?

As hyperesthesia (excessive, often unpleasant sensation) and anesthesia (lack of sensation), the latter being originally limited to touch, but now encompassing all simple sensations. Hypalgesia and analgesia describe reduction or absence of pain. Conversely, hyperpathia and allodynia describe, respectively, hypersensitivity to painful and tactile stimuli.

135 What is a dermatome?

It is a skin cutting in Greek; hence, the cutaneous area supplied by fibers from a single dorsal root. Damage to a nerve root (radiculopathy) typically causes sensory loss in just a dermatome. Still, only a few dermatomes are worth remembering, since their anesthesia can identify the damaged spinal segment—a useful finding for localizing the “level” of a cord lesion (i.e., the most caudal cord section that is still functioning):

136 Which dermatomeric rules should be kept in mind during the exam?

Three:

137 Which sensations should be tested during the neurologic exam?

138 How do you assess pain?

By using an open safety pin. Assess the patient’s ability to differentiate the pin’s sharp point from its blunt end. An abnormal response may include increased pain sensation (hyperesthesia), diminished pain sensation (hypesthesia), or absent pain sensation (anesthesia, or numbness). Remember to discard the safety pin after completion of the test.

139 How do you assess light touch?

By gently stroking the skin with a wisp of cotton or tissue (for diabetics use instead the Semmes-Weinstein monofilament). Patients should perceive touch as light and symmetric.

140 How do you assess temperature?

By touching the patient’s skin with two test tubes, one filled with warm water and the other with cold water. Alternatively, ask patients to discriminate between the cold handle of a tuning fork and the warm feel of the examiner’s finger. Compare sides to each other and also to a benchmark, like the patient’s own forehead (assuming sensation there is normal).

141 What is the clinical significance of nociceptive loss?

Loss of pain, touch, or temperature (i.e., nociception) points to a sensory syndrome, that is, one caused by damage of any components of the sensory pathways: peripheral nerve (peripheral neuropathy), dorsal root (radiculopathy), spinal segment (spinal cord lesion), ascending pathway (lateral medullary infarction), thalamus, or cortex (cerebral hemispheric syndrome).

142 What are the causes of hyperpathia and allodynia?

Increased sensitivity to painful (hyperpathia) or tactile stimuli (allodynia) occurs in peripheral neuropathy, brain stem infarction, and thalamic strokes. It provides no help with localization.

143 How do you assess vibration?

By using a 128-Hz tuning fork (Fig. 19-7). To do so:

Figure 19-7 Vibration testing.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–51.)

A normal 40-year-old should perceive vibrations for at least 11    seconds when the tuning fork is applied to the malleolus, and for 15 seconds when it is applied to the ulnar styloid. Aging shortens these times, with an average loss of 2 seconds per decade. Note that applying the tuning fork to a bony prominence is only aimed at improving transmission of the input. Applying it directly to the soft tissue would still assess vibration.

144 Which vibration frequencies are well perceived by humans?

Those between 200–300   Hz. Frequencies <100   Hz are instead poorly felt.

145 What is the difference between a nociceptive and a proprioceptive loss?

In contrast to nociception, vibration (i.e., proprioception) can be selectively impaired in spinal cord/peripheral nerves’ diseases while remaining instead preserved in cerebral lesions.

146 What is the role of an intact sense of position?

It allows us to “sense” joint and limb position, even though our eyes might be closed—like a Global Positioning System (GPS).

147 How do you test for position sensation?

First of all, ask patients to shut their eyes. Then, use your thumb and forefinger to grasp the lateral aspect of their great toe (or index finger) (Fig. 19-8). Move it up or down, while inquiring about direction of movement. Patients with intact proprioception should detect joint movements of as little as 1–2 degrees, even though 10% of the time they might be wrong in describing direction, since motion is more easily perceived than direction.

Figure 19-8 Testing of proprioception. A, With fingers. B, With toes.

(From Swartz MH: Textbook of Physical Diagnosis: History and Examination, 4th ed. Philadelphia, WB Saunders, 2002, Fig. 20–52.)

Alternatively, touch the index finger of the patients’ outstretched arms; then ask them to close their eyes, let the arm drop by the side, and find again its previous target with the eyes closed. Since proprioception provides a sense of position that is independent of vision, its loss will cause imbalance—especially when vision cannot help (because of closed eyes or darkness).

148 Which conditions are associated with proprioceptive loss?

Those that damage (1) the afferent pathways (diabetic polyneuropathy), (2) the dorsal columns of the spinal cord (tabes dorsalis, B₁₂ deficiency, or multiple sclerosis), or (3) the hemisphere. Conversely, all of these conditions spare pain and temperature.

149 How does the sense of joint position differ from other sensory modalities?

Touch, pain, temperature, and vibration are primary sensory modalities. Hence, they can occur despite cortical damage. Conversely, upward or downward motions of the patient’s limb require cortical integration of both recognition and direction of movement. Hence, they demand a more complex and discriminative cortical sensory function (i.e., an intact contralateral cerebral cortex). In return, this provides a GPS-like perception of joint motion and limb position, even when the eyes are closed. Patients with hemispheric cerebral disease may lose this discriminative sensory function even though they may still maintain the simple sensations of touch, pain, temperature, and vibration.

150 How do you assess the discriminative sensory function?

Through tests that assess the cortical sensory system (i.e., the somatosensory cortex and its central connections). These structures allow for higher integration and processing, such as: (1) detection of position and movement of extremities in space (kinesthetic sensation); (2) recognition of size and shape of objects (stereognosis); (3) tactile sensations of written patterns on the skin (graphesthesia); and (4) tactile localization and tactile discrimination on the same side or both sides of the body (two-point discrimination, touch localization and testing for bilateral simultaneous tactile stimulation). All these maneuvers require closed eyes and intact simple sensations (especially touch); otherwise, input to the cortex will be lacking. Abnormal response to any of these tests points to a lesion of either the contralateral sensory cortex (i.e., the posterior parietal lobe) or the thalamoparietal projections. These compromise proprioception, vibration, and fine touch in the distal extremities, but not over the face and trunk. Simple sensations are preserved. Conversely, lesions of the anterior parietal lobe (or deeper white matter) impair simple sensations of the contralateral hemisoma (trunk, limbs, and face). Since this dense sensory loss resembles that of thalamic lesions, it is referred to as pseudothalamic syndrome.

151 What is two-point discrimination (2PD)? How do you assess it?

2PD is the ability to distinguish two discrete and simultaneous stimuli of the skin. It is tested with the two needles of either a compass or caliper. By varying needles’ distances, one can determine a two-point discrimination threshold. In normal subjects, 2PD is 4–7   cm on the body surface, 8–15   mm on the palm, and 3–6   mm on the fingertips.

152 What is touch localization?

It is the ability to point out with one finger where a touch stimulus was applied. Accuracy in touch localization requires the integrity of the sensory cortex and thalamoparietal projections.

153 What is stereognosis? How do you assess it?

From the Greek stereo (solid) and gnosis (recognition), stereognosis is the ability to identify an object by palpation. Astereognosis is the inability to recognize shape, form, and size of the perceived object, despite normal primary sensation (i.e., touch, pain, temperature, and vibration). To test for it, place some familiar item (coin, key, safety pin) in the patients’ hands while their eyes are closed, and then ask them to identify the object. Lesions of the contralateral sensory cortex (or thalamoparietal pathways) will make this difficult.

154 What is graphesthesia? How do you assess it?

From the Greek graphe (writing) and esteshia (sensing), graphesthesia is the ability to recognize letters or figures drawn on the palm of the hand. This requires intact primary sensory modalities and discriminative (i.e., cortical) function. Hence, its impairment (agraphesthesia) reflects lesions of the right parietal region. To test it, ask patients to identify a number (or letter) you have written on their palm with either your finger or a blunt object (key or back of a pen). The letter/number should be larger than 6   cm, even though fingertips can recognize symbols that are only 1   cm in height. Always repeat the evaluation on the other hand, by drawing a different letter or number.

155 What is bilateral simultaneous tactile stimulation?

The ability to recognize that two sides of your body are being simultaneously touched.

156 What is extinction? How do you test for it?

Extinction is the inability to recognize being touched on one side of the body. To test for it, have patients sit on the edge of the table with their closed eyes. Touch them in one particular place of the trunk or legs, and then ask them to open their eyes and point to where they have been touched. Repeat this by touching them in two places on opposite sides of the body, simultaneously. Then ask them to point to the areas where they have been touched. Normal subjects will point to both areas, whereas patients with extinction will not do so. Instead, they will point to one area only.

157 What is the clinical significance of a sensory loss?

It depends on the area and the extent of the deficit. Sensory loss to only a portion of a limb suggests damage to either a peripheral nerve, or a plexus, or a spinal root. Conversely, sensory loss to a larger part of a limb (or even the trunk) carries a wider differential diagnosis. A unilateral deficit suggests brain stem, thalamic, or cortical lesions, whereas a bilateral one suggests polyneuropathy or spinal disease. Also, pay attention to whether the deficit is associated with (1) a sensory level (which suggests a complete spinal cord lesion—typically presenting with infra-level weakness, urinary retention, and loss of all simple sensations); (2) a sensory dissociation (which suggests an incomplete spinal cord lesion); or (3) a sensory loss on the face (suggesting a supraspinal lesion, involving either the brain stem, thalamus, or cerebral hemisphere).

158 What are the functions of the cerebellar system?

To coordinate proprioceptive input and to work with eyes and ears (i.e., vestibularis system) to provide a sense of position in space.

159 Which clinical findings suggest damage to the cerebellum and its tracts?

(1) Ataxia, (2) atonia (or hypotonia), (3) asthenia, (4) nystagmus, and (5) dysarthria. Except for atonia and asthenia (which can occur in other lesions of the nervous system), all other manifestations are very typical, since cerebellar diseases interfere with smooth and coordinated movements of arms and legs (ataxia), eyes (nystagmus), speech (dysarthria), and stance/gait. Hence, the tremulous, jerky, and clumsy motions of these patients. For example:

160 Are cerebellar manifestations ipsilateral or contralateral to the site of lesion?

Ipsilateral.

161 What is ataxia?

The inability to coordinate voluntary movements into smooth and appropriately directed actions (from the Greek word for anarchy).

162 How do you test for ataxia?

By observing the patient’s gait and by carrying out the following maneuvers, the first two for the upper extremities and the third for the lower. Note, that nondominant hands or upper motor neuron weakness may impair response to these tests, without implying cerebellar dysfunction.

163 What is intention tremor?

An oscillating tremor that accelerates in pace on approaching the target during intentional movements—for example, in a finger-to-nose maneuver. Also referred to as “kinetic tremor.”

164 How do patients with cerebellar deficits walk? How do they stand?

They walk with an ataxic gait: legs spread wide apart, as in a staggering and “drunk” fashion. Especially difficult is tandem walking (i.e., with one foot directly in front of the other [heel-to-toe]), as if on an imaginary tight rope (hence, its use for alcohol intoxication testing). Patients with cerebellar deficits have problems with stance, too, which is unbalanced, incoordinated, and with tendency to sway or fall to one side—especially when unassisted by vision (Romberg, see also Chapter 1, questions 90–94).

165 How common is ataxic gait in cerebellar disease?

Very common. In fact, the most common of all cerebellar manifestations.

166 How is the muscle tone of cebellar patients?

Profoundly reduced. This results in wide swings of the limbs when first raised and then allowed to spontaneously fall. It also results in pendular knee jerks, defined as three or more swings produced by a single blow to the patellar tendon.

167 What is nystagmus?

An involuntary to-and-fro oscillation of the eyes (from the Greek nystagmos, nodding). Although usually detected while testing the cranial nerves responsible for eye movements (i.e., III, IV, and VI), nystagmus is not actually produced by nerve lesions per se, but rather by damage to the brain/brain stem mechanisms responsible for coordinating eye movements. Hence, it is a sign of internuclear ophthalmoplegia, cerebellar lesions, or vestibular disease.

168 Is the direction of nystagmus diagnostically helpful?

Yes and no. In cerebellar diseases, 75% of nystagmus is horizontal (i.e., back-and-forth shaking, elicited by lateral gaze); 15% is rotatory (clockwise/counterclockwise twisting or rotating); and 10% is vertical (up-and-down bouncing of the eye). Yet horizontal nystagmus also can occur in peripheral vestibular disease. Hence, it is not specific.

169 What is optokinetic nystagmus?

The one elicited by looking at moving visual stimuli. A physiologic response in train passengers who try to fixate objects that are moving rapidly across their field of vision (railroad nystagmus).

170 How is the speech of cerebellar disease?

Dysarthric. In other words: slow, irregular, slurred, and with sudden changes in tempo, volume, and pitch (scanning or staccato speech), and yet still capable of conveying meaningful and intelligible words. This is due to discoordination of the muscles of phonation. In contrast to aphasics, patients with cerebellar deficits have no problems understanding or making themselves understood (see also questions 19–27).

171 How common is dysarthria in cerebellar disease?

It is the least common of all manifestations, usually requiring left-sided cerebellar disease.

172 What is the control of walking? How is gait assessed?

Walking is a highly complex action that requires integration of motor, cerebellar, vestibular, sensory, visual, and other systems. Hence, almost any abnormality in the nervous system will affect a patient’s gait. To evaluate it, ask the patient to first walk normally, then on heels and toes, and finally to perform tandem walking. This simple test will allow you to detect many neurologic deficits, including weakness, incoordination, and dizziness (see also Chapter 1, question 71).

173 How do you best evaluate patients with neurologic symptoms?

By first localizing the lesion. Identification of the cause comes only after accurate determination of the lesion site, since anatomic definition narrows the differential diagnosis.

174 How can neuroanatomy be applied clinically, given the great complexity of the CNS?

By thinking in terms of “regions.” For clinical purpose, the most important aspects of neuroanatomy comprise only a few regions, with finer detail left to the specialist. From distal to proximal, regions to localize lesions in are (1) muscle, (2) neuromuscular junction, (3) peripheral nerve, (4) root, (5) spinal cord, (6) brain stem, (7) cerebellum, and (8) cerebral hemisphere.

175 What is the peripheral nervous system (PNS) made of?

(1) The anterior horn cells (in the spinal cord and brain stem); (2) the nerve roots; (3) the peripheral nerves; (4) the neuromuscular junctions; and (5) the muscles. Damage to any of these structures (or to the upper motor neuron) will cause neuromuscular weakness. Depending on which structure is affected, there also may be other symptoms.

176 What are the causes of neuromuscular weakness/paralysis?

Central or peripheral lesions. These include diseases of the (1) upper motor neuron, (2) lower motor neuron, (3) neuromuscular junction, and (4) muscle. The first two are the most common.

177 What are the manifestations of upper motor neuron disease?

Weakness and loss of dexterity, plus increased muscle tone (spasticity), brisk reflexes (hyperreflexia), pathologic reflexes (Babinski) and, occasionally, clonus. In central weakness/paralysis, there is neither atrophy nor fasciculations, but possible sensory changes. Note that distribution of weakness always points to the side of central lesions, whereas associated neurologic findings indicate the lesion level. For example, hemiparesis points to a contralateral central lesion, whereas the associated findings would identify its level: left cerebral hemisphere in patients with aphasia, left brain stem in patients with left sixth nerve palsy.

178 What is dexterity?

The ability to gracefully coordinate movements. More specifically, the skillful use of hands. In this context, dexterity is a motor skill.

179 How do you separate upper from lower motor neuron disease?

Both cause a weakness that is typically confined to the more peripheral (i.e., distal) muscles and that can be either symmetric or asymmetric. Thus, except for hemiparesis (which is a feature of upper motor neuron disease), localization of weakness will not separate upper from lower disease. Associated findings, on the other hand, will do so, especially muscle tone, reflexes, fasciculations, and atrophy. In this regard, lower motor neuron disease weakens or paralyzes muscles, whereas upper motor neuron disease impairs movements.

180 What are the manifestations of lower motor neuron disease?

Muscle weakness with decreased tone (hypotonia or flaccidity), reduced or absent reflexes (hypoflexia or areflexia), and frequent sensory changes (typically following the distribution of spinal segments or peripheral nerves). In time, the weak muscles of patients with peripheral weakness/paralysis undergo atrophy, and fasciculations appear.

181 Describe ways to localize peripheral weakness/paralysis

In lower motor neuron disease, the weakness is always ipsilateral to the lesion. Hence, the challenge is not to localize the damage, but to determine its level—for example, whether the weakness is due to a lesion of the nerve (peripheral neuropathy), spinal segment (radiculopathy), or combination thereof (plexopathy). For clinical examples, see Table 19-4.

182 What about combined upper and lower motor neuron disease?

A combined peripheral and central weakness/paralysis points to a spinal cord lesion, and thus narrows diagnosis to only two entities: myelopathy and amyotrophic lateral sclerosis (ALS).

183 What is myelopathy? What are its manifestations?

Myelopathy is a spinal cord lesion produced by trauma, tumor, or disc disease. It can affect any section of the spinal cord (cervical, thoracic, or lumbosacral myelopathy) and is typically characterized by a discrete level, with motor, sensory, and reflex abnormalities both at and below it. Weakness, for example, is peripheral at the level of the lesion (i.e., flaccid, with atrophy and fasciculations), but central just below it (i.e., spastic and hyperreflexic). Myelopathy patients also have concomitant sensory findings, which are never present in ALS.

184 What is ALS?

A degenerative disease of pyramidal tracts and anterior horn cells. Hence, its presentation includes both the hyperreflexia of upper motor neuron disease (plus Babinski in 50% of cases) and the atrophy and fasciculations of peripheral paralysis. Sensation is typically intact (a distinguishing feature from myelopathy). In decreasing order of frequency, onset of symptoms involves the arms (44%), legs (37%), and bulbar muscles (19%). The latter include tongue fasciculations and difficulty with swallowing and phonating.

185 What are the symptoms of muscle disease?

The most common is symmetric proximal weakness, present in more than 90% of myopathic patients. Sensory loss is typically absent, although there may be muscle pain, dysphagia, and weakness of neck muscles. Hence, always ask the following questions:

186 After eliciting myopathic symptoms, which findings can you expect on exam?

Proximal symmetric weakness without sensory loss. Tone is normal or mildly decreased, reflexes also are normal or mildly decreased, and atrophy is seldom significant unless the process is advanced. Similarly, there are no fasciculations, although there may be myotonia.

187 What are the symptoms of neuromuscular junction (NMJ) disease?

188 After eliciting NMJ symptoms, which findings can you expect on exam?

Proximal symmetric weakness without sensory loss. With repetitive testing, muscles weaken, but after a minute of rest they regain strength. Similarly, sustained muscular activity (such as upward gaze) leads to fatigability and progressive weakness (ptosis). Tone, reflexes, and muscle bulk are normal. There also is neither atrophy nor fasciculations nor sensory changes. There may be, however, ptosis or diplopia.

189 What are the symptoms of peripheral neuropathy?

The typical is distal and often asymmetric weakness, associated with sensory changes. Atrophy and fasciculations also may appear. Hence, ask the following:

190 After eliciting neuropathic symptoms, which findings can you expect on exam?

Distal, often asymmetric weakness with atrophy, fasciculations, and sensory loss, such as decreased pinprick, vibration, and occasionally position sense. Tone is normal or decreased, and reflexes diminished. There also may be trophic changes, like loss of hair and nails and smooth, shiny skin.

191 What are the symptoms of root diseases (radiculopathies)?

In addition to pain (the hallmark), radiculopathies have features similar to peripheral neuropathies (i.e., denervation [weakness, atrophy, and fasciculations] with sensory loss). Weakness may be proximal (the most common radiculopathies in the arms involve C5–C6 muscles, which are indeed proximal) or distal (the most common radiculopathies in the legs involve L5–S1 muscles, which are indeed distal). Only pain is unique to root disease and absent in peripheral neuropathy. Pain is severe, often sharp, hot or electric, and commonly radiating down an arm or leg.

192 After eliciting radiculopathic symptoms, which findings can you expect on exam?

Weakness in one group of muscles, such as C5–C6 in the arm or L5–S1 in the legs—sometimes with atrophy and fasciculations. Tone is normal or decreased, and muscular reflexes diminished or absent. Sensory loss has dermatomal distribution. There may be exquisite pain after maneuvers that stretch the root, such as straight-leg raising.

193 What is the presentation of spinal cord disease (SCD)?

The classic one is a triad: (1) sensory level (occurring as a band of sensory change around the chest or abdomen or as a sharp level below which all sensation is lost [sensory level is the hallmark of SCD]); (2) distal, usually symmetric, weakness; and (3) bowel and bladder changes. Hence, questions about SCD should always focus on the following symptoms and signs:

194 After eliciting SCD symptoms, which findings can you expect on exam?

Distal weakness, usually worse in the legs than in the arms, and usually worse in the extensors (i.e., dorsiflexors of the feet and extensors of the wrists and fingers) than in the flexors. Tone is increased, reflexes are brisk, and the extensor plantar reflex (i.e., Babinski) is usually present. A sensory level is typically found, below which all sensory modalities are diminished.

195 What are the symptoms of brain stem disease?

Since the brain stem is basically a spinal cord with cranial nerves stuck in it, brain stem disease is uniquely characterized by cranial nerve abnormalities. Symptoms will therefore consist of a combination of long-tract findings (such as weakness due to pyramidal tract lesions, and numbness due to spinothalamic tract compromission) plus cranial nerve findings. Because the long tracts have crossed (decussated), weakness and numbness will not be in the distribution of a level, but rather present as hemiparesis or hemianesthesia. In addition, damage to one side of the brain stem will cause ipsilateral manifestations for the cranial nerves, and contralateral manifestations for the long tracts. These crossed symptoms are another hallmark of brain stem disease—for example, weakness of one side of the face and the opposite side of the body. Note that CN lesions commonly cause the big D’s: diplopia (III, IV, or VI), decreased sensation in the face (V), decreased strength in the face (VII), dizziness and deafness (VIII), and dysarthria and dysphagia (IX, X, and XII). Hence, history should focus on:

196 After eliciting brain stem symptoms, which findings can you expect on exam?

A combination of cranial nerve and long-tract abnormalities.

197 What are the symptoms of cerebellar disease?

Mostly clumsiness and lack of coordination. Since the cerebellum is responsible for smoothing voluntary movements, any impairment will produce abnormalities in the rate and rhythm of motion. Hence, focus on incoordination in the legs and arms, such as:

198 After eliciting cerebellar symptoms, which findings can you expect on exam?

A staggering gait and difficulty with tandem walking. Also, when sliding a heel down a shin, patients may waver it unsteadily. Arms may show tremor and hesitation when the patient tries to touch his or her own nose, the examiner’s finger, or another target. Finally, there may be difficulty performing rapidly alternating movements in the limbs, resulting in irregular rate and rhythm.

199 What are the symptoms of cerebral hemispheric disease (CHD)?

Disease of the brain itself may cause a variety of symptoms: (1) mental status changes and high-function disturbances such as aphasia, (2) hemiparesis, (3) hemianesthesia, (4) visual field defects, (5) involuntary movements, and (6) seizures. Questions to ask include:

200 After eliciting CHD symptoms, which findings can you expect on exam?

Aphasia or other mental status changes, plus hemiparesis, hemianesthesia, or visual field cuts.

201 What is apraxia? How can you test for it?

Apraxia is the inability to perform upon command simple or complex motor tasks, despite intact motor, sensory, and language functions. It is tested by asking the patient to “stick out the tongue” or “show how to use a comb or a toothbrush.” Apraxic patients may be unable to perform these tasks.

202 What is the cause of apraxia?

A disruption of the pathways responsible for skilled motor tasks. These begin in Wernicke’s, connect to the prefrontal area via the arcuate fibers, then go to the left motor cortex (right side of the body), and finally cross the corpus callosum into the right motor cortex (left side of the body). Any interruption eliminates the “how-to” information for simple or complex motor tasks.

203 What are meningeal signs?

They are signs of meningeal irritation (i.e., meningismus), produced by hemorrhage, tumor, or inflammation. They are primarily three: (1) nuchal rigidity, (2) Kernig’s sign, and (3) Brudzinski’s sign.

204 What is their mechanism?

A reflex, and thus involuntary, attempt by the patient to prevent stretching of nerves that pass through inflamed meninges. Hence, they represent a defensive mechanism.

205 What is nuchal rigidity (or stiffness)?

It is the involuntary resistance offered by a patient in response to the physician’s attempt to flex the neck. It indicates diffuse irritation of the cervical roots from meningeal inflammation. To test for it, place your hand under the patient’s head and gently try to flex the neck. In the awake patient, this can often be elicited by simply asking the patient to touch his/her chest with the chin (which triggers pain). Sometimes, nuchal rigidity can be so pronounced as to result in marked extension of the patient’s entire body, to the point of resting supine on neck and heels (“opisthotonus,” from the Greek opisthen, toward the back, and tonos, tension).

206 What is Kernig’s sign?

The involuntary resistance offered by patients to passive extension of the knee from a position in which hips and knees are flexed. Very much like the straight-leg raising of sciatica. To test for it, flex the hip and knee on one side while the patient is supine. Then extend the knee with the hip still flexed. Hamstring spasm results in pain in the posterior thigh muscle and difficulty with knee extension. In severe meningeal inflammation, the opposite knee may flex during testing.

207 What is Brudzinski’s sign?

The reflex flexion of the hips and knees toward the chest in patients whose necks are being flexed. As a result, the patient assumes a fetal position.

208 How clinically useful are these signs in the detection of meningitis?

It depends on the underlying process: