Diagnosis of Neurological Disease

Published on 12/04/2015 by admin

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Chapter 1 Diagnosis of Neurological Disease

Robert B. Daroff, Gerald M. Fenichel, Joseph Jankovic, John C. Mazziotta

Chapter Outline

Neurological Interview

Chief Complaint

History of Present Illness

Review of Patient-Specific Information

Review of Systems
History of Previous Illnesses
Family History
Social History

Examination

Neurological Examination
General Physical Examination

Assessment of the Cause of the Patient’s Symptoms

Anatomical Localization
Differential Diagnosis
Laboratory Investigations

Management of Neurological Disorders

Experienced Neurologist’s Approach to the Diagnosis of Common Neurological Problems

Neurological diagnosis is sometimes easy, sometimes quite challenging, and specialized skills are required. If a patient shuffles into the physician’s office, demonstrating a pill-rolling tremor of the hands and loss of facial expression, Parkinson disease comes readily to mind. Although making such a “spot diagnosis” can be very satisfying, it is important to consider that this clinical presentation may have another cause entirely—such as neuroleptic-induced parkinsonism—or that the patient may be seeking help for a totally different neurological problem. Therefore, an evaluation of the whole problem is always necessary.

In all disciplines of medicine, the history of symptoms and clinical examination of the patient are key to achieving an accurate diagnosis. This is particularly true in neurology. Standard practice in neurology is to record the patient’s chief complaint and the history of symptom development, followed by the history of illnesses and previous surgical procedures, the family history, personal and social history, and a review of any clinical features involving the main body systems. From these data, one formulates a hypothesis to explain the patient’s illness. The neurologist then performs a neurological examination, which should support the hypothesis generated from the patient’s history. Based on a combination of the history and physical findings, one proceeds with the differential diagnosis to generate a list of possible causes of the patient’s clinical features.

What is unique to neurology is the emphasis on localization and phenomenology. When a patient presents to an internist or surgeon with abdominal or chest symptoms, the localization is practically established by the symptoms, and the etiology then becomes the primary concern. In clinical neurological practice, however, a patient with a weak hand may have a lesion localized to muscles, neuromuscular junctions, nerves in the upper limb, brachial plexus, spinal cord, or brain. The formal neurological examination allows localization of the offending lesion. Similarly, a neurologist skilled in recognizing phenomenology should be able to differentiate between tremor and stereotypy, both rhythmical movements; among tics, myoclonus, and chorea, all jerk-like movements; and among other rhythmical and jerk-like movement disorders, such as seen in dystonia. In general, the history provides the best clues to etiology, and the examination is essential for localization and appropriate disease categorization—all critical for proper diagnosis and treatment.

This diagnostic process consists of a series of steps, as depicted in Fig. 1.1. Although standard teaching is that the patient should be allowed to provide the history in his or her own words, the process also involves active questioning of the patient to elicit pertinent information. At each step, the neurologist should consider the possible anatomical localizations and particularly the etiology of the symptoms (see Fig. 1.1). From the patient’s chief complaint and a detailed history, an astute neurologist can derive clues that lead first to a hypothesis about the location and then to a hypothesis about the etiology of the neurological lesion. From these hypotheses, the experienced neurologist can predict what neurological abnormalities should be present and what should be absent, thereby allowing confirmation of the site of the dysfunction. Alternatively, analysis of the history may suggest two or more possible anatomical locations and diseases, each with a different predicted constellation of neurological signs. The findings on neurological examination can be used to determine which of these various possibilities is the most likely. To achieve a diagnosis, the neurologist needs to have a good knowledge of not only the anatomy, physiology, and biochemistry of the nervous system but also of the clinical features and pathology of the neurological diseases.

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Fig. 1.1 The diagnostic path is illustrated as a series of steps in which the neurologist collects data (Task) with the objective of providing information on the anatomical localization and nature of the disease process (Goal).

Neurological Interview

The neurologist may be an intimidating figure for some patients. To add to the stress of the neurological interview and examination, the patient may already have a preconceived notion that the disease causing the symptoms may be progressively disabling and possibly life threatening. Because of this background, the neurologist should present an empathetic demeanor and do everything possible to put the patient at ease. It is important for the physician to introduce himself or herself to the patient and exchange social pleasantries before leaping into the interview. A few opening questions can break the ice: “Who is your doctor, and who would you like me to write to?” “What type of work have you done most of your life?” “How old are you?” “Are you right- or left-handed?” After this, it is easier to ask, “How can I be of service?” “What brings you to see me?” or “What is bothering you the most?” Such questions establish the physician’s role in the relationship and encourage the patient to volunteer an initial history. At a follow-up visit, it often is helpful to start with more personalized questions: “How have you been?” “Have there been any changes in your condition since your last visit?”

Another technique is to begin by asking, “How can I help you?” This establishes that the doctor is there to provide a service and allows patients to express their expectations for the consultation. It is important for the physician to get a sense of the patient’s expectations from the visit. Usually the patient wants the doctor to find or confirm the diagnosis and cure the disease. Sometimes the patient comes hoping that something is not present (“Please tell me my headaches are not caused by a brain tumor!”). Sometimes the patient claims that other doctors “never told me anything” (which may sometimes be true, although in most cases the patient did not hear or did not like what was said).

Chief Complaint

The chief complaint (or the several main complaints) is the usual starting point of the diagnostic process. For example, the patient may present with the triad of complaints of headache, clumsiness, and double vision. The complaints serve to focus attention on the questions to be addressed in taking the history and provide the first clue to the anatomy and etiology of the underlying disease. In this case, the neurologist would be concerned that the patient may have a tumor in the posterior fossa affecting the cerebellum and brainstem.

The mode of onset is critically important in investigating the etiology. For example, a sudden onset usually indicates a stroke in the vertebrobasilar arterial system. A course characterized by exacerbations and remissions may suggest multiple sclerosis, whereas a slowly progressive course points to a neoplasm. Paroxysmal episodes suggest the possibility of seizures, migraines, or some form of paroxysmal dyskinesia, ataxia, or periodic paralysis.

History of Present Illness

A critical aspect of the information obtained from this portion of the interview has to do with establishing the temporal-severity profile of each symptom reported by the patient. Such information allows the neurologist to categorize the patient’s problems based on the profile. For example, a patient who reports the gradual onset of headache and slowly progressive weakness of one side of the body over weeks to months could be describing the growth of a space-occupying lesion in a cerebral hemisphere. The same symptoms occurring rapidly, in minutes or seconds, with maximal severity from the onset, might be the result of a hemorrhage in a cerebral hemisphere. The symptoms and their severity may be equal at the time of the interview, but the temporal-severity profile leads to totally different hypotheses about the etiology.

Often the patient will give a very clear history of the temporal development of the complaints and will specify the location and severity of the symptoms and the current level of disability. In some instances, however, the patient, particularly if elderly, will provide a tangential account and insist on telling what other doctors did or said, rather than relating specific signs and symptoms. Direct questioning often is needed to clarify the symptoms, but it is important not to “lead” the patient. Patients frequently are all too ready to give a positive response to an authority figure, even if it is patently incorrect. It is important to consider whether the patient is reliable. Reliability depends on the patient’s intelligence, memory, language function, and educational and social status and on the presence of secondary gain issues, such as a disability claim or pending lawsuit.

The clinician should suspect a somatoform or psychogenic disorder in any patient who claims to have symptoms that started suddenly, particularly after a traumatic event, manifested by clinical features that are incongrous with an organic disorder, or with involvement of multiple organ systems. The diagnosis of a psychogenic disorder is based not only on the exclusion of organic causes but also on positive criteria.Getting information from an observer other than the patient is important for characterizing many neurological conditions such as seizures and dementia. Taking a history from a child is complicated by shyness with strangers, a different sense of time, and a limited vocabulary. In children, the history is always the composite perceptions of the child and the parent.

Patients and physicians may use the same word to mean very different things. If the physician accepts a given word at face value without ensuring that the patient’s use of the word matches the physician’s, misinterpretation may lead to misdiagnosis. For instance, patients often describe a limb as being “numb” when it is actually paralyzed. Patients often use the term “dizziness” to refer to lightheadedness, confusion, or weakness, rather than vertigo as the physician would expect. Although a patient may describe vision as being “blurred,” further questioning may reveal diplopia. “Blackouts” may indicate loss of consciousness, loss of vision, or simply confusion. “Pounding” or “throbbing” headaches are not necessarily pulsating.

The neurologist must understand fully the nature, onset, duration, and progression of each sign or symptom and the temporal relationship of one finding to another. Are the symptoms getting better, staying the same, or getting worse? What relieves them, what has no effect, and what makes them worse? In infants and young children, the temporal sequence also includes the timing of developmental milestones.

An example may clarify how the history leads to diagnosis: A 28-year-old woman presents with a 10-year history of recurrent headaches associated with her menses. The unilateral quality of pain in some attacks and the association of flashing lights, nausea, and vomiting together point to a diagnosis of migraine. On the other hand, in the same patient, a progressively worsening headache on wakening, new-onset seizures, and a developing hemiparesis suggest an intracranial space-occupying lesion. Both the absence of expected features and the presence of unexpected features may assist in the diagnosis. A patient with numbness of the feet may have a peripheral neuropathy, but the presence of backache combined with loss of sphincter control suggests that a spinal cord or cauda equina lesion is more likely. Patients may arrive for a neurological consultation with a folder of results of previous laboratory tests and neuroimaging studies. They often dwell on these test results and their interpretation by other physicians. The opinions of other doctors should never be accepted without question, however, because they may have been wrong! The careful neurologist takes a new history and makes a new assessment of the problem.

The history of how the patient or caregiver responded to the signs and symptoms may be important. A pattern of overreaction may be of help in evaluating the significance of the complaints. Nevertheless, a night visit to the emergency department for a new-onset headache should not be dismissed without investigation. Conversely, the child who was not brought to the hospital despite hours of seizures is likely to be the victim of child abuse, or at least of neglect.

Review of Patient-Specific Information

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