The neurological diagnostic consultation

Published on 12/04/2015 by admin

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1 The neurological diagnostic consultation

Introduction

The neurological examination is really no different to any other medical examination except that it appears more impressive for the novice. There is a formula that allows maximal yield from the process.

This chapter will offer discussion of more than just the examination and will cover how to conduct the neurological diagnostic consultation.

History

The most important component of the neurological consultation is a detailed history. Many neurological illnesses lack absolute diagnostic tests and may rely exclusively on the history. It follows that the history must be as comprehensive and searching as possible.

While it is important to listen to what the patient offers as the main presenting complaint, it is equally important not to take this at ‘face value’. Patients can believe all bad headaches are migraines, all disequilibrium is vertigo and all loss of consciousness is a seizure. Nothing could be further from the truth. Patients should be advised to avoid jargon and diagnostic terminology, as far as possible. Severe tension-type headache is far more common than is migraine; loss of balance due to upper respiratory tract infection and blocked Eustachian tube is more common than is true vertigo; and syncope is far more common than is seizure.

Concurrent with overuse of jargon is the use of ambiguous and ill-defined terminology, such as dizziness, giddiness, numbness, blackout or even double vision. It is imperative to ensure that message sent is the same as message received. It follows that if a term can have multiple meanings, both the patient and clinician must agree on the meaning to be adopted. An example of this may be ‘dizziness’, which may mean true vertigo but could also mean light-headedness, loss of balance, disequilibrium, failure to think clearly, or even having a ‘flu-like’ heavy headedness. ‘Numbness’ can mean loss of sensation, a feeling of heaviness of a limb, pins and needles dysaesthesia, impaired movement of a limb or digits with loss of dexterity, or something quite different. It follows that the doctor must interrogate the patient to be sure that both are ‘reading from the same text’. Patients may complain that the doctor doesn’t believe them so it is important to be reassuring. It helps to explain the need for clarity and for avoidance of ambiguity.

Patients often misinterpret symptoms, such as reporting loss of vision in one eye, when what has happened is loss of vision in a visual field, such as homonymous hemianopia. The distinction is very important as monocular loss of vision may be amaurosis fugax, caused by impaired vascular supply to the eye as may occur with temporal (giant cell) arteritis. Monocular loss of vision is rostral, distal to the optic chiasm, while hemianopia is caudal, proximal to the chiasm. When a patient reports loss of vision in one eye it is important to ask if they have tested each eye individually, namely if covering one eye caused total loss of vision while covering the other eye allowed clear vision. This implies that covering the good eye caused binocular loss of vision, while uncovering it allowed the unaffected eye to see normally. Many patients believe left vision comes from the left eye and right vision from the right. With hemianopia it doesn’t matter which eye is covered as the visual loss is the same.

With any symptom, it is important to get a clear description of what actually happened without any ambiguity. Much of this is covered in individual chapters on specific topics. Once one understands the true nature of the actual symptom, ‘What is the problem’ (the first ‘W’), it is time to explore the other three ‘W’s—Where, When and Why. ‘Where’ is ‘where in the body’ (such as focal, unilateral or bilateral) and whether the demarcation is anatomically sound. ‘When’ asks in what situations does the symptom occur; for instance, provocative factors. An example of this is the use of alcohol, which differentiates between tension-type headaches that may be relieved by alcohol, and migraines, which may be provoked or exacerbated by alcohol. It seeks causes, such as stress, which is also important in tension-type headaches and other conditions such as benign essential tremors. ‘Flashing lights’ are a hallmark of photically induced seizures, and benign paroxysmal positional vertigo is provoked by rolling over in bed. ‘Why’ may include auxillary factors that might be important, such as exposure to toxic agents, trauma or genetic predisposition with positive family history.

Diagnosis is much easier if one knows which questions to ask. The first symptoms of Parkinson’s disease may be difficulty getting out of a low chair or a low car seat, such as a sports car, or trouble turning over in bed at night. Much of this subtlety in history taking comes with experience but just asking the patient ‘What did you first notice wrong?’ or ‘When did you first notice things were not right?’ will help. Given a chance and forced to describe symptoms in simple words rather than using jargon, which is often misunderstood by the patient, the description in plain language will greatly improve the diagnostic process.

Before leaving the discussion of history, it is important to set out the formal approach to the taking of an adequate history (see Table 1.1).

TABLE 1.1 The formal approach to taking a history

History

Area covered

Presenting symptom

What caused the patient to seek medical attention?

History of present illness (the 4 ‘W’s)

Personal history

i History of smoking

ii Alcohol consumption

iii Medications: name, strength, dosage

iv Medical past history

v Surgical past history

vi Psychosocial history as may be relevant to the complaint

Symptom review History covering symptoms relevant to other organs

Examination

The examination starts long before the patient reaches the consultation room. An observant receptionist may diagnose sleep apnoea, with excessive daytime sleepiness, before the patient has seen the doctor. An experienced receptionist will usually identify patients with behaviour disorder in the waiting room. A good receptionist will share these thoughts with the doctor.

As already stated, difficulty getting out of a chair may alert the doctor for Parkinson’s disease. A wide-based gait, looking like a drunken sailor, may suggest cerebellar disease. A white stick is self-evident for visual impairment and a hearing aid may be important for the patient complaining of ‘vertigo’. There are many diagnostic gaits, such as the stooped, shuffling, unsteady gait of the Parkinsonian; the hemiparetic gait of the stroke patient; or even the flamboyant, brazen gait of the patient with a psychological disorder.

Similarly language, facial expression or facial asymmetry, ptosis, dystonic posturing or the way in which a walking aid is used (which should be different for balance problems or pain support) all provide diagnostic tools. These provide direction for the consultation. They should alert the doctor if the patient fails to mention something that is important. An example of this is the patient who complains of an unprovoked fall but shows Parkinsonian gait, expressionless face, softly spoken voice, appears younger than the stated age and is moving slowly. The astute doctor will have made the diagnosis before the consultation has commenced: the cause of the fall probably will be ‘failed righting reflexes’. The consultation will then focus on this diagnosis and try to exclude the potential differential diagnoses.

In the majority of neurological cases the diagnosis is obvious once the history has been taken. This is especially so if the clinician has been observant both before the consultation (as the patient moves from the waiting area to the consultation room) and during history taking. In most cases the physical examination is largely unnecessary other than to reassure the patient that the doctor is both competent and diligent. If there is not a strong suspicion of the provisional diagnosis prior to commencing physical examination, it is unlikely that the examination will provide the answer and the missing clue. The examination should confirm the expected findings. The competent neurologist will have anticipated the findings before examining the patient. This translates into students being very impressed because the doctor can afford to be flamboyant in demonstrating the signs and even suggesting additional techniques that the doctor knows will be positive. Concurrently, patients are impressed when the doctor can predict clinical findings, thereby reassuring patients that they are in good hands.

Despite dismissing the need for physical examination, only a foolish doctor would not carry it out. It is part of patient expectation and, hence, part of the mystique that is medicine. It may also uncover other problems unrelated to the presenting complaints, such as goitre, cardiac murmur or skin lesions.

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