The neurological diagnostic consultation

Published on 12/04/2015 by admin

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Last modified 12/04/2015

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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.

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