Vestibular Testing Interpretation: Drill and Practice

Review by L Flood
Middlesborough, UK

This is a spiral-bound work book, which the opening sentence tells us ‘We designed with a trainee or junior practitioner in mind’. Well I feel that significantly underestimates its applicability to a much more senior readership, in covering a poorly understood topic. Most of us would at least seek nystagmus, and get our patients standing, marking time and closing their eyes in the clinic, and then complete a vestibular test battery request form. Some time would pass and the hope was that a spontaneous recovery had ensued, or our clever colleagues had tipped the patient one way or another and moved those otoconia. If not, we would pronounce confidently on ‘vestibular neuritis’, despite the lack of any evidence of an inflammatory lesion, or ‘hydrops’ even if (until very recently) there was precious little evidence it even existed.

The opening chapters review the most commonly employed vestibular function tests, but the bulk of the book, 100 pages, is taken up with 27 case studies that are a clever novelty and very thought-provoking. Actually, the authors do then acknowledge that these may just be of value to ‘practitioners who are more experienced with vestibular testing’. I certainly found them so.

The first chapter covers history taking and the typical presenting features of the best known vestibular disorders. There are also what can only be described as questionable contemporary diagnoses, with vague symptomatology and considerable overlap. Vestibular migraine we have got used to. Superior canal dehiscence many of us rejected as a radiological artefact for years, but were proved wrong. We may yet be equally convinced by vestibular paroxysmia (basically like Ménière’s disease, but responding to carbamazepine) or especially the newest ‘diagnosis’ persistent postural-perceptual dizziness (easier as ‘3PD’, a condition which has no objective testing to confirm its presence, or possibly even its existence as a pathological entity). The chapter then addresses tests seeking nystagmus, whether spontaneous or induced, together with caloric, head impulse, vestibular-evoked myogenic potentials or rotary chair testing. The latter two are particularly well described and explained, which is not easy. Audiometry and imaging (as expected of a vestibular schwannoma and a dehiscent canal) are briefly addressed. Interestingly, it closes with ‘Tests of Limited Diagnostic Use or Historical Importance’. These include posturography, although the text goes on to what I thought an impressive list of potential applications, electrocochleography and, above all, the glycerol dehydration test. There are still believers in the negative summating potential, but hopefully no one is still inflicting such a headache-inducing test as dehydration.

A brief following chapter considers when vestibular testing might be indicated and which tests are appropriate to each individual presentation. A third chapter, despite the book title, addresses management of peripheral vestibular disorders, largely of course, concentrating on canalolithiasis and cupulolithiasis.

Then comes the ‘meat’ of the book, the 27 case presentations. A consistent style is followed throughout. Each starts with a brief history (from some very articulate patients!), followed by a description (curiously never an illustration of) the pure tone audiogram. Then we get the findings on videonystagmography, positional and caloric testing, head thrusting, and spinning in that chair. Each is illustrated with a graph, of exactly the same format reproduced in every case study. The reader is then invited to write into the book one’s ‘own impression’. The authors then offer their interpretation of the findings, followed by a differential diagnosis (which can be remarkably far-reaching in some cases) and suggested therapy.

I found this a very useful insight into the significance of the test battery that resulted from my completion of a request form. Most of these tests, in our unit, were listed, each with a tick box to fill in, and all too often that meant every box ticked, out of sheer ignorance. After reading this, I was left with the conviction that we still have so much to learn about the diagnoses that result. However, I am also convinced that the answer is somewhere between the scepticism of Doubting Thomas and the credulity of The Emperor’s New Clothes. This is a very good introduction to the topic and, after completion of the exercise, one would be quite an expert.

Amazon Link: Vestibular Testing Interpretation: Drill and Practice
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