Biomedical subjects
Publications and source records attributed to C W Hart.
The side of labyrinthine pathology, as indicated by caloric tests, Quix test, audiometry or otoscopy is investigated by Computerised Dynamic Posturography. The correlation level fluctuates from high with audiometry to low with caloric tests. The quantification possibility of the dynamic posture is stressed.
A Caucasian male contracted acquired immune deficiency syndrome (AIDS) following a blood transfusion during heart surgery. Four years later he developed dizziness, dysequilibrium, and emotional disturbances. Neurotologic evaluation implicated central vestibular and auditory dysfunction. Electronystagmographic findings showed ataxic pursuit and optokinetic nystagmus, with a total loss of caloric excitability. The auditory brain stem response indicated delayed absolute and interpeak latencies, and the synthetic sentence identification test yielded abnormally reduced scores bilaterally. Psychological tests suggested organic brain disease with severe anxiety and depression. At autopsy, the AIDS retrovirus was found in mononuclear and multinucleated giant cells in the cortical and subcortical gray matter, cerebral and cerebellar white matter, and throughout the brain stem. Pathologic changes were consistent with the patient's neurotologic profile.
Three-dimensional (3D) computed tomographic reformations have been used successfully as an adjunct to standard axial computed tomography (CT) in the evaluation of disorders affecting areas of complex anatomy. The basic requirements for high-quality 3D reformations are an absence of patient movement and narrow-width transaxial sections. Speed of examination is an important factor in optimizing image quality. One hundred examinations were performed on an IGE CT 9800 scanner. For bone studies, 80 mAs and, for certain soft tissues, 140 or 200 mAs were employed with 120 kVp. The advantages of such a "low-dose" technique are significant reduction in patient skin dose and a faster examination. The main disadvantage is a reduction in signal-to-noise ratio. The image quality obtained in 3D presentations has nevertheless been sufficient to enable all bony abnormalities to be identified. Three-dimensional examinations are now being performed routinely using a dynamic mode and this "low-dose" technique.
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The caloric test is still the most useful vestibular test by far. Rotatory tests may allow more accurate control of the stimulus and the response parameters may vary less in normal individuals, but only the caloric test allows individual testing of each ear. By various means described in this article, it is possible to minimize potential sources of error and thus maximize the reliability of the test. Although the test allows a good measure of horizontal semicircular canal function and, by inference, an estimate of labyrinthine disease, the fact that the reflex arc traverses the vestibular nerve and brain stem renders this pathway liable to damage by central vestibular disease. Thus the electronystagmographic recording of the caloric nystagmus response may show a variety of changes, depending on the site and nature of the central vestibular lesion. Some of these changes are discussed.
Professor Doctor F.H. Quix, of Utrecht, was a keen student of macular function, who published extensively at the beginning of this century. He described many useful tests for otolithic function, and one in particular has continued to be fairly widely used. The so-called "Quix Test" is performed with the patient standing, feet slightly apart, arms outstretched, index fingers extended, and the examiner assumes a similar mirror-image posture, such that the fingertips almost touch. The patient is then requested to close his eyes, and the index fingers are observed for drift. The lateralizing value of this sign of vestibular disease is discussed.
It is proposed that the term Meniere's disease be restricted to patients with the classic symptom and sign complex in whom the etiologic factor is unknown (idiopathic). The term Meniere's syndrome is restricted to patients whose etiologic factor is known, who have an incomplete form of the disease, or who are in the process of being evaluated. Vestibular neuronitis and cochlear hydrops are terms that should be retained until the concepts of vestibular and cochlear Meniere's disease are better understood and can be identified prospectively. The classic symptoms and signs, both positive and negative, are outlined and a standard evaluation format is suggested. This must submit to mathematical reduction for pre- and post-treatment comparisons. Until this basic problem has been solved to the satisfaction of the profession, the inferences that may be drawn from otherwise excellent studies will continue to be of very limited clinical value.
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