Benign paroxysmal vertigo (BPV) is a clinical syndrome of vestibular origin although generally no evidence of vestibular dysfunction can be demonstrated with conventional tests. In a review of 1350 consecutive dizzy patients, there were 125 with BPV and of these, 33 underwent a quantitative rotational test of vestibular function. The rotational results showed reduces vestibular system gain for these BPV patients. In addition, they could be subdivided on the basis of a normal or shorter cupular time constant (Tc). Separation of patients into diagnostic categories revealed that those categorized as cupulolithiasis and viral labyrinthitis had a normal Tc range and those categorized as trauma and idiopathic had a short Tc. The reduced gain and short Tc in the latter group suggest hair cell and/or nerve damage since these same changes occur in patients with destructive peripheral vestibular disease.

Spontaneous nystagmus occurs during a Meniere's attack although the literature indicates that the direction can be variable. Previous observations made during the acute and recovery stages of a Meniere's attack suggested that the direction of the spontaneous nystagmus was consistent with the primary-secondary sequence of nystagmus that occurs with relatively prolonged stimulation of the normal vestibulo-oculomotor system. To evaluate this nystagmus pattern further, spontaneous nystagmus was monitored in eight patients using DC electronystagmography during an acute Meniere's attack. All showed an initial contralateral nystagmus during the acute phase of the attack with reversal to an ipsilateral (or recovery) nystagmus, as the acute symptoms subsided. Such a pattern of nystagmus occurring over a few hours is a helpful diagnostic aid, and when surgery is being considered, it provides objective evidence of the ear with active disease.

Caloric irrigation of the external ear canal represents an inadeqwte vestibular stimulus because the method is not physiologic and the canal irrigation and the heat transfer to the inner ear cannot be well controlled. In rotational testing an accurate acceleration profile can be applied with an appro riate rotating device. A test procedure is presently being for 240 seconds, followed by a similar deceleration (equivalent to acceleration in the revelse direction) and hold. On-line data reduction of the nystagmus response is accomplished automatically using a simple analog technique. This technique provides a concise presentation (on a standard size sheet of paper) of the total slow phase eye displacement resulting from the primary and secondary responses and enables comparison of the results for both directions of acceleration. Experience with the routine use of rotational testing in a vestibular clinic and the significance of various paterns of response with special emphasis on vestibular adaptation function are discussed.used, which consists of constant acce P eration at 3"/sec2 for 50 seconds, hold at constant velocity

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The perilymphatic space of the cat cochlea was perfused with a solution containing a high potassium ion concentration. The auditory response threshold was monitored with brainstem evoked response audiometry. In the majority of animals the initial perfusion produced a reversible decline in response threshold. With repeat perfusions, there was a variable degree of non-reversible response decline leading ultimately to a total loss of the auditory response.