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The monothermal differential caloric test allows determination of vestibular recruitment and decruitment, variables which may help discriminate peripheral from central vestibular lesions. Previous reports indicated a strong association between vestibular recruitment and Menière's disease. This study examined patients having unilateral Menière's disease. Nystagmus beat frequency (NBF) and slow-component velocity (SCV) responses were recorded by electronystagmography (ENG). Electronystagmographic findings showing unilateral dysfunction were present in 54% of patients by slow-component velocity and in 31% by nystagmus beat frequency. Unilateral hypofunction was the most frequent lateralizing ENG finding. Absolute vestibular recruitment occurred in less than 10% of patients but relative recruitment was found in nearly 20% of patients. Slow-component velocity had higher sensitivity than nystagmus beat frequency, with excellent clinical concordance. Monothermal caloric testing as described in this study best detects peripheral vestibular disease in Meniere's patients using slow-component velocity to determine unilateral hypofunction and relative vestibular recruitment.

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A standard photoplethysmograph, modified to differentiate between arterial and venous vasculature in skin tissue, has been used to measure arterial supply in 100 unipedicle skin flaps in 25 pigs. A datum transform from a light intensity scale to a relative arterial blood density scale has been introduced and empirically labelled the vascular coefficient (VC). Statistical analysis of the VC data shows a significant difference between necrotic and surviving flap group mean data as early as 24 hours. Additional analysis in which a normal ogive was fitted to the sample VC data distributions suggests that statistically significant predictions of the probability of eventual flap necrosis can be made using VC measurements obtained immediately postoperatively. It is concluded that the modified photoplethysmograph in conjunction with the VC data transform, constitutes a usable measuring technique for skin flap viability prediction in the experimental animal.

The Békésy audiometer has been adapted to our needs in animal research by substituting for their organic counterparts an extracorporeal decision-maker and button-pusher. In this system, the electrical response to a continuing tonal stimulus from the Békésy audiometer is picked up from any suitable cochlear electrode(s), amplified as usual, and submitted to the decision-maker. This device, functioning as an autocorrelating coherence detector, operates a relay substitute for the button-pusher. As the expected signal rises above or falls below the predetermined threshold level, the relay feeds back this information to the Békésy attenuator motor, thus controlling the stimulus level as usual in Békésy audiometry. This system permits continuous tracking of “thresholds” at levels well below the background noise and is expected to facilitate study of recovery from temporary threshold shift following various types of cochlear insult.