Auditory neuropathy spectrum disorder (ANSD) is now well recognised in audiological circles. Vestibular nerve function has not been extensively studied in ANSD. The authors used cervical vestibular evoked myogenic potential (cVEMP) and caloric tests to assess the integrity of the inferior and superior vestibular nerves respectively in 26 ANSD subjects. There were 16 females and 10 males with ages ranging between 13 years and 42 years (mean 21.8 years). Vestibular complaints were reported by 15 subjects (57.6%) although I would not consider blackouts and loss of consciousness, vestibular in origin. A control group of 26 subjects were recruited. The results in the ANSD group were as follows: in 96.15% subjects (50 ears), cVEMPs were absent. In a further one ear, the amplitude was abnormal. Normal cVEMP was elicited in one ear. Caloric results were classified as hypoactive (86.53%), hyperactive (5.76%) or normal (7.69%). When the cVEMP and caloric abnormalities were combined, bilateral vestibular hypofunction was identified in 76.92%. Asymmetric dysfunction was seen in five subjects (19.23%) whereas in four subjects (15.38%), hypofunction was unilateral. Vestibular dysfunction did not correlate with the pattern and degree of hearing loss. This is an excellent study overall, that shows further evidence that ANSD is more than an ‘auditory’ nerve abnormality and vestibular function tests should perhaps be done in all such patients. The formula used by the authors to determine caloric abnormality was unconventional and it would have been interesting to know if the aetiology of the ANSD had any bearing on the type of caloric abnormality. Should ANSD, with its many synonyms, be renamed? That is a discussion for another time.
Is auditory neuropathy spectrum disorder a disorder of the whole eighth cranial nerve?
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