Subclinical neurological and balance abnormalities in late-onset auditory neuropathy spectrum disorder (ANSD) as a part of multisystem neurological presentation.

Auditory neuropathy spectrum disorder (ANSD) is primarily considered a hearing disorder, with balance issues rarely reported. Although some studies have investigated vestibular abnormalities in ANSD in addition to auditory deficits, the neurological aspects have largely been overlooked. Subtle balance deficits in individuals with ANSD often go unnoticed, which has resulted in limited research in this area. The present study aims to describe a comprehensive battery of neurological and audio-vestibular tests in individuals with acquired ANSD who reported balance-related complaints but did not have a prior diagnosis of a neurological disorder, thus representing clinically under-recognized deficit. Fourteen patients with ANSD underwent a series of clinical assessments, including auditory brainstem response (ABR), cervical and ocular vestibular evoked myogenic potentials (VEMPs), the video head impulse test (vHIT), motor and sensory nerve conduction studies, somatosensory evoked potentials (SSEP), hematological investigations, and magnetic resonance imaging (MRI). All patients were Romberg-positive and showed an impaired tandem gait, despite largely preserved cranial nerves and motor examination findings on routine clinical testing. Auditory assessments revealed varying degrees of hearing loss, absent ABRs, and abnormal VEMPs and vHIT results, while MRI findings were unremarkable. Motor nerve conduction was normal in most patients; however, a few individuals exhibited reduced or absent sensory nerve potentials. In addition, SSEP latencies were abnormal in nine patients. The absence of VEMPs and abnormal vHIT findings suggest an underlying vestibulopathy, whereas nerve conduction and SSEP abnormalities indicate a possible somatosensory deficit in ANSD. These preliminary findings underscore the importance of a multidisciplinary approach to the evaluation of balance deficits in ANSD, an area in which evidence remains scarce.