Neuropathy is an integral component of the cerebellar ataxia with bilateral vestibulopathy syndrome
Purpose: To review patients with the syndrome of cerebellar ataxia with bilateral vestibulopathy (CABV), as described by Halmagyi et al. in Brain 2004, and to characterize the spectrum of the accompanying neuropathy, both clinically and electrophysiologically.
Methods: A retrospective case review was performed of patients diagnosed with the syndrome of CABV to confirm that diagnostic criteria for this syndrome were met and to review the clinical and electrophysiological features of the accompanying neuropathy.
Results: Six patients were identified in whom the diagnosis of CABV could be sustained. All had clinical evidence of vestibular failure, including abnormal dynamic visual acuity and/or impaired caloric and rotational chair results. All also showed broken-up (saccadic) smooth visual pursuit, with an abnormal visually-enhanced vestibulo-ocular reflex (VVOR) in the four in whom this was assessed. All demonstrated other evidence of cerebellar dysfunction, including impaired tandem gait, dysmetria or dysarthria. Nerve conduction studies demonstrated absent upper and lower limb sensory nerve action potentials (SNAPS) in four, with absent sural SNAPS and evidence of mild axonal motor neuropathy in the other two. Clinically, the neuropathy varied from small fibre predominance with almost complete loss of pin prick sensation accompanied by moderate distal reduction of vibration sense, to predominant large fibre length-dependent loss with complete preservation of pin prick perception. The subject with this latter clinical pattern underwent sural nerve biopsy, which revealed significant loss of both myelinated and non-myelinated fibres with 34% segmental remyelination.
Conclusion: A sensory or sensory-motor neuropathy is an integral component of the CABV syndrome. Its anatomical extent and fibre distribution vary, but it may result in severe sensory loss, contributing significantly to the disability in this syndrome.