A 28-year-old woman presents with three weeks of unsteadiness, intermittent diplopia, and a 'pulling' sensation on left lateral gaze. Six months ago she had a self-limited episode of retro-orbital pain and reduced visual acuity in the right eye. Current MRI brain and cervical cord are reported as normal. There are no spinal lesions; oligoclonal bands in CSF are present.

Investigations

How does this VEMP finding contribute to the diagnostic picture?

• ABilaterally prolonged P1 latencies with preserved amplitudes indicate central conduction delay — supportive of demyelination even with normal MRI
• BBilateral peripheral vestibulopathy
• CNormal study
• DBilateral SCD