Case 2 · Foundation

Brief vertigo on rolling over in bed

A 58-year-old reports repeated episodes of intense spinning lasting under a minute, reliably triggered by lying down, sitting up, or rolling over in bed. Between episodes she feels entirely well.

Findings

  • Vertigo provoked by a positional manoeuvre, after a brief latency
  • Transient upbeat-torsional nystagmus that fatigues on repetition
  • Normal hearing and normal head impulse test
  • No symptoms when the head is kept still

What is the most likely underlying mechanism?