Persistent Down-Beating Torsional Positional Nystagmus: Posterior Semicircular Canal Light Cupula?

الملخص EN

A 16-year-old boy with rotatory positional vertigo and nausea, particularly when lying down, visited our clinic.

Initially, we observed vertical/torsional (downward/leftward) nystagmus in the supine position, and it did not diminish.

In the sitting position, nystagmus was not provoked.

Neurological examinations were normal.

We speculated that persistent torsional down-beating nystagmus was caused by the light cupula of the posterior semicircular canal.

This case provides novel insights into the light cupula pathophysiology.