Persistent Geotropic Direction-Changing Positional Nystagmus Treated With Transcutaneous Vagus Nerve Stimulation.

A 50-year-old female patient visited the emergency department of a university hospital complaining of sudden-onset vertigo. Symptoms initiatedwhile the patient was seated at a table andworsened whenever she moved her head. One month prior, the patient had been admitted to a hospital for 2 weeks for geotropic benign paroxysmal positional vertigo of the right lateral semicircular canal (LSCC). At that time, she did not respond well to either repositioning maneuvers or vestibular suppressants. The patient had no other history of chronic illness, migraine, or alcohol or substance abuse, and did not report any auditory symptoms such as tinnitus, aural fullness, or hearing loss. An initial bedside examination using infrared goggles (SLMED, Seoul, Korea) revealed the following findings: no spontaneous nystagmus in the supine position, similar intensities of bilateral apogeotropic DCPN in the supine head roll test, and negative findings in the horizontal head impulse test and on diffusion magnetic resonance imaging. The patient was admitted for further evaluation and treatment. One day after admission, the patient complained of worsening dizziness when turning her head to the right side. The supine head roll test demonstrated persistent geotropic DCPN lasting >2minutes (maximal slow-phase velocity for the right-ear-down position: 12.3°/ s; for the left-ear-down position: 10.3°/s). Additionally, a null point was observedwhere the nystagmus stoppedwhen the patient turned her head slightly to the right. Video head impulse test (vHIT) results indicated aberrantly increased gain in both LSCCs; however, the results of other vestibular tests were negative. tVNS protocol