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Persistent geotropic direction-changing positional nystagmus with a null plane: the light cupula.

Chang-Hee Kim1, Min-Beom Kim, Jae Ho Ban

  • 1Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine.

The Laryngoscope
|October 30, 2013
PubMed
Summary

Persistent geotropic direction-changing positional nystagmus (DCPN) without latency was characterized in 19 patients. This study identified the affected side in 95% of cases and found light cupula in 14.2% of patients with geotropic DCPN.

Keywords:
Benign paroxysmal positional vertigodirection-changing positional nystagmusgeotropic nystagmushead roll testnull plane

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Area of Science:

  • Neurology
  • Ophthalmology
  • Vestibular System Disorders

Background:

  • Benign paroxysmal positional vertigo (BPPV) is a common cause of vertigo.
  • Geotropic direction-changing positional nystagmus (DCPN) is a subtype of BPPV, often associated with canalithiasis.
  • Persistent geotropic DCPN suggests underlying pathophysiology that warrants further investigation.

Purpose of the Study:

  • To characterize the clinical features and nystagmus patterns in patients with persistent geotropic DCPN.
  • To investigate the potential pathophysiology of this condition.
  • To determine the incidence of light cupula in patients presenting with geotropic DCPN.

Main Methods:

  • A prospective case series design was employed.
  • Nineteen patients with persistent geotropic DCPN were included.
  • Videony stagmography was used to analyze positional nystagmus during specific diagnostic maneuvers (bow and lean, supine head roll tests).

Main Results:

  • All 19 patients exhibited persistent geotropic DCPN without latency.
  • A null plane was identified in all patients, indicating a specific orientation where nystagmus ceased.
  • The affected side was identified in 95% of patients, with nystagmus intensity varying between sides in 68% of cases.
  • Approximately 14.2% of patients with geotropic DCPN were diagnosed with light cupula of the horizontal semicircular canal.

Conclusions:

  • Patients with light cupula present with persistent geotropic DCPN lacking latency.
  • The direction and intensity of positional nystagmus, along with the null plane, help identify the affected side.
  • The precise pathophysiology and optimal treatment strategies for light cupula remain areas for future research.