Clinical Analysis of Down Beat Nystagmus in Atypical Positional/ing Vertigo

ABSTRACT

BACKGROUND AND OBJECTIVES:Traditionally, down beat nystagmus is regarded as a sign of central nervous system dysfunction. But, several years has passed since Herdman et al reported the down beat nystagmus developed during treatment maneuvers for posterior semicircular canal benign paroxysmal positional vertigo(BPPV). We undertook this study to evaluate the character and clinical analysis of the positional or positioning down beat nystagmus, to discuss the clinical significance of positional or positioning down beat nystagmus as a diagnostic criteria of superior semicircular canal BPPV, and to propose the new treatment method. MATERIALS AND METHOD:From November 1999 to March 2004, we sampled the 103 patients with positional or positioning down beat nystagmus. Of these patients, we selected 16 patients except for the patients with central nervous system dysfunction, nonspecific or artifact result, idiopathic origin. RESULTS:All of 16 patients had no sign and radiologic result of central nervous system disorder. 10 patients was reported or suspected the diagnosis of posterior semicircular canal BPPV. Fatigability was reported in 9 patients and reversibility was reported in 1 patient. Average latency was checked less than 2 seconds. CONCLUSION:Although the diagnostic criteria of superior semicircular canal BPPV that we reported was not controversial, we expect that this criteria is useful in diagnosis for patients with atypical positional or positioning down beat nystagmus. And the new treatment method that we reported will has the better results than previous method.