Positional and positioning down-beating nystagmus without central nervous system findings.
We report the clinical features of 4 cases with positional or positioning down-beating nystagmus in a head-hanging or supine position without any obvious central nervous system disorder. The 4 cases had some findings in common. There were no abnormal findings on neurological tests or brain MRI. They did not have gaze nystagmus. Their nystagmus was observed only in a supine or head-hanging position and it was never observed upon returning to a sitting position and never reversed. The nystagmus had no or little torsional component, had latency and tended to decrease with time. The positional DBN (p-DBN) is known to be indicative of a central nervous system disorder. Recently there were some reports that canalithiasis of the anterior semicircular canal (ASC) causes p-DBN and that patients who have p-DBN without obvious CNS dysfunction are dealt with anterior semicircular canal (ASC) benign paroxysmal positional vertigo (BPPV). There are some doubts as to the validity of making a diagnosis of ASC-BPPV in a case of p-DBN without CNS findings. It is hard to determine the cause of p-DBN in these cases.
Ogawa
Yasuo
Y
Department of Otorhinolaryngology, Tokyo Medical University, Japan. y-ogawa8@tokyo-med.ac.jp
Suzuki
Mamoru
M
Otsuka
Koji
K
Shimizu
Shigetaka
S
Inagaki
Taro
T
Hayashi
Mami
M
Hagiwara
Akira
A
Kitajima
Naoharu
N
D000328:Adult; D001927:Brain Diseases / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007759:Labyrinth Diseases / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D009759:Nystagmus, Pathologic / Q000175:diagnosis* / Q000503:physiopathology; D009760:Nystagmus, Physiologic / Q000502:physiology*; D010037:Otolithic Membrane / Q000503:physiopathology; D012665:Semicircular Canals / Q000503:physiopathology*; D016683:Supine Position / Q000502:physiology*; D014717:Vertigo / Q000175:diagnosis / Q000503:physiopathology; D055815:Young Adult