Ogawa Yasuo, Suzuki Mamoru, Otsuka Koji, Shimizu Shigetaka, Inagaki Taro, Hayashi Mami, Hagiwara Akira, Kitajima Naoharu
Department of Otorhinolaryngology, Tokyo Medical University, Japan.
Auris Nasus Larynx. 2009 Dec;36(6):698-701. doi: 10.1016/j.anl.2009.04.001. Epub 2009 Apr 26.
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.
我们报告了4例在头悬垂或仰卧位时出现位置性或定位性下跳性眼球震颤且无明显中枢神经系统疾病的临床特征。这4例有一些共同的表现。神经学检查或脑部MRI均无异常发现。他们没有凝视性眼球震颤。他们的眼球震颤仅在仰卧位或头悬垂位时观察到，恢复到坐位时从未观察到且从不反转。眼球震颤无或仅有很少的扭转成分，有潜伏期且往往随时间而减轻。位置性下跳性眼球震颤（p-DBN）已知提示中枢神经系统疾病。最近有一些报道称，前半规管（ASC）管结石症可导致p-DBN，且无明显中枢神经系统功能障碍的p-DBN患者被诊断为前半规管（ASC）良性阵发性位置性眩晕（BPPV）。对于在无中枢神经系统表现的p-DBN病例中诊断ASC-BPPV的有效性存在一些疑问。在这些病例中很难确定p-DBN的病因。
