Deuschl G, Toro C, Valls-Solé J, Zeffiro T, Zee D S, Hallett M
Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
Brain. 1994 Aug;117 ( Pt 4):775-88. doi: 10.1093/brain/117.4.775.
Palatal tremor (brief, rhythmic involuntary movements of the soft palate) apparently comprises two different nosological entities: essential palatal tremor (EPT) and symptomatic palatal tremor (SPT). The site of the abnormality in EPT is unknown, whereas SPT is believed to arise from a lesion of the brainstem or cerebellum (within the Guillain-Mollaret triangle). The clinical and physiological properties of these conditions were studied in four patients with EPT and six patients with SPT. Patients with EPT had normal cerebellar function, but those with SPT had clinical signs of cerebellar dysfunction. The palatal movements were consistent with activation of the tensor veli palatini muscle in EPT and of the levator veli palatini muscle in SPT. During sleep, EPT stopped, whereas SPT continued with only slight variations in the tremor rate. The cycle of palatal tremor could not be reset by stimulation of trigeminal afferents in either EPT or SPT patients, and Valsalva's manoeuvre did not consistently affect the rhythm of the tremor in either group. The palatal tremor cycle exerted remote effects on the tonic electromyographic activity of the upper and lower extremities only in patients with SPT. These effects were present only on the side of the cerebellar signs (opposite the side with the enlarged inferior olive) in patients with a unilateral syndrome. Essential palatal tremor patients had only polysynaptic brainstem reflex abnormalities, whereas SPT patients had abnormalities of monosynaptic, oligosynaptic and polysynaptic brainstem reflexes. Magnetic resonance imaging showed no evidence of structural abnormalities in EPT patients, but SPT patients had a hyperdense signal of the ventral upper medulla (the region of the inferior olive) on T2-weighted images. These observations support the hypothesis that EPT and SPT are two different diseases. In SPT, cerebellar dysfunction ipsilateral to the palatal tremor may be due, in part, to abnormal function of the contralateral hypertrophic inferior olive. The proposed basis of SPT is a disturbance of electrotonic coupling between the cells of the inferior olive induced by a lesion of the dentato-olivary pathway. Similar mechanisms could be responsible for postural tremors in general. The pathophysiological basis of EPT remains unknown.
腭震颤（软腭短暂、有节律的不自主运动）显然包含两种不同的疾病实体：特发性腭震颤（EPT）和症状性腭震颤（SPT）。EPT的异常部位尚不清楚，而SPT被认为起源于脑干或小脑的病变（在 Guillain-Mollaret 三角区内）。对4例EPT患者和6例SPT患者的这些疾病的临床和生理特性进行了研究。EPT患者的小脑功能正常，但SPT患者有小脑功能障碍的临床体征。腭部运动在EPT中与腭帆张肌的激活一致，在SPT中与腭帆提肌的激活一致。睡眠期间，EPT停止，而SPT仅在震颤频率上有轻微变化仍继续。在EPT或SPT患者中，刺激三叉神经传入纤维均不能重置腭震颤周期，Valsalva动作也未始终如一地影响两组的震颤节律。腭震颤周期仅在SPT患者中对上下肢的强直性肌电图活动产生远程影响。在单侧综合征患者中，这些影响仅出现在小脑体征侧（与下橄榄体增大侧相反）。特发性腭震颤患者仅有多突触脑干反射异常，而SPT患者有单突触、寡突触和多突触脑干反射异常。磁共振成像显示EPT患者没有结构异常的证据，但SPT患者在T2加权图像上有延髓腹侧上部（下橄榄体区域）的高信号。这些观察结果支持EPT和SPT是两种不同疾病的假说。在SPT中，与腭震颤同侧的小脑功能障碍可能部分归因于对侧肥大下橄榄体的功能异常。SPT的推测基础是齿状核-橄榄体通路病变引起的下橄榄体细胞间电紧张偶联障碍。类似的机制可能是一般姿势性震颤的原因。EPT的病理生理基础仍然未知。
