Shimizu T, Komori T, Kato S, Kawata A, Hayashi H, Hirai S
Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan.
Amyotroph Lateral Scler Other Motor Neuron Disord. 2001 Dec;2(4):189-95. doi: 10.1080/14660820152882197.
To elucidate underlying abnormalities of the masseter motor system in amyotrophic lateral sclerosis (ALS).
We recorded biphasic EMG suppressions of the masseter muscle (silent or inhibitory periods 1 and 2) after electrical stimulation of the mental nerve during maximum clenching of the teeth in 16 ALS patients and 15 healthy control subjects. We also examined the recovery cycle of the silent periods by delivering paired stimuli with an interstimulus interval of 250 ms.
Silent period 1 in the patients was not significantly different from that in control subjects, whereas silent period 2 (as measured by its area on the graph) was increased in the patients, especially with exaggerated jaw jerk. Only two patients showed absence of silent period 2. The recovery cycle of silent period 2 in the subgroup of patients with exaggerated jaw jerk was significantly lower than the control value.
The abnormalities of the masseter inhibitory reflex in ALS could be ascribable to involvement of the corticobulbar or corticoreticular tract projecting to the inhibitory interneurons mediating silent period 2.
阐明肌萎缩侧索硬化症（ALS）中咬肌运动系统的潜在异常。
我们记录了16例ALS患者和15名健康对照者在最大程度咬紧牙齿时，对颏神经进行电刺激后咬肌的双相肌电图抑制（静息期或抑制期1和2）。我们还通过以250毫秒的刺激间隔给予成对刺激来检查静息期的恢复周期。
患者的静息期1与对照者无显著差异，而患者的静息期2（通过其在图表上的面积测量）增加，尤其是伴有夸张的下颌反射亢进时。仅两名患者表现为静息期2缺失。下颌反射亢进患者亚组中静息期2的恢复周期显著低于对照值。
ALS中咬肌抑制反射的异常可能归因于投射到介导静息期2的抑制性中间神经元的皮质延髓束或皮质网状束受累。
