Clinical uses of H reflexes of upper and lower limb muscles.
Clinical uses of H reflexes of upper and lower limb muscles.
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DOI：
10.1016/j.cnp.2016.02.003
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发表时间：
2016
影响因子：
1.7
通讯作者：
Burke D
中科院分区：
文献类型：
--
作者：
Burke D
H反射可以从许多上肢和下肢肌肉获得（例如，胫骨前肌、鱼际肌和前臂伸肌）。收缩提高了运动神经元的兴奋性，降低了Ib对反射的限制。在休息时从通常不能证明反射的肌肉记录的H反射是反射亢进的证据，如果该肌肉中存在去神经支配，则引起ALS的怀疑。H反射可以从几乎所有具有肌梭的肌肉记录，但是反射增强可能需要反射反应被证明。这可以允许跨近端神经节段和通常由病理涉及的大多数神经根节段的传导。刺激率对处于休息状态的受试者至关重要。然而，在测试肌肉的背景收缩期间，具有更高速率的反射衰减大大降低，如果有的话，潜伏期只有微小的变化。此外，收缩确保反射反应发生在所需的肌肉中。反射潜伏期应根据身高（或肢体长度）和年龄进行校正。因为反射放电需要Ia组传入神经的同步齐射，所以反射潜伏期的大幅增加很少发生在纯粹的感觉损伤中。如果比目鱼肌、股四头肌或桡侧腕屈肌的H反射在休息时不存在，但在接近正常潜伏期的自主收缩期间出现，则存在低中枢兴奋性或主要感觉异常。与前H反射将很难引起整个身体。如果在休息时可以从通常不能显示反射的肌肉上记录到H反射，则存在反射亢进的良好证据。在可能的ALS的背景下，当存在该肌肉中的慢性部分去神经支配的EMG证据时，这是一个重要的发现。
H reflexes can be obtained from many upper and lower limb muscles (e.g., tibialis anterior, the thenar muscles and forearm extensors) during a voluntary contraction of the test muscle. The contraction raises motoneuron excitability and decreases the Ib limitation on the reflex. H reflexes recorded at rest from muscles for which no reflex can normally be demonstrated is evidence of hyperreflexia, raising suspicion of ALS if there is denervation in that muscle. H reflexes can be recorded from virtually all muscles that have muscle spindles, but reflex reinforcement may be required for the reflex response to be demonstrable. This can allow conduction across proximal nerve segments and most nerve root segments commonly involved by pathology. Stimulus rate is critical in subjects who are at rest. However the reflex attenuation with higher rates is greatly reduced during a background contraction of the test muscle, with only minor changes in latency if any. In addition the contraction ensures that the reflex response occurs in the desired muscle. Reflex latencies should be corrected for height (or limb length) and age. Because the reflex discharge requires a synchronised volley in group Ia afferents, large increases in reflex latency occur rarely with purely sensory lesions. If the H reflex of soleus, quadriceps femoris or flexor carpi radialis is absent at rest but appears during a voluntary contraction at near-normal latency, there is either low central excitability or a predominantly sensory abnormality. With the former H reflexes will be difficult to elicit throughout the body. If H reflexes can be recorded at rest from muscles for which no reflex can normally be demonstrated, there is good evidence for hyperreflexia. In the context of possible ALS, this is an important finding when there is EMG evidence of chronic partial denervation in that muscle.