颈5～7神经根性撕脱后神经电生理表现及临床意义

The electrophysiological features of C5-7 nerve root avulsions and its clinical significance

目的分析臂丛颈5～7神经根性撕脱伤后相应皮区感觉神经动作电位（sensory nerve action potential，SNAP）、体感诱发电位（somatosensory evoked potential，SEP）的神经电生理表现及其临床意义。方法随机选择20例经手术探查证实为臂丛颈5—7神经根撕脱的患者，回顾性统计分析术前神经电生理检测所得颈5（三角肌皮区）、颈6（拇指及前臂背外侧、桡骨上至虎口区）、颈，（示指）皮区SNAP和SEP的指标。结果20例臂丛颈5皮区SNAP均未引出。臂丛颈5、6皮区SNAP、SEP检测结果显示：SNAP、SEP均未引出各3例；臂丛颈6皮区SNAP、SEP均可引出10例，其SEP潜伏期较健侧延长14．3％，波幅较健侧降低54．4％。臂丛颈7皮区SNAP、SEP均可引出8例，其SEP潜伏期较健侧延长13．1％，波幅较健侧降低51．8％；臂丛颈6皮区SNAP可引出，SEP未引出7例。臂丛颈，皮区9例。结论三角肌皮区的SNAP未引出可定性为臂丛颈，神经根性完全损伤，需综合其他神经根性损伤证据共同判别颈5神经根性撕脱与否。SNAP、SEP均未引出提示神经损伤均较为严重，可伴有神经节的损毁或臂丛神经多平面损伤。臂丛颈6、7皮区SNAP、SEP均可引出的患者中，SEP潜伏期较对侧延长大于15％或波幅下降大于55％可作为判别神经根节前损伤的佐证。只有不到50％的患者出现SNAP可引出、SEP未引出的典型电生理表现。对臂丛颈6神经根，拇指或前臂背外侧、桡骨上至虎口区中任有一项表现为SNAP可引出、SEP未引出，即有判断神经撕脱的指征。

Objective To analyze the eleetrophysiologieal features and clinical value of SNAP（ sensory nerve action potential）and SSEP（somatosensory evoked potential）in C5, C6 and C7 dermatoroes after bmehial plexus C5-7 avulsion . Methods Twenty randomly selected, surgically confirmed eases of C5-7 root avulsions were reviewed retrospectively for pre-operative SNAP and SSEP values of C5 （deltoid region）, C6 （thumb, dorsolateral forearm, first web space） and CT（index finger） dermatomes. Results In C5 dermatomic area, no SNAP could be detected in all 20 eases. In C5 and C6 dermatomie areas neither SNAP nor SSEP could be detected in 3 cases. In C6 dermatomic area, beth SNAP and SSEP could be detected in 10 cases. Comparing to the uninjured side, SSEP latency prolonged 14.3 % and SSEP amplitude decreased 54.4%. In C7 dermatomie area, beth SNAP and SSEP could be detected in 8 cases. SSEP latency prolonged 13.1% and SSEP amplitude decreased51.8%. There were 7 cases in which SNAP was detectable and SSEP was not detectable in C6 dermatome, and 9 cases in which SNAP was detectable and SSEP was not detectable in C7 dermatome. Coneluslon No detection of SNAP in the deltoid dermatomie area indicates complete C5 root injury. Determination of C5 root avulsion needs other evidences. No detection of SNAP and SSEP indicates severe nerve mot injury, which is accompanied by ganglion damage or multiplanar bmchial plexus injury. If both SNAP and SSEP can be detected in C6, C7 dermatomes, a 15%or over prolongation of SSEP latency or a 55% or more reduction of SSEP amplitude can be useful evidences to diagnosis of preganglionie injury. Less than half of the eases had typical electmphysiological features of detectable SNAP and undetectable SSEP. C6 nerve root andsion can be determined if SNAP is detectable while SSEP is undeteetable in any of the following areas, thumb, dorsolateral forearm, or first web space.