Nalini A, Praveen-Kumar S, Ebenezer Beulah, Ravishankar S, Subbakrishna D K
Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, India.
Neurol India. 2008 Jul-Sep;56(3):368-73. doi: 10.4103/0028-3886.40962.
Brachial monomelic amyotrophy (BMMA) is known to affect the central cervical cord gray matter resulting in single upper limb atrophy and weakness.
Case series of BMMA patients who underwent somatosensory evoked potentials (SEP) studies at a tertiary referral center.
We proposed to record Multichannel Somatosensory Evoked Potentials (MCSSEP) from median and ulnar nerves with neck in neutral and neck fully flexed position in 17 patients with classical BMMA seen over three years.
Recordings were done from both median (MN) and ulnar nerves (UN). N9, P9, N13, N20 potentials were recorded and amplitudes measured. SSEPs were performed in 22 age-matched healthy men. Amplitudes of cervical response were calculated by N13/P9 ratio and compared in both positions.
Among the controls N13 amplitude was always normal {MN: mean N13/P9 - 0.96 in neutral; 0.95 in flexed}{UN: mean N13/P9 - 0.82 in neutral; 0.83 in flexed}, and mean amplitudes did not reveal any difference in both conditions ( P> 0.05). Among 17 patients N9, P9 and N20 responses were normal in neutral position. Flexion showed no change in latency or amplitude of N9 and N20 responses ( P -0.63) whereas the N13 response was abnormal in at least one tested nerve in the affected limb (MN: P < 0.01; UN: P < 0.01). During flexion, N13 response was abnormal in 14 (82%) patients after MN stimulation and in all 17(100%) after UN stimulation {MN: mean N13/P9 - 0.62 in neutral; 0.38 in flexed}{UN: mean N13/P9 - 0.55 in neutral; 0.31 in flexed}.
MCSSEP in BMMA with neck flexion caused a significant reduction of the cervical N13 response indicating segmental cervical cord dysfunction.
已知臂丛单肢肌萎缩症（BMMA）会影响颈髓中央灰质，导致单上肢萎缩和无力。
在一家三级转诊中心对接受体感诱发电位（SEP）研究的BMMA患者进行病例系列研究。
我们计划对17例在三年期间确诊的典型BMMA患者，在颈部处于中立位和完全屈曲位时，记录正中神经和尺神经的多通道体感诱发电位（MCSSEP）。
从正中神经（MN）和尺神经（UN）进行记录。记录N9、P9、N13、N20电位并测量其波幅。对22名年龄匹配的健康男性进行SEP检查。通过N13/P9比值计算颈部反应的波幅，并在两种体位下进行比较。
在对照组中，N13波幅始终正常{正中神经：中立位时平均N13/P9为0.96；屈曲位时为0.95}{尺神经：中立位时平均N13/P9为0.82；屈曲位时为0.83}，且两种情况下平均波幅均无差异（P>0.05）。在17例患者中，中立位时N9、P9和N20反应正常。屈曲时，N9和N20反应的潜伏期和波幅无变化（P=0.63），而患侧肢体至少一条受试神经的N13反应异常（正中神经：P<0.01；尺神经：P<0.01）。屈曲时，正中神经刺激后14例（82%）患者N13反应异常，尺神经刺激后17例（100%）患者N13反应异常{正中神经：中立位时平均N13/P9为0.62；屈曲位时为0.38}{尺神经：中立位时平均N13/P9为0.55；屈曲位时为0.31}。
颈部屈曲时BMMA患者的MCSSEP显示颈段N13反应显著降低，提示颈髓节段性功能障碍。
