Yiannikas Con, Vucic Steve
Department of Neurology, Concord Hospital, Hospital Road, Concord, 2139 Sydney, Australia.
Prince of Wales Medical Research Institute and Department of Neurology, Westmead Hospital, Western Clinical School, University of Sydney, Australia.
Muscle Nerve. 2008 Nov;38(5):1447-1454. doi: 10.1002/mus.21078.
Chronic acquired demyelinating polyneuropathy (CADP) is a heterogeneous syndrome that may be classified into a number of subtypes. Somatosensory evoked potentials (SSEPs) assess proximal segments of sensory nerves, inadequately assessed by routine nerve conduction studies (NCSs). The aim of the present study was to determine the utility of SSEPs in diagnosing and classifying different CADP subtypes. Forty-seven patients with CADP were studied and classified in five groups based on conventional NCSs and SSEPs. Some patients in Group 1 were initially misdiagnosed as having either motor neuron disease or multifocal motor neuropathy due to normal sensory NCSs, but they exhibited abnormal tibial and median nerve SSEPs, as evidenced by marked prolongation or absence of peripheral potentials (N9-median nerve, and N20-tibial nerve). These were reclassified as having chronic inflammatory demyelinating neuropathy (CIDP). In CIDP patients (Group 2), SSEPs were abnormal, thereby confirming the presence of demyelination in the proximal peripheral nerves. Patients with distal acquired demyelinating neuropathy (DADS) (Group 3), as defined by conventional NCS, exhibited abnormal SSEPs when anti-MAG antibodies were present. Anti-MAG-negative DADS patients (Group 3) had normal SSEPs. In the pure sensory ataxic group (Group 4), SSEP studies disclosed poorly formed and delayed cortical potentials with absent lumbar (N20) potentials, thereby suggesting the presence of proximal demyelination. SSEPs were normal in the pure motor CIDP and multifocal motor neuropathy patients (MMN) (Group 5), thereby differentiating asymmetric forms of CIDP from MMN. These findings suggest that SSEPs may be an important complementary investigation to conventional NCSs in the diagnosis of CADP.
慢性获得性脱髓鞘性多发性神经病（CADP）是一种异质性综合征，可分为多个亚型。体感诱发电位（SSEP）用于评估感觉神经的近端节段，而常规神经传导研究（NCS）对其评估并不充分。本研究的目的是确定SSEP在诊断和分类不同CADP亚型中的作用。对47例CADP患者进行了研究，并根据传统NCS和SSEP分为五组。第1组中的一些患者最初因感觉NCS正常而被误诊为运动神经元病或多灶性运动神经病，但他们的胫神经和正中神经SSEP异常，表现为外周电位（正中神经N9和胫神经N20）明显延长或缺失。这些患者被重新分类为慢性炎症性脱髓鞘性神经病（CIDP）。在CIDP患者（第2组）中，SSEP异常，从而证实近端周围神经存在脱髓鞘。根据传统NCS定义的远端获得性脱髓鞘性神经病（DADS）患者（第３组），当存在抗MAG抗体时SSEP异常。抗MAG阴性的DADS患者（第３组）SSEP正常。在纯感觉性共济失调组（第4组）中，SSEP研究显示皮质电位形成不良且延迟，腰段（N20）电位缺失，从而提示近端脱髓鞘的存在。纯运动性CIDP和多灶性运动神经病患者（MMN）（第5组）的SSEP正常，从而将不对称形式的CIDP与MMN区分开来。这些发现表明，在CADP的诊断中，SSEP可能是对传统NCS的一项重要补充检查。
