[P3-140] The utility of short-lantency somatosensory evoked potentials in diagnosis of chronic inflammatory demyelinating polyneuropathy
Objective: The diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) has no especially biomaker.The diagnosis is based on clinical, biological, and electrodiagnostic features. However, electrodiagnostic (EDX) criteria rely on motor conduction velocities assessed by nerve conduction studies (NCS) and may fail to show demyelination either because of secondary axonal degeneration or when motor nerve conduction is normal in pure sensory forms of polyradiculopathy. In these atypical forms, other diagnostic tools are available. In this context somatosensory evoked potentials (SSEPs) that explore conduction in sensory fibers from the periphery to the somatosensory cortex represent an alternative tool for CIDP diagnosis ,it can detect proximal nerve inflammatory demyelinating or axonal degeneration. In this study ,we investigate the utility of short-lantency somatosensory evoked potentials in diagnosis of CIDP. Methods: We conducted 48 confirmed or possible CIDP children to have nerve conduction examinations and short-lantency somatosensory evoked potentials(SSEPs),and compare the positive rate of two examinations.The nerve conduction examinations include at least 4 motor nerves and 2 sensory nerves. All SSEP studies were carried out and interpreted according to the guidelines of the International Federation of Clinical Neurophysiology .SSEPs were recorded after stimulation of median nerves at the wrist and tibial nerves at the ankle.The main parameters are
N13,N22 amplitude and latency. Peripheral and spinal SSEP data were used to classify results into 3 groups according to their diagnostic impact: Normal SSEPs: SSEPs with preserved peripheral potentials at elbow, Erb point, and politeal fossa; normal spinal N13 or N22 latencies since they reflect normal peripheral and dorsal root conduction.Confirmative SSEPs: We classified as confirmative of CIDP diagnosis: 1) median nerve SSEPs with a normal peripheral potential at the elbow and delayed or decreased brachial plexus responses with a abnormal N13 spinal potential reflecting conduction slowing and/or dispersion of the afferent volley in brachial plexus trunks and/or dorsal roots; and 2) tibial nerve SSEPs with a preserved N8 potential and an absent N22 spinal potential reflecting a conduction abnormality in proximal segments of the tibial nerve, lumbosacral plexus trunks, and/or dorsal roots. Non-applicable SSEPs: We classified SSEPs as non-applicable when there was bilateral absence of peripheral potentials at the elbow and in the popliteal fossa.We gathered 40 control healthy group with no statistical difference in height and age to CIDP group.All the 40 healthy group examination SSEPs and compare the results between two groups.We also record the immunotherapy results in possible CIDP children. Results:Among 48 CIDP children, 35 cases were demyelination CIDP which indicated motor and sensory nerve demyelination.8 cases were sensory nerve neuropathy and 5 cases were axonal sensory-motor neuropathy. 35 cases were fulfill CIDP electrodiagnostic (EDX) criterian whereas SSEP abnormal were seen in 40 cases,there were no statistical differencen between two examinations（X2=1.52,P=0.22）.In 8 sensory nerve neruropathy cases and 5 axonal motor and sensory neuropathy ,ssep were abnormal whereas no motor nerve demyelination are found in EDX . Conclusions: SSEP is as usefui as EDX, it can used in diagnosis in CIDP, especially in pure sensory nerve neuropathy and axonal motor and sensory neuropathy.
N13,N22 amplitude and latency. Peripheral and spinal SSEP data were used to classify results into 3 groups according to their diagnostic impact: Normal SSEPs: SSEPs with preserved peripheral potentials at elbow, Erb point, and politeal fossa; normal spinal N13 or N22 latencies since they reflect normal peripheral and dorsal root conduction.Confirmative SSEPs: We classified as confirmative of CIDP diagnosis: 1) median nerve SSEPs with a normal peripheral potential at the elbow and delayed or decreased brachial plexus responses with a abnormal N13 spinal potential reflecting conduction slowing and/or dispersion of the afferent volley in brachial plexus trunks and/or dorsal roots; and 2) tibial nerve SSEPs with a preserved N8 potential and an absent N22 spinal potential reflecting a conduction abnormality in proximal segments of the tibial nerve, lumbosacral plexus trunks, and/or dorsal roots. Non-applicable SSEPs: We classified SSEPs as non-applicable when there was bilateral absence of peripheral potentials at the elbow and in the popliteal fossa.We gathered 40 control healthy group with no statistical difference in height and age to CIDP group.All the 40 healthy group examination SSEPs and compare the results between two groups.We also record the immunotherapy results in possible CIDP children. Results:Among 48 CIDP children, 35 cases were demyelination CIDP which indicated motor and sensory nerve demyelination.8 cases were sensory nerve neuropathy and 5 cases were axonal sensory-motor neuropathy. 35 cases were fulfill CIDP electrodiagnostic (EDX) criterian whereas SSEP abnormal were seen in 40 cases,there were no statistical differencen between two examinations（X2=1.52,P=0.22）.In 8 sensory nerve neruropathy cases and 5 axonal motor and sensory neuropathy ,ssep were abnormal whereas no motor nerve demyelination are found in EDX . Conclusions: SSEP is as usefui as EDX, it can used in diagnosis in CIDP, especially in pure sensory nerve neuropathy and axonal motor and sensory neuropathy.