• John K Kramer, Philippa Taylor, John D Steeves, and Armin Curt.
• International Collaboration on Repair Discoveries (ICORD), Vancouver, British Columbia, Canada. jkramer@icord.org
• Neurorehabil Neural Repair. 2010 May 1; 24 (4): 309-17.

BackgroundDermatomal somatosensory evoked potentials (dSSEPs) not only provide a neurophysiological readout comparable with conventional SSEPs but also provide an opportunity to track changes in sensory function corresponding to individual dermatomes (ie, a single spinal segment) above, at, and below the level of spinal cord injury (SCI).ObjectivesThis study aimed to determine the reliability and responsiveness of dSSEPs and electrical perception thresholds (EPTs) to monitor changes in sensory function after cervical SCI.MethodsInitial and follow-up dSSEPs and EPTs were recorded from cervical dermatomes (C4-C8) of patients with traumatic tetraplegia (C3-C8; ASIA Impairment Scale A-D) during recovery after SCI (n = 18).ResultsFollow-up examination of 74 initial dSSEPs unaffected by SCI (n = 18) revealed no significant change in latency (Delta = 0.0 +/- 1.4 ms; P = .9) or EPT sensitivity (Delta = 0.1 +/- 0.8 mA; P = .3). In 41 dSSEPs initially delayed after SCI (n = 14), latencies significantly decreased on follow-up examination (Delta = -3.1 +/- 2.9 ms; P < .01) without a corresponding increase in sensitivity of the EPT (Delta = 0.2 +/- 3.4 mA; P = .7). dSSEPs that were not measurable initially were subsequently recorded in 11 dermatomes (n = 5) on follow-up examination. This conversion of abolished-to-recordable dSSEPs was often preceded by the perception of an initial EPT and associated with a concomitant recovery of EPT at follow-up.ConclusionSSEPs and EPT can be reliably recorded to monitor changes in sensory function for each individual spinal segment after cervical SCI. dSSEPs may be potentially useful to monitor the safety of a therapeutic drug or cell transplant in early-phase (I/II) clinical trials as well as document the potential efficacy of interventions where the standard neurological assessment might not detect subtle therapeutic effects.

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