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Table 2 Method for recording of multimodal evoked potentials

From: Assessment of bone marrow-derived Cellular Therapy in progressive Multiple Sclerosis (ACTiMuS): study protocol for a randomised controlled trial

Visual evoked potentials (VEPs) will be evoked with a rear-projected checkerboard pattern using an opto-mechanical device subtending 30 degrees at the retina, check-size 1 degree, white brightness of 150cdm−2 and contrast 87.5 %.
Monaural stimulation will be delivered via earphones to each side with rarefaction click stimuli of 0.1 ms duration at an intensity of 75 dB above the subjective hearing threshold whilst the contralateral ear is masked with white noise.
Sensory evoked potentials (SEPs) will be obtained by delivering electrical stimulation with square wave pulses of 0.2 ms duration to the median and the posterior tibial nerves, at the wrist and ankle respectively.
Motor evoked potentials (MEPs) will be recorded from electrodes situated over the abductor pollicis brevis muscle in the hand and the abductor hallucis in the foot using a 9 cm circular coil held over the vertex. The central motor conduction time (CMCT) will be calculated by subtracting ½(M + F + 1) from the MEP latency where M is the distal motor latency and F is the minimum F wave latency.
The GEP score will then be calculated as the sum of left and right brainstem auditory evoked potential (BSAEP) and VEP scores (0–12) and left and right upper and lower SEPs (0–12) and CMCTs (0–12).