Somatosensory and magnetic evoked potentials in a postoperative paraparetic patient: case report

Somatosensory evoked potential (SSEP) testing is increasingly being used to test for spinal cord injuries and to monitor spinal surgery to reduce the risk of paraplegia. It is a sensory test, but it is assumed that any process severe enough to affect the motor tracts will also affect the sensory tracts and, therefore, be identified. Increasingly, however, isolated motor-tract involvement has been reported. A new technique, magnetic coil stimulation of the cortex, directly monitors the motor tracts. We report a case where the SSEP was normal although the magnetic motor-evoked potential was abnormal, supporting the hypothesis that direct testing of motor tracts may be advantageous.