gms | German Medical Science

Spinal cord lipomas are a common cause of cord tethering that can lead to progressive neurological deficits such as motor or sensory deficits or bladder dysfunction. Therefore, especially in patients with only minor preoperative neurological deficits, tumour removal should be combined with intraoperative monitoring techniques to prevent postoperative neurological deterioration.

Nineteen patients (mean age: 24,9 y) have been operated on spinal cord lipomas. Three lipomas were located in the thoracic spinal cord, the remaining 16 being in the conus. Three patients were almost asymptomatic at time of surgery, whereas the others were suffering from pain (14), bladder dysfunction (12), motor dysfunctions (11) or neuro-orthopaedic deformities (8).

In all 19 patients tumour removal was performed under continuous intraoperative neurophysiological monitoring. Intraoperatively, nerve roots and neural tissue were identified by electromyography (free-run EMG) or direct electrical stimulation (triggered EMG) in all 19 patients. Somatosensory evoked potentials were successfully monitored in 14 of the 19 patients. Transcranial electrical stimulation evoked CMAPs in 10 patients. Further monitoring techniques tested were intraoperative reflex and F-response monitoring as well as descending neurogenic evoked potentials.

SSEP showed to be neither specific nor sensitive to individual nerve root function. Transcranial electrical stimulation activates less than 10 percent of the motor axons in the motor nerve root and therefore proved to be not usefull in the surgery of spinal lipomas. Only free-run EMG as well as triggered EMG reliably helped to identify where the motor axons lie within the tumor and/or scar tissue.