gms | German Medical Science

Objective: Silent periods (SP's) in the neurophysiological assessment of Syringomyelia have been introduced with satisfactory results, giving early confirmation of disrupted spinothalamic fibers that convey pain and sensation. However the ability of the SP's to recover after resolution of the syringomyelia is not known.

Methods: Thirty patients with various forms of cervical syringomyelia (chiari malformation, intramedullary tumour, arachnopathic changes) were included in the study: Routine electrophysiological measurements pre- and postoperative (3–9 month after surgery) were applied including SEP and MEP recordings for the upper extremities. SP’s were recorded from the pollicis brevis muscle and electrical stimuli were applied to the ipsilateral digiti II.

Results: Resolution of the syrinx cavity could be noted in 80% of patients and concomitant clinical stabilization. Electrophysiology measurements show some degree of improvement in SSEP/MEP when impaired pre-operatively, although patients with intramedullary surgery first worsened and after a rehabilitation period of 6 month recover. Patients with intact SP's preoperatively have a chance to maintain, patients with distorted SP’s (increased latency/late onset) can recover, however lost silent periods never recurred.

Conclusions: Upper extremity silent period testing is a sensitive neurophysiological technique and an invaluable tool for preoperative assessment of Syringomyelia. As the thin myelinated spinothalamic tract fibers will barely regenerate, as do the clinical signs of neuropathic pain, abolished silent periods do not recover after resolution of the syrinx.