gms | German Medical Science

Objective: Despite the close correlation between intraoperative changes in Motor (MEPs) and Somatosensory Evoked Potentials (SEPs; “EPs”) and postoperative clinical status, it is difficult to distinguish transient versus permanent neurological deficit. This study assesses, whether S100b – a glial derivated protein – might be helpful as an additional marker in intradural and intramedullary spinal tumor surgery to predict long-term outcome.

Methods: Significant intraoperative EP-changes (SEP-amplitude decrement >50% or an MEP loss); the S100b blood serum concentration on perioperative days -1, 0, 1, 3 and 5 (pathological increase ≥0,09 µg/l ≥2 postoperative days) and the clinical status (postoperatively at day 1 and >year after discharge) were evaluated and correlated.

Results: 19 patients (7 m, 12 f; 54±32 years) undergoing intramedullary (6) or intradural (13) cervical or thoracic spinal surgery were studied. 10/19 (53%) patients had no changes of EPs and S100b with a long-term clinical improvement. 4/19 (21%) patients had changes of EPs and S100b with a permanent neurological deterioration in 3 patients and delayed clinical improvement in one patient. 3/19 (16%) patients had only an S100b increase with an unchanged (1) or improved long-term outcome (2). 2/19 (10%) patients had EP changes and an unchanged S100b with either an unchanged or worsened clinical outcome.

Conclusions: Intraoperatively unchanged EPs followed by a normal S100b may predict neurological improvement. In case of unchanged EPs, an increased S100b may imply a relatively constant progression, not indicating a relevant spinal cord lesion. Increased S100b and EP-changes are likely to be followed by a long-term neurological deficit indicating a relevant spinal cord lesion. In summary, the combined use of S100b and EPs may be helpful in the evaluation of the severity of adverse spinal cord damage following surgery.