Alarm Value of Somatosensory Evoked Potential in Idiopathic Scoliosis Surgery.

BACKGROUND: Somatosensory evoked potential (SSEP) monitoring is performed to examine postoperative clinical findings when a monitoring event was noted intraoperatively and to ascertain the alarm threshold for intraoperative neural damage. METHODS: The tibial SSEP of both lower limbs was recorded intraoperatively in patients with idiopathic scoliosis. Change of SSEP amplitude as opposed to the baseline was categorized into 4 levels: decrease <40%, decrease of 40%-50%, decrease of 50%-60%, and decrease >60%. Postoperative neurologic function of patients was examined and compared with SSEP data. RESULTS: The baseline amplitude before incision was significantly different from the amplitude after spine exposure. An amplitude reduction of >60% during scoliosis correction procedures was observed in 6 legs, and 4 of them had postoperative deterioration in motor status. As the measure of threshold for alarm, an amplitude reduction of >50% compared with baseline resulted in more false-positive outcomes compared with amplitude attenuation of >60%. CONCLUSIONS: Compared with the traditional SSEP baseline before skin incision, the baseline acquired after spine exposure results in more accurate monitoring. A >60% decrease in SSEP amplitude could be a more suitable alarm threshold.

A Rare Complication of Spine Surgery: Guillain-Barré Syndrome.

OBJECTIVE: Since little has been reported about Guillain-Barré syndrome (GBS) after spine surgery, we sought to determine some of the clinical features and the management of the condition. METHODS: A total of 4 cases of GBS after spine surgery were included. The medical charts of the patients were reviewed to obtain demographic and clinical details. All the patients underwent neurologic and electrophysiologic examinations and were followed up after surgery. RESULTS: The onset of symptoms about GBS was 2-7 days after the operation. Neurologic evaluation showed weaknesses of upper and lower extremities and repeal of tendon reflexes. The patients exhibited typical clinical symptoms and signs of GBS and electromyographic findings. Lumbar puncture was performed in 2 cases, and cerebrospinal fluid examination showed albuminocytological dissociation. All the 4 patients were diagnosed as GBS on the basis of typical clinical, laboratory, and electrophysiologic findings. Intravenous immunoglobulin was instituted. At follow-up, one patient needed ventilator support; one patient could transfer from bed to chair; one walked with assistive devices; and the remaining patient had residual minor neurologic deficits. CONCLUSIONS: These cases warn surgeons to be alert to the association of GBS and spine surgery. On the basis of our experience, we recommend consideration of this rare diagnosis in patients with paralysis after spine surgery.