Abstract
Objectives: To evaluate the feasibility, sensitivity and specificity of IOM for IDEM and ED metastatic spinal tumours, and to assess usefulness of SSEP for patients in whom MEP was not measurable. Methods and materials: One hundred and one consecutive patients with IDEM and ED metastatic spinal tumours at the cord level (C1 to L1) received surgery under SSEP and/or MEP was included. Feasibility of IOM was defined to be negative in case of no measurable MEP or SSEP under general anaesthesia after confirmation of reversal of neuromuscular block. More than 50% change of MEP or SSEP amplitude and more than 10% delay of SSEP latency were evaluated as positive signs of IOM change. Results: MEP was measurable in 74 out of 101 trials, thus feasibility is 73%. Patient with normal motor power showed higher feasibility than those with motor power 3 or less. (93% vs. 39%) Among 74 patients with measurable MEP, 19 patients showed positive MEP change and 14 patients got worse of their motor power postoperatively.
Highlights
The intraoperative neurophysiologic monitoring (IOM), represented by motor evoked potential (MEP) and somatosensory evoked potential (SSEP), provides the functional integrity of spinal cord, and has become one of the essential procedures to avoid neural injury during spinal surgery [1,2,3,4].The importance of SSEP was appreciated earlier in the spinal deformity surgery, at which the correction of deformity and fixation might cause stretching or compression of the spinal cord [1,2,5]
Whereas SSEP can be monitored in larger proportion of patients than MEP even in patients with motor deficit as it is less vulnerable to systemic conditions including neuro-muscular junction and its tract is composed of relatively numerous number of neurons in ascending dorsal column
Her lower extremity was plegic recovered over a couple of months to grade 1-2. Her lower extremity motor power could not have recovered to preoperative level until she died of lung metastasis 2 years after. This is a retrospective study, we firstly analysed the feasibility of IOM in patients with an intradural extramedullary (IDEM) or ED metastatic spinal tumour compressing spinal cord according to preoperative motor power grade along with sensitivity and specificity of both MEP and SSEP for postoperative motor deficit
Summary
The intraoperative neurophysiologic monitoring (IOM), represented by motor evoked potential (MEP) and somatosensory evoked potential (SSEP), provides the functional integrity of spinal cord, and has become one of the essential procedures to avoid neural injury during spinal surgery [1,2,3,4].The importance of SSEP was appreciated earlier in the spinal deformity surgery, at which the correction of deformity and fixation might cause stretching or compression of the spinal cord [1,2,5]. The intraoperative neurophysiologic monitoring (IOM), represented by motor evoked potential (MEP) and somatosensory evoked potential (SSEP), provides the functional integrity of spinal cord, and has become one of the essential procedures to avoid neural injury during spinal surgery [1,2,3,4]. IOM for IDEM and ED metastatic spinal tumour surgery could purely reflect net results of surgical condition. Whereas SSEP can be monitored in larger proportion of patients than MEP even in patients with motor deficit as it is less vulnerable to systemic conditions including neuro-muscular junction and its tract is composed of relatively numerous number of neurons in ascending dorsal column. In IDEM and ED metastatic spinal tumour surgery, SSEP might reflect the functional integrity of dorsal column and of motor tract as long as the spinal cord maintains its anatomical integrity throughout the surgery. Reports of IOM for spinal tumour surgery is relatively rare and frequently mixed up with other spinal procedure, only a few of separate study of reporting IOM result of IDEM of ED metastatic spinal tumour surgery can be found [8,9,10]
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