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Background motor cortex transcranial electric stimulation in Intraoperative monitoring (IOM) is used to assess the corticospinal functional state by measuring the fast axons conduction (registration of D-wave), motor evoked potentials (MEPs) threshold and amplitude. While D-wave is considered to be a stable parameter independent of anesthesia, the informativeness of MEPs amplitude is controversial due to its instability, especially when in cervical spine surgery. Material and methods 20 patients with cervical degenerative myelopathy underwent surgical decompression with anterior cervical discectomy. In Group 1 (10 patients) the TIVA anaestiological protocol was used and in Group 2 (10 patients) the Sevoflurane 0.6–0.8 MAC was added. In all patients before intubation MEPs threshold for m. abd. pollicis brevis, m.add. digiti minimi, m. tibialis anterior, m. add. hallucis were assessed in response to a train of 5 pulses with a duration of 0.5 ms and inter-pulse interval 2 ms. Results In the course of operation MEPs threshold increase and amplitude decrease were detected in all patients Group2. In 6 patients of Group 1 (4 – unilaterally, 2 – bilaterally) and 4 patients of Group 2 (2– unilaterally, 2 – bilaterally) during surgery MEPs responses were lost; though there were observed no signs of additional neurological deficit after surgery. Unilateral MEP changes in patients operated on cervical spine can be attributed to compression of the plexus related to the position and patient fixation; bilateral – because of traction manipulations and spinal cord ischemia. Conclusions for detection of intraoperational ischemia Multimodal IOM will be preferred. |
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