Application Of Evoked Potential Monitoring In Operations On Lesions Around Brainstem And Central Region

Part I Application of intraoperative evoked potential monitoring in tumors around brainstemObjective: To investigate the applied value of evoked potential monitoring in surgery for tumors around the brainstem.Methods: In 21 patients receiving surgery for tumors around brainstem, brainstem auditory evoked potential (BAEP), somatosensory evoked potential (SEP) and motor evoked potential (MEP) were selectively monitored. The operation should be modified or even stopped when the waveforms changed significantly.Results: The electrophysiological monitoring was performed successfully in all the patients. The waveforms of BAEP changed intraoperatively in 3 patients, 2 out of them recovered gradually without new neurologic deficits occurred postoperatively, and 1 whose BAEP waveform did not recover underwent transient consciousness disturbance for 3 days. Changed waveforms of SEP were found consistently in 1 patient who underwent postoperative persistent coma. Changes of MEP waveforms were detected in 1 case and returned to normal after regulation of electrical stimulation.Conclusion: Monitoring of multiple evoked potentials can protect brainstem functions promptly and effectively in surgery for tumors around brainstem. PARTâ…¡Primary application of evoked potential monitoring and neuronavigation in operations on lesions in the central regionObjective: To valuate the clinical application of evoked potential monitoring and neuronavigation in operations on lesions in the central region.Methods: During the surgery of ten patients with lesions located in the central region, eloquent cortex was located selectively by neuronavigation and neurophysiological monitoring techniques including scalp somatosensory evoked potentials, cortical somatosensory evoked potentials and direct cortical electrical stimulation.Results:Intraoperatively, neuronavigation was performed on 8 patients, 4 of whom in addition accepted functional neuronavigation illustrating pyramidal tracts. Moreover, scalp somatosensory evoked potentials were monitored on 7 patients, and on 1 of them decreased potentials were observed and were well recovered after surgical manipulation was properly adjusted. Cortical somatosensory evoked potentials were monitored in 8 cases, and in 5 of them somatosensory evoked potentials phase reversal or similar waves were detected. Scalp motor evoked potentials and direct cortical electrical stimulation were respectively performed on 2 and 4 patients, 1 of whom showed corresponding limb movements and (or) EMG responses. Among 11 lesions, 7 were totally resected, with 1 near total resected and 3 partially resected. Postoperatively, no patients showed deteriorated or new developed symptoms. Furthermore, 8 patients'symptoms were improved successfully.Conclusion: In operations on lesions in the intracranial central region, application of evoked potential monitoring and neuronavigation is critical to precisely localize lesions and eloquent sensorimotor structures in brain, and therefore is beneficial to greatly improve surgical effects, to ensure the safety of surgery, and to reduce postoperative neurological deficits as well.