The impact of subdural air collection on intraoperative motor and somatosensory evoked potentials: fact or myth?
- نوع فایل : کتاب
- زبان : انگلیسی
- مؤلف : Marcus André Acioly , Florian H. Ebner , Till K. Hauser , Marina Liebsch , Carlos Henrique Carvalho , Alireza Gharabaghi , Marcos Tatagiba
- چاپ و سال / کشور: 2011
Description
Background Surgery in the semi-sitting position is susceptible to changes in motor (MEP) and somatosensory evoked potentials (SEPs), which are not related to neurological impairment. These changes have been suggested to be caused by the insulating effect of subdural air collection. This study sought to investigate the correlation of MEP and SEP final-to-baseline amplitude ratios to postoperative volumetry of frontoparietal subdural air collection. Methods Median nerve SEP and hand MEP findings of 47 patients operated on in the semi-sitting position were compared with 7 patients operated on in the supine position. Computed tomography was routinely performed on the 1st postoperative day in all patients, and subdural air volumetry was calculated. Final-to-baseline MEP and SEP amplitude ratios were calculated and correlated to subdural air volumetry. Findings SEP changed in 12 patients, and MEP changed in 7 patients. Postoperative subdural air collections were significantly different between the groups (semi-sitting group, mean 31.2 cm3; supine group, mean 2 cm3; p=0.000). For the SEP ratios, a moderate negative correlation with subdural volumetry was found in the semi-sitting group (p=0.044). Conversely, there was no correlation in the subset of patients with SEP attenuation (p=0.846). As concerns the MEP ratios, no correlation was demonstrated in any group (semi-sitting, p=0.967; supine, p=0.193). Conclusions Although SEP amplitude reductions were associated with large subdural air collections, this was not observed in the subset of patients with SEP attenuation and for the MEP monitoring, suggesting other pathophysiological mechanisms, such as brain shift, for the artificial amplitude reduction.
Acta Neurochir (2011) 153:1077–1085 DOI 10.1007/s00701-011-0960-2 Received: 23 October 2010 / Accepted: 28 January 2011 / Published online: 18 February 2011 # Springer-Verlag 2011
