gms | German Medical Science

Objective: Highly elevated serum levels of creatine kinase (CK) following surgery may lead to renal dysfunction. High CK levels are known to occur after neurosurgical interventions, but a consensus on possible risk factors is still lacking. Here we investigate risk factors for excess CK in patients undergoing high risk surgical positioning with a special focus on the influence of motor evoked potentials (MEPs) as a modality of intraoperative neurophysiological monitoring (IONM).

Method: We included all patients undergoing elective surgery in lateral position (park bench) between 2010 and 2012 and where IONM was performed and where postoperative CK-levels were available. In these patients, the anaesthesia regimen excluded muscle relaxation. Medical charts were reviewed retrospectively for patient characteristics, CK levels and indicators of renal dysfunction. The MEP response intensity was estimated by the RMS of the EMG signals. Data were analyzed by multivariate logistic regression.

Results: There were 96 patients (55 female, mean age 50 years) who met the inclusion criteria. The maximal CK level (CKmax) occurred on postoperative days 2 or 3 (mean 1763 U/L, range: 53-7172 U/L). In a multivariate linear regression model, log(CKmax) correlated positively with duration of surgery (p<0.001) and BMI (p=0.007), and negatively with age (p=0.007). There was no significant association between MEP response intensity of the muscles at risk and log(CKmax). We did not observe impaired renal function.

Conclusions: MEP was not among relevant risk factors for elevated CK levels. Surgical positioning should be especially careful for long surgeries on young patients with high BMI, in particular if operated in lateral position.