gms | German Medical Science

Objective: Intraoperative neurophysiological monitoring (IONM) has been shown to enhance patient safety in complex neurosurgical vascular cases such as clipping of giant aneurysms or surgery for brain arteriovenous malformations. It remains unclear, however, if IONM is necessary in routine vascular cases, especially in high volume neurovascular centers. We therefore conducted a chart review to retrospectively analyze whether monitoring modalities had an impact on the surgical workflow, showed any abnormalities during routine clipping surgery and whether this was correlated with clinical outcome.

Method: 139 cases with elective aneurysm clipping were identified since introduction of IONM in neurovascular procedures in our department. Motor-evoked potentials (MEP), somatosensory evoked potentials, electromyography and facial-nerve MEP were monitored and analyzed for intraoperative abnormities like diminishing wave amplitudes.

Results: In 130 cases (93.5%) IONM showed no abnormalities. Still, 7 of these patients had a new neurological deficit after the operation. 4 of these patients had a one-sided paresis, 2 had a speech disorder and 1 patient had to be transferred to a rehabilitation ICU because of a persistent comatose state. Furthermore, an additional 5 patients with uneventful IONM had asymptomatic ischemic areas on postoperative CT scans. 9 patients (6.5%) had intraoperative abnormalities on IONM. Of these patients, 4 had a new neurological deficit after the operation, whereas 5 had no deficit. Taken together, IONM had a sensitivity for a new neurological deficit after a routine vascular procedure of 36.3% with a specificity of 96.1%. Positive predictive value was 44.4%.

Conclusions: In summary, our retrospectively analyzed case series suggests that the value of IONM in routine vascular cases in a high-volume tertiary-care center might be limited. Further prospective studies to substantiate this finding seem justified.