Artikel
Continuous monitoring of corticobulbar motor evoked potentials during skull base and brainstem surgery using the double train technique
Suche in Medline nach
Autoren
-
Kathleen Seidel
- Department of Neurosurgery, Inselspital, University of Berne, Switzerland
-
Andreas Raabe
- Department of Neurosurgery, Inselspital, University of Berne, Switzerland
| Veröffentlicht: | 16. September 2010 |
|---|
Gliederung
Text
Objective: To optimize cranial nerve (CN) monitoring recording of corticobulbar motor evoked potentials (MEP) of the facial and the vagal nerve have been described recently. As conventional mapping techniques can only been applied intermittently, methods for continuous monitoring of the functional integrity of the upper and lower motor neuron for all motor CN are needed.
Methods: A consecutive series of 20 patients who underwent skull base or brainstem surgery in our department from May 2009 to January 2010 was stratified in three different groups (G): G1= acoustic neuromas (n=6), G2=tumors in or close to the cranial brainstem (n=6) and G3=tumors in or close to the caudal brainstem (n=8). The following motor CN were continuously monitored by transcranial electrical stimulation (TES): CN III (n=3), CN V (n=15), CN VI (n=3), CN VII (n=20), CN IX (n=7), CN X (n=3), CN XI (n=4) and CN XII (n=6). TES was performed with a train of five anodic stimuli, pulse duration of 500µs within one pulse and an interstimulus interval of 4.0ms. With an intertrain interval of 90ms after this first train, a single pulse was delivered called double train technique. A single pulse which already elicited a motor response was considered as a peripheral response which activated the CN directly and thus this response was not used for further monitoring.
Results: In 14 out of 20 patients (70%) corticobulbar tract (CBT) monitoring was obtained with a high reproductivity. In 3 patients (15%) monitoring of corticobulbar MEP had slight restrictions due to small MEP amplitude or high stimulation intensity. In 3 patients (15%) no continuous corticobulbar MEP could be obtained at baseline due to direct CN activation. Continuous reliable IOM was possible in the following percentage: CN III 100%, CN V 73%, CN VI 66%, CN VII 85%, CN IX 100%, CN X 100%, CN XI 75% and CN XII 83%.
Conclusions: Double train technique provides continuous online assessment of the CBT, the motor CN nuclei and the peripheral CNs in many cases. This method may increase safety of brainstem or cranial base surgery.
