gms | German Medical Science

Objective: Patients with eloquently located cerebral lesions require surgery using intraoperative motor or speech mapping with monopolar or bipolar stimulation. 50-60Hz stimulation with an Ojeman stimulator can mainly be performed by the surgeon independently,whereas monopolar stimulation requires additional trained personnel for handling of the intraoperative monitoring (IONM) system. Here,we report our first experiences using a device that can be operated by the surgeon autonomously for both intraoperative techniques.

Methods: For monopolar and bipolar cortical/subcortical stimulation two preset programmes were available and intraoperatively used. One enabling EMG real-time tracking of 8 muscles for monopolar mapping and a second programme for 60 Hz stimulation. Neither SSEP, MEP nor ECOG monitoring was available. Motor mapping was performed using a standard monopolar probe connected to the device. EMG signals were screened in real-time on the device monitor. For 60 Hz stimulation a standard bipolar stimulation probe was connected through a second port. Preoperative application of subdermal EMG needles as well as intraoperative handling of the device were performed by the surgeons independently. Postoperatively, evaluation of autonomous handling and feasibility of the device for chosen test parameters was conducted.

Results: From 04/19-11/19,40 patients with eloquently located cerebral lesions underwent surgery using the device. Regarding setup and sufficiency for cortical/subcortical monopolar and bipolar mapping the new device was evaluated as independently usable for motor and language mapping in 34 patients. In 6 patients speech testing was performed using an Ojeman stimulator. Complete resection was intraoperatively evaluated in 27 patients (73%). After matching with post-OP MRI a residual tumorvolume was demonstrated in 4 patients (15%), three patients postoperatively suffered from a new neurological deficit, two of them after using standard Ojeman stimulator, follow-ups are still pending.

Conclusion: The device was evaluated as sufficient in 85%. However, missing concurrent SSEP monitoring was seen as a severe limitation in special indications and led to exclusion of patients where extended IONM was required. Concerning grade of resection and neurological outcome results were comparable to IONM procedures using standard devices. In this first cohort surgeons were able to perform motor and speech mapping adequately and safely by independent use of the device.