P157. Incidence and predictability of motor functioning after resection of pre-centrally located brain tumours

Objective In addition to a maximum extent of resection the preservation of important functions such as motor control are the major objectives in brain tumour surgery, not least with respect to consecutive treatments such as radio- or chemotherapy which require a good clinical state of the patients. Brain mapping techniques such as functional MRI and navigated transcranial magnetic stimulation (nTMS) have facilitated a lot the preoperative planning of the resection of eloquent brain tumours. However, the clinical course after resection of precentrally located brain tumours is often associated with hardly predictable, at least transient deterioration of motor functions. Methods A case series of 10 patients (7M/3F, mean age 57.8 yrs) with precentrally located brain tumours was collected within a prospective clinical trial between 2012 and 2014. All of them underwent preoperative nTMS mapping of the tumour-adjacent M1 areas (Nexstim eXimia 4.2). Tumour volume, oedema volume, the minimal distance between tumour/ oedema and the adjacent primary motor (M1) representation (hot spot, margin of map; iPlanNet) and the resting motor threshold (RMT) were compared to the neurological outcome which was evaluated before surgery, immediately after surgery (ICU), at discharge and 3–6 months later (follow-up). Results 7/10 of the patients deteriorated immediately after surgery (ICU). At discharge, 5 patients showed an improved motor status compared to admission (example: Fig. 1 ) and 3 patients had deteriorated of which at least one patient continued with slightly deteriorated motor functioning 3 months after surgery. In 4 of these patients, the neurological symptoms were totally reversible ( Table 1 ). The preliminary analysis revealed a weak correlation ( p Conclusion Aiming at the total resection of brain tumours located anteriorly to the M1 representation, a transient motor deficit should be expected in a high percentage (70% in this study). However, the deficit usually recovers well during the first week after surgery. Mapping techniques for the supplementary and pre-motor area may improve the predictability of transient motor deficits which is not only important for diagnostic decisions but also for the patient management with respect to presurgical consultancy. A novel protocol for non-invasive SMA-mapping by repetitive nTMS is currently under pre-clinical investigation by our group and showed promising preliminary results.