Vestibular-Dependent Functions Following MRgLITT-A Single-Group Longitudinal Study

Temporal lobe epilepsy is the most common pharmaco-resistant type of epilepsy. The chance of obtaining seizure freedom after resective surgery in pharmaco-resistant mesial temporal lobe patients (mTLE) is significantly higher compared to pharmaceutical treatment (at least 50-60% compared to less than 15%). However, some factors (e.g., craniotomy) may prevent epilepsy patients undergoing surgery. A recent advancement in epilepsy surgery, i.e., magnetic resonance guided laser interstitial thermal therapy (MRgLITT), has become an attractive alternative for performance of selective amygdala-hippo-campectomy, especially because of its minimal invasiveness. Among other medial temporal lobe structures, the hippocampus is particularly important for successful processing of vestibular inputs. Nevertheless, it is still unclear whether mTLE patients who underwent MRgLITT perform worse on vestibular-dependent tests, including balancing, spatial orientation and rotational memory.

Nine patients (Age 40.1 ± 14.5; 2 females) underwent vestibular-dependent assessments before and after MRgLITT using the following test battery: (I) clinical balancing test (CBT), (II) triangle completion test (TCT) and (III) rotational memory test (RM).

We found significant improvement from pre- to post-surgery in the vestibular-dependent spatial orientation test, namely in the wheelchair condition of the triangle completion test. Additionally, the obtained effect sizes were medium to large in favor of post-surgery assessment for the majority of conditions in the three tests applied in this study, indicating that the assessment of a larger number of patients could also, potentially, lead to significant results in these cases.

This plausibility study is the first to assess vestibular-dependent balancing, spatial orientation and rotational memory functions before and after MRgLITT in mTLE patients. Even with a small sample of nine patients, significant changes and medium to high effect sizes in favor of surgery were observed. Nevertheless, prospective studies with larger sample sizes are necessary for appropriate estimation of MRgLITT effectiveness in these functional domains.