The interhemispheric fissure-surgical outcome of interhemispheric approaches.

Exposure of the anterior skull base is challenging due to strategic structures. The interhemispheric approach (IHA) has turned out to be a feasible technique. We report our experience with IHAs in patients with extraaxial lesions (EAL). We performed a retrospective chart review at a tertiary neurosurgical center between April 2009 and March 2020. We included patients with resection of EAL through IHAs concentrating on surgical technique, complete resection rate, postoperative outcome, and complications. Seventy-four patients resected by an IHA were included: 49 (66.2%) frontal (FIA), nine (12.1%) parietooccipital (PIA), and 16 (21.6%) frontobasal IHAs (FBIAs). Median age at time of surgery was 59 years (range 16-88 years), 47 (63.5%) female and 27 (36.5%) male. Complete resection rate was 83.8% (FIA 89.8%, PIA 55.6%, FBIA 81.3%). Rate of new minor deficits was 17.6%, rate of major deficits 5.4%, total rate 23.0%. 51 (68.9%) WHO°I meningiomas, ten (13.5%) WHO°II meningiomas, two (2.7%) WHO°III meningiomas, nine (12.2%) metastases, one (1.4%) sarcoma, and one (1.4%) local adenocarcinoma were resected. Total complication rate was 27.0%. Rate of major complications requiring intervention was 9.6%. Mean follow-up was 34.2 (± 33.2) months. In patients with lesions of the interhemispheric fissure, overall morbidity and complications are comparatively high. Extensions of IHAs with potential even higher morbidity are not necessary though; we support the use of standardized IHAs. Our findings suggest regular usage of relatively feasible IHAs for a satisfying outcome. Invasive, complicated, or contralateral trajectories were not needed.