Retrosigmoid transtentorial approach for accessing the mediobasal temporal region: a radiological and anatomical evaluation.

The study assesses the retrosigmoid transtentorial approach for accessing the mediobasal temporal region, hypothesizing benefits such as a shorter surgical path, reduced tissue trauma and improved ergonomic feasibility. It aims to anatomically validate the approach, compare it with existing techniques, and detail predictive radiological metrics to foresee surgical challenges, emphasizing its advantages. In eight cadaveric specimens and 100 brain imaging studies without reported cranial pathology, the tentorial and occipital angles, as well as the distances between the retrosigmoid entry point and key landmarks of the mediobasal temporal region including the temporal pole, temporal horn, and inferior choroidal point were measured. The cadaveric dissections were documented photographically, and the inferomedial exposure of the mediobasal temporal region through the retrosigmoid transtentorial approach was evaluated. The anatomical limitations of this approach were identified, and its surgical safety, advantages, and drawbacks were compared with those of existing approaches. Radiological analysis of the 100 brain MRIs revealed a mean tentorial angle of 41.76° ± 6.8° and an occipital angle of 114.7° ± 8.4°. The average distances from the retrosigmoid entry point (REP) to key anatomical landmarks were as follows: to the temporal pole (TmP), 88.22 ± 9.6 mm; to the temporal horn (Th), 63.84 ± 6.1 mm; and to the inferior choroidal point (IchP), 64.67 ± 6.08 mm. Cadaveric measurements yielded similar findings. The mean tentorial angle was 36.88° ± 4.2° and the occipital angle was 108.86° ± 4.1°. The distances from REP to IchP, Th, and TmP were 68.93 ± 6.8 mm, 68.29 ± 6.6 mm, and 85.21 ± 5.8 mm, respectively.