Two-Stage Surgery (Paramedian Supracerebellar Infratentorial or Interhemispheric Occipital Transtentorial Approach) for Management of Falcotentorial Meningioma; An Anatomical Morphometrical Study and Technical Note With Illustrative Surgical Cases

Objective: The posterior incisural space (PIS) represent a neurosurgical challenge given its depth and complex anatomy. To access the PIS, the midline supracerebellar infratentorial approach (MSIA) has been traditionally applied, but several neurosurgeons propose that a paramedian supracerebellar infratentorial (PSIA) or interhemispheric occipital transtentorial approach (IOTA) might enable a better accessibility. We systematically compared these 3 approaches in cadaver specimens and present the application of PLSIA/IOTA as staged surgery for resection of complex falcotentorial meningiomas.

Methods: We performed eight cadaver dissections assessing morphometrical features related to exposure, operability, brain retraction and obstacles to the PIS during MSIA, PSIA and IOTA. Additionally, we operated two patients presenting supra-infratentorial growing falcotentorial meningiomas through a two-staged endoscopic assisted PSIA combined with IOTA.

Results: Superficial vermian draining veins at an average depth of 11.38 ± 1.5 mm and the superior vermian vein (SVV) at a depth of 54.13 ± 4.12 mm limited the access to the PIS during MSIA. MSIA required sacrifice of these veins and retraction of the vermian culmen of 20.88 ± 2.03 mm to obtain comparable operability indexes (as described by Salma et al) to PSIA and IOTA1. Cerebellar and occipital lobe retraction averaged 14.31 ± 1.014 mm and 14.81 ± 1.17 mm during PSIA and IOTA, respectively, which was significantly lower than during MSIA (both p < 0.001). Only few tiny veins were encountered along the access through PSIA and IOTA. The application of PSIA provided high operability scores around the pineal gland, the ipsilateral colliculus and splenium, and acceptable scores on contralateral structures. The main advantage of the IOTA was improving surgical maneuvers along the ipsilateral splenium. Staged PSIA and IOTA enabled successful resection of both falcotentorial meningiomas. Postoperative course was uneventful and patients recovered without new neurological deficits.

Conclusion: Although IOTA and PSIA may render some difficulties related to tentorial incision and spatial orientation, these approaches may provide advantages in terms of brain retraction, vein sacrifice and operability. Their application can be effective for staged surgery of complex falcotentorial meningiomas.

Publication History

Article published online:
15 February 2022