Anatomical investigation of the superficial venous drainage of the suboccipital surface of the cerebellum

Surgical approaches to the fourth ventricle involve the suboccipital surface of the cerebellum, where the inferior vermian vein (IVV) and inferior hemispheric vein (IHV) are often encountered and are at risk of injury. Iatrogenic injury to these veins could thereby lead to venous infarction and other postoperative complications; however, venous anatomy of these veins remains less well characterised. A retrospective bilateral analysis of contrast-enhanced MRI was conducted for 79 patients (n = 158 hemispheres) focusing on presence, termination and diameter of these veins. Additionally, the dominant patterns of this surface were documented. These factors were then compared on the basis of laterality and sex. The IVV had an overall presence of 88.6% with no bilateral absence noted. The prevalent termination of the IVV was the straight sinus (47.9%). A single IHV was the frequent configuration (65.2%), with a maximum of 3 IHVs per hemisphere. IHVs were further investigated based on their configuration as longitudinal and transverse veins. The prevalent drainage point of the IHV was the tentorial sinus (42.8%). The mean diameter for the IVV and IHV was 1.7 ± 0.5 mm and 1.5 ± 0.4 mm, respectively. The suboccipital surface exhibited a prevalent co-dominant pattern (58.9%), followed by IVV dominant (32.3%) and IHV dominant patterns (8.9%), respectively. These findings provide clinically relevant data that will assist in surgical planning and reduce risk of iatrogenic injury during posterior fossa approaches.