The Anterior Subcallosal Approach to Third Ventricular and Suprasellar Lesions: Anatomical Description and Technical Note

Abstract

Surgical access to the third ventricle is challenging, given the depth of the operative field and close proximity of vital neural structures that must be traversed. For anterior third ventricular lesions, approach options include anterior transcallosal or transcortical, subfrontal, frontotemporal, or endonasal. The subcallosal approach, a translamina terminalis approach, is unique in that the surgical corridor is just below the corpus callosum, minimizes retraction and preserves corpus callosum integrity. Case examples are provided, and an anatomical study delineating the dimensions of the surgical corridor is performed. Two latex-injected cadaver heads were used to describe the subcallosal corridor. A magnetic resonance imaging scan was obtained and registered with neuronavigation for correlative anatomical illustration. Depth, dimensions, and cross-sectional area were measured for the subcommunicating and supracommunicating corridors. The surgical depth for anterior transcallosal, subcallosal, and subfrontal approaches was 7.5 cm, 7.7 cm, and 7.6 cm respectively. The average corridor dimensions for the subcallosal approach were 14.75 × 6.63 mm compared with 8.88 × 5.38 mm for the subcommunicating corridor. Cross-sectional area of the subcommunicating corridor was 30.62 mm(2) compared with 80.42 mm(2) for supracommunicating. This was easily enlarged to 156.62 mm(2) with gentle retraction. The anterior subcallosal approach is a safe approach for lesions of the third ventricle that avoids splitting the corpus callosum and resecting unnecessary brain and minimizes brain retraction. This corridor is superior to the traditional subfrontal approach in terms of working space and compares favorably to the anterior transcallosal approach without disrupting the corpus callosum.