The missing falx: a potential surgical pitfall during interhemispheric transcallosal approach.

One of the standard surgical approaches to lateral ventricular tumors involves interhemispheric dissection along the falx cerebri. The falx cerebri thus provides an important landmark in guiding the surgeon to the midline. Unrecognized absence of falx may lead to surgical complications. A child with tuberous sclerosis presented with refractory epilepsy and a lateral ventricular tumor. The tumor was excised by an interhemispheric trans-callosal approach. The midline falx cerebri was absent anteriorly, rendering the identification of midline difficult. The embryology of a deficient falx and its surgical implications are discussed in this short report.