The dura is opened in a U-shaped fashion and flapped toward the sagittal sinus. This allows for careful inspection for arachnoid granulations and cortical veins draining into the sinus as midline is approached. At this stage the venous anatomy along the midline can be carefully assessed. Arachnoid bands tethering these veins are sharply dissected. There are usually multiple corridors between for interhemispheric dissection. If at all possible, no draining veins are sacrificed. A self retaining retractor is placed along the medial edge of the exposed hemisphere. The cortex is buffered by a Telfa patty prior to retractor placement. A retractor along the falx to widen the operative field is not indicated to avoid cerebral venous sinus thrombosis.
Diffuse intravenous thrombosis induced by cortical vein injury and prolonged brain retraction may be important causes of unexpected delayed postoperative intracerebral hematoma in surgery using the interhemispheric or subtemporal approach 1).
The next step in the approach is the interhemispheric dissection. Identification of the paired pericallosal arteries and the glistening white surface of the corpus callosum complete the initial interhemispheric approach.
Next, an incision is made through the corpus callosum to access the lateral ventricle.
The classic incision is 2 cm long, 2.5 cm behind the genu of the corpus callosum, reliably placing the foramen of Monro in the operative field. The incision is made between the pericallosal arteries
Interhemispheric transcallosal approach.