Interhemispheric Fissure Dissection

In patient with a chronic hydrocephalus, very frequently the two cingulate gyri are very adherent and very, very careful dissection is necessary in order to avoid injury to the cingulate gyri and opening the pericallosal cistern and the identification of the pericallosal artery. In this case, the first one to come into view is the left pericallosal artery. After identification of the left pericallosal artery, we continue the dissection. We identify the right pericallosal artery, and we identify the white ivory color of the corpus callosum that is very well different from the color of the cortex or the cingulate gyri.

The dissection of the pericallosal arteries is continued, and the corpus callosum is exposed on the larger area in order to identify sufficient extension of two centimeters standard callosotomy. The dissection of the pericallosal cistern is continued anteriorly in order to dissect the right and the left pericallosal artery and the larger dissection of the fissure is important in order to avoid injury of excessive retraction during surgery and any possible damage to the surrounding structures during the surgical maneuvers in the depth of the surgical corridor. The right pericallosal artery here is followed until the most anterior part of the surgical field and the corpus callosum is exposed on the area that is sufficient.

The pericallosal arteries are gently retracted on the right and on the left, and the corpus callosum is exposed in a sufficient way in order to allow the callosotomy. Interhemispheric fissure is dissected further posteriorly in order to separate better the two cingulate gyri and avoiding the possible lesion to the structure and possible bleeding due to excessive retraction of structures that have not been properly dissected before. You see how adherent are the two cingulate gyri in this patient with chronic hydrocephalus.

After the careful dissection and the careful identification of the fissure, of the separation between the two cingulate gyri, we can further proceed with a dissection posteriorly in order to have the largest possible view of corpus callosum. Dissection, as you see, is very, very careful when the cingulate gyri are so adherent to each other, but at the end, we obtain very nice separation of the left hemisphere from the right hemisphere and a very nice exposition of the whole middle part of the corpus callosum where we can choose to perform our callosotomy based on the neuro navigation.