Interhemispheric parietooccipital approach

• Commentary: The Case Series of Contralateral Interhemispheric Transfalcine Approach to Medial Parietooccipital Pathologies: Surgical Technique and Results
• The Case Series of Contralateral Interhemispheric Transfalcine Approach to Medial Parietooccipital Pathologies: Surgical Technique and Results
• Posterior Interhemispheric Parietooccipital Fissure Approach for the Posterior Medial Temporal Glioblastoma: 2-Dimensional Operative Video
• Morphometry of depth of interhemispheric fissure on Indian cadaveric brain specimens
• Microsurgical anatomy of the isthmic cingulum: a new white matter crossroad and neurosurgical implications in the posteromedial interhemispheric approaches and the glioma invasion patterns
• The parietooccipital interhemispheric transtentorial approach for pineal tumors
• Endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach for microsurgical resection of vermian arteriovenous malformation: operative video and technical nuances
• Pediatric pineal region tumors: institutional experience of surgical managements with posterior interhemispheric transtentorial approach

see Posterior interhemispheric transprecuneus gyrus approach

The interhemispheric parietooccipital precuneus (para-esplenial) approach, described by Yasargil, provides a short route to the medial wall of the trigone, and at same time avoids injury to the optic radiations as well as avoiding disturbance of cortical functions, even in the dominant hemisphere ^{1) 2)}.

The medial surface is retracted and an incision made in the precuneus cortex leaving a short distance (± 2 cm) to the medial wall of the trigone. This route is indicated for small or medium-size meningiomas with medial projection. The disadvantages are wider brain retraction is necessary, the narrow working angle, narrow surgical corridor and difficult access to the choroidal vessels ^{3) 4) 5)}.

Interhemispheric parietooccipital approaches are associated with limited exposure to the more posterior part of the mesial temporal lobe and require significant brain retraction ^{6) 7)}.

The interhemispheric parietooccipital approach allows only limited exposure of the more lateral PMT regions, and the access provided by this approach is restricted to the posterior portion of the mediobasal temporal lobe. Also, retraction of the occipital lobe may result in new-onset visual deficits ⁸⁾.

Ito et al. published a surgical technique for posterior callosotomy using a interhemispheric parietooccipital approach with a semi-prone park-bench position as a second surgery. Although this procedure requires an additional skin incision in the parietooccipital region, it makes the 2-stage callosotomy safer and easier to perform because of reduced intracranial adhesion, less bleeding, and an easier approach to the splenium of the corpus callosum ⁹⁾.

The approach is mainly used for lesions located in posterior interhemispheric and deep midline structures, including:

Pineal region tumors (e.g., pineocytomas, pineoblastomas, germ cell tumors)

Gliomas of the posterior corpus callosum

Colloid cysts (posterior third ventricle)

Craniopharyngiomas (posterior extension)

Ependymomas of the third ventricle

Meningiomas of the falx, tentorium, or posterior corpus callosum

Arteriovenous malformations (AVMs) in the splenium, precuneus, or cuneus

Cavernomas in the corpus callosum or posterior interhemispheric region

Aneurysms of the posterior pericallosal or splenial arteries

Dural arteriovenous fistulas (dAVFs) in the posterior falx or tentorium

Resection of epileptogenic foci in the precuneus or posterior cingulate gyrus

Corpus callosotomy (partial or complete) for intractable epilepsy

Hydrocephalus due to obstruction of the posterior third ventricle

Callosal disconnection syndromes requiring intervention

Neurocysticercosis or other parasitic cysts in the posterior ventricular system