Cavernous malformations in the third ventricle are based on the medial thalamus or upper midbrain. The eloquence of these structures and their depth give these lesions an air of inoperability, but their risk of hemorrhage and neurological consequences can be significant in young patients. This region can be accessed directly with a transcallosal-transchoroidal fissure approach and our surgical results with cavernous malformations have been good. This video demonstrates this approach in a 48-year-old woman presenting with headaches and obstructive hydrocephalus. The patient consented to publication of her image. A presumptive diagnosis of neurocysticercosis was made, a right frontal ventriculoperitoneal shunt was inserted, and the patient was referred. The shunt collapsed the right ventricle, and a left transcallosal-transchoroidal approach was selected. The head was turned to bring the midline in the horizontal position with gravity retracting the dependent left hemisphere and widening the interhemispheric fissure with no retractors. The choroidal fissure was opened along the tenia fornicea to enter the velum interpositum and enlarge the foramen of Monroe. The trajectory was angled posteriorly over massa intermedia and the malformation was dissected from the right inferioromedial thalamus. Its removal opened the aquaduct of Sylvius. The floor of the third ventricle was also fenestrated in case of future obstruction or shunt malfunction. Magnetic resonance imaging confirmed total resection and she remained intact. The corpus callosum and the choroidal fissure are the only structural barriers to resecting third ventricular cavernous malformations through a transcallosal-transchoroidal fissure approach. The long surgical corridor makes this technically challenging. The fornix must be handled gently to avoid memory dysfunction.
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