Approach selection for intrinsic brainstem pathologies

The interpeduncular fossa approach for resection of ventromedial midbrain lesions

“…1 For deep-seated lesions, the use of the 2-point method in conjunction with described safe entry zones allows the surgeon to minimize injury to critical structures. 4,5 The anterior mesencephalic (i.e., perioculomotor) entry zone is an accepted safe entry zone for lesions located in the ventral midbrain. 4 This safe entry zone makes use of the location of the pyramidal tract to gain access to the ventral midbrain; the pyramidal tract is located in the middle three-fifths of the cerebral peduncle and lateral to the exit point of the oculomotor nerve in the interpeduncular fossa.…”

“…4,5 The anterior mesencephalic (i.e., perioculomotor) entry zone is an accepted safe entry zone for lesions located in the ventral midbrain. 4 This safe entry zone makes use of the location of the pyramidal tract to gain access to the ventral midbrain; the pyramidal tract is located in the middle three-fifths of the cerebral peduncle and lateral to the exit point of the oculomotor nerve in the interpeduncular fossa. The anterior mesencephalic (i.e., perioculomotor) safe entry zone is located lateral to the oculomotor nerve exit from the brainstem, medial to the pyramidal tract, and is bound rostrocaudally by the posterior cerebral artery and the superior cerebellar artery.…”

“…For example, the lateral supracerebellar infratentorial approach can be used to resect lateral or dorsolateral midbrain lesions, often via the lateral mesencephalic sulcus safe entry zone as previously described. 3,4,5 For lesions located in the ventromedial midbrain and medial to the oculomotor nerve, the interpeduncular safe entry zone can be used to remove lesions with acceptable patient morbidity.…”

“…More recently, surgical innovation and development of novel tools have enabled some neurosurgeons to approach deep-seated lesions using several safe entry zones-areas where the brainstem may be traversed with minimal or acceptable morbidity. 2,4,5 Fiber dissections and neuroimaging techniques, such as MRI tractography, are increasingly used to supplement anatomical knowledge by showing the relationship between the lesion and the eloquent white matter tracts; this assists surgeons with the selection of an approach 7,8 and decreases morbidity associated with manipulation of the brainstem during resection. In cases of lesions located deep in the ventral midbrain, the anterior mesencephalic (i.e., perioculomotor) safe entry zone has been described by Cavalcanti et al 2 and Kalani et al 4 This safe entry zone makes use of the placement of the pyramidal tract, which is located in the middle threefifths of the cerebral peduncle, to remove ventral lesions by entering the brainstem medial to this tract, lateral to the oculomotor nerve (cranial nerve [CN] III), and between the posterior cerebral artery and the superior cerebellar artery.…”

Resection of an anterolateral mesencephalic cavernoma via transsylvian/transuncal approach in a child

“…Surgical strategy Therefore, under intraoperative neurophysiological monitoring, the patient underwent microsurgical grosstotal resection of the cavernoma via an orbitozygomatic craniotomy followed by transsylvian/transuncal approach. Oculomotor-tentorial triangle was used to maximize the surface area accessed through this approach (Kalani et al, 2016;Seçkin et al, 2008;Mascitelli et al, 2019b).…”