24 Endoscopic Approach to Pineal Region The endoscope-controlled supracerebellar infratentorial approach for pineal region pathology is a potentially powerful approach that can minimize surgical approach-related morbidity. Patients are positioned in a sitting position, with the secondary surgeon holding the endoscope while the primary surgeon, who maintains bimanual dexterity, visualizes the screen. This is an ergonomic position that can facilitate surgery. A small vertical incision is made in the scalp with a small craniotomy, which is large enough to accommodate the endoscope and microsurgical instruments. • Pineal tumors of any size or pathology, though germinoma could be considered for biopsy and radiation instead. • Large, symptomatic pineal cysts. • Tectal or anterosuperior vermian tumors. • Tentorial incisura tumors. • Many supratentorial tumors can also be approached trans-tentorially. • Pineal tumors that are predominantly in the anterior or mid-part of the third ventricle or the aqueduct should not be approached in this way. • Position: The patient is placed in sitting position with the head fixed with a Mayfield head holder. • Body: Body lies sitting 45° from the horizontal. • Head: The head is flexed an additional 45°, rotated 10° to the contralateral side, not tilted. • Shoulder position: Shoulders are adequately padded in the sitting slouch position. • Anti-decubitus device: Backrest should be at the level of the mid-scapula or lower. • The inion should be facing straight back toward the surgeon, who is standing behind. • Image guidance is very helpful; the midline tentorium should be as close to level with the floor as possible. • Linear vertical unilateral incision ◦ Starting point: Incision starts 1 cm above the line between the inion and the top of the zygoma, 25 mm from midline. ◦ Course: Incision line runs inferiorly from this point for 2.5 cm. ◦ Ending point: It ends 3.5 mm from the top of the incision, ending in the muscles. Fig. 24.1 Patient positioning. (Used with permission from Barrow Neurological Institute, Phoenix, AZ.) • Occipital artery • Greater and lesser occipital nerves • Myofascial level ◦ Incised according to skin incision. • Muscles ◦ Layers of the splenius capitis muscle and semispinalis capitis muscle are visualized at the inferior aspect of the incision. ◦ These are incised along the length of the incision and retracted medially and laterally. • Bone exposure ◦ Subperiosteal dissection of occipital bone overlying the lower part of the transverse sinus and the upper cerebellum, lateral to the torcular, is performed. • Transverse sinus.
24.1 Introduction
24.2 Indications
24.3 Patient Positioning (Fig. 24.1)
24.4 Skin Incision (Fig. 24.2)
24.4.1 Critical Structures
24.5 Soft Tissues Dissection (Fig. 24.3)
24.5.1 Critical Structures
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