Endoscopic Approach to Pineal Region

Hasan A. Zaidi and Peter Nakaji

24.1 Introduction

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.

24.2 Indications

• 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.

24.3 Patient Positioning (Fig. 24.1)

• 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.

24.4 Skin Incision (Fig. 24.2)

• 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.)

Fig. 24.2 Alternative skin incisions are outlined; paramedian incision and extreme lateral excision. (Used with permission from Barrow Neurological Institute, Phoenix, AZ.)
Abbreviations: A = asterion; IL = incision line; IN = inion; M = midline; TS = transverse sinus.

24.4.1 Critical Structures

• Occipital artery

• Greater and lesser occipital nerves

24.5 Soft Tissues Dissection (Fig. 24.3)

• 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.