Indications
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This technique is preferred for lesions of the middle fossa (i.e., cavernous sinus, medial temporal lobe, tentorial region, petrous bone, incisura) and posterior fossa (i.e., extraaxial lesions in the petroclival region, intraaxial lesions in the anteromedial region of the superior cerebellum).
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It is ideal for lesions that can be approached via a right-sided craniotomy.
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Surgical adjuncts such as division of the tentorium, zygomatic osteotomy, and anterior petrosectomy can provide additional working space and versatility to this approach.
Contraindications
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Left-sided approaches owing to the risk the approach places on the vein of Labbé
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Preoperative imaging showing the vein of Labbé to be in the path of the planned surgical trajectory
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Lesions extending below the internal auditory meatus (where tentorial sectioning, superior petrosal sinus ligation, or resection of petrous bone [Kawase triangle] no longer enable sufficient exposure)
Planning and positioning
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Preoperative planning includes assessment of the patient’s cardiopulmonary status, evaluation of comorbidities, and basic laboratory tests, including a basic metabolic panel, complete blood count, coagulation profile, and type and screen. Baseline chest x-ray and electrocardiogram are also useful.
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Preoperative magnetic resonance venography is obtained to determine the caliber of and the location of the vein of Labbé. In addition, its drainage entrance into the transverse sinus can be determined.
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Within 60 minutes of skin incision, perioperative antibiotics are administered.
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Brain relaxation can be achieved by administering mannitol, dexamethasone, and mild hyperventilation.
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For all patients, a lumbar subarachnoid drain is inserted before pinning to facilitate temporal lobe retraction.
Figure 4-1:
The patient is positioned supine with a shoulder roll under the ipsilateral shoulder. After pinning, the head is angled 90 degrees from the vertical plane and then tilted approximately 20 degrees toward the floor such that the zygoma is the highest point in the field. This position allows for the temporal lobe to fall with gravity in addition to providing a line of view flush with the tentorium.
Procedure
