1. lesions of the petrous apex (e.g. petroclival meningiomas)
2. lesions of the clivus (e.g. chordomas) with both posterior fossa and supratentorial components
Spares sinus and otologic apparatuses. Minimizes cerebellar and temporal lobe retraction.
see Petrosal approach.
1. patient supine, ipsilateral shoulder roll
2. elevate thorax 10°: reduces venous distension
3. flex knees
4. Mayfield 3 pin head-holder: close to true AP with single pin on forehead
5. head positioned to place petrous base at highest point of field:
a) head rotated 40–60° from vertical
b) head abducted towards contralateral shoulder
c) neck extended 15°: allows gravity to retract frontal lobe away from skull base
Reverse question mark starting from zygomatic arch 1cm anterior to tragus, arcing posteriorly over ear, descending to 0.5–1cm medial to mastoid notch.
Temporalis muscle and periosteum reflected anteriorly and inferiorly.
Four burr holes are utilized, two on each side of the sinuses (near the junction of the transverse and sigmoid sinuses).