Eyebrow craniotomy

 

Pre-op film review

Know the size of the frontal sinus. If entry to the sinus is expected, know the plan for reconstruction, i.e. pericranial flap, fat graft.

Monitoring

Gardner for tuberculum meningioma - SSEPs only, no EEG, no motors.

Pre-op medications

  • Mannitol 0.5 to 1.0 g/kg
  • Dexamethasone 10 mg
  • Keppra 1000 mg

Positioning

Supine, arm nearest the operator is tucked. Move patient so that their body is on the edge of the bed nearest the operator.
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Pinning

Head is pinned as it is for an EEA. Double pin on the side opposite the pathology, single pin on the other side. Lower double pin and the single pin go on the mastoid. The upper single pin goes anterior, towards the superior temporal line.
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Arm is attached to the outside of the Mayfield.
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Head position

Extend the neck
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Tilt the head slightly to the contralateral side.
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Tarsorrhaphy

Gardner: use 6-0 Prolene suture in a horizontal mattress. Suturing supplies are in a lumbar drain kit. First stitch goes on the upper eyelid, about 4 mm above the lid. Second stitch goes in the lower lid about 2 mm below the lid margin. Do not go on the tarsal plate or right above/below the lashes.
Make sure you have the CV-11, not CV-1 needle. You want to take the largest bites possible with the needle in horizontal direction
The numbers describe the order of needle passes in the first image.
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Prep

Ophthalmic iodine for head. Chloraprep for fat graft site.

Draping

Three blue towels in a triangle around the eye.
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Four blue towels in a square for the fat graft site.
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Greenburg retractor

Always place the clamp on the Mayfield on the side opposite the pathology.
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Approach

Oculoplastics will do the exposure. The incision is marked within the eyebrow itself, not above.
A #10 scalpel blade is used to cut through skin and dermis. The incision is made perpendicular to the eyebrow pad , this is at about 15 degrees tilted down towards eye, this is done to prevent alopecia and stay parallel to hair follicles.
A Colorado-tip Bovie on 15 and 15 is used to deepen the incision to just above the pericranium. Dissection is carried in this layer medially past the supraorbital notch or foramen and laterally to the superior temporal line. It is carried anteriorly to the superior border of the orbit and posteriorly as far as possible.
If a pericranial flap is being raised, use the Colorado tip Bovie to make the incision through pericranium, leaving it pedicled against the brow ridge and the supraorbital bundle. Take the pericranial flap as far posteriorly as possible to get the largest possible flap.
Switch the Bovie to the regular insulated tip and dissect the temporalis from its attachment at the superior temporal line, leaving no cuff. Dissect the temporalis from the temporal fossa and lateral orbit until you can place a single burr hole at MacCarty's key hole. No need to dissect further than is required for a single burr hole.
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Closure 

Close the C shaped dural opening watertight with nuknit overlying dura  +/- fat graft in sinus. The bone flap will often be prepared by oculoplastics, but you want a 2 dog bones/ one burr cover. The dog bones are located one on superior aspect of flap and on inferior medial (under where the eyebrow will be. The burr hole cover is Lateral to cover up the burr hole. Typically, a B1 w/o footplate is used to drill tack up anchor holes so the temporalis can be sutured and reapproximated back to STL (overing burr hole cover). The area that is missing from bone drilling should be eliminated from superior aspect of the bone flap - leaving a large gap under the eyebrow. This is in effort to diminish deformation over forehead.

Quiz questions

  • What is vascular supply to pericranial flap?
    • Supraorbital / supratrochlear
  • What are the bony connections of the clinoid?
    • Roof of the optic canal
    • Lesser wing of the sphenoid
    • Optic strut
  • What structure does the optic strut form when viewed from the inside of the sphenoid sinus?
    • Lateral OCR
  • When doing this approach for Acomm , do you need to split sylvian fissure?
    • Yes, this allows the frontal lobe to fall away from skull base/ temporal lobe to grant access.
  • What injury are patients prone to with the optic strut cut of the clinoidectomy?
    • Carotid injury