Craniopharyngiomas

A 7 year old girl had 4 previous operations by 3 different neurosurgeons in Singapore on her craniopharyngioma. This huge partly cystic and solid tumour took 17 hours to be removed completely. There was no recurrence for 8 years. She attends normal school and tops her class.

APPROACHES

• Pterygonal
• Subfrontal:
  • Unilateral
  • Bilateral, my much preferred method and demonstrated below
• Transphenoidal

TRANSPHENOIDAL APPROACH

• Limited in exposure
• Risk of CSF leak with extensive opening of sella floor and dura

PTERYGONAL APPROACH

• Yarsargil
• Spliting of the Sylvian fissure

Difficulties:

Visualisation of posterior, superior and intrasellar parts of the tumour is impossible

SUBFRONTAL APPROACH

Bilateral subfrontal gives much better access than unilateral. The blind spot behind ipsilateral optic nerve can be visualised from the contralateral side. I never use unilateral approach. Head extended so that frontal lobes fall back by gravity. Do not use lumbar drain because much higher chance of extradural hematoma because frontal lobe often sunken at the end of surgery with drainage of CSF.

Bicoronal curvy incision results in better hair growth than straight one

Skin incision does not need to go all the way down to zygomatic arches unless pterygonal approach is needed as well. In that case head is tilted slightly toward that side

Harvest pericranium for repair using wet gauze to wipe the pericranium off the bone. Temporalis fascia may be harvested toward end of operation if needed for dural repair. Burr holes are made either above lateral orbital rim or behind depending on the amount of exposure needed. Use a long cutting blade to reach near midline and crack the middle.

Alternatively, unilateral craniotomy first, strip off superior sagittal sinus and then cut the other side. Bone cut must go low down, 3 mm above the orbital rim. If necessary, take off the superior orbital rims to get additional exposure to look up. Frontal sinus always entered; for this reason, I always cover the patient with vancomycin and  ceftrixone for 5 days routinely.

SUBFRONTAL – BILATERAL APPROACH

Strip away mucosa and pack sinus with muscle cut from temporalis.Discard contaminated instruments and if the dura is intact, wash wound with hydrogen peroxide and gentamycin solution before opening of dura. Tie off superior sagittal sinus and divide the falx anteriorly as low as possible.The lower one gets the easier approach.

Bicoronal curvy incision results in better hair growth than straight one

Skin incision does not need to go all the way down to zygomatic arches unless pterygonal approach is needed as well. In that case head is tilted slightly toward that side


Harvest pericranium for repair using wet gauze to wipe the pericranium off the bone. Temporalis fascia may be harvested toward end of operation if needed for dural repair. Burr holes are made either above lateral orbital rim or behind depending on the amount of exposure needed. Use a long cutting blade to reach near midline and crack the middle.
Alternatively, unilateral craniotomy first, strip off superior sagittal sinus and then cut the other side. Bone cut must go low down, 3 mm above the orbital rim. If necessary, take off the superior orbital rims to get additional exposure to look up. Frontal sinus always entered; for this reason, I always cover the patient with vancomycin and ceftrixone for 5 days routinely.

SUBFRONTAL – BILATERAL APPROACH

Strip away mucosa and pack sinus with muscle cut from temporalis.Discard contaminated instruments and if the dura is intact, wash wound with hydrogen peroxide and gentamycin solution before opening of dura. Tie off superior sagittal sinus and divide the falx anteriorly as low as possible.The lower one gets the easier approach.

Free olfactory tracts by working alternately on either side; but for re-do cases or large tumour, sacrifice olfactory tracts. Olfactory function is bilaterally represented. If needed, sacrifice only 1 tract. Optic nerve is the next important landmark to find.

A large tumour may stretch the optic nerve, making it difficult to identify. If there is difficulty, go laterally to the sphenoidal wing to trace medially. Open the arachnoid around the optic nerve and chiasma.

Most chiasmas (85%) are post-fixed; with pre-fixed chiasma, one has to go through lamina terminalis, which may be stretched up by the tumour. Suck out cystic content to decompress first. A serrated alligator forcep is most useful in grasping the capsule.

Entering lamina terminalis

Just pull the capsule down from the third ventricle. Blood supplies not from choriodal vessels but from inferiorly. So it is safe to pull down blindly (Apuzzo). Either deal with the suprasellar extension or the intrasellar tumour first depending on which is easier. Incise dura over planumsphenoidale.

Drill planumsphenoidale to enter sphenoidal sinus and then enter pituitary fossa; if possible, leave sinus mucosa intact. I like using a match stick cutting burr to enter the sphenoidal sinus and then a match stick diamond burr to enter the pituitary fossa. Open dura to re-enter intracranial cavity.

 

Additional drilling required for reaching bottom of pituitary fossa -2

Free capsule from dura and especially cavernous sinus on the sides; if bleeding from cavernous sinus, just pack with a tiny piece of surgical. Venous bleeding always stops with pressure, posture and patience.

Watch pituitary gland and pituitary stalk, which is usually at the back of the tumour. With prefixed chiasma it is often impossible to preserve the stalk which is often in front of the tumour. But if the patient is older, might be better to leave a small piece of tumour than sacrifice stalk function.
With growth of the tumour, stalk function will be gone. Therefore I am prepared to sacrifice the stalk in order to achieve conplete excision especially in a child or young adult. But one must be sure that the patient can afford life-long minirin replacement.

Closure of dural defect over planumsphenoidale

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Regards
Dr Lee