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| Skull
Base Surgery |
| Infratemporal
Fossa Approach |
| The
infratemporal fossa approach of Fisch encompasses three distinct
variations for use in specific clinical situations. The key point
of the Type-A approach is the anterior transposition of the facial
nerve, which provides optimal access to the infralabyrinthine and
jugular foramen regions as well as the vertical portion of the internal
carotid artery. It is useful for the management of glomus jugulare
tumours, neuromas and meningiomas of the jugular foramen and petrous
bone cholesteatomas.
The Type-B approach allows access from the sigmoid
sinus to the petrous tip, including exposure of the horizontal ICA
and foramen ovale, to reach lesions of the petrous apex and mid
clivus, such as chordomas, meningiomas and extensive petrous apex
cholesteatomas.
The Type-C approach expands this to include the
parasellar region, the cavernous sinus, foramen rotundum, and foramen
lacerum. Removal of the pterygoid plates in this approach also facilitates
access to the nasopharynx. This approach is used in the resection
of small nasopharyngeal carcinomas and angiofibromas. All three
variations of the infratemporal fossa approach involve mastoidectomy,
facial nerve dissection (and transposition), obliteration of the
eustachian tube, middle ear and external auditory canal with resultant
permanent conductive hearing deficit.
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| Case-1
An 18 year old
male presented with pulsatile tinnitus, impaired hearing, change
of voice and slight difficulty in swallowing. A red, pulsatile mass
was seen arising from the floor of the external ear canal, completely
occluding the view of the tympanic membrane. CT & MRI showed
a vascular tumour in the jugular bulb area with erosion of the skull
base. The carotid canal was free and there was no intradural extension.
Angiography revealed a highly vascular tumour fed mainly by the
ascending pharyngeal artery and the tumour was embolised. Three
days after embolisation the tumour (glomus jugulare) was excised
using the Infratemporal Fossa Type A approach.
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| MRI
shows the extent of tumour. No intradural extension is seen.
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MRI
shows the extent of tumour. No intradural extension is seen. |
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| Angiogram
shows the tumour to be highly vascular and it was embolised.
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Blind
closure of external ear canal. |
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| Facial
nerve (arrows) is decompressed from geniculate ganglion to
its division in the parotid gland.
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Facial
nerve is rerouted anteriorly. |
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| After
complete removal of the tumour. White arrow - rerouted facial
nerve; Asterisk- Enlarged jugular foramen area seen after removal
of the tumour. |
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Postoperative CT shows no residual tumour. |
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