Approaches to Skull Base
I Anterior Cranial Base
  Anterior craniofacial resection
Basal subfrontal approach
II Middle Cranial Base

Central Compartment  

  Trans septal sphenoid
Transpalatal
Extended maxillotomy
Midfacial split		  

Lateral Compartment  

  Infratemporal fossa approach l case 1 l case 2
Transparotid
Subtemporal preauricular infratemporal fossa approach
Trans facial approaches

  Facial translocation approach l case 1 l case 2

Extended osteoplastic maxillotomy approach

Extended transfacial subcranial approach l case 1 l case 2

III Approaches to posterior cranial base

Transtemporal approaches
  Translabyrinthine approach
Transotic approach
Transcochlear approach l Case 1 l Case 2

Extreme lateral/transcondylar approach

 
Skull Base Surgery

Transtemporal Approaches

The skull base approaches through the temporal bone include the transcochlear, translabyrinthine, transotic and combined approaches. These are lateral, primarily extradural techniques that traverse the mastoid and petrous portions of the temporal bone to provide exposure of lesions of the petrous apex, clivus and cerebellopontine angle (CPA).


In the translabyrinthine approach, a transmastoid labyrinthectomy and skeletonization of the sigmoid sinus and posterior fossa dura precede wide exposure of the internal auditory canal and CPA. While the translabyrinthine approach offers wide exposure of the posterior/lateral CPA, the cochlea and petrous apex block access to the anterior aspects of CPA and the ventral brain stem. In transotic and transcochlear approaches by definition, removal of the cochlea, follows a translabyrinthine approach to extend the exposure anteriorly. The distinction between the transotic and transcochlear approach is that the facial nerve is transposed posteriorly in the transcochlear approach.


Transtemporal appraoches are often used in the management of tumours of the posterior cranial base such as acoustic neuromas, petroclival meningiomas, and aggressive cholesteatomas. They can be used to enhance the exposure of advanced lesions of the middle cranial base that have secondarily extended into or beyond the petroclival region and posterior to the course of the ICA. Postoperative consequences include permanent unilateral deafness, and facial paralysis of variable degree and duration caused by seventh nerve decompression or transposition.

Malignant tumours affecting the temporal bone are rare. Surgery and radiation therapy, alone or in combination, are the treatment options. In general, four types of resections are performed. These are sleeve resection, lateral temporal bone resection, subtotal temporal bone resection and total temporal bone resection. The above picture schematically depicts lateral temporal bone resection and subtotal temporal bone resection, the two commonly performed procedures.