The development of the infratemporal fossa approach, as pioneered by Fisch, has allowed the excision of lateral skull base and petrous apex lesions which were previously deemed unresectable. 

These approaches are classified as type Fisch A, B and C. 

TYPE A approach: click for intra operative video clippings

This approach is used for removal of tumors involving the jugular foramen and vertical, segment of petrous internal carotid artery, primarily class C and D glomus temporal tumors.  This approach is also indicated for meningiomas, cholesteatoma involving the internal carotid artery and petrous apex, for intratemporal neuromas of  cranial nerves IX-XII and for lesions reaching the skull base from below (Carotid artery aneurysms, glomus vagale tumors etc).

Operative technique:

Surgical highlights: 

Retroauriculo – cervico – temporal skin incision 

Blind sac closure of external auditory canal 

Facial nerve exposed in parotid 

Great vessels and cranial nerves exposed in the neck 

Subtotal petrosectomy

Permanent anterior transposition of facial nerve

Ligation of the sigmoid sinus 

Eustachian tube obliterated 

Mandible displaced anteriorly 

Internal carotid artery exposed 

Jugular foramen and infralabyrinthine space exposed for tumor removal 

Middle ear cleft obliterated with fat and temporal is muscle flap. 

The key point of this approach is the anterior transposition of the facial nerve, which provides optimal control of the infralabyrinthine and jugular foramen regions, as well as the vertical portion of the internal carotid artery. 

A standard, curvilinear post auricular incision is extended into the upper neck.  The anterior flap is elevated superficial to periosteium over the mastoid and deep to platysma in the neck. The external canal is transected at the bony cartilaginous junction and the flap continued forward over the parotid for 2-3 cms.  The lateral external ear canal skin is undermined from underlying soft tissues, everted, and over sewn to create a blind-sac closure of the EAC. The facial nerve is dissected out in the parotid.   The upper neck is next dissected, vessel loops are placed proximally around the internal and external carotids and silk ties are placed, but not yet tied, around the internal jugular vein.    The vagus and accessory nerves are identified as they exit the jugular foramen and the hypoglossal is noted as it crosses the carotid bifurcation.  The sternomastoid muscle is dissected from the lateral and medial mastoid tip and mobilized with the post auricular flap.  A well beveled canal wall down mastoidectomy is next performed. The remaining EAC skin, tympanic membrane, malleus and incus are excised, and the sigmoid sinus is completely skeletonised.   The entire middle ear and mastoid course of the facial nerve is identified using cochlear form process, horizontal semicircular canal and digastric ridge as landmarks.     The facial nerve is decompressed to 270 of its circumference where possible, from the geniculate ganglion to the stylomastoid foramen.   The mastoid tip and the bony EAC are quickly removed with large cutting burr and bone roungeurs while constantly keeping facial nerve in view.   If there is limited intradural extension, the dura is opened without injury to the endolymphatic sac.   Tumor is carefully removed from the carotid artery anteriorly, if necessary.  Often, a surgical plane between the carotid artery adventia and tumor can be identified.  When such a plane is not present and tumor is adherent to the adventitia, residual tumor is left on carotid and later cauterized.   Deep infralabyrinthine tumor extension may involve the inferior internal auditory canal, thereby placing the cranial nerves VII and VIII at risk.  At times labyrinthectomy may be necessary to permit exposure and safe tumor removal from the IAC.     Whenever possible, the medial wall of the jugular bulb is left intact, thereby protecting the cranial nerves IX through XI.   The eustachian tube is obliterated with muscle and facial plugs.   The surgical cavity is obliterated with abdominal fat.  The procedure described above is used for glomus jugulare tumors.   TYPE B approach:

Skin incision and blind closure of EAM                                   Rerouted 7th nerve                                  Tumor bed after excision                             Pre and post OP CT

In this approach, the skin incision is extended anteriorly, the zygomatic arch is divided and the petrous carotid artery is skeletonized.  The temperomandibular join is then disarticulated, the eustachian tube detached anteriorly with associated soft tissue, and the middle meningeal artery and mandibular nerve divided as needed. This  provides access to the clivus and petrous apex and is applicable to glomus tumors involving the horizontal petrous carotid artery, clival chordoma, and congenital cholesteatoma of the petrous apex.   

TYPE C approach: 

This is an anterior extension of type B and allows for exposure of the parasellar region, nasopharynx, pterygomaxillary fossa and eustachian tube.  It has been used primarily for extensive juvenile nasopharyngeal angiofibroma and radiation failure squamous cell carcinoma. 

The management of intracranial tumor extension depends on the size and location of the tumor, and the status of the patient.  Small intracranial tumor extension are removed with the jugular bulb because this is typically the site of dural penetration.  The decision to remove large intracranial extensions is based on the hemodynamic status of the patient. 

Blood loss in excess of 3 liters usually prompts a second stage approach to total tumor removal. 

Post-operative care:

All patients who have undergone infratemporal fossa dissection are monitored overnight in the intensive care unit for evidence of hemorrhage or evolving neurological injury.  

Postoperative hemorrhage is extremely rare due to the extensive measures taken to ensure intraoperative vascular control.  However, given the complexities of modern skull base surgery and the advanced stage in which most skull base tumors present, postoperative cranial nerve deficits are inevitable.  Jacksons reported that 76% of his patients with extensive skull base neoplasms suffered a new intraoperative cranial nerve deficit, the most common being a glosso pharyngeal / vagal lesion. Likewise, Spector found that 19% of glomus jugulare patient suffered a partial or complete VII nerve paralysis postoperatively.  In the later stages of growth, many skull base neoplasms tend to envelop rather than infiltrate the contiguous cranial nerves. Consequently, it may be possible to maintain anatomic neural integrity by microsurgical tumor dissection of the nerves, if the involved nerves are not intentionally sacrificed during tumor removal. Because such dissection tends to devascularize the nerve, many patients will suffer a transient cranial nerve palsy as a result of their surgery and will require temporary supportive care.

In all cases of facial paralysis, either transient or permanent, it is essential that adequate corneal protection be provided by medication, temporary taping, placement of gold weights or tarsorrhaphy.

Because of the high incidence of transient dysphagia and aspiration, most patients remain intubated for at least 24 hours or until they are fully cognizant.  In selected cases, tracheotomy and nasogastric tube feeding may be required for several weeks, particularly if multiple cranial nerve palsies including X, XI, XII have occurred.  Early vocal cord medialization, either by endoscopic teflon injection or external thyropalsty, may be necessary to permit decannulation in those cases with new vagal lesion and severe aspiration.  In rare instances, combined vagal and hypoglossal injury may lead to permanent tracheotomy and gastrostomy. Except in those cases with extensive intracrianl extension, cerebrospinal fluid leak and meningitis are rare due to the multiple layers of protection offered by EAC and eustachian tube closure along with mastoid cavity obliteration.  When CSF leak does occur as heralded by external wound leakage or rhinorrhea, initial treatment is bed rest with head elevated, lumbar drainage, and pressure dressings.  If conservative measures fail wound exploration with possible repacking of the cavity and/or ventriculo peritoneal shunting may be necessary.

Summary: 

The infratemporal fossa approach, in conjunction with the application of microsurgical technique and improved perioperative care, has permitted significant advances in lateral skull base surgery.  The glomus jugular tumor is the prototypical neoplasm resected by this approach, although this technique can be applied to a host of additional benign and malignant lesions of the skull base.  This approach entails identification and control of the cranial nerves and great vessels in the neck, anterior transposition of the facial nerve, and infralabyrinthine petrosectomy. Intracranial tumor extension and petrous carotid artery involvement remain limiting factors. Significant morbidity, particularly neurological deficit and hemorrhage, may occur due to the nature and location of lateral skull base tumors.  Recent advances in preoperative embolization and temporary carotid artery balloon occlusion have advanced the limits of resection via the infratemporal fossa approach.