- Craniofacial Resection
- Facial Translocation
- Infratemporal Fossa
- Extreme Lateral/Transcondylar
- Glomous Tumours (Paraganglioma)
- Midline Labiomandibuloglossotomy
- Pre-Auricular Subtemporal
- Temporal Bone Resection
The combined craniofacial approach to manage tumours involving the anterior skull base has gradually evolved over the past five decades into a safe and reliable technique. It can be extended to resect tumours involving the infratemporal fossa, middle cranial fossa and cavernous sinus.
The tumours most commonly requiring combined anterior craniofacial surgery usually begin in the nose or sinuses. Both malignant and benign tumours occur in this region. Tumours with a primary intracranial origin such as meningioma, chordoma or chondrosarcoma require combined resection when they clearly violate the anterior fossa floor.
General anesthesia should be performed by a team experienced in neurosurgical procedures. A lumbar drain is routinely placed and patients are given prophylactic peroperative antibiotic. The patient is then placed in a Mayfield head holder and positioned to optimize both the neurosurgical and facial approaches. The leg is prepped to obtain a skin graft and fascia lata if needed.
The anterior craniofacial approach incorporates a combination of transfacial and transcranial procedures. The facial approach consists of a graduated greater exposure depending on the extent of disease. The basic is done through a lateral rhinotomy approach (Fig.1) coupled with a low craniotomy. The lateral rhinotomy incision may be extended into a Weber-Ferguson incision if a more extensive maxillary excision is required.
The craniotomy is tailored according to the extent of involvement of the anterior fossa floor and the degree of dural or frontal lobe invasion. A bicoronal scalp incision (Fig.2) is made running 2 to 3 cms behind the hairline. The flap is elevated in the subgaleal plane down to the eyebrows, then to the lateral orbital walls laterally and just below the nasal globella medially. A large flap of pericranial tissue (Fig.3) is created that will be used for later reconstruction. As the dissection proceeds the brows, the supratrochlear and supraorbital neurovascular bundles are exposed and preserved.
The anterior cranial fossa is then exposed by removing a segment of bone, which may be pedicled on the temporalis muscle or completely separated. The lower horizontal bone cut should be kept low to lessen the need for subsequent brain retraction. Withdrawing 25 to 50 ml of CSF from the lumbar subarachnoid catheter, lowering pCO2 through controlled hyperventilation, and occasionally administering mannitol or steroids further reduce the need for mechanical frontal lobe retraction. The dura is then carefully dissected off the crista galli and cribriform plate dividing the dural sleeves that extend along the olfactory nerves. The intracranial portion of the tumor extension is then assessed. If it involves the dura or in certain situations, frontal lobe this will have to be resected, together with the tumor, If the dura is intact, it is retracted back to the planum sphenoidale.
Lateral rhinotomy incision & medial maxillectomy osteotomy
Bicoronal and lateral rhinotomy incisions & its extensions
Defect in anterior skull base after tumour removal
The facial approach depends on the extent of the tumor. Often utilizes modifications of a lateral rhinotomy incision which may or may not transect the upper lip. This depends on whether a total maxillectomy is done in conjunction with the resection. The periosteum is elevated from the nasal bone as well as from the medial and inferior surfaces of the orbit. The nasolacrimal duct is identified and transected distally. The anterior and posterior ethmoidal arteries are then identified and cauterized or clipped.
In most cases it is necessary to perform a complete enbloc ethmoidectomy. For this purpose a contra lateral lynch incision is made to elevate the contra lateral periorbita, cauterize the anterior and posterior ethmoidal vessels, and make the appropriate osteotomies. If preoperative imaging studies confirm the presence of tumour in the soft tissues of the orbit, then extending the incision laterally to include a portion of the eyelids may facilitate orbital exenteration.
Once the exposure is completed, necessary bone cuts are made with a chisel or saw from above and below to encompass the tumour and the specimen is delivered leaving a large skull base defect (Fig.4).
The secret of avoidance of post operative complications in anterior skull base surgery is the water tight dural closure. If a portion of the dura has been excised, it is repaired with fascia lata.
The pericranium is used for anterior cranial fossa reconstruction. It is usually pedicled on the supraorbital and supratrochlear arteries. The pericranial flap is placed across the defect in anterior cranial fossa. The distal end is placed between the cranial floor bone and the overlying dura. It may be secured with sutures through the bone or anchored with fibrin glue. Unless a large amount of anterior cranial fossa bone has been resected and concern for brain herination exists, it is usually not necessary to place a bone graft across the bony defect.
Once the pericranial flap is in place the spinal drain is clamped so that no further intraoperative CSF decompression will take place. This will allow gradual reexpansion of the brain to make contact with the pericranial flap, obliterating any residual dead space. Since the pericranial flap traverses the frontal sinus, it is necessary to obliterate the frontal sinus with fat or free muscle after removing all the mucosa in the sinus. If the sinus is quite large, it may be advisable to remove the posterior wall of the sinus completely and allow the brain and dura to expand and fill the space (Cranialization of the frontal sinus)
The bifrontal craniotomy bone flap is then replaced and secured according to the surgeon's preference. This may be done with wires, plates or sutures. In all cases, an exclusive nasal pack is placed for at least 5 days post operatively and a lumbar drain kept for the same duration. In significantly larger defects, particularly if orbital exenteration and facial skin is excised, a bulky free flap is considered.
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Facial Translocation Approach
Facial trasnslocation approach is designed for exposing tumours in the nasopharynx and infratemporal fossa without involving maxilla and nasal cavity. The principle of facial translocation approach is to translocate a superficial bony structure (maxilla) temporarily, retaining its blood supply, as an osteoplastic flap, to expose a deeply located tumour. This is a modular approach. We can translocate maxilla with or without the nose or both maxillae can be rotated on either side. After removal of the tumour, the bone is repositioned in its original place to regain the form and function.
1. Maxillary Swing
2. Rhinomaxillary Swing
3. Midfacial Split
The translabyrinthine approach is used to remove vestibular schwannoma when preservation of hearing isn't a concern. Following the extended cortical mastoidectomy and exenteration of the posterior part of the labyrinth, the internal auditory canal is exposed. The dural plates of the middle cranial fossa and posterior cranial fossa are removed, which affords not only better exposure, but also sufficient working space. It is done without disturbing the integrity of the external auditory canal and tympanic cavity. In this approach, the facial nerve is identified at the beginning of tumour removal and therefore, the chances of preserving the facial nerve function is high.
Infratemporal Fossa Approaches
Management of tumours of the temporal bone and base of skull is one of the most challenging problems. The intimate association of these tumours with the internal carotid artery, internal jugular vein & jugular bulb and the V through XII cranial nerves has in the past rendered many patients inoperable. The development of the infratemporal fossa approach, as pioneered by Fisch, has allowed the excision of lateral skull base and petrous apex lesions that were previously deemed unresectable.
These approaches are classified as Fisch type A, B and C.
TYPE A Approach:
This approach is used for removal of tumours involving the jugular foramen and vertical segment of petrous internal carotid artery, primarily class C and D glomus temporal tumours. 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, glomusvagale tumors etc).
Surgical Highlights1. Retroauricularcervicotemporalskinincision
2. Blind sac closure of external auditory canal
3. Facial nerve exposure in parotid
4. Exposure of great vessels and cranial nerves in the neck
5. Subtotal petrosectomy
6. Permanent anterior transposition of facial nerve
7. Ligation of the sigmoid sinus
8. Eustachian tube obliteration
9. Anterior displacement of mandible
10. Internal carotid artery exposure
11. Jugular foramen and infralabyrinthine space exposure for tumour removal
12. Middle ear cleft obliterated with fat and temporalis 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 made from the temporal region to the level of cricoid. The anterior flap is elevated superficial to temporalis and sternomastoid muscles. The external canal is transected at the bony cartilaginous junction and the flap continued forward over the parotid for 2-3 cms. The external ear canal skin is undermined from underlying cartilage, everted, and over sewn to create a blind-sac closure of the EAC. The extratemporal facial nerve is dissected out in the parotid upto its bifurcation.
The upper neck is next dissected, vessel loops are placed proximally around the internal and external carotid arteries. Hypoglossal nerve, vagus nerve, spinal accessory nerve and internal jugular vein were indentified. The sternomastoid muscle is dissected from the mastoid tip.
A well bevelled 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 2700 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. The facial nerve is rerouted anteriorly. After ligating the internal jugular vein, the tumour is excised along with the lateral wall of jugular bulb. Whenever possible, the medial wall of the jugular bulb is left intact, thereby protecting the cranial nerves IX through XI.
Tumour is carefully removed from the carotid artery anteriorly, if necessary. Often, a surgical plane between the carotid artery adventia and tumour can be identified. When such a plane is not present and tumour is adherent to the adventitia, residual tumour is left on carotid and later cauterized. Deep infralabyrinthinetumour 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 tumour removal from the IAC.
The management of intracranial tumour extension depends on the size and location of the tumour, and the status of the patient. Small intracranial tumour extension is 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 haemodynamic status of the patient. Blood loss in excess of 3 litres usually prompts a second stage approach to total tumour removal.
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 glomusjugularetumours.
TYPE B Approach:
In this approach, the skin incision is extended anteriorly at the temporal region, 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 glomustumours involving the horizontal petrous carotid artery, clivalchordoma, 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 recurrent nasopharyngeal carcinoma.
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.
Considering the complexities of modern skull base surgery and the advanced stage in which most skull base tumours present, postoperative cranial nerve deficits are inevitable. All patients who underwent rerouting of facial nerve during this surgery develop facial palsy. It is usually temporary and most of them regain facial movement. Some will develop mass movement (synkinesis).In all cases of facial paralysis, it is essential that adequate corneal protection be provided by medication and temporary taping. Patients who develop facial palsy before surgery due to tumour infiltration may not recover full facial function. If the paralysis is permanent, placement of gold weights or tarsorrhaphy must be considered.
Jacksons reported that 76% of his patients with extensive skull base neoplasms suffered a new intraoperative cranial nerve deficit, the most common being a glossopharyngeal / vagal lesion. 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 continuity of the nerve by microsurgicaltumour dissection. Because such dissection tends to devascularize the nerve, many patients will suffer transient cranial nerve palsy as a result of their surgery and will require temporary supportive care.
Because of the high incidence of transient dysphagia and aspiration, tracheostomy 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. Except in those cases with extensive intracrianl extension, cerebrospinal fluid leak and meningitis are rare.
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 tumour is the typical 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 infralabyrinthinepetrosectomy. Intracranial tumour 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 tumours. Recent advances in preoperative embolization and temporary carotid artery balloon occlusion have advanced the limits of resection via the infratemporal fossa approach.
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Glomus Jugulare - VIDEO - Excision of Jugular Bulb
Glomus Jugulare - VIDEO - Inferior Petrosal Sinus Opening
This approach is designed for exposing tumours involving lower clivus and involving vertebral artery. Retrosigmoidcraniectomy is extended to open the foramen magnum. Posterior arch of atlas is removed. Foramen transversorium of C1 is opened and the vertebral artery is rerouted posteriorly. Upto 1/3 of the occipital condyle can be drilled out to maximize the exposure. Dura is incised anterior to and around the point of dural entry of vertebral artery.
Glomous Tumours (Paraganglioma)1. Glomus tympanicum
2. Glomus jugulare
3. Glomus vagale
4. Carotid body tumour
These are rare, slow-growing, very vascular tumours of a group called paragangliomas. They are derived from glomus bodies which themselves are derived from neural tissue. They occur at carotid bifurcation, the vagus nerve, top of internal jugular vein known as jugular bulb and the middle ear. Rarely, they may be found at other sites, including the periaortic area, trachea, larynx, mandible, nose, ciliary ganglion and Fallopian canal.
These tumours tend to be benign and slow growing but they can be locally aggressive. Malignancy is rare and only about 4% metastasise to the lung, lymph nodes, liver, vertebrae, ribs and spleen. Upto 3% of tumours produce adrenaline-like hormones, resulting in a clinical picture similar to phaeochromocytoma with hypertension and tachycardia.
This patient had carotid body tumour, glomus vagale and glomus jugulare on one side (CT and angiogram) and a small carotid body tumour on contralateral side (CT).
They sometimes run in families in an autosomal dominant fashion with incomplete penetrance. These tumours can arise at multiple sites(Fig.1). The incidence of multicentric origin is about 10% and it goes up to 50% in familial cases.
Glomusjugulare arises at the skull base in an area known as jugular foramen. A number of structures pass through this foramen viz. internal jugular vein that takes the impure blood from brain to the heart and three cranial nerves, which control the speech and swallowing. It is also closely related to the middle and inner ear. Therefore, the symptoms are related to loss of function of the ear and cranial nerves. These can include partial or complete hearing loss, a ringing or pulsing sound, which is called tinnitus and dizziness. If the tumour is large enough and grows towards the neck, it can causefacial paralysis, difficulty in swallowing, hoarseness, drooping shoulders and tongue weakness. In a small percentage of glomusjugularetumours, the mass may produce hormones and cause additional symptoms like headache, tremors, flushing, anxiety, high blood pressure and a rapid heart rate.
1) CT & MRI are done to know(a) the site & extent of tumour, involvement of neurovascular structures
(b) presence of any other glomustumour
2) Blood and urine tests are done to detect hormones that are produced in up to 3% of tumors. It is important to detect these hormones before surgical removal because the hormones can spill from the tumour during surgical removal and cause the blood pressure to rise to dangerous levels. If you are diagnosed to have a tumor, which produces these hormones, you will be given medications to protect you from the effects of spilled hormones during surgery.
If the tumour is very small and limited to the space behind the eardrum (middle ear), the tumour is known as a glomustympanicum. These tumours are easily removed by lifting the eardrum through the ear canal. Surgery for glomustympanicumtumours can generally be done safely as an outpatient.
The management of glomusjugularetumours depends on a number of factors including age, overall health status, presenting symptoms, tumour size, and patient preference. Treatment options include observation, partial or total surgical removal, external beam radiation, or a combination of surgery and radiation therapy.
Observation with serial imaging studies (CT or MRI) is often recommended in patients with advanced age, multiple health issues, or according to patient preference.
The treatment of choice for a glomusjugularetumour is surgery. It may be completely removed using traditional skull base surgical techniques. The process is difficult because there are so many nerves in the area. These nerves control the muscles of the tongue, the throat, the vocal cords, and the shoulder, and are at risk for injury during surgery. State of the art intraoperative nerve monitoring techniques are utilized to minimize nerve trauma during tumour removal. If the tumour can be taken out without damaging any nerves, no other treatment is needed. Complete surgical removal is typically recommended in younger patients. Temporary facial weakness is the most common side effect in the removal of these tumours because the facial nerve often has to be moved out of its normal position to allow direct access to the jugular foramen.
These tumours are highly vascular and excessive blood loss happens during surgery. In recent years, the neuroradiologist does carotid angiography 24 to 48 hours before surgery, finds the blood vessel that feeds the tumour and blocks it. It is known as embolization. This reduces the bleeding during surgery and the procedure can be performed with greater safety. Also the preservation of vital structures around the tumour is enhanced, including cranial nerves going to the throat, vocal cords and face.
If the tumour is adherent to internal carotid artery or to the cranial nerves that are functioning (normal swallowing function, shoulder function, tongue movement and voice), a small amount of tumour may be left on these structures to reduce morbidity and this residual tumour can be taken care with postoperative radiotherapy. Radiation treatment can be used as primary therapyfor patients who are not fit for surgery or following recurrence or planned partial excision.
Glomus tumour which occur in the upper part of neck typically arise along a nerve called the vagus nerve, which controls the movement of vocal cord and is known as glomusvagale. Usually present with change in the voice caused by injury to the vagus nerve. Surgery for a glomusvagaletumour is generally done through an incision high in the neck.
Carotid Body Tumor
If the tumour occurs at the level of the bifurcation of the carotid artery, it is called a carotid body tumour. These are typically noticed first as a soft lump in the neck. Surgery for a carotid body tumour is done through an incision in the neck, and rarely causes any nerve problems. The tumour is dissected off the internal, external and common carotid arteries. In large tumours, the tumour may be adherent to the internal carotid artery which may necessitate resection and grafting of internal carotid artery.
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Glomus Jugulare - Steps of ITF type-A approach
Glomus Jugulare - Giant Tumour
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Glomus Jugulare - Post-op facial nerve function after anterior rerouting
Glomus Jugulare - VIDEO - ITF-A App
Glomus Jugulare - VIDEO - Excision of Jugular Bulb
Glomus Jugulare - VIDEO - Inferior Petrosal Sinus Opening
In traditional mandibulotomy approach to expose oropharynx, the mandible is split between the lateral incisor and canine teeth (to preserve the genioglossus muscle attachment) and then the mucosal incision runs along the floor of mouth. This can result in devitalization of the incisors as well as injury to lingual and hypoglossal nerves. This can result in poor functional outcome.
In midline Labiomandibuloglossotomyapproach the oropharynx is exposed without significant morbidity. Since the mandible is split in midline, there is no desensitization of teeth. Tongue is split in midline avascular plane. Therefore, no injury to lingual artery and its branches as well as no injury to sensory and motor nerves. Therefore, the patient is able to speak and swallow without any problem after surgery. Another advantage is that after resecting posterior 1/3 of tongue tumour, reconstruction can be done using the anterior 2/3 of tongue (anterior tongue setback).Tumours involving the posterior 1/3 of tongue, posterior pharyngeal wall and vertebral column from lower clivus to C5 can be exposed with this approach.
Pre-Auricular Subtemporal Approach
The subtemporal preauricular approach to the infratemporal fossa (ITF) is ideal in the surgical exposure and resection of any lesion, benign or malignant, which involves the ITF and adjacent regions. In contrast to Fisch’s infratemporal fossa approaches, this approach to the ITF affords access to this area without loss of hearing.
It is an approach to the skull base through the anterior portion of the petrous temporal bone and is used for the removal of predominantly extradural tumors in this region. This approach can be used for the management of intradural lesions in the region of the clivus. Its main advantages include avoidance of brain retraction, the use of an extrapharyngeal route, and exposure of the ventral aspect of the pons and medulla and related structures caudal to the trigeminal root.
Temporal Bone Resection
The treatment for temporal bone cancers is surgery and radiotherapy. Depending on the stage of the cancer, patient may also have chemotherapy.
The type and extent of surgery needed depends on the area of ear(Fig.1) affected, and whether it has spread into nearby structures, such as the bone, dura, parotid etc. Surgeon will remove the tumour together with an area of tissue surrounding it that is completely free of cancer cells. Doing this helps to lower the risk of the cancer coming back.
Fig.1. ECA - external auditory canal. TM - tympanic membrane. IJV - internal jugular vein. JB - jugular bulb. ME - middle ear. ICA - internal carotid artery. Lab - labyrinth. SCC - superior semicircular canal.
Fig.2. Lateral temporal bone resection - for T1 tumours limited to EAC.
Surgery may involve having some or all of the following removed.
1. The ear canal
2. Part or all of the temporal bone
3. The middle ear
4. The inner ear
The operations to remove the temporal bone tumour may range from a mastoidectomytototal temporal bone resection.They may also need to remove the lymph nodes nearby in the neck and the salivary gland on that side of the head.Rarely, surgeon may need to remove the facial nerve, which runs through the temporal bone. In that case, nerve grafting is done to regain the facial movement.
If the middle and inner ear were removed it is unlikely that the patient will be able to hear on that side. Balance may be affected and the patient may feel dizzy temporarily. Sometimes it is possible for the surgeon to rebuild (reconstruct) some of the ear so that hearing can be preserved.With this operation, appearance won’t change for most people. Scar line is likely to be behind the ear.
Management of the Primary Site
For tumours limited to external auditory canal, lateral temporal bone resection(LTBR)is done. The LTBR includes resection of the EAC, tympanic membrane, malleus, and incus(Fig.2). The boundaries are the middle ear cavity and stapes medially, the mastoid cavity posteriorly, the epitympanum and zygomatic root superiorly, the temporomandibular joint (TMJ) capsule anteriorly, and the medial tympanic ring or infratemporal fossa (ITF) inferiorly. The lateral margin depends on the extent of spread. The otic capsule and facial nerve are preserved. The LTBR is appropriate for T1 and T2 tumors.
The LTBR begins with a long, postauricular incision extending from the temporal fossa into the neck. If the pinna is to be preserved, a second incision is made within the concha lateral to the lesion. If the pinna is to be resected, a preauricular incision is incorporated to the postauricular incision allowing the pinna and surrounding skin to be included in the specimen. A cortical mastoidectomy is performed and the facial nerve identified. Bone removal is extended into the zygomatic root and to the digastric ridge. An extended facial recess is made, and the incudostapedial joint is separated. The facial recess is continued inferiorly and anteriorly lateral to the facial nerve, but medial to the annulus, until the specimen is attached only at the anterior canal bony wall at the level of the temporomandibular capsule. An osteotome is used to separate the bony specimen. The parotidectomy is performed en bloc.
Medina (1990) described several modifications of the lateral temporal bone dissection based on the location of disease. A modified LTBR removes the EAC and leaves the uninvolved tympanic membrane intact. This type of resection is appropriate for tumors originating in the concha without involvement of the EAC.
Fig.3. Subtotal temporal bone resection for tumours extending into middle ear.
Fig.4. Total temporal bone resection.
A subtotal Temporal Bone Resection (STBR) is performed when invasion medial to the tympanic membrane or into the mastoid (T3 disease) is evident. In this case, the medial margin may be obtained in a piecemeal fashion, usually with a drill. The specimen includes the LTBR with additional dissection of the otic capsule and the medial bony wall of the middle ear and mastoid(Fig.3). The margins of resection are the sigmoid sinus and posterior fossa dura posteriorly, middle fossa dura superiorly, internal carotid artery anteriorly, jugular bulb inferiorly, and petrous apex medially. Based on the extent of tumor spread, dissection may include the condyle of the mandible, the facial nerve, dura, sigmoid sinus, and contents of the infratemporal fossa. The carotid artery is skeletonized and becomes the medial margin.
Tumor involvement of the jugular bulb requires ligation of the inferior jugular vein and proximal control of the sigmoid sinus. The facial nerve is traditionally sacrificed, with the proximal margin taken in the labyrinthine or internal auditory canal segment. However, the surgeon may elect to preserve the nerve if no indication of nerve involvement exists. The medial extent of dissection at the level of the otic capsule depends on the depth of involvement and is done piecemeal. Tumor extension into the protympanum, eustachian tube, or carotid artery is addressed with an infratemporal fossa dissection. The temporalis muscle is reflected and the zygomatic arch removed. The mandibular condyle is resected. The dissection proceeds based on the extent of disease but may include identification of the pterygoid plate, the mandibular nerve (V3), and the horizontal carotid artery and may include a temporal craniotomy.
A Total Temporal Bone Resection(Fig.4)can be used to address T4 disease. However, this procedure is associated with significant morbidity and may not significantly improve survival in these cases of advanced disease. The resection includes the STBR with the additional resection of the petrous apex. The internal carotid artery may be isolated, mobilized, and preserved or resected. The sigmoid sinus, jugular vein, carotid artery, dura and CNs are removed as indicated by the extent of the tumor.
Management of the Parotid and Temporomandibular Joint
The intraparotid lymph nodes are a first echelon drainage site for cancers of the EAC and middle ear. An adequate anterior margin for the temporal bone resection routinely involves resection of the parotid gland, temporomandibular joint, and condyle. Resection of these soft tissues will also address minimal soft tissue extension beyond the temporal bone. Ideally, this is performed en bloc with the temporal bone. A superficial parotidectomy is performed with preservation of the facial nerve for T1 and T2 tumors. When the facial nerve is resected for more advanced lesions, a total parotidectomy may be performed.
Management of the Dura and Brain
Although involvement of the dura and brain carry a poor prognosis, an aggressive approach includes resection of the dura and a small volume of the temporal lobe with a healthy margin.
Management of facial nerve paralysis may include CN XII to VII grafting, cross facial grafting, and static procedures. Extensive resections may result in large soft tissue defects. A temporalis muscle flap can be used to fill small to medium defects. The pedicledmyocutaneous trapezius flap is an excellent option for reconstruction of the soft tissue and skin defect. The pectoralis flap has limited distant reach to the resected margin. The anterolateral thigh free flap and rectus abdominus free flap are particularly suited for the area. Dural defects should be repaired primarily or with graft reconstruction.