DIAGNOSTIC EVALUATION

The diagnostic evaluation begins with a thorough history and physical examination, with special emphasis on the chronology of developing cranial neuropathies. The pathway of tumor spread occasionally can be deduced from a careful history. Facial nerve function, hearing, and balance function should be carefully documented. Examination includes palpation of the parotid gland and cervical lymph glands for the presence of local spread and regional metastases. Patients should be questioned and tested for temporal lobe signs (e.g., memory loss, dysphasia, left-sided neglect, hemiparesis, and olfactory hallucinations) and cerebellar signs (e.g., ocular dysmetria, truncal ataxia, nystagmus, and dysdiadochokinesia).

Imaging allows determination of the extent of tumor involvement. High-resolution axial and coronal computed tomography (CT) imaging at 1.5 mm thickness can identify areas of bony involvement. Enhanced and unenhanced magnetic resonance imaging (MRI) can determine intracranial involvement.

Histologic confirmation of the lesion is essential in further treatment planning. Biopsy specimens of lesions involving the EAC or periauricular skin can be easily obtained. Needle aspiration biopsy of parotid lesions can also be performed.

Angiography is used when involvement of the major vessels is suspected on preoperative imaging, or when surgical exposure of the petrous carotid artery is anticipated. The venous phase of the study can provide important information regarding blood flow through the dural venous sinuses. Embolization of feeding vessels is rarely required because most lesions are relatively avascular.

Cerebral blood flow evaluation is indicated when involvement of the ICA is present. Patency of the anterior and posterior communicating arteries on angiography is an inadequate evaluation for collateral flow. Our current method of preoperative carotid artery testing is described.³ A 30-minute temporary balloon occlusion of the ICA allows identification of patients who would most likely tolerate carotid artery sacrifice. Transfemoral introduction of a nondetachable intravascular balloon, inflated in the ICA, is performed in the patient while sensory, motor, and higher cortical functions are assessed.

Patients who develop a neurologic deficit during temporary occlusion are at high risk for stroke after carotid sacrifice. Preoperative or intraoperative extracranial-to-intracranial arterial bypass should be considered. Repeating the temporary balloon occlusion before surgical extirpation should also be considered. Conservative treatment options should also be discussed with these patients.

Patients who tolerate a 30-minute balloon occlusion of the ICA are at low risk for development of a stroke, provided that a long “distal” stump is avoided. Permanent ICA occlusion can be performed angiographically. Hypotension and hypovolemia in the perioperative period should be avoided if permanent ICA occlusion is performed.

PREOPERATIVE PREPARATION

Preoperative preparation sets the stage for the operative and postoperative course. The evening before surgery, the operative site is shampooed and scrubbed with hexachlorophene. Intravenous phenytoin or phenobarbital and cefuroxime are used for prophylactic anticonvulsant and antibiotic coverage. To facilitate intraoperative cranial nerve monitoring, short-acting neuromuscular blocking agents are used only for the induction of anesthesia, and not during the operation.

On the morning of the operation, sequential compression stockings are placed on both legs to help decrease the incidence of thromboembolic disease. After insertion of a central venous catheter and an arterial line, the patient is intubated, and the endotracheal tube is secured. The operating table is turned 90 degrees from the anesthesiologist, giving him or her access to the contralateral arm. The head is positioned on a horseshoe (Mayfield) head holder to allow repositioning during the course of the operation. Temporary bilateral tarsorrhaphies are placed to prevent corneal abrasions. The operative site, which includes the temporal fossa, lateral half of the face, postauricular area, neck, and ipsilateral thigh and lower leg (for the potential use of tensor fascia lata and sural nerve), is shaved and scrubbed with an iodine-based solution. Bipolar facial electromyographic electrodes are placed in areas where facial function exists.

SURGICAL PROCEDURE

Incisions vary according to the extent of the tumor (Fig. 4-1). For lesions contained within the temporal bone, a C-shaped incision extending from the temporal fossa postauricularly into the neck is used. A blind-sac closure of the EAC helps contain the specimen. When tumor invasion of the conchal cartilage or periauricular skin is suspected, an appropriate skin island is incorporated into the overall design. The EAC skin is sutured shut to avoid tumor spillage. The outline of the incisions should preserve the blood supply to the remaining auricle. The anterior and posterior skin flaps are elevated (Fig. 4-2A). The superficial temporal fat pad is elevated with the anterior skin flap in a subperiosteal plane over the zygomatic arch. The superficial temporal and middle temporal arteries are ligated.

FIGURE 4-1 Incisions vary according to whether the tumor is contained in the temporal bone.

FIGURE 4-2. A, The facial nerve can be divided peripherally at the distal branches or centrally at the facial nerve trunk, depending on involvement of the parotid gland. B, After osteotomies and removal of the zygomatic arch and mandibular segments, dissection in the infratemporal fossa continues. EAC, external auditory canal.

The facial nerve can be handled differently, depending on tumor invasion of the parotid gland. When the gland is involved, peripheral branches of the facial nerve are identified with the help of the facial nerve monitor and then divided. The stumps of the anterior segments are secured to the anterior skin flap. The entire parotid gland is dissected off the masseteric fascia, provided that the latter is free of disease, and mobilized posteriorly, while the attachment to the EAC is maintained. When the parotid gland is suspected to be free of tumor, the facial nerve trunk is located in the usual manner at the tympanomastoid suture and divided. The parotid gland, along with the distal stump of the facial nerve, is dissected free of the EAC and mobilized anteriorly off the masseteric fascia.

The jugulodigastric region is explored, and cervical lymph nodes are sent for frozen section pathologic analysis. Regional metastases determine the need for a formal cervical lymphadenectomy. The ninth cranial nerve, the greater auricular nerve, or cervical cutaneous nerves can be used as cable grafts for facial nerve reconstruction. CN IX, X, XI, and XII; the internal jugular vein; and the external carotid artery and ICA are dissected in an inferosuperior direction toward the temporal bone. The sternocleidomastoid and digastric muscles are detached from their attachment to the mastoid.

The masseter is detached from the zygomatic arch, allowing exposure of the zygoma and mandible. Zygomatic and mandibular osteotomies (see Fig. 4-2A) can then be performed. The meniscus of the temporomandibular joint is separated from the glenoid fossa, and the chorda tympani nerve emerging from the petrotympanic fissure is divided. The stylomandibular and sphenomandibular ligaments are divided and allow removal of the mandibular segment (Fig. 4-2B). The temporalis muscle is elevated in a subperiosteal fashion and reflected inferiorly. The temporalis muscle must be separated from the lateral pterygoid muscle, and care should be taken not to injure the deep temporal arteries supplying blood to the temporalis muscle. The lateral and medial pterygoid muscles are resected either en bloc with the specimen or separately, depending on tumor invasion.

In a subperiosteal manner, the contents of the infratemporal fossa are elevated off the floor of the middle fossa to expose the middle meningeal artery and vein in the foramen spinosum and the mandibular division of the trigeminal nerve in the foramen ovale. The contents of the foramen spinosum are bipolarly coagulated and divided. Frequently, the venous plexus of the foramen ovale requires bipolar coagulation and packing with oxidized cellulose. The lesser petrosal nerve can be seen emerging from the innominate canal, on its way to the otic ganglion.

The stylohyoid, stylopharyngeus, and styloglossus muscles (Riolan’s bouquet) are detached from the styloid process, which is then rongeured away. The branches of the external carotid artery are dissected in the infratemporal fossa. The anterior tympanic and deep auricular branches of the internal maxillary artery are often divided before identification, and may require bipolar coagulation. The internal maxillary artery is preserved up to the branches of the deep temporal artery. When the internal maxillary artery must be sacrificed, brisk backflow from the anterior stump indicates that the temporalis muscle may derive its blood supply from reversed flow via the pterygoid system. If brisk backflow is not observed, the temporalis muscle cannot be relied on to reconstruct the surgical defect, and microvascular free flap options must be considered. The cartilaginous eustachian tube is divided, and the anterior end is sutured closed to prevent postoperative cerebrospinal fluid rhinorrhea (Fig. 4-3A).

FIGURE 4-3 A, Further dissection in the infratemporal fossa allows division and ligation of the eustachian tube and exposure of the petrous carotid artery. B, The petrous carotid artery is dissected further according to whether a subtotal or total temporal bone resection is performed. ICA, internal carotid artery; STBR, subtotal temporal bone resection.

The ICA is dissected toward the carotid canal, and care is taken not to injure CN IX, which crosses its anterior surface. Kerrison rongeurs are used to uncover the vertical and horizontal petrous segments of the carotid artery (Fig. 4-3B). Occasionally, bleeding from the pericarotid venous plexus requires bipolar coagulation. The caroticotympanic artery is also divided when the petrous carotid artery is separated from the specimen. The extent of petrous carotid mobilization depends on whether STBR or TTBR is performed. When STBR is performed, the vertical petrous carotid artery is mobilized from the carotid foramen and canal. When TTBR is performed, the vertical and horizontal petrous carotid artery is mobilized out of the carotid canal to the foramen ovale.

A temporal craniectomy is performed, and the intracranial portion of the middle meningeal vessels is coagulated (see Fig. 4-3B). The patient is hyperventilated to keep the Pco₂ at 25 mm Hg for adequate brain relaxation. Mannitol and furosemide can improve brain relaxation. Subtemporal dural elevation proceeds in a posteroanterior direction. The greater superficial petrosal nerve and accompanying petrosal artery are coagulated and divided to lessen traction on the geniculate ganglion. The lesser petrosal nerve and superior tympanic artery are similarly divided. Subtemporal dural elevation proceeds as far medially as possible to expose the superior petrosal sinus. When carcinomatous involvement of the middle fossa dura is suspected, an intradural approach keeps the involved dura attached to the specimen.

The extent of the mastoidectomy depends on whether tumor is present in the mastoid air cells. Care is taken to avoid exposure of tumor in the mastoid. In this case, the confluence of the transverse, sigmoid, and superior petrosal sinuses is decorticated to expose posterior fossa dura on either side of the sigmoid sinus. When posterior fossa dural involvement is suspected, a presigmoid intradural approach with gentle retraction of the cerebellum (Fig. 4-4A) allows exposure of the vessels and nerves in the cerebellopontine angle that are keeping the involved dura attached to the specimen. When the mastoid air cells are thought to be free of tumor, a translabyrinthine approach to the IAC is used (Fig. 4-4B). The anterior inferior cerebellar artery is retracted after the labyrinthine artery is bipolarly coagulated and divided. The superior and inferior vestibular nerves, cochlear nerve, facial nerve, and nervus intermedius (nerve of Wrisberg) are divided. A segment of the proximal facial nerve stump can be sent for frozen section pathologic examination if it is suspicious for carcinoma. The dome of the jugular bulb must be separated from the specimen when the dural venous sinuses are spared.

FIGURE 4-4 A (left and right), When tumor is thought to be present in the mastoid, a presigmoid intradural approach (enlarged view on the right) to the porus acusticus is used. B, When the mastoid is thought to be free of tumor, a translabyrinthine approach allows exposure of the internal auditory canal. AICA, anterior inferior cerebellar artery; ICA, internal carotid artery.

The surgical technique from here varies according to whether the dural venous sinuses or the ICA is preserved. When both are preserved, and STBR is being performed, the bone between the bony canal of the carotid artery at the junction of the vertical and horizontal segments (Fig. 4-5A) and the fundus of the IAC is removed with a high-powered drill. Separation of the petro-occipital synchondrosis sometimes requires insertion of an osteotome just above the jugular bulb. This step releases the specimen en bloc from attachment to the clivus. Packing oxidized cellulose intraluminally toward the cavernous sinus controls bleeding from the inferior petrosal sinus.

FIGURE 4-5 A, A drill, inserted at the junction of the vertical and horizontal petrous carotid canal, is aimed toward the fundus of the internal auditory canal (IAC) to allow removal of the subtotal temporal bone specimen. B, A drill, inserted at the horizontal petrous carotid canal just posterior to the foramen ovale, is directed slightly posteriorly to avoid entry into the foramen lacerum. This releases the total temporal bone specimen.

FIGURE 4-6. When the dural venous sinus is sacrificed, the internal jugular vein is mobilized toward the cranial base as the sigmoid sinus is intraluminally packed.

When both vascular structures are preserved, and TTBR is being performed, the bone between the posterior edge of the foramen ovale and spheno-occipital synchondrosis is removed (Fig. 4-5B). The petro-occipital synchondrosis may require an additional osteotomy before the specimen is delivered.

When the dural venous sinuses are sacrificed, the internal jugular vein is double ligated in the upper cervical area and mobilized toward the jugular bulb (Fig. 4-6). The superior petrosal sinus and sigmoid sinus are divided and intraluminally packed with oxidized cellulose. Care is taken not to overpack the sigmoid sinus proximally to avoid obstruction of the vein of Labbé; this can cause hemorrhagic necrosis of the temporal lobe. Similarly, excessive packing of the inferior petrosal sinus can lead to cavernous sinus thrombosis. The sigmoid sinus is opened toward the jugular bulb and resected. Intraluminal rather than extraluminal packing of the inferior petrosal sinus is preferred to avoid injury to cranial nerves traversing the jugular foramen.

The results of the temporary balloon occlusion determine whether the ICA can be safely resected. When the patient is at high risk for stroke after sacrifice of the ICA, the patient requires revascularization to ensure adequate cerebral blood flow. An extracranial-to-intracranial arterial bypass, such as a superficial temporal artery–to–middle cerebral artery bypass, must be considered.

The middle and posterior fossa dura is inspected for carcinomatous involvement. Any involved areas are resected, and margins are sent for frozen section pathologic examination. The temporal lobe and cerebellum are also examined, and limited involvement of the inferior temporal gyrus and cerebellum can be resected. When intradural hemostasis is achieved, the dura is closed in a watertight manner using pericranium, fascia lata, or cadaveric dura.

Reconstruction includes restoration of facial nerve continuity and closing the dead space after tumor resection. The greater auricular nerve, cervical cutaneous nerve, or CN XI can be used as a cable graft from the facial nerve in the IAC to the peripheral branches. When greater length is required, the sural nerve can be harvested from the lower leg. Use of vascularized tissue, rather than autogenous fat, is preferred to fill in the surgical defect. The temporalis muscle can be rotated into the defect. Split-thickness skin grafts can be used for cutaneous defects. A small bolus dressing is placed to ensure adequate adhesion. When the temporalis is unavailable, plastic surgery teams can harvest microvascular free flaps. Jackson-Pratt drains are installed under the neck and scalp skin flaps to ensure tissue coaptation.

POSTOPERATIVE CARE

After extubation in the operating room, the patient is examined for neurologic deficits. Unanticipated neurologic deficits are studied further by noncontrast CT imaging to evaluate the presence of intracranial edema or bleeding. Antibiotics are continued postoperatively until the drains are removed, or if an infectious process dictates otherwise. Dexamethasone is continued for 48 hours and then tapered over 5 days.

When the ICA has been sacrificed, great care is taken to avoid even minor hypotensive and hypovolemic periods. These events can reduce the cerebral blood flow through the remaining contralateral carotid artery and lead to cerebral ischemia.

Intermittent spinal drainage, through a lumbar drain installed at the end of the procedure, reduces the pressure in the subarachnoid space and accelerates healing of dural defects. Continuous spinal drainage can cause overdrainage and pneumocephalus and is not used. Depending on patient tolerance, 35 to 50 mL of spinal fluid is drained every 8 hours for 48 hours. The drain is then clamped for 24 hours and removed.

POTENTIAL COMPLICATIONS

Inadvertent carotid artery injury can be managed initially by local pressure to the site of entry and placement of temporary clips on either side. After systemic heparinization, the tear is examined, irrigated with heparinized saline, and repaired using 8-0 Novofil suture. Before placement of the last suture, the lumen is irrigated with heparinized saline to clear any clots. The hemoclips are released, and any minor leaks are managed with oxidized cellulose. If the tear is beyond repair, the results of the preoperative temporary balloon occlusion dictate further management.

ADJUVANT TREATMENT

Treatment of temporal bone malignancies extending into the middle ear should consist of surgical resection of all visible disease followed by external-beam radiotherapy. Occasionally, large, aggressive tumors invading brain parenchyma, the dominant carotid artery, or dural venous sinus are encountered, and total tumor removal is impossible without serious neurologic deficits. In these instances, brachytherapy catheters can be inserted and used.

REHABILITATION

Facial palsy after temporal bone resection requires careful assessment and treatment. A temporary tarsorrhaphy at the conclusion of the operation affords early corneal protection. When the periorbital edema subsides, a gold weight implant in the upper eyelid can offer long-term corneal protection. Elderly patients also may require lower eyelid tightening procedures. Facial nerve recovery can be expected at 12 to 18 months. The best facial function a patient can expect with a cable graft, in our hands, is House-Brackmann grade III.

Excessive packing of the inferior petrosal sinus can lead to lower cranial nerve dysfunction (CN IX, X, and XI) that can be debilitating. Some patients require temporary tracheostomy and gastrostomy, and others can be treated with polytetrafluoroethylene (Teflon) injection of the vocal fold or an Isshiki thyroplasty.⁴

FOLLOW-UP

Patients are seen every month for the first year, and repeat imaging (CT and MRI) is obtained at 6 months and yearly thereafter. Enhancing tumors are best visualized by contrast-enhanced fat-suppression MRI, which helps differentiate transposed flaps from tumor recurrence. Any suspicious areas require biopsies either directly or by needle aspiration techniques with or without CT guidance.

RESULTS

Temporal bone neoplasms occur infrequently. The limited experience makes analysis of treatment difficult. Because of this difficulty, we reviewed the literature for all cases of squamous cell carcinoma of the temporal bone,⁵ analyzed the extent of disease present, studied the different treatment strategies employed, and reported on outcome. Our findings are presented.

All publications in the English language from 1915 to 1992 dealing with the treatment of squamous cell carcinoma of the temporal bone were reviewed; 96 publications^1,6–100 were encountered, of which 26 articles^75–100 contained enough information on 144 patients. Various parameters were then analyzed. The major reason for exclusion of a study was the lack of a descriptive table in which the extent of disease, type of treatment, and follow-up for each patient were carefully documented.

Several conclusions about overall survival could be made. When disease was confined to the EAC, no statistically significant difference in 5-year survival was found between patients treated with LTBR (48.6%) and patients treated with STBR (50%). When disease extended into the middle ear, patients who had STBR had better 5-year survival (41.7%) than patients who had LTBR (28.6%) (Fig. 4-7). The experience with carcinoma that invaded the petrous apex was limited. Four patients treated with TTBR had a 50% 1-year survival and 0% 2-year survival. One patient treated with STBR was dead of disease at 1 year.

FIGURE 4-7 Treatment-specific survival for patients with carcinoma extending to the middle ear. TBR, temporal bone resection.

(From Prasad S, Janecka IP: Efficacy of surgical treatments for squamous cell carcinoma of the temporal bone. Otol Head Neck Surg 110:270-280, 1994.)

The value of preoperative or postoperative radiation therapy was also analyzed. When disease was confined to the EAC, the addition of either preoperative or postoperative radiation therapy to LTBR did not significantly improve 5-year survival (48% with radiation therapy, 44.4% without radiation therapy) (Fig. 4-8). This was the only group in which a conclusion regarding radiation treatment could be made.

FIGURE 4-8 Survival of patients with carcinoma confined to the external auditory canal treated with lateral temporal bone resection (TBR) with or without preoperative or postoperative radiation therapy (RT).

(From Prasad S, Janecka IP: Efficacy of surgical treatments for squamous cell carcinoma of the temporal bone. Otol Head Neck Surg 110:270-280, 1994.)

The prognostic value of dural involvement was also studied. Resection of involved dura mater did not improve overall 5-year survival (11.1% with or without resection). Margin status was not always reported.

Four patients had extension of disease to involve the ICA. Of the two patients treated with TTBR and ICA sacrifice, one died of postoperative cerebral ischemia, and the other died of disease at 14 months of regional and distant failure. The other two patients who were treated in a method that spared the ICA died of disease shortly after resection.

Two patients with carcinomatous invasion of the temporal lobe treated with limited resection also died of disease shortly after resection. No patient was encountered who had resection of involved cerebral or cerebellar tissue.

Site of failure was also studied. Of 54 patients who died of disease, 45 had local failure, 5 had locoregional failure, 3 had regional failure alone, and 1 had regional distant failure.

Several other aspects of this disease could not be studied because of the lack of information provided by the authors. First, the histologic differentiation of the tumor and its relationship to overall survival could not be analyzed. Second, the method of temporal bone removal, whether by en bloc resection, piecemeal resection, or a drillout, and its relationship to survival could not be ascertained. The status of the margins of resection and relationship to overall survival remains to be studied.

SUMMARY

Radical resection of the temporal bone requires thorough knowledge of the intricate anatomy of the temporal bone and surrounding structures. There is no substitute for laboratory dissection before embarking on such an operation. Thorough preoperative imaging, delineation of the extent of tumor involvement, and preoperative carotid artery testing are imperative.

The indications for the operation are slowly evolving as we gain experience and collate data for analysis. From our literature review regarding squamous cell carcinoma,⁵ it seems that cancerous involvement of the middle ear is best treated by STBR rather than LTBR and gross removal of middle ear disease. When the tumor involves the petrous apex, we believe that TTBR can allow total tumor extirpation and possibly prolonged survival, although the latter remains to be proved. Prospective, randomized studies are needed to define the value of margin-free dural, carotid artery, and brain parenchymal resection. The value of adjunctive radiation therapy for extensive lesions also requires further study.