SURGICAL PROCEDURE

A preoperative arteriogram and embolization are performed 48 hours before the surgical procedure.¹³ Facial nerve monitoring is carried out in all cases. The surgeon may consider additional monitoring, including auditory brainstem evoked potentials, somatosensory evoked potentials, motor evoked potentials, and monitoring of CN X, XI, and XII. An electromyographic endotracheal tube can be used for CN X monitoring, and electrodes placed directly into the sternocleidomastoid muscle and the tongue can be used for CN XI and XII monitoring. Before the incision, perioperative antibiotics and corticosteroids are administered.

Patient positioning and incision differ for the dorsolateral and anterolateral modifications. For the dorsolateral ELITE procedure, the patient is placed in a lateral decubitus position (Fig. 59-2A and B). For the anterolateral approach, the patient is positioned in a supine fashion with the head displaced away from the side of the lesion. A shoulder roll is placed to aid with the high cervical portion of the procedure and to raise the shoulder on the side of the lesion. Obese patients and patients with very short necks may be placed in a lateral position if necessary. The patient should be padded and secured for ease of rotation of the table throughout the case.

FIGURE 59-2 A and B, Patient positioning for dorsolateral ELITE procedure, lateral decubitus position. C, Incisions. 1 shows lazy S incision for dorsolateral approach; 2 shows question mark–shaped incision for anterolateral ELITE approach. SCM, sternocleidomastoid muscle.

Incisions are shown in Figure 59-2C. For the dorsolateral approach, a lazy S incision is used, 1 to 2 cm posterior to the mastoid bone, and extending inferiorly along the hairline. For the anterolateral ELITE procedure, a retroauricular curvilinear C-shaped, or question mark–shaped, skin incision is begun approximately 2 to 3 cm posterior to the upper border of the ear. Inferiorly, this incision is carried down into the neck, traversing the border of the sternocleidomastoid muscle (SCM) and running parallel to the body of the mandible, approximately two fingerbreadths below. The skin flaps are raised. For the dorsolateral approach, the SCM is retracted anteriorly; for the anterolateral approach, the SCM is retracted posteriorly. The inferior edge is raised in the subplatysmal plane. Superiorly, the temporoparietal fascia is elevated as a separate flap under the skin flap, after it is dissected off the bone with the periosteum.

The anterior flap is now reflected, and the posterior auricular muscle should be visible behind the external auditory canal. Inferiorly, the greater auricular nerve should be seen crossing the SCM approximately 3 cm below the mastoid tip. This nerve can be preserved for use as an interposition graft, if needed. The posterior flap is displaced, and the posterolateral neck muscles are reflected to expose the mastoid more fully. This group of muscles is composed of three layers (Fig. 59-3). The superficial layer is composed of the SCM and splenius capitis muscles. The middle layer consists of the longissimus capitis and semispinalis capitis. These muscles are reflected to expose the deep layer, which consists of the rectus capitis posterior major, the obliquus capitis superior, and the obliquus capitis inferior muscles. These muscles form the suboccipital triangle (Fig. 59-4A). The styloid diaphragm also is identified in this region. Beneath that diaphragm runs the occipital artery as it courses beneath the posterior belly of the digastric muscle (Fig. 59-4B).

FIGURE 59-3 A, Superficial dissection. B, Middle layer. FM, foramen magnum; GON, greater occipital nerve; IJV, internal jugular vein; INL, inferior nuchal line; M, mastoid process; SCM, sternocleidomastoid muscle; SNL, superior nuchal line.

FIGURE 59-4 A, Deep muscle layer, including suboccipital triangle. B, Dissection deep to muscle. IJV, internal jugular vein; M, mastoid process; SCM, sternocleidomastoid muscle.

A mastoidectomy is performed. The sigmoid sinus and jugular bulb must be thoroughly skeletonized. Mastoid cells should be removed to visualize the middle fossa dura, presigmoid dura, superior petrosal sinus, and retrosigmoid dura.

The digastric ridge must be widely exposed and identified. The bony labyrinth should be skeletonized for ease of retrolabyrinthine dissection. The facial nerve should be skeletonized. The retrofacial air tract must be drilled to expose the jugular bulb completely. The bone between the sigmoid sinus and the jugular bulb can be quite adherent to these structures, and the dissection is prone to bleeding.

For resection of glomus jugulare tumors, a high cervical approach is necessary to identify the lower cranial nerves (CN IX-XII), and to gain lower control of the internal carotid artery and IJV. When the subplatysmal flaps are raised, the posterior angle of the mandible is identified as the anterior limit of dissection. The mastoid tip is defined as the posterior limit. Dissection is carried anterior to the SCM to identify the posterior belly of the digastric muscle. The stylomastoid diaphragm is removed, and the occipital artery, running just below, is controlled. The digastric muscle can be displaced superoanteriorly to cover the facial nerve and gain access to the transverse process of C1. The accessory nerve can be seen coursing posteroinferiorly from the lateral point (defined as 3 to 15 mm inferolateral to the transverse process of C1). The accessory nerve is usually seen running lateral to the IJV, medial to the digastric. The hypoglossal nerve is identified as it courses over the IJV. The carotid sheath is opened to identify the vagus nerve. The stylohyoid, stylopharyngeus, and styloglossus muscles lie anterior to the carotid artery. Detaching the styloid process from the base of the cranium improves exposure of the carotid canal at the skull base. The glossopharyngeal nerve is identified 1 to 2 cm from this point, crossing the carotid inferomedially. Gently retracting the IJV can help expose the carotid branch of CN IX.

The facial nerve is skeletonized in its vertical portion, and the mastoid tip is removed. The styloid process (already detached) is reflected anteriorly to expose the infratemporal carotid artery. Facial nerve rerouting is rarely performed. Instead, a limited anterior translocation (approximately 5 mm) may be performed to gain anterior exposure in cases of tumor extension to the internal carotid artery (C7 portion). Preserving the periosteum of the facial nerve can minimize the risk of postoperative paresis with this procedure. The carotid canal is drilled out to expose the petrous carotid. CN IX exits dorsal to the carotid in this location and can be injured without proper care. Jacobsen’s nerve can be seen branching from CN IX before reaching the jugular bulb.

It is essential to identify the V3 segment of the vertebral artery to avoid injury during this exposure. V3 can be identified in one of three ways: by dissection of the suboccipital triangle, by identification of the vertebral sulcus or J groove of the C1 lamina, or by use of a Doppler probe (Fig. 59-5). For identification of the suboccipital triangle, the deep layer of muscles mentioned previously serves as the guide to this anatomic region. The rectus capitis posterior major inserts superiorly on the nuchal line and attaches inferiorly on the spinous process of C2. The obliquus capitis inferior muscle inserts superiorly on the transverse processes of C1 and inferiorly on the spinous process of C2. The obliquus capitis superior attaches superiorly at the temporo-occipital suture and inferiorly on the transverse process of C1. The suboccipital triangle is opened by detaching the superior and inferior oblique muscles off of the transverse process of C1 and reflecting them posteriorly. The rectus capitis posterior major is reflected posteriorly as well, after freeing it from the inferior nuchal line; this helps identify the C1 lamina and the vertebral artery.

FIGURE 59-5 A-C, Identification of V3 segment of vertebral artery (VA), including use of J groove in dissection. SS, sigmoid sinus.

Alternatively, the vertebral artery can also be identified by following the C1 lamina from the posterior point along its superior edge until the vertebral sulcus or J groove is identified. The vertebral artery is encased by a venous plexus as it exits the foramen transversarium of C1 and then travels in the vertebral sulcus until its medial turn into the atlanto-occipital membrane. The venous plexus can be avoided by dissecting in the subperiosteal plane as the vertebral artery is freed from the sulcus. Venous plexus bleeding can be controlled by using bipolar cautery or absorbable knitted fabric (Surgicel). Care should be taken to avoid injuring an extradural posterior spinal artery or the posterior inferior cerebellar artery. The atlanto-occipital membrane is incised to expose the craniocervical dura.

The lateral suboccipital craniotomy is performed with a craniotome. The boundaries of the craniotomy are about 3 cm posterior to the retrosigmoid line, superiorly to the nuchal line (transverse sinus), inferiorly to the posterior rim of the foramen magnum, and lateral to the occipital condyle. Exposure of the jugular bulb and sigmoid sinus is crucial. The posterior condylar emissary vein is encountered as it exits the jugular bulb and can be controlled by bipolar cautery and Surgicel packing. In most cases, the lateral edge of the foramen magnum needs to be totally removed.

The posterior and medial one third of the occipital condyle is removed in front of the C1 dura, using a high-speed diamond drill. Resecting more than half of the condyle can cause instability of the craniovertebral junction, and stabilization should be considered on resection. As the condyle is removed, the surgeon proceeds through a cortical layer leading to a cancellous bony layer. Venous bleeding may be present and should be controlled with bone wax and Surgicel before proceeding. The next cortical layer overlies the hypoglossal canal. The hypoglossal nerve, branch of the ascending pharyngeal artery, and venous plexus of the canal are located within the canal. Because the canal sits superior to the condylar facet and inferior to the jugular tubercle and is directed slightly cephalad at a 60 degree anterolateral plane, skeletonization of the canal to its lateral extent indicates a one third resection of the superomedial portion of the occipital condyle. Removal of this portion of the condyle provides easier access to the ventral foramen magnum (Fig. 59-6A and B).

FIGURE 59-6 A and B, Dissection of occipital condyle. C-E, Further dissection toward foramen magnum and clivus, with exposure of ventral medullary area.

Dissection continues superiorly toward the jugular tubercle. The jugular tubercle is a smooth osseous protrusion on either side of the occipital bone.¹⁴ The base of the tubercle is defined by the hypoglossal canal, and it extends anteriorly 20 mm toward the clivus. Reduction of the tubercle permits access to the anterior clivus. Because the tubercle lies medial to the jugular foramen, CN IX, X, and XI are at risk as the tubercle is drilled out. Risk of injury can be minimized by drilling within a core of the tubercle and working anteriorly, deeper toward the clivus, minimizing heat and potential stretch injury to the nerves. Drilling should be carried 20 to 25 mm deep toward the clival junction. A 3 mm smooth diamond burr is ideal here, and can then be sized down to a 2 mm burr. Remaining thin bone can be dissected; inner cortical bone can be preserved to avoid damage to CN IX and X. It is important to have flat access from the lateral edge of the foramen magnum under CN IX, X, and XI to the inferior clivus and ventral medullary area (Fig. 59-6C-E). Between the jugular bulb and the C1 transverse process, the small rectus lateralis muscle must be removed. Occasionally, the C1 transverse process is shaved to expose the V3-V4 genu for wider exposure. In this process, care should be taken not to injure CN XI.

Adequate exposure of the sigmoid sinus, jugular bulb and IJV, and all lower cranial nerves should allow for preservation of vital functions and easy identification of the tumor within these structures. Figure 59-7 shows the exposure of these structures provided by this approach. The approach used for resection of large glomus jugulare tumors includes (1) the suprajugular, retrofacial, infralabyrinthine approach; (2) the infrajugular-transcondylar approach; and (3) the high cervical approach.

FIGURE 59-7 Exposure afforded by various approaches. 1, suprajugular, retrofacial, infralabyrinthine approach; 2, infrajugular-transcondylar approach; 3, high cervical approach.

Before tumor resections, it is important at this point to control the arterial feeders to the tumor. The IJV is then ligated inferiorly. The sigmoid is occluded above the tumor mass. The IJV lateral wall can be incised, and the tumor specimen can be resected up to the jugular bulb. The medial wall of the jugular bulb is preserved, and the tumor is excised from the pars nervosa. The dural sheath over the lower cranial nerves should be left intact. Bleeding should be controlled with gentle packing because bipolar cautery can damage the cranial nerves.

The intradural portion of the tumor is addressed next. The dural incision is curvilinear and is placed several millimeters posterior to the sigmoid sinus. It is carried inferiorly to the point where the vertebral artery pierces the dura. The dura is reflected back with multiple tacking sutures. With sufficient drilling of the occipital condyle and jugular tubercle, the accessory nerve is readily identifiable. Dissection can expose the medullary branch of the accessory nerve, the vagal vein and vagus nerve, and the glossopharyngeal nerve. The tumor is dissected free from the cranial nerves after the jugular foramen is inspected for further extension. Blood supply from the posterior inferior cerebellar artery can be cauterized (Fig. 59-8).

FIGURE 59-8 ELITE exposure including high cervical dissection. AICA, anterior inferior cerebellar artery; Ba, basilar artery; Ce, cerebellum; JB, jugular bulb; PICA, posterior inferior cerebellar artery; Va, vertebral artery; Vv, vagal vein.

The lower clivus can be accessed, if necessary, by inferior translocation of the lower cranial nerves and anterior translocation of the vertical petrous segment of the internal carotid artery. The dural sleeve over the lower cranial nerves can protect them from trauma. Resection of the clivus can continue toward the petrous apex.

The wound is irrigated, and reconstruction of the cranial base is performed to obtain a watertight dural closure. Options include fascia for smaller defects, a pericranial flap, or a free flap reconstruction for larger defects. The use of vascularized myofascial flaps for reconstruction is thought to reduce the incidence of postoperative CSF leak.¹⁵ Abdominal fat should be harvested to fill the mastoid defect. Lumbar drainage is used in most cases.

COMPLICATIONS

Complications of cranial base surgery for tumors of the jugular foramen are well described. Several series have reported common complications, including CSF leak and wound infection, with an incidence of approximately 5% to 10% for each case.^16,17 Facial nerve and hearing deficits are common, and outcomes vary significantly depending on preoperative function, approach, and tumor extent. Lower cranial nerve deficit, often producing aspiration and voice disorder, was the most common surgical complication in one large series, at almost 10%.¹⁵ Other complications include cerebrovascular accident, meningitis, pulmonary embolus, hydrocephalus, and death. These more severe complications are rare, occurring in about 1% of cases.^16,17 Craniovertebral instability is a concern with over-resection of the condyle; however, with preservation of at least 50% of the condyle, stabilization should be unnecessary.¹⁸

RESULTS

Liu and colleagues¹⁸ reported surgical outcomes from resection of glomus jugulare tumors in 30 patients using the ELITE procedure. Mean follow-up was 28.5 months. Total resection was achieved in 73%, and near-total resection was achieved in 20% of patients. Eight patients (27%) had worsened facial nerve palsy postoperatively, and four of those patients maintained a permanent deficit. Two patients with permanent facial paralysis underwent partial anterior transposition of CN VII, and two required an interposition cable graft because of tumor invasion of the nerve. Four patients developed sensorineural hearing loss; all were patients with significant intradural tumor. Cochlear function was thought to be compromised secondary to any of various factors, including traction on the cerebellum or CN VIII, or violation of the cochlea during bone dissection or tumor resection. Of patients, 30% had worsened CN IX and X function, six with permanent deficit, and three patients went on to laryngoplasty to improve swallowing and voice function. There were five CN XI and three CN XII pareses. There were no CSF leaks and no operative mortality. No patients required stabilization of the occipitocervical junction.

One advantage of the ELITE surgical approach is tumor access with minimal manipulation of the facial nerve. It is recognized that long facial nerve rerouting results in interruption of the deep petrosal artery, leading to perigeniculate ischemia. There is also a chance of mechanical trauma with mobilization of the nerve from the narrow labyrinthine segment and manipulation of the epineurium in the internal auditory canal.¹⁹ The key to preserving facial function is minimal dissection, and translocation only as necessitated by the tumor and the approach. Preservation of the periosteum of the bone surrounding the facial nerve can help to preserve the stylomastoid artery, which supplies the mastoid segment of the facial nerve. We describe a select anterior translocation only as necessary to gain access to the vertical C7 (infratemporal) portion of the carotid artery.

Although the approaches used by many surgeons require facial nerve rerouting, more conservative facial nerve management has been advocated, at least for some tumors without extensive anterior involvement. Pensak and Jackler²⁰ described the fallopian bridge technique, and reported usage in a large percentage of glomus jugulare tumors in their practices. In this technique, the facial nerve is skeletonized and left in situ, and the external auditory canal is not violated. This approach cannot be used when there is anterior extension of tumor to the carotid genu, but is not contraindicated by the presence of an intradural tumor component. They report outcomes in 35 patients using this technique, with a House-Brackmann grade I result in 92% at 6 months after surgery.

Results of glomus jugulare tumor resection using the ELITE approach may be compared with reports of series using other approaches. Pareschi and coworkers²¹ described their experience with 52 glomus jugulare tumors. Of those tumors, 42 were at least Fisch classification type C, and 37 underwent surgery, with an overall resection rate of 96%. Overall, 33 patients required an infratemporal fossa approach with 5 requiring A and B types. Two patients required second-stage petro-occipital transsigmoid approach. The external and middle ear was sacrificed in all cases. Facial nerve function at 1 year was House-Brackmann grade I or II in 51% of patients, and grade III or better in 84%. The facial nerve was transposed in 70% of patients, and preserved anatomically in 80%. The glossopharyngeal and vagus nerves were preserved anatomically in 48% and 35%. The authors noted that most patients have some difficulty with dysphagia, but there were no reported pneumonias. Twelve patients required vocal cord medialization. CSF leaks were not reported; however, three patients developed a subcutaneous CSF collection that was managed conservatively.

Jackson and colleagues²² reported results for 182 lateral skull base surgeries for glomus jugulare tumors. Of those patients, 21% were class I, 20% were class II, 35% were class III, and 23% were class IV. Total surgical control was reported as 85%. Their series included 66 patients with intracranial extent, 44 of which had pars nervosa involvement requiring resection of CN IX through XII. Jackson and colleagues²² noted that one or more new cranial nerve deficits arose in 59% of patients. Complete tumor removal was possible without any cranial nerve resection in 31%. CSF leak was reported in 3 of 66 cases after 1987, when complex reconstruction of the cranial base began in their practice.

The Otology Group¹⁶ described their management of the facial nerve in lateral skull base surgery for benign tumors. Their outcomes are reported as good (House-Brackmann grade I-II), fair (House-Brackmann grade III-IV), and poor (House-Brackmann grade V-VI). The patients in whom the nerve was left in situ had normal function. Procedures with short translocation preserved good function in 92%, while procedures with long translocation preserved good function in 66%. Extreme translocation resulted in good function in only 38% of patients. Patients with resected and grafted nerves had much poorer results, as would be expected.

Oghalai and associates²³ reported on results of surgical treatment using a transjugular craniotomy for resection of a series of 28 jugular foramen tumors with intracranial extent, including 6 glomus jugulare tumors. A fallopian bridge technique of facial nerve dissection, which leaves the vertical portion of the facial nerve in situ, was used when possible. Of the 24 patients with normal or near-normal preoperative facial nerve function, function was preserved (House-Brackmann grade I-II) postoperatively in 22. Patients who did not require facial nerve translocation did not experience deterioration of function. Tumor access required ear canal closure in a few (21%) cases. Of patients, 60% had good preoperative hearing levels (defined as American Academy of Otolaryngology–Head and Neck Surgery class A or B), and 41% had good hearing postoperatively. All nine patients who were spared destructive otologic procedures (ear canal closure, translabyrinthine or transcochlear procedures) maintained good hearing postoperatively. A 53% incidence of complete lower cranial nerve palsy was identified in the patient population preoperatively, and new lower cranial nerve deficits were noted in 27%.

In the series reported by Fisch and colleagues and cited by Moe and colleagues,¹⁷ 132 patients with glomus jugulare tumors were reviewed. Most (n = 119) of the patients had advanced tumors (class C and D); 81 had intradural extension. Total tumor removal was reported in 83% of the total population. Of patients, 84% required an advanced infratemporal fossa approach, 72% required an anterior displacement of the facial nerve, and approximately 15% required facial nerve resection, with either grafting or anastomosis. Results with anterior displacement were favorable, with good function (House-Brackmann grade I-II) retained in 88% of patients. Preservation of the lower cranial nerves for class C and D tumors varied depending on class and nerve. CN VIII and IX were most at risk and had preservation rates between 20% and 50%. CN X, XI, and XII fared better, with preservation rates of 60% to 80%. In the reported follow-up, 10% of patients had aspiration. Ten percent were noted to have CSF leaks postoperatively.

DISCUSSION

The ELITE approach to glomus jugulare tumors and other tumors of the jugular foramen provides safe, effective access to the cranial base. It is ideal for tumors around the jugular foramen, lower clivus, and high cervical region. Resection results and postoperative function compares favorably with other large series in the literature as shown previously.

Good facial nerve function is important for quality of life, and injury to the facial nerve carries significant morbidity. Classically, large glomus jugulare tumor resection required rerouting of the facial nerve and possibly resection of the nerve to complete surgical resection. Numerous techniques have been described to translocate the facial nerve.¹⁹ The ELITE approach may use a slight anterior translocation if needed to gain access to the petrous portion of the carotid artery. Anterior dislocation of the mandible can produce symptoms of trismus, pain, malocclusion, and first bite syndrome.¹⁶ The transcondylar transtubercular approach allows the surgeon to work posterior to the angle of the mandible without displacement, and the petrous portion of the carotid artery can still be accessed without the corresponding morbidity. In a similar manner, this exposure prevents violation of the external ear canal, sparing the patient a conductive hearing loss.

Access to the lower clivus is difficult to achieve. It is necessary to displace the petrous portion of the carotid anteriorly and translocate the lower cranial nerves inferiorly. Lower cranial nerve morbidity is common during glomus jugulare surgery because these nerves are intimately related to the tumor.²⁴ Preserving the dural covering of the lower cranial nerves as they are displaced can help minimize this morbidity.

The ELITE approach is a versatile one-stage approach to difficult tumors of the jugular foramen. Surgical results are favorable compared with results described in the literature. It is a useful tool in the armamentarium of the neurotologic surgeon when planning management of these complex tumors.