Chapter 59 Extreme Lateral Infrajugular Transcondylar Approach for Resection of Skull Base Tumors

Debara L. Tucci, Thomas M. Pilkington, Takanori Fukushima

The extreme lateral infrajugular transcondylar (ELITE) approach was born out of the anatomic constraints and operative challenges presented by the cranial base. The transcondylar approach was first devised as an avenue for access to the foramen magnum and ventral medulla.^1,² In 1986, Heros³ described the extreme lateral inferior suboccipital approach for access to vertebral and vertebrobasilar artery lesions. The ELITE approach is a special transcondylar and transjugular tubercle skull base approach developed and elaborated in Germany and Japan in 1987.^4,⁵ After years of refinement, this has become a very useful and well-described approach for this region of the skull base.

The standard ELITE approach involves drill resection of the medial and superior medial one third of the occipital condyle and jugular tubercle. This is an excellent approach for vertebral artery and posterior inferior cerebellar artery aneurysms; vertebrobasilar junction aneurysms; and more complex foramen magnum, infrajugular, and anterior brainstem tumors. An anterolateral approach modification includes addition of a high cervical exposure, which is ideal for large glomus jugulare tumors. Other modifications include a limited transcondylar approach for some smaller vertebral artery and posterior inferior cerebellar artery lesions, and an extensive ELITE approach involving partial resection of the occipital condyle and resection of the C1 arch for access to chordomas, chondrosarcomas, and high cervical spine lesions. These modifications are beyond the scope of this chapter.

Paragangliomas of the temporal bone were first identified as a unique entity in 1945.⁶ Attempts at characterization and ultimate surgical resection were initially fraught with high morbidity and mortality because of their location amidst complex anatomic structures. Primary treatment with radiation therapy soon became the mainstay for therapy with the hopes of limiting complications. Radiation therapy has been shown to be superior to observation of these lesions; however, the long-term risks of malignancy and radiation morbidity limit its success.⁷^–¹⁰ Definitive surgical resection remains the mainstay for attempted cure.

Attempts at surgical resection and cure led to the development of tumor classification strategies to help guide surgical planning and to improve communication of results. Two main classification schemes were devised and remain in use today, primarily in the otology/neurotology literature—the Fisch ¹¹ and Glasscock-Jackson classifications.¹² The Fisch scheme is as follows:

Type A: Tumors limited to the middle ear cleft

Type B: Tumors limited to the tympanomastoid area

Type C: Tumors involving the infralabyrinthine region

Type D1: Tumors with an intracranial extension less than 2 cm in diameter

Type D2: Tumors with an intracranial extension greater than 2 cm in diameter

The Glasscock-Jackson scheme is divided for tympanicum and jugulare tumors. The following glomus jugulare scheme includes a superscript for degree of intracranial extent (e.g., a paraganglioma type IV^2.0 is a lesion with 2 cm of intracranial extension):

Type I: Small tumor involving the jugular bulb, middle ear, and mastoid process

Type II: Tumor extending under the internal auditory canal; may have intracranial extension

Type III: Tumor extending into the petrous apex; may have intracranial extension

Type IV: Tumor extending beyond the petrous apex into clivus or infratemporal fossa; may have intracranial extension

Glomus jugulare tumors with advanced stage (Fisch class C and D, Glasscock-Jackson class II-IV) typically are treated surgically with a classic Fisch infratemporal fossa approach (types A or B). Key to surgical treatment of glomus jugulare tumors is safe access to surgical margins while preserving vital nerves and vessels. Classic approaches described have surgical morbidity, including facial nerve dysfunction owing to translocation, sacrifice of the external auditory canal, hearing loss, anterior dislocation of the mandible to gain access to the petrous portion of the carotid artery, and cerebrospinal fluid (CSF) leak. Additionally, some tumors with intracranial extent can require a two-stage procedure to minimize complications.

The authors have used a simpler classification of tumors in this location, and modifications and additions to the ELITE approach—including transsigmoid, transjugular, infrajugular, and high cervical approaches—are tailored to provide needed exposure for tumor resection (Fig. 59-1):

Type A: Main tumor mass is intradural—uses primarily an ELITE approach

Type B: Main mass is combined intradural and intrajugular—uses transjugular and ELITE approaches

Type C: Main mass is intradural, intrajugular, and high cervical, typical of extensive glomus jugulare tumor—uses ELITE, transsigmoid, transjugular, infrajugular, and high cervical exposure

FIGURE 59-1 Intradural tumor, type A (top). Tumor mass intradural and transjugular, type B (bottom left). Tumor mass intradural, transjugular, and high cervical, type C (bottom right).

The ELITE approach provides a one-stage transjugular posterior infratemporal fossa approach to resect complex glomus jugulare tumors and other lesions of the jugular foramen. This method can avoid rerouting of the facial nerve, and may preserve the external auditory canal and hearing function. The petrous portion of the carotid is accessible without anterior dislocation of the mandible. Two modifications of this approach are described. The dorsolateral ELITE approach is used for intradural, type A, tumors involving the vertebral artery, posterior inferior cerebellar artery aneurysms, foramen magnum meningiomas, and glomus jugulare tumors with a large intradural component. The anterolateral ELITE approach is used for type B and C tumors, including extensive glomus jugulare tumors. The approach can be broken down into a series of maneuvers, as follows:

1. Postauricular infratemporal incision

2. Retrolabyrinthine mastoidectomy

3. High cervical exposure

4. Skeletonization and (if needed) anterior translocation of the facial nerve

5. Lateral suboccipital and transcondylar-transtubercular exposure

6. Removal of the internal jugular vein (IJV), jugular bulb, and sigmoid sinus

7. Intradural exposure

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).