37 Infratemporal Fossa Approach to the Jugular Foramen
Guilherme Henrique Weiler Ceccato, Duarte N. C. Cândido, Jean G. de Oliveira, and Luis A. B. Borba
Abstract
This chapter will give the reader full description on the infratemporal retroauricular transmastoid approach to skull base lesions, especially in relation with the jugular foramen. We describe the step-by-step technique to deal with difficult lesions such as the most common one at this region, the glomus jugulare tumors. They account for 80% of the jugular foramen tumors and are the second most common head and neck paragangliomas. Rosenwasser was the first surgeon to attempt total resection and described it in 1945. Fisch evolved the technique and effectively classified this pathology into types A, B, C, and D. Our special interest are the advanced types C and D (the latter with intradural extension). Here we will demonstrate our experience on how do we do this stepwise dissections without mobilizing the facial nerve from its mastoid canal, remembering all the special steps to deal with in this highly vascularized pathology.
Keywords: skull base, glomus tumor, glomus jugulare, brain tumor, brain anatomy
37.1 Introduction
The most common tumors at the jugular foramen region are jugular paragangliomas, also known as glomus jugulare tumors (GJ) or jugular chemodectomas. They account for 80% of the jugular foramen tumors, and are the second most common head and neck paragangliomas.1 , 2 This are benign and highly vascularized lesions that arise around the tympanic branch of the glossopharyngeal nerve (Jacobson’s nerve), auricular branch of the vagus nerve (Arnold’s nerve), or along the adventitia of the jugular bulb, through the paraganglia of the chemoreceptor system.1 , 3 , 4 , 5 They exhibit intense local aggressiveness with invasion and erosion of the surrounding bony structures, such as temporal and occipital bones, tympanic cavity, and lower cranial nerves (IX, X, XI, and XII), encasement and invasion of skull base major vessels, like the carotid artery and jugular bulb and vein, and intracranial and cervical extension. For this reason when the mastoid invasion extends to the tympanic cavity we also call them tympanojugular paragangliomas (TJP) or tympanojugular glomus.1 , 3 , 4 , 5
The first report about removing this complex lesions is from Rosenwasser in 1945.6 Fisch (1982) evolved the technique with rerouting of the facial nerve when using the infratemporal fossa approach, to lesions involving classes C and D of his classification.7 The Fisch’s classification is still widely accepted and the best in stratification of the extent of the tumor, assisting in planning the most suitable surgical approach.8 We prefer to approach this advanced Fisch types of TJP (D1 and D2) without facial nerve rerouting, especially when there is no facial nerve or facial canal involvement, as described by the senior author L. Borba in 2004, minimizing the facial paresis that is a constant when performing Fisch’s previous descriptions.
The aim of this chapter is not to discuss the best treatment option for glomus jugulare, but to describe the steps of surgical removal of this frequent lesion at this region, in a “How Do We Do It” description.
37.2 Anatomy
The complex regional anatomy makes TJP one of the most challenging lesions to remove completely. The surgeon must have full knowledge of skull base and craniocervical anatomy and should be specially prepared to deal with highly vascularized tumors.10 , 11 , 12 , 13 Full anatomic description is found in the chapter Microsurgical Anatomy of the Jugular Foramen. The main surgical steps are summarized in the following stepwise anatomical dissections: skin incision and muscular stage (Fig. 37.1); mastoidectomy and exposure of jugular foramen region (Fig. 37.2); basic steps of mastoidectomy (Fig. 37.3); and upper cervical region exposure (Fig. 37.4).
Fig. 37.3Stepwise dissection of mastoid process simulating a mastoidectomy. (a) Following cortical bone removal, the air cells are exposed. (b) Gentle drilling gradually removes air cells and delineates underlying structures. (c) Semicircular canals are skeletonized and part of middle fossa and presigmoid (posterior fossa) dura are exposed. There is a dural band between sigmoid sinus and bony labyrinth called endolymphatic sac, which is usually transected to release the sinus. (d) Tympanic and mastoid segments of facial nerve are identified as well as incus pointing toward tympanic segment. (e) Better exposure of facial recess bounded by facial nerve posteriorly and chorda tympani anteriorly. It gives access to tympanic cavity. (f) Global view of adjacent structures related with mastoidectomy. LSC, lateral semicircular canal; PSC, posterior semicircular canal; SSC, superior semicircular canal.
Fig. 37.4Stepwise cervical dissection to expose carotid bifurcation. (a, b) Sternocleidomastoid muscle is reflected posteriorly, exposing the external jugular vein running superficial to it, and the internal carotid artery and jugular vein deeply located. (c) Following division of external jugular vein, the underlying vascular structures are better exposed. Facial vein draining to internal jugular vein in some cases can obstruct the view of carotid bifurcation. It is possible to observe hypoglossal nerve crossing over carotid bifurcation and running anteriorly toward the tongue. At the region where the nerve turns forward it gives its branch to ansa cervicalis that continues downward. (d) Ligation of facial vein better exposes carotid bifurcation. (e) Global view. Further posterior sternocleidomastoid muscle reflection depicts proximity of suboccipital triangle. Reflection of digastric muscle exposes underlying facial nerve. Also, internal jugular vein running toward jugular foramen is better observed anteriorly to rectus capitis lateralis muscle. Br. Ans. Cerv., branch to ansa cervicalis; CCA, common carotid artery; CN, cranial nerve; Digast. Gr., digastric groove; Digast. Musc., digastric muscle; ECA, external carotid artery; EJV, external jugular vein; Ext. Aud. Canal, external auditory canal; Fac. V., facial vein; ICA, internal carotid artery; Inf. Obliq., inferior oblique muscle; IJV, internal jugular vein; Mast. Proces., mastoid process; Parot. Gland., parotid gland; Rec. Cap. Lat., rectus capitis lateralis muscle; Scap. Lev., scapula levator muscle; Temp. Musc., temporalis muscle; VA, vertebral artery.
37.3 Technique and Tactics
37.3.1 Positioning
We use a three-point head fixation device. The patient stays in a supine position with the head turned 60 degrees to the contralateral side and extended until the malar eminence is the highest point. Then the head is tilted obliquely toward the floor in order to open the space between the mandible angle and the neck (Fig. 37.5 and Fig. 37.6).
Fig. 37.5Patient positioning and demonstration of skin incision. (a, c) Patient is placed supine with the head rotated 60 degrees to contralateral side. (b, d, e) Incision varies according to the pathology extensions, and usually starts above pinna and runs posteriorly and downward coursing behind mastoid and extending to the cervical region crossing sternocleidomastoid muscle. (e) Regions for harvesting of abdominal fat and fascia lata may be prepared at the beginning of the procedure.
Fig. 37.6Patient positioning and demonstration of skin incision. (a) Demonstration of skin incision, running from above and around the pinna up to cervical area. (b) Head is rotated approximately 60 degrees to the contralateral side. (c) Global view of patient positioning, and demonstration of region of thigh to be prepared in case of need of fascia lata harvesting. Ipsilateral shoulder is slightly elevated. (d) Skin incision running from above pinna until upper cervical area.
Fig. 37.7Soft tissues step. (a) Following anterior skin reflection temporalis and sternocleidomastoid muscles are exposed. Great auricular nerve is identified and, depending upon the exposure, external jugular vein can be also observed. (b) Temporalis fascia is dissected from the underlying temporalis muscle, which is kept attached to sternocleidomastoid muscle. (c) Bony exposure following reflection of temporalis and sternocleidomastoid muscles. (d) Mastoidectomy and removal of mastoid tip and surrounding bone. (e) Demonstration of use of temporalis muscle to close skull base defects. (f) Employment of temporalis fascia attached to sternocleidomastoid muscle to help close skull base defects. Ext. Aud. Canal, external auditory canal; Great Aur. N., great auricular nerve; Mast. Proc., mastoid process; Temp. Muscle, temporalis muscle; Sternocleid. Muscle, sternocleidomastoid muscle; Transv. Proc., transverse process; Zygom. Root, zygomatic root.
37.3.2 Incision and Superficial Dissection
An arciform skin incision is made starting 2 cm over the pinna and then around 2 cm posterior to the ear and passing over the anterior margin of the sternocleidomastoid muscle (SCM) for circa 4 cm and three finger breaths under the mastoid tip level, keeping the mastoid tip in the center of the incision (Fig. 37.5 and Fig. 37.6).
The cutaneous flap is elevated over the temporalis fascia on the superior margin and over the SCM at the inferior margin. Attention should be paid as the auricular major nerve is crossing the SCM at this point (circa 5 cm under the mastoid tip). Harvesting this nerve prior to its resection is advisable as one could use it for facial nerve reconstruction as needed (Fig. 37.2).14 The external acoustic meatus is identified, transected, and a closed sac suture performed (Fig. 37.1 and Fig. 37.7).7 , 14
Fig. 37.2Stepwise dissection of region around jugular foramen. (a) Bony exposure of mastoid. Exit point of facial nerve running toward parotid gland is demonstrated along with stylomastoid artery. Rectus capitis lateralis muscle bounds posterior aspect of internal jugular vein of related posterior aspect of jugular foramen. (b) Close view demonstrating site of mastoidectomy. (c) Global view of the region of mastoidectomy and cervical area. (d) Close view of mastoidectomy area. (e) Following removal of mastoid tip and surrounding bone the course of sigmoid sinus toward internal jugular vein is demonstrated. Removal of bone around external auditory canal exposes deep tympanic membrane, and the course of facial is depicted. (f) Close perspective demonstrating relationship between internal jugular vein and carotid artery around jugular foramen region, as well as the facial nerve course and semicircular canals. CCA, common carotid artery; CN, cranial nerve; Digast. Muscle, digastric muscle; Ext. Aud. Canal, external auditory canal; Fac. Rec., facial recess; Great. Aur. N., great auricular nerve; ICA, internal carotid artery; IJV, internal jugular vein; Inf. Obliq., inferior oblique muscle; JB, jugular bulb; Lev. Scap., levator scapulae muscle; Parot. Gland, parotid gland; Rec. Cap. Lat., rectus capitis lateralis muscle; SCCs, semicircular canals; Sig. Sin., sigmoid sinus; Sternocleid. Muscle, sternocleidomastoid muscle; Stylomast. A., stylomastoid artery; Temp. Muscle, temporalis muscle; Tymp. Cav., tympanic cavity; Tymp. Memb., tympanic membrane; VA, vertebral artery; Zygom. Root, zygomatic root.
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