Glomus Tumors - Clinical Tree

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Paraganglioma or glomus tumor is a tumor of the neuroendocrine system derived from neural crest cells and chemoreceptor cells. Although most tumors are sporadic, familial glomus tumors may occur in 20% of patients with glomus tumors. Some of the tumors are multicentric and bilateral at the time of presentation, which typically occur at an earlier age in successive generations in families harboring genetic mutations. Glomus tumors are slow-growing, invasive, highly vascular neoplasms that are in proximity to the important temporal bone structures that can include the facial nerve, internal carotid artery (ICA), and lower cranial nerves. Glomus tympanicum tumors typically arise in the middle ear space and may involve the middle ear with or without extension to the hypotympanum, attic, and mastoid, and rarely, the ICA and petrous apex or intracranial areas. These tumors typically do not involve the lower cranial nerves, so the cranial nerve morbidity from treatments is usually limited to the facial nerve and hearing/vestibular apparatus. In contrast, glomus jugulare tumors arise in the jugular foramen and typically involve the superior and lateral wall of the jugular bulb. In addition to the cranial nerves at risk for glomus tympanicum tumors, the lower cranial nerves, IX, X, XI, and sometimes XII, may be involved and place the patient at significant risk for dysphagia, dysphonia, and shoulder dysfunction that may be extremely debilitating.

Two classification systems have been offered for nomenclature and staging. Fisch described and modified a classification system based on the size and extent of the tumor ( Box 142.1 ). The other classification system was devised by Glasscock and Jackson ( Box 142.2 ). Both classifications address the pertinent issues of tumor size, petrous apex or carotid artery involvement, and intracranial extension. This provides critical information necessary to design an operative approach and plan.

BOX 142.1

Glomus Tumor Classification: Fisch

Data from Fisch U: Infratemporal fossa approach for glomus tumors of the temporal bone. Ann Otol Rhinol Laryngol 91:474-479, 1982, and Fisch U, Mattox D: Classification of glomus temporal tumors. In Fisch U, Mattox D (eds): Microsurgery of the Skull Base. Stuttgart and New York: Georg Thieme; 1988, pp 149-153.

Type	Description
A	Tumor limited to middle ear cleft (promontory)
B	Tumor confined to middle ear, hypotympanum, and mastoid
C ₁	Tumor eroding jugular bulb and carotid foramen; not invading carotid artery
C ₂	Tumor involving infralabyrinthine and apical temporal bone; erosion of vertical carotid artery
C ₃	Tumor involving infralabyrinthine and apical temporal bone; erosion of horizontal carotid artery
C ₄	Tumor involving infralabyrinthine and apical temporal bone; tumor grows to foramen lacerum and cavernous sinus
D ₁	Intracranial tumor <2 cm
D ₂	Intracranial tumor >2 cm; e, extradural; i, intradural
Di ₃	Unresectable intracranial extension

BOX 142.2

Glomus Tumor Classification: Glasscock-Jackson

Data from Jackson CG, Glasscock ME, Harris PF: Glomus tumors: diagnosis, classification, and management of large lesions. Arch Otolaryngol 108:401-410, 1982.

Type	Description
Glomus Tympanicum
I	Small mass limited to promontory
II	Tumor completely filling middle ear space
III	Tumor filling middle ear and extending into mastoid
IV	Tumor filling middle ear, extending into mastoid or through tympanic membrane to fill external auditory canal; may extend anterior to carotid
Glomus Jugulare
I	Small tumor involving jugular bulb, middle ear, and mastoid
II	Tumor extending under internal auditory canal; may have intracranial extension
III	Tumor extending into petrous apex; may have intracranial extension
IV	Tumor extending beyond petrous apex into clivus or infratemporal fossa; may have intracranial extension

Treatment options for glomus tumors of the temporal bone include observation with serial scanning to monitor for growth, microsurgical excision, and radiation therapy (XRT). For advanced tumors that approximate or involve the lower cranial nerves, the standard practice in the past consisted of aggressive surgical removal with possible adjuvant radiation in some cases. Complete surgical resection of these tumors minimizes the chance for recurrence but may result in significant morbidity. This treatment may incur lower cranial dysfunction, requiring the need for a tracheotomy, nasogastric tube placement, or percutaneous gastrostomy feeding tube, along with complications of aspiration, pneumonia, malnutrition, and weakness of the shoulder and tongue. In addition, sacrifice of the ICA is avoided as much as possible to prevent the morbidity of ischemic cerebral damage.

Radiation therapy does not eliminate the tumor but is intended to halt tumor progression. Proponents for surgery have suggested that radiation is indicated for palliation, following incomplete tumor excision or for patients who are medically infirm or elderly. However, there is strong evidence indicating that radiotherapy could also be considered the definitive treatment strategy for skull base glomus tumors. Glomus jugulare tumors have traditionally been treated by fractionated XRT. Newer techniques using a frame-based linear accelerator, gamma radiation from cobalt delivered through the Gamma Knife, or photon beam from a robot-mounted mini-linear accelerator such as the CyberKnife are available for single or multiple focused treatments (fractions), providing submillimeter accuracy in treatment delivery.

Based on the apparent success of varied radiation procedures, the management recommendations have evolved recently to treatment options that preserve function as much as possible. This approach may entail observation, primary radiation, or subtotal function preserving tumor resection followed by observation or radiation of the residual tumor.

Key Operative Learning Points

Surgical treatments for glomus tympanicum tumors are typically limited to tympanoplasty and mastoidectomy dissections.
Surgical treatments for glomus jugulare tumors are more extensive and, in addition to those noted previously, include various degrees of infratemporal fossa dissection, exposure of the skull base from the upper neck, possible petrous apex, and intracranial exposures.
If the lower cranial nerves of the jugular foramen are to be preserved, the medial wall of the jugular bulb must be left intact, and care should be taken not to compress the contents of the pars nervosa.
For jugulare tumors, the facial nerve may be managed by the fallopian bridge technique in most cases and facial nerve transposition for very extensive tumors.
The prevention of cerebrospinal fluid (CSF) leak in cases of dural penetration can be managed with various techniques, from adipose tissue graft packing of a more isolated posterior temporal bone CSF leak with preservation of the hearing mechanism to eustachian tube (ET) and external auditory canal (EAC) closure and possible use of a temporalis muscle rotation flap.

Preoperative Period

History

1.
History of present illness
- a.
  Pulsatile tinnitus
- b.
  Hearing loss
- c.
  Dizziness: Vertigo and/or imbalance
- d.
  Otalgia
- e.
  Facial weakness or twitching
- f.
  Dysphagia
- g.
  Hoarseness
- h.
  Shoulder weakness and/or pain
- i.
  Dysarthria, tongue dysfunction
- j.
  Labile hypertension, tachycardia, headache, perspiration, pallor, and nausea—may indicate a significant catecholamine release from the tumor requiring medical management
2.
Past medical history
- a.
  Prior treatment with surgery or radiation
- b.
  Medical illness such as coronary artery disease, lung disease, bleeding disorders
- c.
  Family history of vascular or endocrine tumors

Physical Examination

1.
Otologic evaluation: Ear microscopy or endoscopy
- a.
  Vascular middle ear lesion
- b.
  Tympanic membrane involvement
- c.
  Extension into the ear canal
- d.
  Brown’s sign: Tumor blanching with ear insufflation
- e.
  Tuning fork
2.
Balance evaluation
- a.
  Gait
- b.
  Tandem gait
- c.
  Romberg test
3.
Cranial nerve evaluation
- a.
  Facial nerve
- b.
  Cranial nerves IX, X, XI, XII
4.
Neck: Mass in the upper neck
5.
Audiologic evaluation
- a.
  Pure tones
- b.
  Speech discrimination scores
- c.
  Tympanogram

Imaging

1.
Computed tomography (CT) of the temporal bone with 0.6 mm axial and coronal cuts ( Fig. 142.1 )
- a.
  Opacification or soft tissue masses of the middle ear, attic, or mastoid
- b.
  Bony erosion along the jugular bulb and jugular foramen
- c.
  Involvement of the ICA
- d.
  Erosion of bone along the posterior petrous bone that could indicate extension of the tumor into the posterior fossa
- e.
  Bony erosion into the otic capsule
2.
Magnetic resonance imaging (MRI) with gadolinium of the brain, internal auditory canal, and neck
- a.
  Enhancing lesion involving the middle ear, attic, mastoid, hypotympanum, jugular foramen, petrous apex, internal carotid artery, or intracranial areas
- b.
  Flow void within the sigmoid sinus, jugular bulb, and jugular vein
- c.
  Identification of any synchronous tumors of the head and neck or skull base
3.
Angiography: Four-vessel cerebral arteriogram may be done during preoperative tumor embolization if embolization is planned.
- a.
  Tumor blush
- b.
  Identification of feeder vessels
- c.
  Identification of any synchronous vascular tumors of the head and neck or skull base
4.
Magnetic resonance angiography (MRA) or CT angiography (CTA) may be done as a noninvasive alternative to angiography, although it is not as sensitive as formal angiography.

Indications

1.
The main goal of intervention is to prevent and/or halt the progression of bothersome symptoms and to avoid incurring additional symptoms.
- a.
  Pulsatile tinnitus
- b.
  Hearing loss
- c.
  Dizziness
- d.
  Dysphagia
- e.
  Hoarseness
- f.
  Shoulder dysfunction
- g.
  Symptoms related to catecholamine release
2.
Most symptomatic glomus tympanicum tumors can be surgically removed with limited risk of significant morbidity.
3.
Many glomus jugulare tumors can be removed completely with mild risk of increased morbidity, unless there is involvement of the jugular foramen pars nervosa, significant ICA involvement, or intracranial extension.
4.
Tumors that involve structures that will incur significant patient morbidity associated with total resection may be considered for alternative treatments.
- a.
  Observation with serial MRI
- b.
  Subtotal resection (STR), leaving tumors in sensitive areas, followed by options of observation or radiation
- c.
  Primary radiation options
5.
Most small to medium tumors can also be considered for observation with serial MRI versus primary radiation.

Contraindications

1.
Advanced age and medical comorbidities with increased risk for general anesthesia may make any surgical option too risky for some patients.
2.
Patients with pre-existing dysphagia related to prior cerebrospinal accident (CVA) or other diseases not related to the tumor may not tolerate treatment related injury to the lower cranial nerves.

Preoperative Preparation

1.
Medical treatment of any tumor-associated elevation of circulating catecholamines—alpha and beta blockade
2.
Angiographic embolization of tumor, in most cases of glomus jugulare tumors, typically 1 to 2 days prior to surgery
3.
If there is significant involvement of the ICA that may be at risk for vascular injury, the patient typically undergoes balloon test occlusion with xenon perfusion to see if sacrifice of the carotid will be tolerated. Alternatively, a protective ICA stent may be placed.
4.
Type and cross 2 to 4 units of red blood cells when operating on glomus jugulare tumors.

Operative Period

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Video 142.1 , Video 142.2 , Video 142.3