# Paragangliomas of the Head and Neck

## Introduction

**Paragangliomas** are rare, slow-growing, highly vascular neoplasms arising from paraganglia of the autonomic nervous system. In the head and neck, they most commonly arise from the **carotid body**, **jugular bulb**, **middle ear (glomus tympanicum)**, and the **vagal nerve**. Although typically benign, they can cause significant morbidity through local extension and cranial nerve involvement.

## Embryology and Pathophysiology

Arise from **neural crest-derived paraganglion cells** (chief cells). Function as **chemoreceptors** (carotid body) or **baroreceptors**. Carotid body paragangliomas are more common at **high altitude** due to chronic hypoxia-induced hyperplasia. Approximately **10% are familial**, associated with mutations in succinate dehydrogenase (SDH) subunit genes (SDHB, SDHC, SDHD). **SDHB mutations** carry the highest risk of malignancy (up to 30-50%). Multicentric tumors occur in 10-20% of sporadic cases and up to 80% in familial cases.

## Classification

### By Location
**Carotid body tumor (CBT)**: most common head and neck paraganglioma. **Glomus jugulare**: arising from the jugular bulb adventitia. **Glomus tympanicum**: arising from Jacobson nerve (CN IX) on the cochlear promontory. **Glomus vagale**: arising from the nodose ganglion of CN X.

### Shamblin Classification (Carotid Body Tumors)

| Type | Relationship to Vessels | Surgical Implications |
|------|------------------------|----------------------|
| I | Minimal attachment; easily dissected | Low risk of vascular injury |
| II | Partially encases carotid vessels; adherent but separable | Moderate risk; careful dissection |
| III | Completely encases carotid bifurcation | May require vessel sacrifice and grafting |

**Type I**: small, minimal attachment to vessels, easily dissected. **Type II**: partially encases the carotid vessels, adherent but separable. **Type III**: completely encases the carotid bifurcation; may require vessel sacrifice and grafting.

### Fisch Classification (Glomus Jugulare/Tympanicum)
**Type A**: limited to the middle ear (tympanicum). **Type B**: limited to the tympanomastoid area. **Type C**: involves the infralabyrinthine compartment and carotid canal. **Type D**: intracranial extension.

![CT angiography showing a Shamblin Type II carotid body tumor splaying the internal and external carotid arteries](/images/carotid-body-tumor-cta.jpg)

## Clinical Presentation

**Carotid body tumor**: painless, slowly enlarging lateral neck mass; positive **Fontaine sign** (mobile horizontally but not vertically). **Glomus tympanicum**: pulsatile tinnitus, conductive hearing loss; **reddish mass behind the tympanic membrane**. **Glomus jugulare**: pulsatile tinnitus, hearing loss, lower cranial nerve palsies (IX, X, XI, XII). **Glomus vagale**: neck mass with hoarseness (vocal fold paralysis). **Functional paragangliomas** (catecholamine-secreting) occur in <5% of head and neck cases; screen with serum/urine catecholamines and metanephrines.

## Diagnostic Workup

**CT with contrast**: enhancing mass with characteristic "salt and pepper" appearance on MRI. **MRI with gadolinium**: best for soft tissue detail and intracranial extension. **CT angiography or MR angiography**: defines vascular anatomy and feeding vessels. **Conventional angiography**: both diagnostic and allows preoperative **embolization**. **Genetic testing**: recommended for all patients, especially those with multicentric or bilateral tumors, family history, or age <40. **24-hour urine catecholamines/metanephrines**: rule out functional tumor before surgery.

![MRI demonstrating a glomus jugulare with classic salt-and-pepper signal intensity on T1-weighted imaging](/images/glomus-jugulare-mri.jpg)

## Management

### Observation
Appropriate for elderly patients, small asymptomatic tumors, or those with significant comorbidities. Average growth rate: 1-2 mm/year.

### Surgery
**Carotid body tumors**: surgical excision is the treatment of choice; preoperative embolization 24-48 hours before surgery reduces blood loss. **Glomus tympanicum**: transcanal or postauricular approach for limited tumors. **Glomus jugulare**: infratemporal fossa approach (Fisch approach) for large tumors. **Risk of cranial nerve injury** increases with Shamblin type and Fisch class.

### Radiation Therapy
Stereotactic radiosurgery (Gamma Knife) or fractionated radiation. Tumor control rates: 90-95%. Does not eliminate the tumor but halts growth. Preferred for elderly patients, poor surgical candidates, or residual/recurrent disease.

![Angiogram demonstrating a hypervascular carotid body tumor with characteristic tumor blush before embolization](/images/paraganglioma-angiogram.jpg)

## Key Clinical Pearls

Always obtain **genetic testing** in patients with head and neck paragangliomas; SDHB carriers need lifelong surveillance. Never biopsy a pulsatile middle ear mass — it may be a glomus tumor and will bleed significantly. **Preoperative embolization** 24-48 hours before surgery reduces intraoperative blood loss. The **Fontaine sign** is classic for carotid body tumors: mobile side to side but not cephalocaudally. Screen for bilateral and multicentric tumors, particularly in familial cases.

## References

1. Boedeker CC, Ridder GJ, Schipper J. Paragangliomas of the head and neck: diagnosis and treatment. *Fam Cancer*. 2005;4(1):55-59.
2. Shamblin WR, ReMine WH, Sheps SG, Harrison EG Jr. Carotid body tumor (chemodectoma): clinicopathologic analysis of ninety cases. *Am J Surg*. 1971;122(6):732-739.
3. Neumann HP, Erlic Z, Boedeker CC, et al. Clinical predictors for germline mutations in head and neck paraganglioma patients: cost reduction strategy in genetic diagnostic process. *Cancer Res*. 2009;69(8):3650-3656.
4. Carlson ML, Sweeney AD, Pelosi S, et al. Glomus tympanicum: a review of 115 cases over 4 decades. *Otolaryngol Head Neck Surg*. 2015;152(1):136-142.