Glomus Tumors

Introduction & Epidemiology - Tumor Tidbits

• Definition: Highly vascular, typically benign neoplasms (paragangliomas).
• Origin: Neural crest cells (paraganglia) along glossopharyngeal (CN IX) & vagus (CN X) nerves within the temporal bone.
• Common Types:
  • Glomus Tympanicum: Middle ear origin (Jacobson’s nerve on cochlear promontory).
  • Glomus Jugulare: Jugular foramen/bulb origin.

⭐ Glomus tumors are the most common benign tumors of the middle ear.

• Prevalence: Rare overall. Female predominance (F:M ≈ 3:1). Peak incidence 40-50 years.
• Genetics: Familial in ~10-50%; linked to Succinate Dehydrogenase (SDH) gene mutations (e.g., SDHD, SDHB). ​

Clinical Presentation - Symptom Symphony

• Hallmark: Pulsatile tinnitus (often earliest).

  ⭐ Pulsatile tinnitus is the hallmark symptom of glomus tumors.

• Key Otoscopic Signs:

  • Rising Sun Sign: Reddish-blue vascular mass behind intact TM (Glomus Tympanicum).
  • Brown's Sign: Blanching of mass with positive pressure (pneumatic otoscopy).
  • Aquino's Sign: Blanching of mass with ipsilateral carotid artery compression.

• Glomus Tympanicum vs. Glomus Jugulare:

  Feature	Glomus Tympanicum	Glomus Jugulare
  Tinnitus	Pulsatile	Pulsatile
  Hearing Loss	Conductive (CHL)	CHL / SNHL / Mixed
  Key Sign	'Rising sun' behind TM	Often involves CN palsies
  CN Palsies	Rare	IX-XII (Vernet's: IX,X,XI). - IX: Dysphagia - X: Hoarseness - XI: Shoulder drop - XII: Tongue deviation

📌 Mnemonic for Jugulare CNs (IX-XII): "Jugular foramen is home to 9, 10, 11, 12 nerves."

Diagnosis & Imaging - Detective Work

• Otoscopy:
  • Reddish-blue pulsatile mass behind intact TM (Rising Sun sign).
  • Brown's sign: Blanching/↓pulsation on +ve pressure (pneumotoscopy).
• Audiometry: Conductive (CHL), mixed (MHL), or sensorineural (SNHL) hearing loss.
• Imaging:
  • HRCT (Temporal Bone): Phelp's sign (tumor mass at jugular foramen), details bony erosion.
  • MRI (Gadolinium): 'Salt & pepper' appearance (T1WI+C: flow voids, hemorrhage); defines extent, intracranial spread.
  • Angiography: 'Mother-in-law' sign (early blush, late retention); identifies feeders; pre-op embolization.
• ⚠️ Biopsy: Generally contraindicated: high vascularity, significant bleeding risk.
• Biochemical Tests: If functional suspected: 24-hr urine VMA, metanephrines; plasma free metanephrines.

⭐ The "salt and pepper" appearance on T1-weighted MRI with contrast is characteristic of paragangliomas.

Staging & Management - Battle Plan

Fisch Classification:

• Glomus Tympanicum (Middle Ear):
  • Type A: Tumor limited to middle ear cleft.
  • Type B: Tumor involving tympanomastoid compartment.
  • Type C: Tumor involving infralabyrinthine compartment & petrous apex.
  • Type D: Intracranial extension < 2 cm.
• Glomus Jugulare (Jugular Foramen):
  • Type A: Tumor limited to jugular bulb, middle ear, mastoid.
  • Type B: Tumor extending to infralabyrinthine compartment, petrous apex.
  • Type C: Tumor extending into petrous apex, carotid canal, foramen lacerum.
  • Type D: Intracranial extension (D1: < 2 cm; D2: > 2 cm).

Management Options:

• Observation: Small, asymptomatic, elderly/comorbid patients.
• Surgery: Mainstay treatment.
  • Pre-operative embolization: Often 24-48 hours prior.
  • Approaches: Transcanal, transmastoid, infratemporal fossa.
• Radiotherapy (RT): Stereotactic Radiosurgery (SRS) / Stereotactic Radiotherapy (SRT).
  • Primary (elderly/unfit/recurrent) or adjuvant.

⭐ Pre-operative embolization is often performed 24-48 hours before surgery for vascular glomus tumors to reduce intraoperative bleeding.

High‑Yield Points - ⚡ Biggest Takeaways

• Most common benign tumor of the middle ear; arises from paraganglia.
• Pulsatile tinnitus (synchronous with pulse) is the classic symptom.
• "Rising sun" sign: Reddish vascular mass behind the tympanic membrane.
• Brown's sign: Blanching of mass with pneumatic otoscopy (positive pressure).
• Phelp's sign (CT): Assesses bony erosion, e.g., jugular foramen.
• Aquino's sign: Blanching with ipsilateral carotid artery compression.
• Surgery is primary treatment; radiotherapy for specific cases.