Can a right sigmoid sinus diverticulum with dehiscence and an enlarged right emissary mastoid vein, without transverse sinus stenosis, cause bilateral aural fullness?

Can Right Sigmoid Sinus Diverticulum with Dehiscence and Enlarged Emissary Vein Cause Bilateral Aural Fullness Without Transverse Sinus Stenosis?

Yes, right-sided sigmoid sinus wall abnormalities can cause bilateral aural fullness even without transverse sinus stenosis, though this presentation is uncommon and the mechanism for contralateral symptoms remains incompletely understood.

Primary Evidence for Unilateral Venous Abnormalities Causing Symptoms

Sigmoid sinus diverticulum and dehiscence with enlarged emissary veins are established causes of aural fullness, but the literature predominantly describes ipsilateral symptoms. 1, 2

• In a cohort of 15 patients with pulsatile tinnitus and CT-confirmed sigmoid sinus wall abnormalities, aural fullness occurred in 80% (12/15) of cases, confirming this as a frequent associated symptom alongside the hallmark finding of pulsatile tinnitus 2
• Altered venous flow dynamics from these bony defects generate turbulent flow that stimulates adjacent vestibular and cochlear structures, producing pressure sensations independent of elevated intracranial pressure 1
• The pathophysiology involves abnormal hemodynamic stress on the sigmoid plate and turbulent venous drainage through enlarged emissary channels 1, 3

The Challenge of Bilateral Symptoms from Unilateral Pathology

Bilateral aural fullness from strictly unilateral venous pathology is not well-documented in the literature, creating a diagnostic dilemma.

• The available evidence focuses on ipsilateral symptoms corresponding to the side of the sigmoid sinus wall abnormality 2, 4
• However, 20% of patients with sigmoid sinus wall abnormalities have bilateral lesions 2, which could explain bilateral symptoms if your patient has contralateral abnormalities not yet identified
• In the study by Eisenman et al., bilateral sigmoid plate dehiscence was present in 53.3% (8/15) of patients 5, suggesting that apparently "unilateral" cases on initial review may have subtle contralateral findings

Critical Differential Diagnoses to Exclude

Before attributing bilateral aural fullness to unilateral venous pathology, you must systematically exclude other causes that commonly present with bilateral symptoms:

Ménière's Disease and Autoimmune Inner Ear Disease

• Bilateral aural fullness with fluctuating hearing loss should prompt evaluation for Ménière's disease or autoimmune inner ear disease, both of which present with fluctuating aural symptoms and can be bilateral at onset 6, 7
• Ménière's disease is defined by spontaneous vertigo attacks (20 minutes to 12 hours), documented low- to mid-frequency sensorineural hearing loss, and fluctuating aural symptoms (hearing loss, tinnitus, or fullness) 7
• Prior episodes of fluctuating hearing loss make idiopathic causes less likely and should raise suspicion for Ménière's disease, autoimmune inner ear disease, or Cogan's syndrome 6

Idiopathic Intracranial Hypertension (IIH)

• Even though your patient lacks transverse sinus stenosis, IIH can present with bilateral aural fullness, headache, and visual symptoms 8, 9
• The absence of transverse sinus stenosis does not exclude IIH, as stenosis is present in only a subset of cases 9
• Look for papilledema on fundoscopic examination and consider lumbar puncture with opening pressure measurement if clinical suspicion is high 8

Superior Semicircular Canal Dehiscence (SSCD)

• SSCD causes pressure-induced dizziness, autophony, and aural fullness and can be bilateral 1
• Diagnosis requires high-resolution CT temporal bone with thin-section reconstructions to visualize the superior semicircular canal 1

Spontaneous Intracranial Hypotension

• Orthostatic headache with aural fullness should prompt brain MRI with contrast to evaluate for pachymeningeal enhancement, venous sinus engorgement, and brain sagging 1

Recommended Diagnostic Algorithm

To determine whether your patient's bilateral aural fullness is related to the right-sided venous abnormality or represents a separate pathology:

1. Obtain high-resolution CT temporal bone with thin-section bone-window reconstructions bilaterally to assess for:

   • Contralateral sigmoid sinus dehiscence or diverticulum 1, 2
   • Bilateral superior semicircular canal dehiscence 1
   • Enlarged emissary veins on the left side 1

2. Perform audiometry to document:

   • Low- to mid-frequency sensorineural hearing loss (suggests Ménière's disease) 6, 7
   • Bilateral hearing loss (suggests systemic or bilateral pathology) 6

3. Assess for pulsatile tinnitus characteristics:

   • Pulsatile tinnitus synchronous with heartbeat is the hallmark symptom of sigmoid sinus wall abnormalities 10
   • Absence of pulsatile tinnitus makes venous pathology a less likely primary cause, though rare cases without pulsatile tinnitus have been reported 11

4. Evaluate for IIH features even without transverse sinus stenosis:

   • Fundoscopic examination for papilledema 8
   • Body mass index (BMI) assessment—patients with sigmoid sinus wall abnormalities have elevated BMI (mean 32.2) 2
   • Consider lumbar puncture if clinical suspicion warrants 8

5. If CT venography and temporal bone CT are unrevealing, obtain CT angiography of the head and neck to exclude arterial causes (dural arteriovenous fistula, arteriovenous malformation, cervical artery dissection) 1

Treatment Considerations if Venous Pathology is Confirmed

If imaging confirms that bilateral symptoms correlate with bilateral venous abnormalities or if ipsilateral treatment resolves bilateral symptoms:

• Targeted wall-reconstruction surgery for sigmoid sinus dehiscence leads to resolution of head pressure and dizziness in 90% of appropriately selected patients 1, 4
• Endovascular stenting of transverse sinus stenosis (when present) resolves pulsatile tinnitus in 86.1% of cases at 3 months, even without dedicated treatment of sigmoid sinus wall abnormalities 12
• Coiling of sigmoid sinus diverticulum and emissary vein eliminates turbulent flow and may permit bone regrowth over 6-24 months 3, 5
• Patients require at least 6 months of antithrombotic therapy after venous sinus stent placement, typically dual antiplatelet agents transitioning to monotherapy 1

Key Clinical Pitfalls

• Do not assume unilateral venous pathology explains bilateral symptoms without excluding bilateral disease or alternative diagnoses 6, 2
• Sigmoid sinus wall abnormalities are progressive, not congenital, and can worsen over time—serial imaging may be warranted 13
• Approximately one-third of patients develop stent-adjacent stenosis requiring retreatment after venous sinus intervention 1
• Patients with isolated dehiscence without diverticulum, transverse sinus stenosis, or empty sella are less likely to respond to surgical repair 4