In a thin patient (BMI 18) with low‑pitched pulsatile tinnitus, autophony, ear fullness, and headaches possibly worsened by tight hair styles, should we evaluate for a high‑riding jugular bulb or superior semicircular canal dehiscence?

Evaluation for High-Riding Jugular Bulb and Semicircular Canal Dehiscence

Yes, you should absolutely evaluate this patient for both high-riding jugular bulb (HRJB) and superior semicircular canal dehiscence (SSCD), as these are well-established causes of pulsatile tinnitus with autophony and ear fullness, and the low BMI actually makes IIH less likely, strengthening the indication for temporal bone imaging. 1

Why These Diagnoses Fit

Your clinical reasoning is sound. The constellation of:

• Low-pitched pulsatile tinnitus ("whoosh")
• Autophony (hearing one's own voice/breathing)
• Ear fullness
• Low BMI (making IIH unlikely)

...creates a strong clinical picture for either HRJB or SSCD, or potentially both occurring together 2, 3.

Key Clinical Distinctions

SSCD typically presents with:

• Autophony (classic finding) 2
• Sound-induced vertigo (Tullio phenomenon)
• Pressure-induced vertigo (Hennebert sign)
• Conductive hearing loss on audiometry despite intact tympanic membrane
• Pulsatile tinnitus 2

HRJB presents with:

• Pulsatile tinnitus (most common symptom - present in 58% of cases) 4
• Autophony and ear fullness 3, 5
• Can cause conductive, sensorineural, or mixed hearing loss 4
• Importantly, HRJB can actually cause posterior semicircular canal dehiscence 3, 5

The fact that she tolerates high-intensity exercise without symptoms makes vestibular dysfunction less prominent but doesn't rule out SSCD, as symptom severity varies widely 2.

Recommended Imaging Algorithm

First-line imaging: High-resolution CT temporal bone without contrast 1

This single study can diagnose:

• SSCD (requires fine-cut 0.5-0.6mm collimation reformatted parallel and orthogonal to the superior canal plane) 1, 2
• HRJB and jugular bulb dehiscence 1, 4
• Sigmoid sinus abnormalities
• Other bony temporal bone pathology

Do NOT order:

• CT with contrast (adds no value for these diagnoses) 1
• CT head (wrong field of view, insufficient resolution) 1
• MRI as first-line (less sensitive for bony dehiscence)

Consider adding CTA head and neck with IV contrast if:

• CT temporal bone is negative but symptoms persist
• You need to rule out vascular causes (dAVF, AVM, arterial dissection)
• The thin bone reconstructions from CTA can also show temporal bone pathology, though with lower resolution than dedicated temporal bone CT 1

Additional Diagnostic Testing

Audiometry is essential:

• Look for conductive hearing loss with intact tympanic membrane (suggests third window lesion from SSCD or HRJB) 2, 4
• HRJB patients show conductive loss in 70% of cases when symptomatic 4

Vestibular evoked myogenic potentials (VEMP):

• Useful for confirming SSCD if CT findings are equivocal 2
• Shows decreased thresholds and increased amplitudes in SSCD

Regarding the Tight Hair Buns

While tight hairstyles can contribute to tension-type headaches, they would not explain the pulsatile tinnitus, autophony, or ear fullness. Address this as a separate contributing factor to her headaches, but don't let it distract from the otologic workup. The temporal bone pathology needs evaluation regardless.

Clinical Pitfalls to Avoid

1. Don't dismiss pulsatile tinnitus in thin patients as "just IIH" - you're correct that BMI 18 makes IIH unlikely, and this presentation demands temporal bone imaging 1

2. HRJB can erode the posterior semicircular canal, creating a "double pathology" scenario 3, 5 - both conditions may coexist

3. Right-sided predominance is common for HRJB (70% right-sided in one series) 4, so laterality matters

4. The incidence of HRJB is 22%, with 3.5% showing dehiscence 4 - these are not rare findings and are frequently associated with tinnitus 6

Treatment Implications

If imaging confirms either diagnosis:

• SSCD: Surgical resurfacing, plugging, or capping via middle fossa or transmastoid approach for symptomatic patients 2
• HRJB with dehiscence: Surgical resurfacing of the dehiscent bone, or newer endovascular techniques with stent-assisted coil embolization 7, 8
• Combined pathology: Resurfacing may address both issues 5

The prognosis is generally good with appropriate surgical intervention when symptoms are bothersome enough to warrant treatment 2, 5.