What is the most likely diagnosis and recommended workup for a 16‑year‑old overweight female with left‑sided pulsatile tinnitus relieved by firm pressure on the left carotid artery, mixed low‑frequency (250‑500 Hz) hearing loss in the left ear, type A tympanogram, and normal ipsilateral and contralateral acoustic reflexes?

Most Likely Diagnosis: Idiopathic Intracranial Hypertension (IIH)

This 16-year-old overweight female with left-sided pulsatile tinnitus relieved by carotid compression, low-frequency mixed hearing loss, and normal tympanometry most likely has idiopathic intracranial hypertension (pseudotumor cerebri), which is the second most common cause of pulsatile tinnitus and classically presents in young overweight women. 1

Key Diagnostic Features Supporting IIH

• Relief with carotid compression strongly suggests a venous etiology, specifically sigmoid sinus abnormalities or elevated intracranial pressure, rather than arterial pathology 1, 2

• Young overweight female demographic represents the highest-risk population for IIH, which accounts for the second most common cause of pulsatile tinnitus overall 1

• Low-frequency (250-500 Hz) mixed hearing loss is characteristic of IIH, as elevated intracranial pressure can affect cochlear function and create conductive-pattern hearing loss at low frequencies 1

• Type A tympanogram with normal reflexes excludes middle ear pathology (effusion, otosclerosis, ossicular chain problems) and points toward a vascular or pressure-related etiology 1

Critical Differential Diagnoses to Exclude

While IIH is most likely, life-threatening causes must be ruled out:

• Sigmoid sinus diverticulum or dehiscence is commonly associated with intracranial hypertension and can present identically, often coexisting with IIH 1

• Dural arteriovenous fistula accounts for 8% of pulsatile tinnitus cases and represents a life-threatening condition that can lead to hemorrhagic or ischemic stroke if missed 1, 3

• Arterial dissection is potentially catastrophic and requires urgent identification, though less likely given relief with compression 1

• Highly vascularized skull base tumors (paragangliomas, glomus tumors) account for 16% of pulsatile tinnitus cases but would typically show a vascular retrotympanic mass on otoscopy 1, 4

Recommended Workup Algorithm

Step 1: Immediate Imaging (First-Line)

Order CT angiography (CTA) of the head and neck with contrast using a mixed arterial-venous phase (20-25 seconds post-contrast) as the initial study. 1

• CTA captures both arterial pathology (dissection, atherosclerosis, AVF) and venous abnormalities (sigmoid sinus stenosis, diverticulum, transverse sinus stenosis) in a single acquisition 1

• This approach identifies life-threatening vascular causes while simultaneously evaluating for venous sinus abnormalities associated with IIH 1

• CTA source images can be reconstructed to create dedicated temporal bone CT images without additional radiation exposure 1

Step 2: Ophthalmologic Evaluation (Urgent)

Obtain urgent ophthalmology consultation with fundoscopic examination to assess for papilledema, which is the hallmark of IIH and can lead to permanent vision loss if untreated 1

• Young overweight women with pulsatile tinnitus represent a high-risk demographic for IIH, and missing papilledema can result in irreversible blindness 1

Step 3: Additional Imaging if CTA is Negative

If CTA shows no arterial or arteriovenous pathology but demonstrates venous sinus abnormalities:

• Proceed to MRI brain with contrast and MR venography (MRV) to further characterize venous sinus stenosis, sigmoid sinus wall abnormalities, and rule out cerebellopontine angle lesions 1

• MRI is superior for detecting subtle sigmoid sinus diverticulum, venous sinus stenosis, and associated brain parenchymal changes 1

Step 4: Lumbar Puncture with Opening Pressure

If imaging suggests IIH (venous sinus stenosis, sigmoid sinus abnormalities, empty sella) and ophthalmology confirms papilledema:

• Perform lumbar puncture with opening pressure measurement to confirm elevated intracranial pressure (>25 cm H₂O in non-obese, >28 cm H₂O in obese patients) 1

• Opening pressure >25 cm H₂O with normal CSF composition confirms IIH diagnosis 1

Common Pitfalls to Avoid

• Dismissing pulsatile tinnitus as benign without imaging is dangerous, as identifiable and treatable causes exist in over 70% of cases, including life-threatening conditions like dural AVF 1, 3

• Missing dural AVF is catastrophic—this condition can present with isolated pulsatile tinnitus before hemorrhagic stroke, requiring high clinical suspicion and appropriate vascular imaging 1

• Overlooking papilledema in young overweight women leads to preventable vision loss, as IIH-related optic nerve damage is irreversible once advanced 1

• Inadequate otoscopic examination can miss vascular retrotympanic masses (paragangliomas) that would change the imaging strategy entirely 1

• Ordering MRI alone without vascular imaging is insufficient, as MRV alone cannot adequately evaluate arterial or arteriovenous causes of pulsatile tinnitus 1

Treatment Considerations Based on Diagnosis

If IIH is Confirmed:

• Weight loss is first-line therapy and can resolve symptoms in nearly 100% of cases when pulsatile tinnitus is truly from IIH 1

• Acetazolamide reduces CSF production and lowers intracranial pressure 1

• Serial lumbar punctures provide temporary relief and diagnostic confirmation 1

• Venous sinus stenting may be considered for refractory cases with documented venous sinus stenosis 1

• Optic nerve sheath fenestration or ventriculoperitoneal shunt reserved for vision-threatening cases unresponsive to medical therapy 1

If Sigmoid Sinus Abnormality is Identified:

• Surgical repair or endovascular intervention may be indicated for symptomatic sigmoid sinus diverticulum or dehiscence 1, 2

If Dural AVF is Found:

• Urgent neurosurgical or interventional neuroradiology consultation for endovascular embolization or surgical disconnection to prevent hemorrhagic stroke 1

Why This Approach Prioritizes Morbidity and Mortality

This algorithmic workup ensures that life-threatening vascular causes (dural AVF, arterial dissection) are identified first through CTA, while simultaneously evaluating for the most likely diagnosis (IIH) in this demographic. 1 The urgent ophthalmology referral prevents irreversible vision loss, the most devastating morbidity of untreated IIH. 1 This strategy balances comprehensive evaluation of dangerous pathology with efficient diagnosis of the most probable cause in a young overweight female with characteristic clinical features.