TINNITUS: A Comprehensive ENT Review

1. DEFINITIONS AND CLASSIFICATION

Classification Framework

• Subjective non-pulsatile tinnitus is by far the most common, representing ~90% of all referrals
• Objective tinnitus is rare - even at tertiary centers it accounts for only 1.5% of all tinnitus complaints
• Pulsatile tinnitus accounts for approximately 11% of otolaryngology tinnitus referrals; of these, 86% are subjective and 14% are objective

2. PULSATILE TINNITUS

Definition

• Synchronous with arterial pulse - suggests vascular etiology
• Asynchronous with pulse - suggests muscular, middle ear, or joint etiology

Differential Diagnosis (Cummings Box 153.1)

• Cardiovascular: Hypertension, valvular heart disease
• Intraosseous: Paget disease, otosclerosis
• Neoplasm: Paraganglioma (glomus tympanicum or jugulare), vestibular schwannoma, endolymphatic sac tumor, hemangiopericytoma, meningioma, temporal bone hemangioma, vascular skull base metastases
• Vascular stenosis: Carotid artery atherosclerosis (most common arterial cause), fibromuscular dysplasia
• Skull base variants: Persistent stapedial artery, aberrant/dehiscent internal carotid artery (intratympanic)
• Arteriovenous fistula or malformation, aneurysm, arterial dissection
• Vascular compression of CN VIII
• Hyperdynamic states: Anemia, thyrotoxicosis, pregnancy

• Sigmoid sinus and jugular bulb anomalies
• Idiopathic intracranial hypertension (IIH) - a major cause, especially in obese young women
• Dilated mastoid or condylar emissary veins
• Dural sinus stenosis (transverse or sigmoid sinus)
• Idiopathic/essential tinnitus, venous hum

• Muscular myoclonus: Palatal, tensor tympani, stapedial muscle myoclonus
• Patulous Eustachian tube
• Ossicular or tympanic membrane abnormality, otosclerosis
• Semicircular canal dehiscence
• Middle ear effusion
• Temporomandibular joint disease

Key Points in Pulsatile Tinnitus

• In a normal ear exam, intracranial venous abnormalities are the most common cause of pulsatile tinnitus
• Among arterial causes, cervical atherosclerotic disease is most common, followed by dehiscent internal carotid artery, persistent stapedial artery, and fibromuscular dysplasia
• Higher likelihood of organic etiology compared to subjective non-pulsatile tinnitus - mandates a systematic, evidence-based diagnostic approach with radiographic imaging

Imaging in Pulsatile Tinnitus

• CT temporal bone (high resolution) - for bony anomalies, jugular bulb, sigmoid sinus
• MRI/MRA/MRV - for soft tissue, vascular, intracranial causes
• Digital subtraction angiography - gold standard for vascular lesions when intervention is planned
• Doppler ultrasound of carotid - for atherosclerotic disease

3. PATHOPHYSIOLOGY OF NON-PULSATILE TINNITUS

Peripheral (Cochlear) Mechanisms

Central Mechanisms

4. TINNITUS MARKERS AND ASSESSMENT

Audiological/Psychoacoustic Markers

Validated Questionnaires

Tinnitus Handicap Inventory (THI) Grading

Imaging Indications

• MRI is the modality of choice for:
  • Unilateral tinnitus
  • Asymmetric sensorineural hearing loss
  • Associated neurological symptoms
  • Suspected retrocochlear pathology (vestibular schwannoma)
• CT is used when MRI is contraindicated (pacemakers, metallic foreign bodies)

5. MANAGEMENT OF TINNITUS

A. General Principles

1. Rule out treatable secondary causes first (cerumen, otitis media, otosclerosis, Meniere's, retrocochlear pathology, IIH, vascular lesion)
2. Stop ototoxic medications when possible
3. Counselling and education - tinnitus is not dangerous; habituation is achievable
4. Address comorbidities - anxiety, depression, insomnia

B. Sound-Based Therapies

Masking

Hearing Aids

Sound Therapy / Tinnitus Retraining Therapy (TRT)

• Sound generators are worn to reduce contrast between tinnitus and background
• Counselling aims to reclassify tinnitus as a "neutral" stimulus
• 12-18 months treatment; success rates reported at 80%

Customized/Notched Sound Therapy

• S Tones (Serenade device): Customized tones calibrated to the patient's tinnitus pitch - shown to have modest benefit over wideband sound
• Notched music therapy: Music is filtered to remove the frequency of the tinnitus, theoretically reducing auditory cortex over-representation at that frequency

Acoustic CR (Coordinated Reset) Neuromodulation

C. Psychological Therapies

Cognitive Behavioural Therapy (CBT)

Mindfulness-Based Cognitive Therapy (MBCT)

Acceptance and Commitment Therapy (ACT)

D. Pharmacotherapy (Limited Evidence)

Key message: There is currently no pharmacotherapy with proven efficacy for subjective non-pulsatile tinnitus. Treating patients with "there is no medication or surgery" without offering any therapeutic intervention is discouraged.

E. Neuromodulation - Recent and Emerging Modalities

Transcranial Magnetic Stimulation (TMS)

• Repetitive TMS (rTMS) applied to the auditory cortex (targeting the tonotopic area corresponding to tinnitus pitch)
• Aims to suppress hyperactive auditory cortex activity
• Studies show statistically significant but clinically modest reductions in tinnitus severity
• Effect is temporary without repeated sessions

Transcranial Direct Current Stimulation (tDCS)

• Non-invasive cortical stimulation; targets auditory and prefrontal cortex
• Early positive results; needs larger trials

Deep Brain Stimulation (DBS) / Auditory Cortex Stimulation

• Invasive; under investigation for severe refractory tinnitus

Vagus Nerve Stimulation (VNS) Paired with Sound

• Based on cortical map reorganization theory
• Animal studies showed VNS + paired tone stimulation can reverse maladaptive auditory cortex changes
• Human trials using implanted electrodes in neck and transcutaneous routes have been conducted
• Insufficient evidence yet for clinical recommendation, but the most promising experimental modality

Bimodal Stimulation (Sound + Somatosensory)

• Lenire device (Mute Button technology): Acoustic stimulation paired with electrical stimulation of trigeminal nerve fibres in the anterior tongue
• Exploits crossover between auditory and somatosensory pathways
• Available in Republic of Ireland; scientific evidence currently limited to conference proceedings
• Multimodal approach based on the principle that somatosensory inputs modulate central auditory processing

Cochlear Implants

• In patients with severe-to-profound SNHL, cochlear implantation can suppress tinnitus as a secondary benefit
• The electrical stimulation appears to interrupt tinnitus-generating central activity

F. Management of Pulsatile Tinnitus

G. Tinnitus Management Pathway Summary

TINNITUS PATIENT
    |
    ├── History + Examination + PTA + Tympanometry
    |
    ├── Pulsatile? ──YES──> Imaging (CT/MRI/MRA) → Treat underlying cause
    |
    ├── Objective? ──YES──> Auscultation → Source identification → Treat
    |
    └── Subjective Non-pulsatile (90%)
            |
            ├── Unilateral / Asymmetric SNHL → MRI (rule out VS)
            ├── THI scoring + HADS + ISI
            ├── Hearing aid if hearing loss present
            ├── Sound therapy / TRT
            ├── CBT (best evidence for distress)
            ├── Address anxiety/depression/sleep
            └── Novel: rTMS / VNS-paired stimulation in refractory cases

6. RECENT MODALITIES - 2025/2026 Update

• A 2025 Network Meta-Analysis (BMJ Open, PMID 40441764) evaluated pharmacotherapy for subjective tinnitus and confirmed no single drug has robust evidence; investigational agents being explored include NMDA antagonists and glutamate modulators.
• A 2026 Nature Reviews Disease Primers article (PMID 42168216) confirms the multidisciplinary nature of tinnitus management - integrating audiological, psychological, and neuromodulatory approaches.
• A 2025 Narrative Review on Pulsatile Tinnitus (PMID 40693879) emphasizes systematic vascular imaging and individualized vascular intervention.
• Bimodal neuromodulation (VNS + sound) and transcranial stimulation remain the most actively researched non-invasive modalities for refractory non-pulsatile tinnitus.

Key Takeaways

1. Tinnitus affects ~10% of adults; only a minority are significantly disabled
2. Classification (pulsatile vs. non-pulsatile, subjective vs. objective, primary vs. secondary) drives workup
3. Pulsatile tinnitus demands imaging - venous causes (IIH, sigmoid sinus) most common; arterial causes must be excluded
4. THI is the most used validated tool; always assess anxiety/depression/sleep
5. CBT has the strongest evidence for reducing tinnitus-related distress
6. TRT (sound + counselling) is an established first-line approach
7. No pharmacotherapy is currently recommended as routine
8. Emerging modalities: VNS-paired sound therapy, rTMS, bimodal stimulation (Lenire) - all need more evidence
9. Pulsatile tinnitus is managed by treating the underlying cause