What testing is recommended for a patient with typewriter tinnitus and no prior hearing issues?

Testing for Typewriter Tinnitus

A patient with typewriter tinnitus and no prior hearing issues requires comprehensive audiologic examination (pure tone audiometry, speech audiometry, and acoustic reflex testing) and MRI with contrast to evaluate for vascular compression of the auditory nerve. 1, 2, 3

Initial Audiologic Evaluation

• Obtain comprehensive audiologic examination including pure tone audiometry, speech audiometry, and acoustic reflex testing, even though the patient reports no hearing difficulties—unsuspected hearing loss may be present and patients often don't perceive mild losses 1, 2
• This testing should be performed promptly (within 4 weeks) rather than waiting, as unilateral tinnitus mandates early evaluation to identify serious underlying pathology 2
• Measure loudness discomfort levels at audiometric frequencies if the patient reports any sound tolerance problems (hyperacusis) 1, 4

Imaging Studies

• Obtain MRI with contrast to evaluate for vascular compression of the auditory nerve ipsilateral to the tinnitus, as this is the underlying pathology in typewriter tinnitus 3
• Vascular compression of the auditory nerve was detected in 4 of 5 imaged patients with typewriter tinnitus in the key study describing this syndrome 3
• MRI is indicated because typewriter tinnitus is unilateral (localizes to one ear), which meets criteria for imaging even in the absence of hearing loss or neurological abnormalities 1, 2

Clinical Characteristics to Document

• Record the staccato, intermittent quality of the tinnitus (described as "typewriter," "popcorn," or "Morse code" pattern) 3
• Document laterality—typewriter tinnitus is always unilateral 3
• Note sudden onset and age at presentation 3
• Assess for any associated vestibular symptoms, though these are typically absent in typewriter tinnitus 3

Key Distinction from Other Tinnitus Types

• Typewriter tinnitus differs from pulsatile tinnitus (which would require CT angiography or CTA as first-line imaging) because it has a staccato, non-rhythmic pattern rather than synchronization with heartbeat 5, 3
• The audiogram in typewriter tinnitus is typically symmetric and age-appropriate, unlike acoustic neuroma which presents with asymmetric hearing loss 3
• This syndrome responds to carbamazepine treatment, similar to other cranial nerve vascular compression syndromes (trigeminal neuralgia, hemifacial spasm), providing further evidence for neurovascular compression as the mechanism 3

Common Pitfalls to Avoid

• Do not skip audiologic testing based on patient's report of normal hearing—documentation of symmetric hearing is essential to distinguish typewriter tinnitus from acoustic neuroma 2, 3
• Do not order CT temporal bone or CTA as first-line imaging—MRI with contrast is the appropriate study for evaluating neurovascular compression and excluding cerebellopontine angle lesions 2, 5
• Do not delay imaging waiting for symptoms to persist 6 months—unilateral tinnitus warrants immediate evaluation regardless of duration 2