13Unusual and Rare Forms of Tinnitus

FWhy pattern recognition matters

Most tinnitus is a steady, subjective hiss or ring. A minority of patients describe something qualitatively different: a rhythmic clicking, a recognisable tune, a single thunderclap as they fall asleep, or a sound that changes when they move their eyes. These rare forms are frequently dismissed or misattributed to anxiety, yet several of them point to a specific mechanism and, occasionally, a specific cure [2013].

The practical skill is listening to the character of the sound rather than only its presence. A handful of targeted questions — Is it rhythmic? Does it have a tune? Did it start with a single bang? Does anything physical change it? — sorts most of these entities at the bedside before any test is ordered [2013].

TTypewriter tinnitus

Typewriter tinnitus is a paroxysmal phenotype: brief staccato bursts likened to a typewriter, Morse code, or popcorn, often superimposed on a quieter background. The episodes are intermittent and can be triggered or stopped abruptly, unlike the unremitting drone of cochlear tinnitus. Levine described it as a discrete, carbamazepine-responsive syndrome attributed to vascular compression and ephaptic firing of the auditory nerve [2006].

The diagnostic reward is therapeutic: a trial of a sodium-channel-blocking anticonvulsant (carbamazepine or oxcarbazepine) frequently abolishes the bursts, and a positive response is itself confirmatory. Auditory brainstem responses may show abnormalities consistent with neural conduction disturbance and can support both diagnosis and prognosis [2023]. The key is simply to ask whether the sound is staccato rather than steady.

TMusical ear syndrome

Musical ear syndrome (MES) is the auditory equivalent of the Charles–Bonnet visual hallucinations of the partially sighted: hearing-impaired but cognitively intact people perceive music — hymns, carols, half-remembered tunes — with no external source and with full insight that it is not real. It is best understood as a release phenomenon, the deprived auditory cortex generating its own complex output [2015].

MES is under-recognised because patients fear they are developing a psychiatric illness and stay silent. It is reported in a meaningful minority of those with significant hearing loss, including cochlear-implant users, and the most useful first intervention is often amplification or richer sound input rather than psychotropic medication [2021]. Reassurance that this is a recognised consequence of deafness, not madness, is therapeutic in itself.

CExploding head syndrome, gaze-evoked tinnitus, and fistula

Exploding head syndrome (EHS) is a benign parasomnia of the sleep–wake transition: the patient is jolted awake by the perception of a sudden loud bang, gunshot, or crash inside the head, usually painless, often with a fright response and a flash of light. It is common, frequently misdiagnosed, and reassurance plus sleep-hygiene measures is the mainstay; it is not a sign of intracranial disease [2020].

Gaze-evoked tinnitus — sound that appears or changes amplitude on eccentric eye movement — is a deafferentation phenomenon classically seen after cerebellopontine-angle surgery, where reorganised neural circuits couple oculomotor activity to auditory perception [2001]. Pneumolabyrinth and perilymph fistula complete the list: an abnormal communication between the inner ear and middle ear or air, typically post-traumatic or barotraumatic, producing tinnitus with fluctuating hearing, dizziness, and positional or pressure sensitivity that demands imaging and sometimes exploratory surgery [2020].

CThe Hum and low-frequency tinnitus

A small group of patients describe a persistent low-frequency throb or rumble — the so-called Hum — resembling an idling diesel engine, worse indoors and at night, and (crucially) attributed by the patient to an external source. Some are perceiving genuine environmental low-frequency noise; others have an internally generated low-pitched tinnitus that is highly annoying out of proportion to its loudness [2004].

The clinical task is to separate a true external source (which environmental measurement can sometimes confirm) from a low-frequency tinnitus percept, because management diverges sharply: the former is an acoustics problem, the latter a tinnitus-distress problem managed with sound enrichment and cognitive approaches. Either way, validating that the experience is real protects the therapeutic relationship [2013].