4Temporal Pattern, Onset and Fluctuation

FWhy the clock matters

Two patients can describe the same hissing in the same ear, yet one has had it for a fortnight and the other for fifteen years. The temporal profile — onset, course and fluctuation — turns an undifferentiated complaint into a working diagnosis. It tells you how urgent the work-up is, which mechanisms are plausible, and how much spontaneous improvement you can still hope for.

Recency is the first axis. Tinnitus that began within the last few months sits in a window where the auditory system is still adapting and where a treatable trigger — a sudden hearing loss, a new drug, a noise event — may still be reversible. Tinnitus present for years is, by contrast, a stabilised percept maintained by central plasticity rather than ongoing peripheral injury [2013].

TAcute, subacute and chronic

By convention tinnitus is called acute when it has lasted less than three months, subacute between three and six months, and chronic beyond six months. The three-to-six-month threshold is not arbitrary: it marks the period over which most habituation occurs and beyond which the percept is far less likely to resolve on its own [2013].

Chronicity carries prognostic weight. Longer-standing tinnitus is associated with greater distress, poorer response to treatment, and the entrenchment of maladaptive auditory–limbic loops. The practical lesson is one of timing: a recent-onset patient deserves a prompt search for a reversible cause, whereas a chronic patient is usually best served by management of the reaction rather than a hunt for a peripheral lesion [2005].

TContinuous versus intermittent, and the diurnal curve

Ask whether the sound is ever truly absent. Continuous tinnitus — present every waking moment — is the commonest pattern in chronic subjective tinnitus tied to hearing loss. Intermittent tinnitus that switches on and off, or appears only in quiet, points either to a milder percept unmasked by silence or to an episodic generator.

Most patients also report a diurnal rhythm: the percept is least obtrusive amid daytime sound and most intrusive at night, when environmental masking falls away and attention turns inward. This evening crescendo is a feature of the reaction to tinnitus rather than a change in its source, and recognising that distinction reassures patients who fear their tinnitus is worsening.

CWhat fluctuation is telling you

Genuine fluctuation — the loudness or pitch of the tinnitus itself rising and falling over hours or days — is a clinical signpost. When fluctuation tracks fullness, vertigo and a low-pitched roar, suspect Menière’s disease and endolymphatic hydrops, where tinnitus often heralds or accompanies an attack [2013]. When the percept changes with jaw, neck or posture, the generator is likely somatosensory rather than purely cochlear [1999].

Fluctuation that follows noise exposure — louder after a concert, settling over a day or two — reflects reversible cochlear and central gain changes and is a teachable warning sign for hearing conservation. Steady, unwavering, strictly unilateral tinnitus, by contrast, is the pattern that should prompt closer scrutiny for a retrocochlear lesion. The temporal story thus does double duty: it suggests the mechanism and flags the patient who needs imaging [2013].