8Neurologic Causes of Tinnitus

FBehind the cochlea: a different kind of tinnitus

Neurologic causes generate tinnitus by disturbing the auditory nerve or the central pathways rather than the cochlear hair cells. The list is shorter than the otologic one but contains the diagnoses you cannot afford to miss — tumours of the eighth nerve, demyelinating disease, and the somatosensory circuits that let the jaw and neck reach into the hearing system [2013].

The single most useful screening rule lives here: unilateral or markedly asymmetric tinnitus, especially with asymmetric hearing loss, must be taken seriously as a possible retrocochlear lesion [2014]. Bilateral, symmetric tinnitus is reassuringly ordinary; a one-sided phantom sound is a question that imaging answers.

TVestibular schwannoma and the unilateral-tinnitus rule

A vestibular schwannoma (acoustic neuroma) is a benign tumour of the eighth cranial nerve, and tinnitus is one of its commonest presenting symptoms — reported by a large proportion of patients, often unilateral and high-pitched, and sometimes preceding any measurable hearing loss [2025]. Although the tumour springs from the vestibular nerve, it compresses the adjacent cochlear nerve, so hearing symptoms dominate the clinical picture.

This is where the unilateral-tinnitus rule becomes concrete. Persistent one-sided tinnitus, particularly with asymmetric sensorineural hearing loss, warrants MRI of the internal auditory canals with gadolinium to exclude a retrocochlear lesion [2014]. The yield per scan is low, but the cost of a missed schwannoma is high, which is exactly why asymmetry is the threshold that triggers imaging [2025].

CMultiple sclerosis and central (retrocochlear) tinnitus

Multiple sclerosis can cause tinnitus when demyelinating plaques strike the central auditory pathways in the brainstem — the pons and the region of the inferior colliculi — disrupting the temporal precision on which normal hearing depends [2013]. The resulting tinnitus may be bilateral or non-localising and is often accompanied by other brainstem auditory signs such as distorted hearing or abnormal auditory brainstem responses.

Two features mark this central pattern: the tinnitus can fluctuate with disease activity, and it sits among other neurological deficits rather than alone. A young adult with new tinnitus plus diplopia, limb symptoms or a relapsing course should prompt thought of demyelination and a neurological referral, not just an audiogram [2014].

TSomatosensory tinnitus: when the jaw and neck join in

A distinct subset of patients can change the loudness or pitch of their tinnitus by clenching the jaw, turning the head, or pressing on the neck. This somatosensory (or somatic) tinnitus reflects a real anatomical convergence: the dorsal cochlear nucleus receives input not only from the auditory nerve but also from the trigeminal and cervical somatosensory systems [2005].

When cochlear input falls, these somatosensory projections can become disinhibited and dominate firing in the DCN, so jaw and neck signals begin to drive the auditory percept [2005]. Clinically this links tinnitus to temporomandibular-joint dysfunction, bruxism and cervical-spine problems — and, helpfully, predicts that physiotherapy or dental and cervical treatment can modulate the tinnitus in this group [2011].

CPutting the neurologic work-up together

Three questions sort the neurologic causes at the bedside. Is the tinnitus asymmetric? Then image the internal auditory canals for a schwannoma [2014]. Are there other neurological signs or a relapsing course? Then think central pathology such as MS [2013]. Can the patient modulate it with jaw or neck manoeuvres? Then it is likely somatosensory and may respond to musculoskeletal treatment [2011].

The somatic-testing manoeuvre is free and quick: ask the patient to clench, open wide against resistance, and rotate the neck while reporting any change in the sound. A positive response reframes the whole management plan toward the somatosensory pathway rather than the cochlea [2005].