How can I differentiate between tinnitus caused by otological issues and that related to systemic conditions?

Differentiating between tinnitus caused by otological issues and systemic conditions involves assessing the characteristics of the tinnitus and any associated symptoms, followed by appropriate investigations and referrals ²,³.

• Characteristics of Tinnitus:
  • Pulsatile Tinnitus: Tinnitus that is pulsatile (synchronous with heartbeat) often suggests a vascular cause and may be related to systemic conditions such as intracranial vascular tumours, aneurysms, carotid atherosclerosis, or brainstem pathology ¹,². Sudden onset pulsatile tinnitus requires immediate referral to an Ear, Nose, and Throat (ENT) service ². Persistent pulsatile tinnitus also warrants imaging ²,⁴.
  • Unilateral or Asymmetric Tinnitus: Tinnitus affecting only one ear or being significantly worse in one ear is less common than bilateral tinnitus and may indicate a more serious underlying condition, including otological issues like vestibular schwannoma (acoustic neuroma), Meniere's disease, or otosclerosis, as well as cerebellopontine angle tumours or glomus tumours ¹,².
  • Objective Tinnitus: Tinnitus that can be heard by an examiner (objective tinnitus) is rare and often points to a specific underlying cause, which could be vascular or muscular ².
• Associated Symptoms:
  • Neurological Symptoms: The presence of sudden onset significant neurological symptoms or signs, such as facial weakness or altered facial sensation, suggests a systemic or neurological cause like a vestibular schwannoma, cerebellopontine angle (CPA) lesion, or stroke ¹,²,³. Immediate referral for neurological assessment or stroke pathway is necessary ²,³.
  • Vestibular Symptoms: Acute uncontrolled vestibular symptoms, such as vertigo that has not fully resolved or is recurrent, may indicate conditions like Meniere's disease, vestibular schwannoma, perilymphatic fistula, or acute ischaemia of the labyrinth or brainstem ¹,²,³. Immediate referral for neurological assessment is required for acute uncontrolled vestibular symptoms ².
  • Ear-Specific Symptoms: Persistent otalgia (ear pain) or otorrhoea (ear discharge) that does not resolve with routine treatment, or an abnormal appearance of the outer ear or eardrum (e.g., inflammation, polyp formation, perforation, swelling, blood), are strong indicators of an underlying otological issue ²,³. Middle ear effusion not associated with an upper respiratory tract infection can also be an otological sign ³.
  • Hearing Loss: The nature of associated hearing loss is crucial. Sudden onset or rapidly worsening hearing loss (over 3 days or 4-90 days respectively) in one or both ears, not explained by external or middle ear causes, requires urgent ENT or audiovestibular referral ²,³. Unilateral or asymmetric sensorineural hearing loss, or fluctuating hearing loss not associated with an upper respiratory tract infection, also points towards specific otological conditions ¹,³.
  • Head Trauma: Tinnitus secondary to head trauma is an otological cause requiring immediate referral ².
• Diagnostic Assessments:
  • Audiological Assessment: Pure tone audiometry is essential to assess hearing thresholds and differentiate between conductive and sensorineural hearing loss, which helps characterise the severity and pattern of hearing loss at various frequencies ¹,³. Tympanometry may also be indicated ³.
  • Imaging: Imaging is a key differentiator. For pulsatile tinnitus, imaging (e.g., magnetic resonance angiogram, MRI, or contrast-enhanced CT of head, neck, temporal bone, and internal auditory meati) is offered to investigate the cause ²,⁴. For non-pulsatile tinnitus, MRI of the internal auditory meati (IAM) is offered if there are associated neurological, otological, or head and neck signs and symptoms, or considered for unilateral or asymmetrical non-pulsatile tinnitus even without other signs ⁴. Imaging is generally not offered for symmetrical non-pulsatile tinnitus without associated signs ⁴.