Urgent considerations

See Differentials for more details

Any sudden loss of hearing occurring in <72 hours needs prompt investigation and, if hearing loss is >30 decibels in ≥3 frequencies, urgent otolaryngeal referral is required. Bedside tuning fork tests should be performed to establish whether the hearing loss is conductive or sensorineural. Formal audiological testing and magnetic resonance imaging are usually required to distinguish possible causes of sudden hearing loss and should be performed within 14 days of symptom onset.[2]

The National Institute for Health and Care Excellence (NICE) in the UK recommends that any adult with sudden-onset or rapidly worsening hearing loss in one or both ears, not otherwise explained by external or middle ear causes, should be referred to a specialist.[55]​ NICE also makes recommendations on how soon this should be done based on the presenting history.[55]

Necrotising otitis externa

This usually occurs in patients with diabetes and can be fatal if not treated aggressively. The ear canal may show oedema and granulation tissue at the bony cartilaginous junction. The hearing loss is usually conductive owing to swelling of the ear canal or middle-ear fluid but can also be sensorineural. The hallmark is pain, which may awaken the patient from sleep. Patients in advanced disease may present with lower cranial nerve paralysis. Urgent otolaryngological referral is indicated. Treatment includes biopsy to rule out a malignant neoplasm, such as squamous cell carcinoma, as well as imaging studies to assess the degree of bony and soft-tissue involvement.​[56]​​

Sudden sensorineural hearing loss

Sudden sensorineural hearing loss is a subjective sensation of rapid-onset hearing impairment in one or both ears.[2] Patients often have symptoms of tinnitus and/or vertigo. On Weber's testing, the patient hears the tuning fork louder in the contralateral ear. Prompt otolaryngology referral is indicated because oral corticosteroid therapy, and sometimes intra-tympanic corticosteroid therapy, may have a role in preventing permanent hearing loss in these conditions.[2]

Facial nerve palsy

The facial nerve arises from the pons and passes through the acoustic auditory meatus in the petrous temporal bone, in close proximity to the inner ear. Temporal bone fractures, mastoiditis, cholesteatoma, malignant otitis externa, acoustic neuroma and stroke may all cause facial nerve palsy.[57][58][59]​​​​ Patients with new onset facial weakness should be referred promptly to an otolaryngologist.[60]

When the eyelids fail to close properly, the lubricating tear film and blink reflex become ineffective. Additionally, parasympathetic dysfunction to the lacrimal gland may result in reduced tear production. Consequently patients may develop keratoconjunctivitis sicca (dry eye) and exposure keratopathy, which can lead to ulcerative keratitis and blindness. Such complications are prevented through the use of a transparent eye shield during the day, artificial tears as needed during waking hours, and an ophthalmological lubricant ointment together with taping of the eyelids closed at bedtime. Indications for ophthalmological consultation include: only seeing eye affected, suspicion of exposure keratitis, and decreased or absent corneal sensation.

Basilar skull fracture

Basilar skull fractures often have specific clinical features. Blood pooling from these fractures can result in ecchymosis over the mastoid area (e.g., Battle's sign); periorbital ecchymosis (raccoon eyes), particularly if unilateral; and bloody otorrhoea. Cerebrospinal fluid (CSF) leakage can result in CSF rhinorrhoea or otorrhoea. Battle's sign and otorrhoea are most often associated with fractures of the petrous portion of the temporal bone.[61] Temporal bone trauma may be accompanied by a tympanic membrane perforation, but hearing loss may also be due to discontinuity of the ossicle chain.[Figure caption and citation for the preceding image starts]: Battle’s signReproduced with permission from van Dijk GW. The bare essentials: head injury. Pract Neurol. 2011 Feb;11(1):50-5. [Citation ends].com.bmj.content.model.assessment.Caption@6b4d47f9[Figure caption and citation for the preceding image starts]: HaemotympanumReproduced with permission from van Dijk GW. The bare essentials: head injury. Pract Neurol. 2011 Feb;11(1):50-5. [Citation ends].com.bmj.content.model.assessment.Caption@1ffba099

Non-contrast CT is the imaging modality of choice and is superior to MRI for detecting skull fracture in both paediatric and adult patients.[62] Patients who have a basilar skull fracture should be referred urgently to a neurosurgeon.[63]

Ischaemic stroke

Ischaemic stroke affecting the distribution of the internal auditory artery (also called the labyrinthine artery) can cause sudden onset sensorineural hearing loss.[64][65]​​​ This may affect both ears and is usually associated with other neurologic findings. In the majority of people, the internal auditory artery is a branch of the anterior cerebellar artery, although it can also arise from the basilar artery. Associated symptoms include tinnitus, vertigo, nausea and vomiting. Other neurological signs are present, e.g. dysarthria, ataxia, facial nerve palsy, nystagmus, diplopia, hemiparesis and/or hemisensory loss.[65][66][67]​​

All patients with a suspected ischaemic stroke should have a non-contrast CT scan of the brain to rule out intracranial haemorrhage. Check blood glucose in all patients with suspected stroke. Prompt administration of intravenous thrombolysis with recombinant tissue plasminogen activator may be indicated to minimise the effects of thrombotic strokes.[68]

Vertebral artery dissection

Sudden sensorineural hearing loss can rarely be a symptom of vertebral artery dissection. The most common manifestations of vertebral artery dissection are headache or neck pain.[69][70][71] Vertigo, ataxia, nausea, vomiting, nystagmus and cranial nerve palsies may also be present.[72] Computed tomography imaging with angiography (CT/CTA) and magnetic resonance imaging with angiography (MRI/MRA) can identify vertebral artery dissection. MRI/MRA better identifies small intramural hematomas, however CT is usually easier to access in the emergency setting.[73]

Anticoagulation or antiplatelet treatment should be started after confirming the diagnosis and continued for 3 to 6 months to reduce the risk of thrombosis at the dissection site.[74][75]​​​ Intravascular therapy is available in some centres. A combination of techniques including thrombolysis, thrombectomy, stenting and angioplasty is used.[76]

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