From the Guidelines
Bilateral sudden sensorineural hearing loss (SSNHL) is most commonly caused by systemic conditions such as infections, autoimmune disorders, ototoxic medications, trauma, genetic disorders, mitochondrial disorders, stroke, and neoplastic conditions, as outlined in the 2019 clinical practice guideline on sudden hearing loss 1. The causes of bilateral SSNHL can be diverse and include:
- Infections (viral, bacterial, mycoplasma, Lyme, tuberculosis, syphilis, fungal) which may present with headache, fever, and other cranial nerve palsies 1
- Autoimmune inner ear disease, characterized by hearing fluctuation and vertigo 1
- Ototoxic medication, which can also cause vestibular loss and oscillopsia 1
- Trauma, including temporal bone fracture, cochlear concussion, and barotrauma 1
- Genetic disorders, which may be syndromic or nonsyndromic and present later in life 1
- Mitochondrial disorders, such as MELAS, which can cause confusion, stroke-like spells, and elevated lactate levels 1
- Stroke, which may present with vertigo, dysarthria, facial weakness, ataxia, and nystagmus 1
- Cogan’s syndrome, characterized by interstitial keratitis, hearing loss, and vertigo 1
- Neoplastic conditions, such as neurofibromatosis II and carcinomatous meningitis, which may cause abnormal brain MRI and cerebrospinal fluid findings 1
- Sarcoidosis, which can cause pulmonary symptoms, bilateral vestibular loss, and elevated angiotensin-converting enzyme levels 1
- Hyperviscosity syndrome, characterized by mucous membrane bleeding, neurologic and pulmonary symptoms, and associated retinopathy 1 Given the potential for serious underlying conditions, prompt diagnosis and treatment of bilateral SSNHL are crucial, and may involve high-dose corticosteroids, antiviral medications, immunosuppressants, and comprehensive evaluation including audiometry, laboratory studies, and imaging 1.
From the Research
Causes of Bilateral Sudden Sensorineural Hearing Loss (SSNHL)
The causes of bilateral SSNHL are varied and can be attributed to several factors, including:
- Toxic conditions 2
- Autoimmune disorders, such as Behçet disease 3
- Neoplastic conditions 2
- Vascular conditions, including cerebral venous thrombosis 4
- Viral infections, which may be more common in females 5
Systemic Conditions Associated with Bilateral SSNHL
Bilateral SSNHL is often associated with serious systemic conditions, which can have a significant impact on morbidity and mortality 2, 6. These conditions can include:
- Autoinflammatory vasculitis, such as Behçet disease 3
- Cerebral venous thrombosis, which can cause sudden bilateral hearing loss 4
- Other systemic diseases that can affect the inner ear and cause hearing loss
Clinical Features and Outcomes
The clinical features and outcomes of bilateral SSNHL can vary depending on the underlying cause and the severity of the hearing loss 5. Some common features include:
- Severe to profound hearing loss, which can be more severe in patients with simultaneous onset of bilateral SSNHL 5
- Poorer recovery rates compared to unilateral SSNHL 2
- Higher mortality rates, with a reported 35% mortality rate in one study 2
- Less common vestibular symptoms compared to unilateral SSNHL 2