Is sudden hearing loss a sign of impending stroke?

Sudden Hearing Loss and Stroke: What You Need to Know

While sudden hearing loss can occasionally be associated with stroke, it is not typically a common or primary sign of impending stroke. According to the American Academy of Otolaryngology-Head and Neck Surgery, sudden onset of hearing loss resulting from a stroke is uncommon 1.

Understanding Sudden Hearing Loss

Sudden hearing loss is defined as a rapid onset (within 72 hours) of subjective hearing impairment in one or both ears 1. The majority of cases are:

• Unilateral (affecting one ear) 2
• Idiopathic (without identifiable cause) despite investigation 1
• Presumptively attributed to vascular, viral, or multiple etiologies 1

When Sudden Hearing Loss May Indicate Stroke

Certain characteristics of sudden hearing loss should raise suspicion for stroke:

1. Bilateral sudden hearing loss - Sudden onset of hearing loss in both ears is relatively rare and should raise concern for specific causes, including vascular events 1, 2

2. Accompanying neurological symptoms - Be alert for:

   • Focal weakness
   • Dysarthria (slurred speech)
   • Hemiataxia (one-sided lack of coordination)
   • Encephalopathy
   • Severe headaches
   • Diplopia (double vision)
   • Downbeating or gaze-evoked nystagmus 1

3. Vertebrobasilar territory involvement - Sudden hearing loss may occasionally be an early warning sign of vertebrobasilar ischemic stroke 3

4. Risk factors - Patients with three or more stroke risk factors, bilateral hearing loss, moderately severe to total hearing loss, and intracranial large artery stenosis/occlusion (≥50%) are at higher risk of developing ischemic stroke 4

Diagnostic Approach

When evaluating sudden hearing loss:

1. Assess for neurological findings - Clinicians should assess patients with presumptive sudden sensorineural hearing loss (SSNHL) for bilateral hearing loss, recurrent episodes, or focal neurologic findings 1

2. Imaging considerations:

   • MRI is preferred when evaluating for retrocochlear pathology 1
   • CT scans of the brain are NOT recommended in the initial evaluation of patients with presumed idiopathic sudden hearing loss 2

3. Audiometric testing - Diagnose presumptive idiopathic SSNHL if audiometry confirms a 30-dB hearing loss at 3 consecutive frequencies and an underlying condition cannot be identified by history and physical examination 1

Important Clinical Distinctions

• Fluctuating hearing loss suggests non-idiopathic causes such as Ménière's disease, autoimmune inner ear disease, Cogan syndrome, or hyperviscosity syndrome 2

• Vertigo with sudden hearing loss should increase suspicion for stroke, particularly in the posterior circulation 4

• Bilateral cortical deafness is a rare but recognized symptom of stroke that requires urgent evaluation 5

Long-term Considerations

The risk of stroke at 5 years in patients with SSNHL is 1.64 times higher than in controls 2, though some studies suggest the annual stroke incidence rate after idiopathic SSNHL is comparable to the general population 6.

Clinical Pitfalls to Avoid

1. Missing neurological symptoms - In patients with sudden hearing loss, subtle neurological deficits may be overlooked

2. Delayed diagnosis - Immediate stroke workup should be prioritized in patients with sudden bilateral deafness, as acute revascularizing treatment is time-sensitive 5

3. Inadequate follow-up - Long-term follow-up is recommended as some patients will have an underlying cause identified that may not be evident at initial presentation 1

Remember that while most cases of sudden hearing loss are not due to stroke, careful evaluation for neurological symptoms and risk factors is essential to identify those cases where urgent intervention may be needed.