Sudden Hearing Loss: A Quick Review of the Guidelines

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Although I’ve talked about the issues with the guidelines in the past, some do a reasonable job of discussing the evidence, and they’re often helpful for conditions that are rarely seen. Sudden hearing loss is a problem I only see occasionally in the emergency department and I’ve never felt completely confident in my assessment. I thought this guideline from the American Academy of Otolaryngology – Head and Neck Surgery was good, so I decided to summarize the key points.

The paper

Chandrasekhar SS, Tsai Do BS, Schwartz SR, et al. Clinical Practice Guideline: Sudden Hearing Loss (updated). Otolaryngol head and neck surgery. 2019 Aug;161(1_suppl):S1-S45. doi: 10.1177/0194599819859885. PMID: 31369359.

Summary

I think that’s a reasonably well-made guideline. I’m only giving a very basic summary here. For each recommendation, this guideline provides a brief discussion under each of these headings: “opportunity for quality improvement”, “overall quality of the evidence”, “level of certainty of the evidence”, “benefits”, ” risks, harms, costs”, “benefits-harm assessment”, “value judgments”, “intentional vagueness”, “role of patient preferences”, “exceptions”, “policy level” and “differences of opinion”. As a result, there is an easy-to-read summary that gives you a good idea not only of the recommendations, but also of the uncertainty and debate behind the recommendations.

The guideline focuses on sudden sensorineural hearing loss (SSNHL), which affects between 5 and 25 in every 100,000 people per year. The majority of cases are idiopathic.

Sudden hearing loss is either sensorineural, conductive or mixed. Physical examination is the key to distinguishing between conductive hearing loss and sensorineural hearing loss. The official diagnosis of SSHNL requires audiometric testing and therefore will not be performed in the emergency department.

Recommendation 1: Clinicians should distinguish SSNHL from conductive hearing loss when the patient first presents.

“A reasonable alternative to the Weber tuning fork test is the buzzing test – the patient is asked to hum and if they hear their own louder buzzing in the affected ear, there is probably conductive hearing loss in sensitivity, specificity and diagnostic accuracy of the hum test are similar to those of the Weber test.

Recommendation 2: Clinicians should evaluate patients with suspected SSNHL by history and physical examination to detect bilateral SHL, recurrent episodes of SHL, and/or focal neurological signs.

Recommendation 3: Clinicians should not order routine computed tomography (CT) of the head during the initial evaluation of a patient with suspected SSNHL. (The word routine is added here because CT scanning will sometimes be warranted if there are focal neurological signs on examination.)

Recommendation 4: In patients with sudden hearing loss, clinicians should obtain, or refer to a clinician who can obtain, audiometry as soon as possible (within 14 days of symptom onset) to confirm the diagnosis of SSNHL.

Recommendation 5: Clinicians should not obtain routine laboratory tests in patients with SSNHL.

The only test that may be required without other signs or symptoms is Lyme serology, as Lyme disease can cause SSNHL. With the significant increase in Lyme distribution in recent years, this testing may be more important, but there are no good data on the value of screening.

Recommendation 6: Clinicians should evaluate patients with SSNHL for retrocochlear pathology by obtaining magnetic resonance imaging (MRI) or auditory brainstem response (ABR).

“Several studies report a relatively high prevalence of cerebellopontine angle tumors in patients with SSNHL, ranging from 2.7% to 10.2% of patients assessed by MRI.” Personally, I leave that to the ENT who sees the patient in follow-up, but in some systems the ER or primary care physician may order an MRI.

Recommendation 7: Clinicians should educate patients with SSNHL about the natural history of the disease, the benefits and risks of medical interventions, and the limitations of existing evidence regarding effectiveness.

A patient document is available here.

Recommendation 8: Clinicians can offer corticosteroids as initial therapy to patients with SSNHL within 2 weeks of symptom onset.

There are only 3 small RCTs, judged to be at high risk of bias. 2 showed no difference. 1 showed improvement in hearing in 61% of the steroid group compared to 32% of the control group. I haven’t done a formal review myself, but based on this summary, it seems unlikely that the steroids will be helpful, and the cons probably outweigh the benefits.

Recommendation 9: Clinicians can offer, or refer to a clinician who can offer, hyperbaric oxygen therapy (HBOT) plus corticosteroid therapy within 2 weeks of the onset of SSNHL. Clinicians can offer, or refer to a clinician who can offer, hyperbaric oxygen therapy (HBOT) plus corticosteroid therapy as salvage within one month of the onset of SSNHL.

For acute treatment, there are 7 RCTs with a total of 392 patients, and the Cochrane review main analysis showed no difference. However, an alternative analysis looking at a “25% improvement in hearing” was positive, with an NNT of just 5. This obviously has a high risk of bias, and the best we can say is, “we don’t know “. Personally, I would not refer anyone for this therapy at this time.

Recommendation 10: Clinicians should offer, or refer to a clinician who can offer, intratympanic corticosteroid therapy when patients have incomplete recovery from SSNHL 2 to 6 weeks after symptom onset.

There is only one RCT of 50 patients – but that will be the ENT’s choice anyway.

Recommendation 11: Clinicians should not routinely prescribe antivirals, thrombolytics, vasodilators, or vasoactive substances to patients with SSNHL.

Recommendation 12: Clinicians should obtain a follow-up audiometric evaluation for patients with SSNHL at the end of treatment and within 6 months of the end of treatment.

Recommendation 12: Clinicians should counsel patients with SSNHL who have residual hearing loss and/or tinnitus about the possible benefits of audiological rehabilitation and other supportive measures.

Emergency medicine translation

In a patient with sudden hearing loss, your job is to distinguish between conductive hearing loss and sensorineural hearing loss. For sensorineural hearing loss, take a complete and physical history, but unless there are abnormalities, you should not order laboratory or imaging tests. Our main job is to counsel patients with the understanding that almost all cases are idiopathic and about half resolve on their own, but there is a risk of permanent hearing loss and tinnitus. The evidence for treatment is mixed and inconclusive. Steroids may be used and in some centers hyperbaric oxygen is considered. Discuss with your local ENT group to determine their preference, but based on the low quality evidence discussed, I doubt either will be helpful. Urgent follow-up is essential, as these patients need urgent audiometry, but may also benefit from procedures such as intratympanic steroids.


Photo by Dylann Hendricks | 딜란 on Unsplash

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