When faced with sudden sensorineural hearing loss, patients often first present to their general practitioner (GP). As treatment is only effective if started early, prompt management and timely referral is crucial. Singapore General Hospital shares key pointers for GPs in the management of these cases.
INTRODUCTION
What it is
Sudden sensorineural hearing loss (SSNHL) is a rapid decline of hearing over a period of less than three days, of more than 30 dB over three contiguous frequencies.
Prevalence
The prevalence of SSNHL is estimated to be five to 20 cases per 100,000 individuals annually. With our population of six million in Singapore, that would equate to 300 to 1,200 cases per year.
These patients often present to the GP or emergency department. It is important to treat SSNHL promptly as treatment is only effective when administered early.
DIAGNOSIS
At times, patients may not complain of hearing loss, but may instead complain of sudden tinnitus or a blocked ear sensation. Hence, it is vital to do a tuning fork examination to establish sensorineural hearing loss.
In the Weber test, a 512 Hz tuning fork is placed on a central bony prominence such as the forehead or occiput. In SSNHL, the sound will lateralise away from the affected ear.
In the Rinne test, the air conduction will be louder than bone conduction for the affected ear, but the reverse may also be possible due to the sound transmitting to the good ear.
Otoscopy examination is normal in SSNHL, and an audiogram is needed to confirm the diagnosis of SSNHL.
WHAT THE GP SHOULD DO
RED FLAGS OF A STROKE
Patients with SSNHL may also experience vertigo. The vertigo is usually severe and can be associated with nausea and vomiting. Head movements worsen the vertigo.
A differential diagnosis of SSNHL with vertigo is an anterior inferior cerebellar artery (AICA) territory stroke. The AICA supplies the cerebellum and inner ear.
The red flags of a stroke would be:
Nystagmus that is not reduced with visual fixation
Nystagmus that is multidirectional or vertical
Skew deviation of the eyes
A normal head impulse test
Focal neurological symptoms or signs such as headache, diplopia, dysarthria, focal weakness or numbness
INVESTIGATIONS
More than 90% of SSNHL cases are idiopathic. There may be a triggering event such as an upper respiratory tract infection. Various pathophysiologies of idiopathic SSNHL (iSSNHL) have been postulated, namely viral infection, vascular insufficiency or transient immune process.
Primary SSNHL
The only investigation needed for primary SSNHL is MRI of the internal auditory meatus.1 Studies looking at inner ear and central nervous system pathology presenting with SSNHL have reported abnormal MRI findings ranging from 10.7 to 47.5%.2
Abnormal findings include cerebellopontine angle tumours, labyrinthine haemorrhage and demyelinating process. 10 to 20% of vestibular schwannomas can present with SSNHL.
Bilateral, fluctuating or recurrent SSNHL
In cases of bilateral, fluctuating or recurrent SSNHL, causes such as Meniere’s disease, autoimmune inner ear disease, syphilis and risk factors for vasculopathy need to be ruled out and blood investigations are necessary.
Blood investigations include:
A recent systematic review looked at the association of SSNHL with hypercholesterolaemia, diabetes and hypertension.3 Pooled analysis showed that hypertriglyceridaemia and high total cholesterol significantly increased the risk of SSNHL with odds radio (OR) 1.54, 95% confidence interval (CI) 1.18-2.02 and OR 2.09, 95% CI 1.52-2.87 respectively.
The blood tests can be done at the primary healthcare setting or by ENT.
TREATMENT
One-third to two-thirds of patients with SSNHL may recover some of their hearing within two weeks.
Poor prognostic factors include:
Watchful waiting
As patients may recover their hearing spontaneously, there is the option of watchful waiting.
Active treatment with steroids
Active treatment involves giving oral prednisolone at 1 mg/kg body weight in a single dose – maximum start dose of 60 mg for one week, with a taper the following one week by 10 mg every two days.
Active treatment with oral prednisolone should be immediate, within two weeks of symptom onset. There is little benefit with treatment after four weeks.
If oral prednisolone is given, it is important not to underdose.
The equivalent dose of 60 mg of prednisolone is 10 mg of dexamethasone. While other steroid regimes have been reported, there is limited data comparing various regimes.
Caution should be taken in giving steroids to patients with poorly controlled diabetes, peptic ulcer disease, liver disease or psychiatric conditions.
A shared decision should be made with regard to the risks and benefits, as there is still a lack of clear evidence to support systemic steroids in SSNHL and there are potential adverse treatment effects in this group of patients.
Managing vertigo
Vertigo in SSNHL may be managed with vestibular suppressants and antiemetics such as ondansetron, Maxolon, Stemetil and cinnarizine.
As these vestibular suppressants prevent central compensation, they should only be taken for a few days. Betahistine can be given on a longer basis to relieve vertigo.4 Patients can be taught vestibular exercises to aid central compensation.
There is no role of antivirals, thrombolytics, vasodilators, antioxidants and gingko in treating SSNHL.
Patient education and addressing fears
Patients can be taught sound-masking strategies to drown out the tinnitus. Strategies include focusing on background sounds such as a desk fan or listening to a podcast or soft music.
They can also learn relaxation techniques such as breathing exercises, jaw relaxation exercises or meditation.
It is also crucial to address patients’ fears and anxiety in SSNHL. They should be reassured that their normal ear is at low risk of SSNHL.
Other treatment options
Upon seeing ENT, these patients will be counselled about other treatment options including intratympanic steroids, hyperbaric oxygen therapy (HBOT) and hearing rehabilitation.
SSNHL is a medical emergency Use a 512 Hz tuning fork test to confirm SSNHL Steroids need to be given within two weeks of symptom onset: Oral prednisolone 1 mg/kg/day (single dose for seven consecutive days) and taper over the following seven days Refer to the ENT department within two weeks of symptom onset
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CONCLUSION
In conclusion, SSNHL is an emergency. The tuning fork test is vital to aid the diagnosis and oral steroids should be started immediately.
Patients must see ENT within two weeks of symptom onset for an audiogram and to discuss the other treatment options of intratympanic steroids and HBOT. These treatments should be given within two to four weeks of symptom onset.
Continued follow-up with ENT will allow the patients’ hearing to be monitored and facilitate hearing rehabilitation options.
REFERENCES
Chandrasekhar SS, Tsai Do BS, Schwartz SR, et al. Clinical Practice Guideline: Sudden Hearing Loss (Update). Otolaryngol Head Neck Surg. 2019;161(1_suppl):S1-s45.
Chau JK, Lin JR, Atashband S, Irvine RA, Westerberg BD. Systematic review of the evidence for the etiology of adult sudden sensorineural hearing loss. Laryngoscope. 2010;120(5):1011-1021.
Simões J, Vlaminck S, Seiça RMF, Acke F, Miguéis ACE. Cardiovascular Risk and Sudden Sensorineural Hearing Loss: A Systematic Review and Meta-Analysis. Laryngoscope. 2023;133(1):15-24.
Murdin L, Hussain K, Schilder AG. Betahistine for symptoms of vertigo. Cochrane Database Syst Rev. 2016;2016(6):Cd010696.
Acknowledgements:
Dr Kaymond Yang for his invaluable advice on how to make this article relevant to primary healthcare.
Dr Vanessa Tan is the Director of the Centre for Hearing and Ear Implants at Singapore General Hospital. She completed her fellowship in Otology and Neuro-otology with the Royal Victorian Eye and Ear Hospital and Royal Melbourne Hospital in 2021.
She has a keen interest in educating the next generation and holds the following educator posts: Core Faculty of the SingHealth ENT Residency Programme, and Clinical Assistant Professor at Duke-NUS Medical School and the Yong Loo Lin School of Medicine. Her clinical interests include hearing implants and skull base tumours such as acoustic neuromas. Her research interests include preventing ototoxicity from nasopharyngeal cancer treatment and single-sided deafness.
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