Hearing Loss

Sudden Sensorineural Hearing Loss (SSNHL) Update

The acute onset of hearing loss of 30 dB in three contiguous frequencies which may have occurred instantaneously or progressively over several days. 1,2
Patients often describe a numbness or blockage as opposed to an obvious hearing loss.
The incidence is 5 to 20 per 100,000 patients per year. 3
Untreated, spontaneous recovery has been reported to range from 30-60%. 4
While a viral or microvascular aetiolgy is proposed, it is essentially a diagnosis of exclusion: cerebellopontine angle tumours, auto-immune disease, multiple sclerosis (MS), infectious aetiologies, intralbyrinthine haemorrhage 5, perilymph fistula and Meniere’s disease must be excluded. 6
Poor prognostic factors include a severe, flat pattern to the hearing loss and associated vestibular dysfunction.

Investigation
Otoscopic examination is normal. Occasionally a middle ear effusion can result in toxic inner ear damage.
A Weber tuning fork test lateralising to the worst hearing ear is highly suggestive of a sensorineural hearing loss.
Audiometry with speech discrimination
Blood tests: FBC, CRP, Syphilis serology, RF, ANA, ENA, ANCA, serum electrophoresis. The utility of running any blood tests unless there is a history of systemic autioimmune type symptoms is very marginal.2
MRI brain and CPA: urgent if other neurologic signs and symptoms.

Management
Oral Steroids are the only effective therapy shown in randomised controlled trials.7 Varying doses and length of therapy are used. 8,9 However, a recent meta-analysis has questioned the true effectiveness of oral steroids. 10
Generally the benefit to hearing occurs if therapy started within 7 days, with treatment worthwhile out to 14 days. 4
30-50% will show no response. 11
The general approach is to treat for a week and then repeat a hearing test.
High dose Vitamin E, Vitamin C and Magnesium have been reported to add minor benefit to steroids. 12,13
No definitive benefit from antivirals, haemodilution agents or hyperbaric oxygen.7 14,15

Steroid Treatment Regimes
Oral Prednisone: Usually 50mg a day, followed by a taper over the next couple of weeks
Intratympanic Steroid [Dexamethasone, Methylprednisolone]. This can be performed in the office under local anaesthesia, but there are some advantages performing the first injection under a general anaesthetic to maximise absorption through the round window into the inner ear.
Transtympanic, multiple dose. 16,17 This can be administered via a ventilation tube or grommet.
Intratympanic, single dose.
Success of around 40% in selected patients, defined as at least 20dB or 20%. 16,18-20 Although not all studies have reproduced these results. It is important to note that approximately 10% will show some improvement after more than 1 month 21 when analysing results of salvage therapy.

Some evidence to suggest increased benefit is seen if intratympanic steroid is instituted within 7-10 days. 22
Recent reports suggest routine combination oral prednisone and Intratympanic dexamethasone treatment may give the best chance of hearing improvement23 4,20,24,25

It is important to realise that to experience true binaural hearing, that hearing thresholds must be within 15-20dB in both ears.
In rare cases, where there has been a response to steroids, but further decline once the prednisone is reduced, and long term high dose prednisone is required, steroid sparing agents such as methotrexate is considered.

Conclusion
SSNHL is an otologic emergency which requires prompt diagnosis and institution of management in order to optimise the chance of recovery. The patient must be thoroughly informed as to the limitations of current treatments. There is evolving evidence that a subset of patients may benefit from intratympanic steroids. 23 Bilateral sudden sensorineural hearing loss is much rarer, but is more likely to be associated with significant systemic disease.27

Rehabilitation
Consideration must be given to hearing rehabilitation. Assistive listening devices and hearing aids are useful when there is measurable hearing. BiCross or a bone anchored hearing aid, BAHA is an option when there is a residual severe sensorineural hearing loss. It provides the sensation of binaural hearing in a majority of cases by re-routing a signal to the contra-lateral ear.28,29 The other option is cochlear implantation. This allows stimulation of the damaged cochlear allowing true binaural hearing, and is especially useful if tinnitus is a particular problem.30-33
Vestibular rehabilitation is also an important component in the management of this condition, if the balance is also affected.

References
1. Crane RA, Camilon M, Nguyen S, Meyer TA. Steroids for treatment of sudden sensorineural hearing loss: A meta-analysis of randomized controlled trials. The Laryngoscope 2014.
2. Stachler RJ, Chandrasekhar SS, Archer SM, et al. Clinical practice guideline: sudden hearing loss. Otolaryngol Head Neck Surg 2012;146:S1-35.
3. Alexander TH, Harris JP. Incidence of sudden sensorineural hearing loss. Otol Neurotol 2013;34:1586-9.
4. Fitzgerald DC, McGuire JF. Intratympanic steroids for idiopathic sudden sensorineural hearing loss. The Annals of otology, rhinology, and laryngology 2007;116:253-6.
5. Cervantes SS, Barrs DM. Sudden Sensorineural Hearing Loss Associated With Intralabyrinthine Hemorrhage. Otol Neurotol 2014.
6. Jackler RB, D. Neurotology. 2nd ed. Philadelphia: Elselvier Mosby; 2005.
7. Conlin AE, Parnes LS. Treatment of sudden sensorineural hearing loss: I. A systematic review. Archives of otolaryngology–head & neck surgery 2007;133:573-81.
8. Wilson WR, Byl FM, Laird N. The efficacy of steroids in the treatment of idiopathic sudden hearing loss. A double-blind clinical study. Arch Otolaryngol 1980;106:772-6.
9. Slattery WH, Fisher LM, Iqbal Z, Liu N. Oral steroid regimens for idiopathic sudden sensorineural hearing loss. Otolaryngol Head Neck Surg 2005;132:5-10.
10. Conlin AE, Parnes LS. Treatment of sudden sensorineural hearing loss: II. A Meta-analysis. Archives of otolaryngology–head & neck surgery 2007;133:582-6.
11. Rauch SD. Intratympanic steroids for sensorineural hearing loss. Otolaryngologic clinics of North America 2004;37:1061-74.
12. Hatano M, Uramoto N, Okabe Y, Furukawa M, Ito M. Vitamin E and vitamin C in the treatment of idiopathic sudden sensorineural hearing loss. Acta oto-laryngologica 2007:1-6.
13. Nageris BI, Ulanovski D, Attias J. Magnesium treatment for sudden hearing loss. The Annals of otology, rhinology, and laryngology 2004;113:672-5.
14. Tucci DL, Farmer JC, Jr., Kitch RD, Witsell DL. Treatment of sudden sensorineural hearing loss with systemic steroids and valacyclovir. Otol Neurotol 2002;23:301-8.
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18. Haynes DS, O’Malley M, Cohen S, Watford K, Labadie RF. Intratympanic dexamethasone for sudden sensorineural hearing loss after failure of systemic therapy. The Laryngoscope 2007;117:3-15.
19. Plaza G, Herraiz C. Intratympanic steroids for treatment of sudden hearing loss after failure of intravenous therapy. Otolaryngol Head Neck Surg 2007;137:74-8.
20. Battaglia A, Burchette R, Cueva R. Combination Therapy (Intratympanic Dexamethasone + High-Dose Prednisone Taper) for the Treatment of Idiopathic Sudden Sensorineural Hearing Loss. Otol Neurotol 2008.
21. Yeo SW, Lee DH, Jun BC, Park SY, Park YS. Hearing outcome of sudden sensorineural hearing loss: long-term follow-up. Otolaryngol Head Neck Surg 2007;136:221-4.
22. Battista RA. Intratympanic dexamethasone for profound idiopathic sudden sensorineural hearing loss. Otolaryngol Head Neck Surg 2005;132:902-5.
23. Battaglia A, Lualhati A, Lin H, Burchette R, Cueva R. A prospective, multi-centered study of the treatment of idiopathic sudden sensorineural hearing loss with combination therapy versus high-dose prednisone alone: a 139 patient follow-up. Otol Neurotol 2014;35:1091-8.
24. Yang CH, Wu RW, Hwang CF. Comparison of intratympanic steroid injection, hyperbaric oxygen and combination therapy in refractory sudden sensorineural hearing loss. Otol Neurotol 2013;34:1411-6.
25. Chou YF, Chen PR, Kuo IJ, Yu SH, Wen YH, Wu HP. Comparison of intermittent intratympanic steroid injection and near-continual transtympanic steroid perfusion as salvage treatments for sudden sensorineural hearing loss. The Laryngoscope 2013;123:2264-9.
26. Siegel LG. The treatment of idiopathic sudden sensorineural hearing loss. Otolaryngologic clinics of North America 1975;8:467-73.
27. Sara SA, Teh BM, Friedland P. Bilateral sudden sensorineural hearing loss: review. The Journal of laryngology and otology 2014;128 Suppl 1:S8-15.
28. Peters JP, Smit AL, Stegeman I, Grolman W. Review: Bone conduction devices and contralateral routing of sound systems in single-sided deafness. The Laryngoscope 2014.
29. Son HJ, Choo D. Optimal management of single-sided deafness. The Laryngoscope 2013;123:304-5.
30. Vlastarakos PV, Nazos K, Tavoulari EF, Nikolopoulos TP. Cochlear implantation for single-sided deafness: the outcomes. An evidence-based approach. Eur Arch Otorhinolaryngol 2014;271:2119-26.
31. Tokita J, Dunn C, Hansen MR. Cochlear implantation and single-sided deafness. Current opinion in otolaryngology & head and neck surgery 2014;22:353-8.
32. Nawaz S, McNeill C, Greenberg SL. Improving sound localization after cochlear implantation and auditory training for the management of single-sided deafness. Otol Neurotol 2014;35:271-6.
33. Hansen MR, Gantz BJ, Dunn C. Outcomes after cochlear implantation for patients with single-sided deafness, including those with recalcitrant Meniere’s disease. Otol Neurotol 2013;34:1681-7.