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Sudden Sensorineural Hearing Loss and Tinnitus

by Barry Keate

There are two basic types of hearing loss: conductive hearing loss (CHL) and sensorineural hearing loss (SNHL). Conductive hearing loss occurs when sound is not conducted efficiently through the outer ear canal to the eardrum and the small bones of the middle ear. Sensorineural hearing loss occurs when there is damage to the cochlea or to the nerve pathways from the inner ear to the brain.

Conductive hearing loss is generally treatable. Causes include fluid in the middle ear from colds or allergies, eustachian tube dysfunction, infection, otosclerosis (an abnormal bone growth in the middle ear) and impacted earwax.

Sensorineural hearing loss is much more difficult to treat. Primary causes include disease, ototoxic medications, noise exposure, viral infections, head trauma, aging and tumors.

Sudden sensorineural hearing loss (SSNHL) is a frightening subset of SNHL. This is characterized by the sudden decrease in hearing of at least 30 dB, affecting at least 3 frequencies over a 72 hour period or less. It may occur over a few hours, a few minutes, or even instantaneously. People afflicted with this typically feel fullness in the ear; they may experience a “pop”, and frequently have vertigo. Tinnitus is an almost universal effect of SSNHL. In about 96% of cases, SSNHL affects only one ear.

Many doctors believe the cause of SSNHL is autoimmune or viral in nature, although this is far from certain, there may very well be a vascular component involved. In about 90% of cases there is no specific cause that can be identified. This is termed idiopathic SSNHL.

SSNHL reportedly affects 5 to 20 per 100,000 people with some estimates are as high as 160 per 100,000. There are about 4,000 new cases reported in the US each year. Many of these cases will recover spontaneously. Some reports suggest 32 to 65% will recover but many physicians believe this is high. Most clinicians feel that one-third of people recover completely, another third recover a portion of their hearing and the remaining third don’t recover any hearing.

There is no standardized treatment for SSNHL and there have been very few clinical studies conducted on the treatments most commonly used. Physicians do agree that treatment should begin as soon as possible, within a few days, in order to secure a favorable outcome. What the treatment should be and the success of any specific treatment, however, is the subject of ongoing discussion. Unfortunately, there is no single treatment that has proven effective in reversing this type of hearing loss.

To clarify this situation, the American Academy of Otolaryngology-Head Neck Surgery Foundation, also known as the AAO (Ear, Nose & Throat physicians) has published a clinical practice guideline for treating the condition. This is the first guideline ever published for the treatment of SSNHL. They do not discuss any alternative or nutraceutical interventions for prevention or treatment, with the exception of Hyperbaric Oxygen Treatment, but focus mostly on imaging techniques and the medications most commonly used.

There is quite a bit of clinical evidence that SSNHL can be prevented or treated with a variety of alternative and nutraceutical treatments. We will discuss these first, then move on to the AAO guidelines.

Alternative and Nutraceutical Prevention and Treatment

Elevated homocysteine levels in the blood have been shown to lead to atherosclerosis, heart disease and hearing loss, as well as several types of cancer and Alzheimer’s disease. Homocysteine is the agent that damages blood vessel lining and allows the formation of plaque build-up.

Homocysteine is an amino acid formed from the metabolism of methionine, found in high concentrations in meat and dairy products. The western diet is rich in these foods and elevated homocysteine levels are the result. Homocysteine can be metabolized and neutralized by the vitamins B-6, B-12 and folic acid.

 

A study conducted in 2005 on the subject of sudden hearing loss and folic acid found that SSNHL patients had higher homocysteine levels and lower folate (folic acid) levels than healthy controls. A growing body of evidence suggests that B vitamins and folic acid can lower homocysteine levels and decrease the likelihood of experiencing thrombotic events and SSNHL. (1)

 

Other studies examining the effect of folic acid on hearing loss found that folate levels are significantly lower in SSNHL patients than those without hearing loss and a significant relationship was found between low folate levels and high homocysteine levels in all patients. (2)

Also, a study presented at the 2009 AAO’s annual meeting in San Diego, CA shows that higher folate levels decrease the risk of hearing loss in men over the age of 60 by 20%. (3)

Folic acid is primarily found in green, leafy vegetables such as spinach, asparagus and turnip greens. It is essential to numerous bodily functions including the health of the inner ear.

Folic acid should always be accompanied by vitamin B-12 supplementation to prevent folic acid from masking a vitamin B-12 deficiency. Also, vitamin B-12 and folic acid, along with vitamin B-6 are necessary to metabolize excess homocysteine and preserve hearing health. All these important B vitamins are found in Arches Tinnitus Stress and B12 Formula

Hyperbaric Oxygen Therapy (HBOT) is one alternative treatment that is gaining popularity, both for treating tinnitus and SSNHL. In both cases, it is much more effective in the early stages. In HBOT, the patient sits inside a pressurized chamber. Air pressure inside the chamber is increased to 2.5 times normal atmospheric pressure. The patient then breathes pure oxygen from a mask for 1 to 2 hours. Sessions are repeated on successive days for 10 or 15 times.

Due to the increased pressure inside the chamber, far more oxygen is dissolved in the bloodstream than under normal conditions. HBOT enables the oxygen content of the blood to reach up to 7%, which is 20 times higher than normal. This increases oxygen pressure in the inner ear.

It has been shown that there is a profound decrease in oxygenation of the cochlea during and after acoustic stress and in SSNHL. During exposure to HBOT, the oxygenation in the cochlea increases up to 460%. (4) The hair cells in the cochlea have no direct vascular supply of oxygen and depend entirely on oxygen supplied by diffusion. An increase in oxygen compensates for oxygen deficiency caused by trauma and gives rise to mechanisms that are involved in functional recovery.

A study conducted in Europe involved 50 patients who were admitted within 48 hours of SSNHL. Thirty patients underwent HBOT while 20 we given vasodilators. Of the 30 HBOT patients, 25 (83.3%) experienced either a very good (50% or more) or a significant (25% to 50%) improvement. (5)

Ginkgo Biloba has been shown in at least one clinical study to be effective in treating patients with SSNHL. (6) German researchers used oral Ginkgo biloba on patients whose hearing loss occurred less than 10 days before they were included in the study. The researchers used two dosages of 24 mg and 240 mg daily and compared the groups in a randomized, double-blind study.

They found that large majorities of both groups recovered completely but patients given the higher dosage recovered better. They concluded, “A higher dosage of EGb 761 (Ginkgo biloba) appears to speed up and secure the recovery of SSNHL patients, with a good chance they will recover completely, even with little treatment.”

Arches Tinnitus Formula products contain therapeutic amounts of Ginkgo biloba, Vitamins B-6, B-12 and folic acid to neutralize many of the causes of SSNHL and to help recovery if SSNHL has occurred. They should be used by anyone with hearing problems, tinnitus, or sudden hearing loss.

Clinical Practice Guideline

The following is excerpted from the AAO Supplement, titled Clinical Practice Guideline: Sudden Hearing Loss. (7) This is the protocol the majority of ENT physicians will use to treat SSNHL in the future. It consists of 13 statements and supporting evaluations.

In the prologue, the guideline states, “Treatment options are myriad and include systemic and topical steroids, antiviral agents, rheologic agents, diuretics, hyperbaric oxygen treatment, other medications, middle ear surgery for fistula repair, and observation alone. The comparative efficacy of these treatments, however, is not known, considering that the definitive etiology (cause) is also commonly not known.”

Statement 1. Clinicians should distinguish sensorineural hearing loss (SSNHL) from conductive hearing loss (CHL). This allows causes of CHL, such as impacted cerumen, to be treated and isolate those with SSNHL. This should be conducted during the initial visit.

Statement 2. Clinicians should assess patients with presumptive SSNHL for bilateral sudden hearing loss, recurrent episodes of sudden hearing loss, or neurological deficits in nerve, spinal cord or brain function. This helps in identifying patients with potentially serious underlying causes.

Statement 3. Clinicians should NOT order computerized tomography (CT scan) of the head/brain in the initial evaluation of a patient with presumptive SSNHL. This is a strong recommendation based on the benefits of avoidance of radiation, cost savings, less inconvenience for the patient and avoiding a false sense of security from a false negative scan.

Statement 4. Clinicians should diagnose presumptive idiopathic (unknown origin) SSNHL if audiology confirms a 30 dB hearing loss at 3 consecutive frequencies AND an underlying condition cannot be identified by history and physical examination.

Statement 5. Clinicians should NOT obtain routine laboratory tests in patients with idiopathic SSNHL. The use of the word “routine” is intentionally vague as some tests may be useful for some patients based on specific individual patient conditions.

Statement 6. Clinicians should evaluate patients with idiopathic SSNHL for retrocochlear pathology (behind the cochlea, denoting the 8th cranial nerve) by obtaining an MRI, auditory brainstem response (ABR), or audiometric follow-up. This can identify brain tumors, other conditions that might benefit from early treatment, and patient peace of mind.

Statement 7. Clinicians should educate patients with idiopathic SSNHL about the natural history of the condition, the benefits and risks of medical interventions, and the limitations of existing evidence regarding efficacy.

Statement 8. Clinicians may offer corticosteroids as initial therapy to patients with idiopathic SSNHL. There are risks to this treatment. For oral corticosteroids, systemic side effects are possible and include: hypertension, ulcers, diabetes, cataracts, substantial weight gain, interference with healing, and others. For intratympanic (through the ear drum) corticosteroids, there are issues of localized pain, high cost and multiple office visits. The panel states that even a small possibility of hearing improvement makes corticosteroids a reasonable treatment to offer patients, considering the profound impact that a quality of life hearing improvement may offer.

Statement 9. Clinicians may offer Hyperbaric Oxygen Therapy (HBOT) within three months of diagnosis of idiopathic SSNHL. Although HBOT is not widely available in the US and is not recognized by many US clinicians as an intervention for idiopathic SSNHL, the panel felt that the level of evidence for hearing improvement, although modest and imprecise, was sufficient to promote greater awareness of HBOT as an intervention.

Statement 10. Clinicians should NOT routinely prescribe antivirals, thrombolytics, vasodilators, vasoactive substances, or antioxidants to patients with idiopathic SSNHL. The use of the word “routine” is used to avoid setting a standard recognizing there may be patient specific indications for one or more of these therapies that may be reasonable to try.

Statement 11. Clinicians should allow intratympanic steroid perfusion when patients have incomplete recovery from idiopathic SSNHL after failure of initial management.

Statement 12. Clinicians should obtain follow-up audiometric evaluation within six month of diagnosis for patients with idiopathic SSNHL.  This allows them to assess outcome of intervention, identify patients who may benefit from audiological rehabilitation, identify cause of hearing loss, identify progressive hearing loss and improve counseling.

Statement 13. Clinicians should counsel patients with incomplete recovery of hearing about the possible benefits of amplification and hearing assistive technology (HAT) and other supportive measures.

 

References

1 – Hall J. Sudden Hearing Loss and Folic Acid. Journal Watch Pediatrics and Adolescent Medicine. June 13, 2005.

2 – Cadoni G, Agostino S, et al. Low Serum Folate Levels: a Risk Factor for Sudden Sensorineural Hearing Loss? Acta Oto-Laryngologica 2004, Vol. 124, No. 5, pp 608-611.

3 – Shargoradsky J, Curhan G, et al. A Prospective Study of Vitamin Intake and the Risk of Hearing Loss in Men. Otolaryngology-Head and Neck Surgery, Vol. 142, No. 2, Feb. 2010, pp 231-236.

4 – Lamm K. Simultane Sauerstoffpartialdruckestimmung in der Skala Tympani, Electrokochleographie und Blutdruckmessungen nach Knalltraumata bei Meerschweinchen. HNO 3791989) 45-55.

5 –Fattori B, Berrettini S, Casani A, et al. Sudden Hypoacusis Treated with Hyperbaric Oxygen Therapy; a Controlled Study. Ear, Nose & Throat Journal Sept. 2001.

6 – Burschka MA, Hassan HA, eat al. Effect of Treatment with Ginkgo Biloba Extract EGb 761 (oral) on Unilateral Idiopathic Sudden Hearing Loss in a Prospective Randomized Double-Blind Study of 106 Outpatients. Eur Arch Otorhinolaryngol. 2001 Jul; 258(5); 213-9.

7 – Stachler RJ, Chandrasekhar SS, et al. Clinical Practice Guideline: Sudden Hearing Loss. Supplement to Otolaryngology – Head and Neck Surgery. Vol. 146 Supplement 1, March 2012.