Anatomy of the Human Ear

Outer Ear Middle Ear The Inner Ear HEARING Loudness, Pitch, and Tone DISEASES OF THE HUMAN EAR Middle Ear Infection Inner Ear Diseases Ear Pain, Scuba Diving Earache Earwax Ear Exam Otoscope Ear Surgery

Circulatory system Respiratory system
Digestive system Esophagus Gall bladder Large intestine Lips, cheeks and palate Salivary glands Serous membranes Small intestine Stomach Tunics
Teeth Tongue Digestive Process in Mouth Sleep Right Mouth Guard
Endocrine system Glandular Structure Gonads Hormones Pancreas Parathyroid Glands Pineal Gland Pituitary Gland Pituitary Hormones Thymus Thyroid Gland

Disease of the Inner Ear

 Diseases of the inner ear can affect the sense of balance and cause symptoms of motion sickness. Anemia, tumors of the acoustic nerve, exposure to abnormal heat, disturbances of the circulatory system, skull injuries, poisoning, emotional disorders, and hyperemia, or increased blood flow, may also cause these symptoms. Méniere’s disease results from abnormalities in the semicircular canals and produces nausea, hearing loss, a disturbed sense of balance, and tinnitus, or a persistent ringing in the ears. Destruction of the inner ear by cryosurgery or ultrasound is sometimes used to combat intractable dizziness.

 Damage to the organ of Corti in the inner ear accounts for the condition of many people who are either totally deaf or severely hearing-impaired. Scientists have addressed the difficulties of such people by developing an electronic device called a cochlear implant. This device is more sophisticated than a hearing aid, which merely increases the volume of the sounds that pass through the normal hearing organs. The cochlear implant works by translating sound waves into electric signals. These signals are relayed to electrodes that have been surgically implanted in the cochlea so that the auditory nerve is directly stimulated. After successful surgery, once deaf or severely hearing-impaired patients can usually detect a wide range of sounds, but results depend on factors that include the health of the auditory nerves and the duration of deafness. Nonetheless, lip-reading ability often improves, and implant users have varying degrees of success in using the telephone.

 Otalgia, or earache, is not necessarily associated with ear disease; occasionally it is caused by impacted teeth, sinus disease, inflamed tonsils, infections in the nose and pharnyx, or swelling of the lymph nodes in the neck. Tinnitus may also result from these conditions. Permanent tinnitus is most often caused by prolonged exposure to loud noise, which damages the hair cells of the cochlea. A sound masker, worn like a hearing aid, may offer relief to some sufferers by blocking the perception of ringing in the ears.

Autoimmune Inner Ear Disease

 The role of immunity in sensorineural hearing loss was first suggested in 1958 by Lenhart. Kikuchi, in 1959, wrote of "sympathetic otitis" whereby surgery on one ear affected hearing in the other. He proposed an autoimmune phenomena as the etiology. In 1961 Beickert, and two years later, Terrayama presented data supporting autoimmunity in experimental guinea pig cochleas. McCabe described 18 patients with bilateral asymmetric hearing loss progressing over weeks to months which responded to steroid therapy. His 1979 paper asserted the importance of a high index of suspicion in these patients since, if diagnosed early, they could be treated and their hearing preserved.

 Humoral and cell mediated immunity, the lymphocyte-macrophage system, and the complement cascade work in homeostatic harmony to provide immune protection to the host. B cells are produced in the bone marrow and, through antigen stimulation and differentiation into plasma cells, produce specific antibodies. T cells are derived in the thymus and provide regulatory function for B cells, cytotoxic activity, and generate lymphokines. B and T cells also form immunologic memory. Cells of the lymphocyte-macrophage system phagocytose foreign cellular components, process antigen, and produce interferons. The complement cascade amplifies antigen antibody reactions. Chemotactic, anaphylotoxic, opsoninization, and immune adherence functions arise from the complement system. Kinin-like substances are also complement generated.

 The inner ear is immunologically active. The endolymphatic sac acts as the afferent limb of inner ear immunity since it can concentrate and primarily synthesize antibody. IgG is the most common antibody produced with IgM, IgA, and secretory component being present in lower concentrations. The distal endolymphatic sac is the site of immunologic activity due to extensive perisaccular lymphatics. Antibody production is independent of serum or cerebrospinal fluid levels. Secondary exposure to antigen in the inner ear induces a more intense response than primary exposure to antigen.

 Autoimmunity occurs with loss of homeostatic control in the immune system. Host tissues become recognized as foreign and induce damaging vasculitis and fibrosis. Veldman described a continuum of autoimmunity. On one end, organ specific responses with organ specific autoantibodies and T cells produce tissue alteration (i.e. Hashimoto's thyroiditis). On the opposite end of the spectrum is non-organ specific diseases with circulating non-specific autoantibodies (i.e. systemic lupus erythematosus). In between is organ specific disease with non-specific autoantibodies (ie primary biliary cirrhosis).

 Patients with idiopathic autoimmune sensorineural hearing loss present most commonly with bilateral progressive hearing loss. Fifty percent have vestibular signs, and symptomatically progress over weeks to months. Females between the ages of 17 to 42 years represent 65% of the cases reported by Hughes. Twenty percent of Hughes' study later manifested signs of systemic autoimmune disease.

 McCabe proposed using ESR, ANA, RF, complement levels, and quantitative immunoglobulin levels as a screening panel for autoimmune inner ear disease in high risk patients. Positive values in any of the screening tests would warrant leukocyte inhibition testing. Hughes classified patients as high risk if they had bilateral and progressive sensorineural hearing loss, no response to conventional therapy, concomitant immune disorders, abnormal screening tests or improvement of hearing with steroid therapy.

 Treatment goals in autoimmune inner ear disease include improving speech thresholds to levels treatable with hearing aids in severely affected patients and recovery of hearing to near normal levels in those with mild to moderate losses. Steroids, cytoxan, and plasmapheresis compose the available therapeutic modalities. Hughes advocates high dose (prednisone 20 mg four times daily for 10 days then 10 mg every other day for 3-6 months) steroids as initial treatment. Patients are tapered slowly and restarted if symptoms recur. As initial therapy, McCabe recommends cytoxan (2mg/kg twice daily) combined with steroids (prednisone 30 mg every other day) for 3 weeks. If speech discrimination scores increase by 20% or pure tone average improves by 15 dB, therapy is continued for 3 months. Cyclophosphamide is tapered first followed by steroids. If symptoms recur both drugs are restarted. Three month cycles are continued until patients can be weaned. No patient required more than 24 months of treatment in McCabe's study. Hughes advises plasmapheresis for those patients unresponsive to steroids and cytoxan after 6 to 8 weeks at the above stated doses. Plasmapheresis theoretically removes unwanted humoral and cellular elements. Treatments are given three times weekly for 2 weeks followed by once weekly for 4 additional weeks.

 In summary, otolaryngologists need a high index of suspicion for autoimmune etiologies in patients with sensorineural hearing loss. Ophthalmologic, neurologic and rheumatologic consultations are useful in ruling out systemic vasculitic diseases. Steroids and cyclophosphamide remain the cornerstones of treatment in autoimmune inner ear disease, with reservation of plasmapheresis for refractory cases. If caught early, and with aggressive medical management, hearing stabilization and possible improvement are feasible. ©2016.