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Labryinthitis
ALTERNATIVE NAMES: Inner ear infection.
DEFINITION: Inflammation of the inner ear.
WHAT IS GOING ON IN MY BODY? The inner ear has essentially two components. There is the cochlea, which is involved in converting the mechanical movement of air caused by sound into an electrical signal that is transmitted to the brain, which is then interpreted into the whole panoply of sounds that we identify. The inner ear is made of two fluid-filled compartments, one inside of the other. The inner compartment is filled with endolymph, which drains through a duct into a sac. In composition it is very similar to blood plasma. The outer fluid component is filled with perilymph, which is similar in composition to cerebral spinal fluid, which is the fluid that bathes the outside of the brain and spinal cord. Perilymph drains through a separate perilymphatic duct that communicates directly with the extracerebral compartments containing spinal fluid. Labyrinthitis can be grouped into acute and chronic forms. The acute form is an inflammation or infection of the fluid-filled compartments, with resultant deafness and vertigo. Acute otitis media can spread into the inner ear and cause labyrinthitis, either by spread of toxic products from the infection behind the eardrum through the round window membrane into the inner ear, or direct bacterial extension from the middle ear into the inner ear. Bacterial meningitis is another cause of bacterial labyrinthitis, whereby bacteria in the spinal fluid extends through the aqueduct into the inner ear. Erosion of the bone surrounding the inner ear, usually by cholesteatoma, exposes the membranes lining the inner ear, allowing infection or toxic material to easily extend into the inner ear.
WHAT ARE THE SIGNS AND SYMPTOMS? If the labyrinthitis is caused by meningitis or acute otitis media, then these are usually present some time before the balance and hearing loss effects occur. If it is caused by a viral infection, then usually the first symptoms are diminished hearing and vertigo.
WHAT ARE THE CAUSES AND RISKS? As mentioned above, the main causes would be direct bacterial extension from meningitis or acute otitis media, inflammation from spread of bacterial and inflammatory toxins generated during a middle ear infection into the inner ear space (serous labyrinthitis), and lastly by direct viral involvement of inner ear.
HOW TO PREVENT THE DISEASE: It is very difficult to prevent acute otitis media; but with the advent of antibiotic treatment, the complications of acute otitis media, such as meningitis, brain abscess, and labyrinthitis, have decreased. Early identification and treatment of meningitis could help prevent the extension of bacteria into the inner ear. As it is not exactly clear what the viral factors are causing viral labyrinthitis, prevention of the viral infection is not possible.
HOW IS IT DIAGNOSED? In the individual with viral labyrinthitis, the ear examination is normal, but a hearing test will demonstrate a nerve-related hearing loss. Since the balance component of the inner ear is infected, abnormal eye movements (nystagmus) occur. Nystagmus is a back-and-forth eye movement that has a fast phase followed by a slower recovery phase in the opposite direction. It can be horizontal, vertical, or rotational. The direction of the fast eye movement is usually toward the ear that is functioning normally, and the slower recovery phase is toward the ear with the infection. Special testing, such as an electronystagmogram or caloric testing, quantify the magnitude and velocity of these eye movements.
WHAT ARE THE LONG-TERM EFFECTS? Direct bacterial extension into the inner ear usually causes profound nerve deafness and complete destruction of the balance component of the inner ear. Over time the fluid-filled compartments are replaced by bone. Although the hearing loss may not improve, the brain can make adjustments for a dysfunctional ear balance system, and therefore, the vertigo usually improves over time and only becomes manifest with high velocity or complex head movements. Individuals with the viral form of the illness can have varying degrees of balance and hearing deficits.
AM I PUTTING OTHERS AT RISK? No.
WHAT ARE THE TREATMENTS? Aggressive antibiotic therapy for meningitis or acute otitis media could hopefully prevent bacterial labyrinthitis from occurring. For an individual in whom bacterial labyrinthitis is already present, antibiotics still need to be administered. For those with viral labyrinthitis, using steroids and anti-virals may be helpful. If there is a permanent nerve injury, a hearing aid may be of use. To treat the acute vertigo, anti-vertigo medications can be employed short-term but should be avoided long-term in order to allow the brain to compensate for the inner ear injury. Vestibular rehabilitation exercises can often hasten and maximize the brain compensation for the inner ear injury.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? These would be limited to the specific side effects of the medications employed.
WHAT HAPPENS AFTER TREATMENT? Physical therapy of the residual balance dysfunction maximizes function, but there could still continue to be some mild balance disturbances.
HOW DO I MONITOR THE DISEASE? The simultaneous onset of vertigo and hearing loss should be considered a medical emergency and treatment sought immediately. Any acute ear infection where vertigo may be present should be evaluated immediately. Needless to say, meningitis is a medical emergency that left untreated has a significant mortality rate.
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