Sudden Hearing Loss

In most people, no cause can be found for their sudden hearing loss. However, doctors have several theories. Possible causes include viral infections Overview of Viral Infections A virus is composed of nucleic acid, either DNA or RNA, surrounded by a protein coat. It requires a living cell in which to multiply. A viral infection can lead to a spectrum of symptoms from... read more (particularly infections with herpes simplex virus Overview of Herpesvirus Infections Some common viral infections are caused by herpesviruses. Eight different herpesviruses infect people: Three herpesviruses— herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster... read more ), an attack on the inner ear or its nerves by the body's immune system (autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more ), and blockage of the small blood vessels of the inner ear or the blood vessels of its nerves. Perhaps different causes affect different people.

In many other people, a cause for the sudden hearing loss is obvious. Such causes include

Head injury (such as a fracture of the temporal bone in the skull or sometimes a severe concussion without a fracture) can damage the inner ear and cause sudden hearing loss.

Severe pressure changes (such as those that can occur with diving or less often by bearing down during weightlifting) can cause a hole (fistula) to form between the middle and inner ear. Sometimes, such a fistula is present from birth and can spontaneously cause sudden hearing loss or make the person more susceptible to hearing loss after a head injury or pressure changes.

Ototoxic drugs are drugs that have damaging side effects to the ears. Some drugs can rapidly cause hearing loss, sometimes within a day (especially with an overdose). A few people have a rare genetic disorder that makes them more susceptible to hearing loss from the class of antibiotics called aminoglycosides. All people taking such antibiotics should have blood tests while on the drug to screen for toxic levels that can cause hearing loss. People receiving drugs that are excreted in the urine, such as aminoglycosides, should also have their kidney function checked and monitored to avoid kidney damage.

A number of infections cause sudden hearing loss during or immediately after acute illness. These infections include bacterial meningitis Meningococcal Infections Meningococcal infections are caused by the bacteria Neisseria meningitidis (meningococci) and include meningitis and sepsis. Infection is spread by direct contact with nasal and throat... read more , Lyme disease Lyme Disease Lyme disease is a tick-transmitted infection caused by Borrelia species, primarily by Borrelia burgdorferi and sometimes by Borrelia mayonii in the United States. These... read more , and many viral infections. The most common viral causes in the developed world are mumps Mumps Mumps is a contagious viral infection that causes painful enlargement of the salivary glands. The infection may also affect the testes, brain, and pancreas, especially in adolescents and adults... read more and herpes simplex Herpes Simplex Virus (HSV) Infections Herpes simplex virus infection causes recurring episodes of small, painful, fluid-filled blisters on the skin, mouth, lips (cold sores), eyes, or genitals. This very contagious viral infection... read more brain infection. Measles Measles Measles is a highly contagious viral infection that causes various cold-like symptoms and a characteristic rash. Measles is caused by a virus. Symptoms include fever, runny nose, hacking cough... read more is a very rare cause because most people are immunized against the infection.

Sudden hearing loss rarely can be the first symptom of some disorders that usually have other initial symptoms. Such disorders include a tumor of the auditory nerve called acoustic neuroma Vestibular Schwannoma A vestibular schwannoma (also called an acoustic neuroma) is a noncancerous (benign) tumor that originates in the cells that wrap around the vestibular nerve (Schwann cells). Vestibular schwannomas... read more , multiple sclerosis Multiple Sclerosis (MS) In multiple sclerosis, patches of myelin (the substance that covers most nerve fibers) and underlying nerve fibers in the brain, optic nerves, and spinal cord are damaged or destroyed. The cause... read more , Meniere disease Meniere Disease Meniere disease is a disorder characterized by recurring attacks of disabling vertigo (a false sensation of moving or spinning), nausea, fluctuating hearing loss (in the lower frequencies),... read more , or a small stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction). Symptoms occur suddenly... read more due to a blockage of a branch of the artery that goes to the balance center of the brain (the cerebellum). Sometimes a syphilis infection Syphilis Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum. It can occur in three stages of symptoms, separated by periods of apparent good health. Syphilis... read more reactivates in people who have HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more . This reactivation can cause sudden hearing loss.

Rarer disorders include Cogan syndrome Cogan Syndrome Cogan syndrome is a rare autoimmune disease that can affect the cornea. Eye pain, decreased vision, increased sensitivity to bright light, and redness of the eye are common symptoms. Diagnosis... read more , in which an autoimmune reaction attacks the inner ear (and also the surface of the eye); certain disorders involving blood vessel inflammation (vasculitis Overview of Vasculitis Vasculitic disorders are caused by inflammation of the blood vessels (vasculitis). Vasculitis can be triggered by certain infections or drugs or can occur for unknown reasons. People may have... read more ); and blood disorders such as Waldenström macroglobulinemia Macroglobulinemia Macroglobulinemia is a plasma cell cancer in which a single clone of plasma cells produces excessive amounts of a certain type of large antibody (IgM) called macroglobulins. Although many people... read more , sickle cell disease Sickle Cell Disease Sickle cell disease is an inherited genetic abnormality of hemoglobin (the oxygen-carrying protein found in red blood cells) characterized by sickle (crescent)-shaped red blood cells and chronic... read more , and some forms of leukemia Overview of Leukemia Leukemias are cancers of white blood cells or of cells that develop into white blood cells. White blood cells develop from stem cells in the bone marrow. Sometimes the development goes awry... read more .

Sudden hearing loss is itself a warning sign.

Anyone with sudden hearing loss should see a doctor right away because some causes must be treated quickly. If symptoms of dysfunction of the nervous system other than hearing loss are present, hearing loss may be a symptom of nerve or brain dysfunction.

Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination may suggest a cause of the sudden hearing loss and the tests that may need to be done.

Doctors note whether hearing loss affects one or both ears and whether a specific event such as head injury Overview of Head Injuries Head injuries that involve the brain are particularly concerning. Common causes of head injuries include falls, motor vehicle crashes, assaults, and mishaps during sports and recreational activities... read more , diving injury Barotrauma Barotrauma is tissue injury caused by a change in pressure, which compresses or expands gas contained in various body structures. The lungs, gastrointestinal tract, part of the face covered... read more , or infectious illness occurred. They ask about accompanying symptoms that involve the ear (such as ringing in the ears or ear discharge), balance center (such as disorientation in the dark or vertigo), and other parts of the brain and nervous system (such as headache, weakness, or an abnormal sense of taste). They try to identify whether people are currently taking (or recently took) any ototoxic drugs Ear Disorders Caused by Drugs Many drugs, including medications, can damage the ears. These drugs are called ototoxic drugs. They include the antibiotics streptomycin, tobramycin, gentamicin, neomycin, and vancomycin, as... read more .

The physical examination focuses on the ears and hearing and on examination of the nervous system.

Typically, people should have an audiogram (a hearing test Testing ). Unless doctors think the problem is clearly an acute infection or drug toxicity, they usually also do gadolinium-enhanced magnetic resonance imaging (MRI) or computed tomography (CT), particularly when the hearing loss is greater in one ear. Other tests are done based on the likely cause. For example, people who had a head injury should have MRI. People at risk of sexually transmitted infections should have blood tests for HIV infection and syphilis.