A neuro-otologist is called on to manage a variety of different problems related to the ear and adjacent skull-base structures. The evaluation of these disorders often requires one or more of the following tests:

• Audiogram (hearing evaluation)
• Electronystagmography (inner ear balance evaluation)
• Auditory brainstem response (ABR- electrophysiologic evaluation of brainstem hearing pathway)
• Magnetic resonance imaging (MRI) of the brain/skull base
• Computed tomography (CT) of the ear/skull base
• Angiogram (X-ray evaluation of major blood supply to the ear/skull base)

Glomus Tumors

    Glomus tumors represent the most common tumor of the middle ear (space behind the eardrum) and the second-most common tumor of the temporal bone (bone that contains the ear structures and forms a large portion of the skull base); acoustic neuroma being the most common tumor. These lesions are benign (noncancerous) and usually grow at a slow rate. They originate either directly behind the eardrum (called glomus tympanicum) or in the base of the temporal bone (called glomus jugulare). They infiltrate the surrounding structures and have an abundant blood supply. Pressure on the eardrum or bones of hearing (ossicles) usually leads to a noticeable hearing loss, and a pounding noise or pulsation in synchrony with the heartbeat is usually present due to the rich blood supply to the tumor. As they enlarge, surrounding nerves may be affected which control facial movement, swallowing, vocal cord movement (leading to hoarseness), shoulder and tongue strength. Direct invasion of the inner ear usually leads to nerve deafness hearing loss and dizziness.
  Complete evaluation requires a search for pre-existing deficits of the nerves related to the temporal bone. Generally a CT and MRI scan of the skull base will determine the extent of the lesion and involvement of surrounding structures. In addition, an angiogram is routinely obtained for all but the smallest glomus tumors to delineate the abundant blood supply to these lesions.
    The mainstay of treatment consists of surgical excision. Tympanicum tumors can generally be removed by lifting up the eardrum and/or through the mastoid (bone directly behind the ear). Jugulare lesions, however, require more extensive surgery involving the base of the skull and upper neck. Patients in poor general health or the elderly who have enlarging tumors are occasionally treated with radiation therapy to try and halt or slow the growth of the lesion. However, radiation therapy will not "cure" the tumor.

Cholesteatoma

    Cholesteatoma consists of a skin cyst or pouch that develops from the eardrum and invades the deeper areas of the ear and mastoid bone. While they represent a benign or nonmalignant condition, cholesteatomas are locally invasive and erode the surrounding structures of the ear. They have the potential to erode the bones of hearing (ossicles) behind the eardrum and commonly cause hearing loss. Erosion into the inner ear is less common, but if present may lead to significant dizziness and nerve deafness hearing loss. Invasion of the facial nerve as it courses through the ear can lead to paralysis of the nerve and subsequent loss of muscle movement on the same side of the face. If the lesion becomes infected, it commonly causes persistent drainage from the ear that usually is not controlled with antibiotics. Rarely, cholesteatomas may erode into the intracranial cavity and can allow infection to spread further, leading to meningitis or a brain abscess. Cholesteatomas are relatively slow-growing lesions, however do require surgical excision (see chronic otitis media below).

Chronic Otitis Media

  An infection of the middle ear (area behind the eardrum) generally will lead to pain or fullness along with diminished hearing due to accumulation of fluid and swelling of the lining of the ear cavity. Most infections are readily treated with antibiotics. However, severe or persistent infections may not resolve and can lead to a ruptured eardrum with intermittent or constant drainage from the ear canal. Unresolved infection may lead to an irreversibly diseased ear which contains thickened, inflamed tissue (called granulation tissue) and a hole in the eardrum that will not heal. At this stage, chronic otitis media is present. Cholesteatomas (see above) may be associated with this state. The granulation tissue often surrounds the ossicles and may begin to dissolve these structures. The mastoid bone behind the ear is generally involved also.

  Treatment at this stage is surgical, as further antibiotics are rarely successful. Thorough removal of diseased tissue in the middle ear with reconstruction of the hearing mechanism and repair of the eardrum defect (known as tympanoplasty) is combined with removal of disease within the mastoid bone (known as mastoidectomy). Untreated chronic otitis media may spread to cause infection within the bone of the surrounding skull base (osteomyelitis) or lead to intracranial complications such as meningitis or brain abscess.

 
Facial Nerve Disorders

  These can fall into two broad categories: weakness (paralysis) or hyperactivity (tics or spasms). The facial nerve takes a tortuous course through the temporal bone and controls movement of the facial muscles on the same side of the face (i.e. blinking, raising your eyebrow, smiling, etc.). The most common disorder to affect the facial nerve consists of a fairly sudden onset (within 24-72 hours) paralysis due to a viral infection. This is known as Bell's palsy and generally has a good prognosis for recovery (85% of patients have return of normal function), which occurs over weeks to several months. This disorder is often treated with steroids to decrease inflammatory swelling of the nerve and antiviral medications. Even though recovery is the rule of thumb, a complete evaluation of the ear and hearing are in order to rule out other potential, and more serious, causes of the paralysis. More aggressive viral infections may also involve the nerve of hearing and balance in addition to the facial nerve in a condition known as herpes zoster oticus. Primary tumors of the facial nerve, known as facial neuromas, also will lead to paralysis that does not spontaneously improve. Other tumors of the ear such as acoustic neuromas or glomus tumors may also secondarily compress or invade the facial nerve, leading to facial paralysis. Another important cause of facial paralysis is trauma to the ear, specifically temporal bone fracture. A fracture through the bony channel containing the facial nerve may lead to partial or complete disruption of the nerve fibers. Often CT scans of the ear and electrical stimulation tests of the nerve are necessary to evaluate the degree of injury. In severe cases, surgical decompression of the nerve or grafting of the injured portion may be required.

  Hyperactivity of the facial nerve, on the other hand, leads to involuntary contraction of the facial muscles. This may range from mild twitches of a portion of the face to forceful contractions of the entire side of the face. Spasm of the eyelid muscles leads to uncontrollable blinking and severe cases can prevent driving an automobile or carrying out other routine activities. The condition known as hemifacial spasm usually affects the entire side of the face and is due to compression of the facial nerve as it exits the brain and before it enters the temporal bone by an intracranial artery. Surgical exploration and displacement of the artery off the nerve is very successful in alleviating the spasms. However, many of the same lesions that cause facial paralysis (such as facial nerve neuromas, acoustic neuromas or cholesteatoma) can also irritate the nerve and cause hyperexcitability.

Otosclerosis

  Otosclerosis consists of an abnormal growth of bone in the ear that leads to fixation of the innermost of the three bones of hearing (the stirrup or stapes), causing hearing loss. Under normal conditions, sound pressure waves impinge on the eardrum, leading to vibratory movement of this structure and the bones of hearing known as ossicles (see Figure under section How Does The Ear Work?). This vibratory movement is transferred to the fluids of the inner ear, which in turn leads to electrical stimulation of the nerve of hearing. With otosclerosis, abnormal bone bridges the flexible seal between the footplate of the stapes and surrounding bony shell of the inner ear. This fixes the stapes in place, preventing vibratory movement in response to sound. The diagnosis is usually apparent, and is based on a lack of other abnormal findings on the office evaluation and a characteristic pattern of hearing loss readily detected on an audiogram (hearing test).

  The treatment of otosclerosis consists of either a hearing aid or a surgical procedure known as stapedectomy. Surgery involves lifting up the eardrum as a flap (working through the ear canal with the patient under light sedation and local anesthesia) to visualize the stapes. After confirming the diagnosis, the stapes bone is removed (often using the laser) and a new opening is created into the inner ear. Following this, a specially-made prosthesis is inserted into the opening and connected to the adjacent bone of hearing (the anvil or incus). This prosthesis effectively replaces the fixed stapes and again allows vibratory movement from sound stimulation to be transmitted to the fluids of the inner ear. Surgery is successful for significant hearing improvement in approximately 90% of patients.

Encephalocele (Brain Herniation)

  This condition may develop in the presence of a bony defect in the roof of the temporal bone. Over time, this lack of bony support for the overlying brain allows it to herniate into the middle ear space. This leads to thinning out of the dura mater (covering around the entire brain that contains cerebrospinal fluid), and often a subsequent leak of this fluid into the ear behind the eardrum develops. This fluid and the herniated brain tissue lead to decreased movement of the bones of hearing, causing hearing loss and often a feeling of fullness in the ear. Encephaloceles into the ear may also cause chronic headaches, seizures and represent a potential route for intracranial spread of infection, specifically meningitis. As the brain tissue herniates into the ear, it is no longer functional.

     Treatment consists of surgical resection of the nonviable tissue with reconstruction of the bony defect in the roof of the ear and sealing of the cerebrospinal fluid leak. This can occasionally be accomplished through the middle ear and mastoid, but often requires a combined approach through the ear and intracranially from above the defect in the skull base.

Other Conditions

  A multitude of other disorders or tumors may affect the ear and skull base which include meningiomas, cancer of the ear, eosinophilic granulomas, cholesterol granulomas, cranial nerve schwannomas, epidermoids and congenital / developmental defects. For further information on these and other conditions, contact your physician.