Complications of Middle Ear Pathology

Intracranial complications occur in 0.25 to 0.5 percent of all cases of otitis media. The mortality rate of intracranial complications has decreased dramatically over the last century, from approximately 90 percent in the pre-antibiotic era to 10 percent now. However, significant morbidity still exists despite this improvement in survival. Diagnosis of an intracranial complication of otitis media relies heavily on an accurate history. Important elements include determining whether the patient has acute or chronic otitis media, a prior history of otologic disease or surgery, a history of head trauma or temporal bone fracture, previous antibiotic treatment, and symptoms suggesting intracranial involvement such as headache, lethargy, visual changes, fever, and nausea or vomiting.

The differential diagnosis for a patient with otitis media and symptoms and signs of intracranial involvement is long, and potential complications are numerous, including extradural abscesses or granulation tissue, dural venous sinus thrombosis, petrous apicitis (Gradenigo syndrome; Fig. 23-1 ), intraparenchymal brain abscesses, subdural abscesses, otitic hydrocephalus, and meningitis (most commonly purulent).

Computed tomography (CT) scan showing right petrous apicitis. Upper scan : Soft tissue windowing demonstrating enhancement at the tip of the petrous apex affecting Dorello canal ( arrow head ). Lower scan : Bone windowing demonstrating a lytic cell in the petrous apex with loss of septation ( arrow ).

(Courtesy of Hugh D. Curtin, MD, Massachusetts Eye and Ear Infirmary, Boston.)

The microbiology of the intracranial complications of otitis media varies with the duration of otitis as well as the type of complication. Complications of acute otitis media usually are secondary to Streptococcus pneumoniae or Haemophilus influenzae . Chronic otitis media frequently leads to complications with gram-negative bacteria, such as Pseudomonas aeruginosa , or anaerobes. The most common organisms implicated in otitic meningitis include S. pneumoniae , H. influenzae , Proteus species, P. aeruginosa , and Staphylococcus aureus. Brain abscesses are typically polymicrobial.

If an intracranial complication is suspected on the basis of the history or physical findings, further evaluation should include computerized tomography (CT) of the temporal bones to evaluate for bony erosion, congenital malformation, or fracture; contrast-enhanced magnetic resonance imaging (MRI) or CT of the head to evaluate for enhancement of the meninges, dural sinus thrombosis ( Fig. 23-2 ), or brain abscess; and a lumbar puncture if no mass effect is visualized on imaging. The cerebrospinal fluid (CSF) will typically show increased protein and decreased glucose concentrations along with organisms on Gram stain in bacterial meningitis; those patients given antibiotics in the days or weeks preceding the spinal tap may have more normal-appearing CSF chemistries and a negative Gram stain, but should be treated with antibiotics until cultures are negative, given the possibility of a partially treated bacterial meningitis. In otitic hydrocephalus, the opening pressure will be increased, but the other studies will be normal.

Sigmoid sinus thrombosis. CT venography performed after retromastoid craniectomy reveals a filling defect in the right transverse ( dashed arrow ) and sigmoid ( solid arrow ) sinuses, representing subocclusive thrombus.

(Courtesy of Barton F. Branstetter, MD, University of Pittsburgh.)

Treatment of the intracranial complications of otitis media includes medical stabilization and usually requires inpatient admission. Broad-spectrum intravenous antibiotics should be initiated empirically. Complications due to acute otitis media may be treated with a second- or third-generation cephalosporin to target the usual three pathogens: H. influenzae , Moraxella catarrhalis , and S. pneumoniae. Gram-negative and anaerobic coverage should be added for complications of chronic otitis media. Corticosteroids such as dexamethasone should be administered concurrently with intravenous anti-biotics for otogenic meningitis in order to reduce the chance of sensorineural hearing loss and, in meningitis caused by S. pneumoniae , to reduce mortality.

Labyrinthine Disorders

Meniere disease and benign paroxysmal positional vertigo are two of the most common labyrinthine disorders that cause vertigo and dysequilibrium. The pathologic correlate of Meniere disease is endolymphatic hydrops, which is usually idiopathic but may occur following inner ear trauma or infection. Patients with Meniere disease typically experience episodes of unilateral tinnitus, unilateral hearing loss, unilateral ear fullness, and vertigo lasting for minutes to hours. They do not typically experience neurologic symptoms that cannot be attributable directly to the inner ear. However, some patients experience visual changes, especially blurred vision, during attacks of Meniere disease, and headaches may occur. Other patients become anxious during attacks and may experience numbness and paresthesias. The first attack of Meniere disease often prompts an evaluation in an emergency department, leading to brain imaging to exclude cerebellar hemorrhage or infarction. First-line treatment of Meniere disease consists of sodium restriction and a diuretic, typically a combination of hydrochlorothiazide and triamterene. Non-ablative procedures, such as intratympanic steroid infusion, and ablative procedures, such as intratympanic gentamicin or labyrinthectomy, are options for patients who do not respond to conservative management.

Benign paroxysmal positional vertigo is caused by free-floating otolithic debris in the posterior semicircular canal. As with Meniere disease, benign paroxysmal positional vertigo may follow inner ear trauma or infections but usually is idiopathic. Patients typically have positionally induced vertigo when rolling over in bed or looking up. The vertigo typically lasts for less than 1 minute but more generalized symptoms of dizziness and dysequilibrium may persist for several hours. Neurologic symptoms other than vertigo and transitory visual difficulties are generally absent although patients may have difficulty in walking due to their vertigo. On physical examination, the findings on Dix–Hallpike maneuvers, illustrated in Figure 23-3 , are diagnostic. Treatment consists of a particle repositioning maneuver ( Fig. 23-4 ), which is highly successful and can be taught to the patient for use in future attacks. Despite the “benign” nature of benign paroxysmal positional vertigo, the initial episode often leads to emergency medical care. Since several nonbenign conditions, such as posterior fossa tumors, may present with positional dizziness, a thorough neurologic evaluation of all patients with positional vertigo is warranted.

Dix–Hallpike Maneuver. The Dix–Hallpike test of a patient with benign paroxysmal positional vertigo affecting the right ear. A , The examiner stands at the patient’s right side and rotates the patient’s head 45 degrees to the right to align the right posterior semicircular canal with the sagittal plane of the body. B , The examiner moves the patient, whose eyes are open, from the seated to the supine right-ear-down position and then extends the patient’s neck so that the chin is pointed slightly upward. The latency, duration, and direction of nystagmus, if present, and the latency and duration of vertigo, if present, should be noted. The arrows in the inset depict the direction of nystagmus in patients with typical benign paroxysmal positional vertigo. The presumed location in the labyrinth of the free-floating debris thought to cause the disorders is also shown.

(From Furman JM, Cass SPC: Benign paroxysmal positional vertigo. N Engl J Med 341:1590, 1999, with permission.)

Particle repositioning maneuver for the bedside treatment of a patient with benign paroxysmal positional vertigo affecting the right ear. The presumed position of the debris within the labyrinth during the maneuver is shown in each panel. The maneuver is a three-step procedure. First, a Dix–Hallpike test is performed with the patient’s head rotated 45 degrees toward the right ear and the neck slightly extended with the chin pointed slightly upward. This position results in the patient’s head hanging to the right ( A ). Once the vertigo and nystagmus provoked by the Dix–Hallpike test cease, the patient’s head is rotated about the rostral-caudal body axis until the left ear is down ( B ). Then the head and body are further rotated until the head is face down ( C ). The vertex of the head is kept tilted downward throughout the rotation. The maneuver usually provokes brief vertigo. The patient should be kept in the final, face-down position for about 10 to 15 seconds. With the head kept turned toward the left shoulder, the patient is brought into the seated position ( D ). Once the patient is upright, the head is tilted so that the chin is pointed slightly downward.

(From Furman JM, Cass SPC: Benign paroxysmal positional vertigo. N Engl J Med 341:1590, 1999, with permission.)

Eighth Nerve Lesions

Eighth nerve lesions leading to neurologic manifestations include auditory neuropathy and vestibular neuronitis. Auditory neuropathy is a disorder of dysfunction or dyssynchrony of the inner hair cells or cochlear nerve, leading to hearing loss and impaired speech discrimination with intact outer hair cell function. Risk factors for auditory neuropathy include prematurity, hyperbilirubinemia, and exposure to ototoxic medications, although genetic factors have also been implicated. This type of hearing loss can be associated with other neurologic diseases and may be seen in up to 11 percent of children with sensorineural hearing loss.

Vestibular neuronitis is an idiopathic inflammation of the vestibular portion of the eighth cranial nerve leading to acute symptoms of vertigo, nystagmus, nausea, and vomiting. Acute symptoms persist for several days and are often preceded by viral illness. In some patients, mild symptoms can last for weeks or months. Unilateral reduction in vestibular response is seen on caloric testing or vestibular evoked myogenic potentials. Possible etiologies include viral infection, immunologic causes, or vascular occlusion. The superior or inferior vestibular nerve, or both, may be involved.

Cerebellopontine Angle Disorders

Cerebellopontine angle masses may cause hearing loss, tinnitus, and vertigo. The most common type of mass found in this location is a vestibular schwannoma, commonly referred to as an acoustic neuroma. Symptoms are typically of insidious onset, but sudden hearing loss or vertigo may occur. Additionally, facial numbness may be seen with large tumors due to compression of the trigeminal nerve. Facial nerve dysfunction from vestibular schwannoma is uncommon. Without treatment, lower cranial nerve involvement and brainstem compression may eventually occur ( Fig. 23-5 ). MRI of the internal auditory canal is the typical modality used to identify these lesions. Acoustic neuromas are treated with surgical excision or stereotactic radiation; small tumors may be observed for evidence of growth. Other masses occurring in the cerebellopontine angle include meningiomas, epidermoid tumors, and metastases, which may cause similar symptoms, although the time scale of symptomatology is typically more rapid with metastatic lesions in this area.

Magnetic resonance imaging (MRI) of a large acoustic neuroma with brainstem compression. Axial contrast-enhanced T1-weighted MRI reveals a large, lobulated, enhancing mass ( arrows ) filling the left cerebellopontine angle, with compression of the pons and thinning of the brachium pontis. The patient was known to have neurofibromatosis type 2, and this lesion is most likely a schwannoma of the eighth cranial nerve.

(Courtesy of Barton F. Branstetter, MD, University of Pittsburgh.)

Superior Semicircular Canal Dehiscence Syndrome

Superior semicircular canal dehiscence syndrome was first recognized in 1998 as a cause of vertigo.

The disorder is caused by a defect in the bone over the superior semicircular canal, which renders the canal sound sensitive. Symptoms of superior semicircular canal dehiscence syndrome include vertigo induced by sound or pressure (such as during a Valsalva maneuver), hearing loss, and autophony. Systemic neurologic symptoms are absent. Noncontrast CT scan of the temporal bone demonstrates the absence of bone over the superior semicircular canal. Treatment consists of surgically plugging the superior canal in patients with bothersome vestibular symptoms ( Fig. 23-6 ).

Coronal CT scan through the level of the temporal bone demonstrating superior canal dehiscence. Arrow points to the left superior semicircular canal dehiscence. The membranous superior semicircular canal (seen in cross section) is in contact with the overlying contents of the middle cranial fossa. Compare this with the right side, where a very thin plate of bone is separating the superior semicircular canal from the middle cranial fossa.

(Courtesy of Andrew A. McCall, MD, University of Pittsburgh.)

Central Vestibular Disorders

The most common central vestibular disorders include migraine-related dizziness, vascular disease affecting the brainstem and cerebellar vestibular pathways, cerebellar degeneration, and Chiari malformation. Migraine-related dizziness, which can be considered a migraine variant, affects women more often than men, particularly women in their childbearing years. As with migraine headache, it is a diagnosis of exclusion, since there are no pathognomonic tests for this condition. Diagnostic criteria consist of a combination of the International Headache Society criteria for migraine headache and criteria developed specifically for migraine-related dizziness. Establishing a diagnosis of migraine-related dizziness requires a temporal association between dizziness and either migraine headache or typical migrainous symptoms and the absence of another diagnosis that can account for the dizziness. The pathophysiology is uncertain but is likely to be related to serotonin effects on central vestibular structures. Treatment is similar to the treatment for migraine headache and includes both decreasing triggers for migraine and use of pharmacotherapy. For patients with frequent (greater than 1 per week) episodes of migraine-related dizziness, prophylactic medications are indicated to reduce the frequency and severity of attacks and include antidepressants, beta-blockers, anticonvulsants, and calcium-channel blockers. Some patients may benefit from triptans for acute attacks.

Central vestibular structures in the brainstem and cerebellum are supplied by the posterior inferior cerebellar artery and the anterior inferior cerebellar artery. Infarction of the lateral medulla in the territory of the posterior inferior cerebellar artery leads to a Wallenberg syndrome, wherein one of two vestibular nuclear complexes is damaged, leading to central vestibular imbalance. Accompanying symptoms are caused by involvement of the ascending spinothalamic tract and descending sympathetic tracts. Patients with Wallenberg syndrome may experience lateropulsion (i.e., a sense of being pushed or pulled to one side). Infarction in the territory of the anterior inferior cerebellar artery leads to a similar syndrome but may also include the presence of unilateral hearing loss resulting from cochlear ischemia because the internal auditory artery arises from the anterior inferior cerebellar artery.

Another condition to be considered in patients with acute vertigo and accompanying neurologic disturbances referable to the brainstem and cerebellum is that of cerebellar hemorrhage or infarction with concomitant brainstem compression, or even of brainstem stroke alone. This condition represents a neurosurgical emergency. Brain imaging provides definitive diagnostic information.

Vertebrobasilar insufficiency may present with various neurologic symptoms including vertigo and changes in hearing as well as symptoms referable to parenchymal posterior fossa structures, such as changes in vision, sensation, strength, or level of consciousness. Symptoms typically last for minutes. Isolated vertigo is rarely a result of vertebrobasilar insufficiency. Diagnostic imaging such as MR or CT angiography is helpful in establishing a diagnosis of vertebrobasilar insufficiency in the context of appropriate symptoms. Treatment with antiplatelet agents and management of risk factors for cardiovascular disease are warranted for most cases; endovascular treatment with angioplasty, stenting, or both, is rarely employed.

Cerebellar degeneration can be associated with dizziness and dysequilibrium. Some types of cerebellar degeneration (particularly spinocerebellar ataxia, type 6) can also be associated with episodic features including episodic vertigo and dysequilibrium. In association with such symptoms, patients with cerebellar degeneration often demonstrate limb ataxia and sometimes long-tract signs. Chiari malformations sometimes present with “dizziness” and dysequilibrium. Physical examination may disclose down-beating nystagmus (i.e., vertical nystagmus with a downward fast component), which may reflect a central vestibular imbalance. Additionally, patients with a Chiari malformation often have nonvestibular symptoms such as dysphagia and long-tract signs. A diagnosis of a Chiari malformation can be confirmed by sagittal MRI ( Fig. 23-7 ). Treatment is surgical and involves suboccipital craniotomy.

Chiari malformation. Sagittal T2-weighted MRI through the cranio-cervical junction shows the cerebellar tonsils ( solid arrow ) extending far below the foramen magnum ( dashed line ). The medulla is compressed.

(Courtesy of Barton F. Branstetter, MD, University of Pittsburgh.)

Central Auditory Processing Disorder

Central auditory processing disorder, as its name implies, is characterized by defects in higher-level processing of auditory information in the setting of normal hearing as measured by conventional audiometry. This disorder leads to difficulty in understanding oral communication, particularly when there is background noise, and can be associated with attention deficit–hyperactivity disorder, learning disabilities, head trauma, and other neurologic disorders. Psychoacoustic testing often identifies specific deficits that correlate with patients’ symptoms. Treatment consists of improving the signal-to-noise ratio with amplification or reduction of background noise, as well as auditory training.

Infection

Many infections can cause otoneurologic symptoms and signs. Viral infection, in particular herpes simplex virus, has been implicated in Bell palsy. Figure 23-8 shows herpes simplex virus type 1 particles seen by electron microscopy in the geniculate ganglion of mice with experimentally induced Bell palsy. Corticosteroids are used for treatment. Viral infection is also thought to play a role in idiopathic sudden sensorineural hearing loss and vestibular neuronitis. Mumps, measles, and congenital rubella infection may cause significant hearing loss.

Herpes simplex virus (HSV) in a mouse model of Bell palsy. A , The intratemporal portion of the facial nerve from the paralyzed side showing a neuron in the geniculate ganglion. Replicating HSV-1 viruses in the rough endoplasmic reticulum of a neuron in the geniculate ganglion are indicated by the arrows. B , The geniculate portion of the facial motor nerve. Arrows indicate vacuolar changes in the cytoplasm of a Schwann cell which resulted in demyelination. Scale bars: A, 1 µm; B, 5 µm.

(From Takahashi H, Hitsumoto Y, Honda N, et al: Mouse model of Bell’s palsy induced by reactivation of herpes simplex virus type 1. J Neuropathol Exp Neurol 60:621, 2001, with permission.)

Another member of the herpes virus family, varicella-zoster virus, causes herpes zoster oticus, often referred to as Ramsay Hunt syndrome. This syndrome, from reactivation of varicella-zoster virus in the geniculate ganglion, is characterized by facial weakness associated with vesicular lesions in the external auditory canal and auricle. The symptoms are typically preceded by otalgia. Sensorineural hearing loss and vertigo are sometimes present. Investigators have postulated that the reactivation of varicella-zoster virus may occur in the vestibular and spiral ganglia as well. Ramsay Hunt syndrome may involve other cranial nerves; polymerase chain reaction has localized viral material to the CSF in some cases. MRI typically reveals enhancement of the geniculate ganglion on the affected side. Treatment is with antiviral agents and corticosteroids. The facial palsy associated with Ramsay Hunt syndrome has a poorer prognosis than that of Bell palsy.

Otosyphilis was first described in 1887 by Politzer. Following the introduction of penicillin, it became rare. However, with the emergence of human immunodeficiency virus (HIV) infection, syphilis has experienced a resurgence in the United States and Western Europe. Otoneurologic manifestations may occur in secondary, tertiary, or congenital syphilis. Sensorineural hearing loss and hydropic symptoms of episodic tinnitus and vertigo may occur. Treatment is with penicillin G and corticosteroids.

Lyme disease may cause sudden sensorineural hearing loss or facial palsy. Vertigo is uncommon but has been reported. The mainstay of treatment is intravenous ceftriaxone; corticosteroids may be added for treatment of hearing loss.

Tuberculosis may affect the ear. As with syphilis, tuberculosis has become increasingly common in patients with HIV infection. Tuberculous otitis media remains rare. The classic description of mycobacterial otitis media is of chronic otorrhea and multiple perforations of the tympanic membrane. Polyps and granulation tissue may also be seen. Treatment is primarily medical, with surgery reserved for complications.

HIV infection and immunodeficiency may cause otologic symptoms. Otitis externa may be caused by common pathogens such as P. aeruginosa ; however, opportunistic infections such as Pneumocystis species may also be responsible in these populations. There are also reports of malignant otitis externa (i.e., skull base osteomyelitis secondary to otitis externa) in individuals with HIV infection, although some authors note that the incidence of malignant otitis externa is not increased in the HIV-infected population as a whole. Children with HIV infection often suffer from chronic otitis media. Serous otitis media may result from eustachian tube obstruction secondary to adenoid hypertrophy. Sensorineural hearing loss occurs in 21 to 49 percent of HIV-positive patients and is thought to be multifactorial. Possible causes include secondary infection, central nervous system (CNS) involvement, and ototoxicity. Finally, facial palsy is more common in HIV-positive patients.

Immune-Mediated and Connective Tissue Disease

There are a number of autoimmune and connective tissue disorders that cause otoneurologic symptoms, ranging from otitis media to hearing loss or vertigo.

Wegener granulomatosis is characterized by vasculitis of medium and small vessels, as well as by necrotizing granulomas of the upper and lower respiratory tract. Up to 70 percent of patients with this disorder experience otologic symptoms. The most common otoneurologic manifestation of Wegener granulomatosis is serous otitis media. The middle ear space can be affected by granulomas, leading to a clinical picture resembling chronic suppurative otitis media ( Fig. 23-9 ). Facial palsy may also result, from either vasculitis or direct involvement of the facial nerve by the granulomatous process. Sensorineural hearing loss occurs in 8 percent of patients and is sometimes rapidly progressive. Vertigo is uncommon. Wegener granulomatosis is diagnosed by the presence of cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) and by the combination of necrotizing granulomas and vasculitis seen on histopathology. Treatment is with high-dose corticosteroids and immunosuppressive agents.

Chronic otitis media in Wegener granulomatosis. Granulomatous swelling of the posterior part of the left eardrum viewed through an otomicroscope ( arrow ). The large white area inferior and to the left of the eardrum is the anterior wall of the external ear canal.

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