- ACRONYMS AND DEFINITIONS
- AAO-HNS - American Academy of Otolaryngology—Head and Neck Surgery
- BPPV - Benign paroxysmal positional vertigo
- CNS - Central nervous system
- CRP - Canalith repositioning procedures
- EFAS - European Federation of Autonomic Societies
- MD - Meniere's disease
- TIA - Transient ischemic attack
- Dizziness is a general term for a broad range of symptoms that are related to an altered sense of equilibrium. Up to 30% of the population reports feeling dizzy each year, and it is the chief complaint in 3 - 5% of all primary care and ER visits. The incidence of dizziness increases with age and women are affected more than men.
- Dizziness can be categorized into 4 types: lightheadedness, presyncope, disequilibrium, and vertigo. Around 50% of patients with dizziness have features and findings consistent with vertigo, 15% have disequilibrium, 15% have presyncope, and the remainder have nonspecific features that don't fit any of these types and are therefore categorized as lightheadedness. [1,2]
- VESTIBULAR PHYSIOLOGY
- Balance and equilibrium are complex processes that involve an interplay between sensory input from peripheral organs and central processes that control muscle movement and tone. Central control occurs primarily in the brainstem and cerebellum, and peripheral input is provided by the vestibular system, eyes, and proprioceptors that innervate muscles and tendons. Most types of vertigo and disequilibrium involve issues with the vestibular system which is reviewed briefly below.
- The vestibular system is composed of two vestibular apparatuses that are encased in the temporal bone next to the ear on each side of the head. Each apparatus contains three semicircular canals and an utricle and saccule. [vestibular system illustration] The semicircular canals contain endolymph fluid that flows through the canals with head movement. At the base of each canal there is an ampulla that contains cells with cilia on their surface (hair cells). The cilia detect fluid movement across the surface of the cell, and this causes the cell to send a signal to the vestibular nerve.
- The utricle and saccule are sac-like structures that are lined with sensory hair cells similar to the ones in the ampullas of the semicircular canals. Above the cells, calcium carbonate crystals called otoliths are suspended in a gel matrix. When a person moves forward, the otoliths are displaced and this causes the cilia on the hair cells to move. The hair cells then send a signal to the vestibular nerve.
- Another important part of the vestibular system is the vestibulo-ocular reflex which keeps the eyes fixed on an object during head movement. Without it, the slightest change in head position would cause a centered object to lose focus. The reflex works in the following way: (1) head movement is sensed by the semicircular canals, (2) the semicircular canals send a signal to the eye muscles that causes them to adjust the eyeball in the direction opposite the movement, (3) near instantaneous eyeball adjustment keeps the object in the center of focus. In BPPV, displaced otoliths in the semicircular canals create false signals that interfere with the vestibulo-ocular reflex. This causes the jerky, oscillatory eye movements called nystagmus that are characteristic of the condition. [2,8]
- TYPES OF DIZZINESS
- Dizziness is a general term for a broad range of symptoms that are used to describe an altered sense of equilibrium. Dizziness can be difficult to evaluate because it is a subjective feeling, and patients often give vague and/or nonspecific descriptions of what they are feeling (e.g. unsteady, weak, faint, woozy, off-balance).
- When evaluating dizziness, it is helpful to try and categorize the patient's symptoms into one of four groups: lightheadedness, presyncope, disequilibrium, and vertigo. While these categories are not entirely objective, particularly lightheadedness which is a catch-all category for anything that does not fit the other three, they do provide a starting point for formulating a diagnostic approach.
- Vertigo - vertigo is the illusion of movement that is often described as rotatory or "spinning" in nature. Unlike presyncope, the patient does not feel like they are going to lose consciousness.
- Disequilibrium - disequilibrium is the sensation that one's balance or steadiness is impaired. Unlike vertigo, there is no illusion that the environment is moving or spinning.
- Presyncope - presyncope is the feeling of an impending loss of consciousness. Patients with presyncope may describe an array of symptoms that include palpitations, nausea, fear, and diaphoresis. Presyncope is different from vertigo and disequilibrium in that presyncopal symptoms are typically brief and related to a precipitating event such as standing for a long period, fear, rising from a sitting position, or exertion. See syncope for a review of the different types of syncope and their features. [2,9]
- Lightheadedness - lightheadedness is a catch-all term for dizziness symptoms that are not consistent with vertigo, presyncope, or disequilibrium. Patients often describe vague symptoms that may include feeling "disconnected," "woozy," "brain fog," or "off." The term lightheadedness is also used synonymously with feeling faint, so it is important to question the patient about presyncopal symptoms when they report lightheadedness.
- Evaluating dizziness can be challenging, particularly when patients report vague, nonspecific symptoms. All patients who present with dizziness should have a physical exam that includes a cardiac, neurologic, and ear exam. It's also important to review the patient's medications because drugs have been implicated in up to 23% of dizziness cases (see medications associated with dizziness below).
- The recommendations presented below are derived from review articles and a limited number of guidelines. While this information is helpful, any provider who has evaluated a significant number of dizziness complaints knows that a lot of patients don't fit "neatly" into any one category; in these instances, clinical judgement should prevail.
- STEP 1 - Continuous vs episodic
- Once it is established that a patient is experiencing vertigo, the first step is to determine if vertigo is episodic or constant. Episodic symptoms that are related to head movement are consistent with BPPV, and these patients should be evaluated with the Dix-Hallpike maneuver and supine head roll test.
- If the vertigo is described as continuous, the next step is to determine if it is central or peripheral (see central vs peripheral vertigo below). One important caveat to remember is that patients with continuous vertigo will often complain of worsening symptoms with head movement. This should not be misinterpreted as episodic vertigo. [7,14]
- STEP 2 - Central vs peripheral vertigo
- After establishing that the patient is experiencing constant vertigo, the next step is to determine if the vertigo is peripheral (semicircular canals, saccule, utricle, vestibular nerve) or central (brainstem, cerebellum). This distinction is important because central causes of vertigo (see central vertigo causes) include serious conditions like posterior circulation strokes and TIAs whereas peripheral causes (see peripheral vertigo causes) are more likely to be benign and/or nonemergent. Three maneuvers have been developed that can help distinguish peripheral from central vertigo. Collectively, these tests are referred to as the HINTS exam and include the Head Impulse test, Nystagmus test, and Test of Skew. If any of the 3 tests have findings that are consistent with central vertigo, a stroke cannot be ruled out. If all 3 tests are consistent with peripheral vertigo, a stroke is unlikely; studies have shown the HINTS exam to have > 95% sensitivity for any stroke. In order for the exam to be accurate, it must be performed in patients who are experiencing an acute vestibular syndrome which is defined as an acute onset of continuous vertigo, dizziness, or unsteadiness that may accompanied by other symptoms of vestibular dysfunction (e.g. nausea, vomiting, nystagmus, head motion intolerance). Patients must be symptomatic when the exam is performed.
- The three components of the HINTS exam are described below, and a table comparing the features of central and peripheral vertigo is also provided (see central vs peripheral table). [4,5,6,14]
- Head impulse test
- The head impulse test is performed with the following steps:
- Patient sits upright on the exam table
- Patient is instructed to keep their eyes fixed on an object (e.g. picture on wall, examiner's nose)
- Examiner quickly turns the patient's head to the right or left by about 10 - 15 degrees. The turn is then repeated in the opposite direction.
- Peripheral vertigo - the eyes are briefly dragged off the object in the direction of the head turn before rapidly correcting in the opposite direction to focus back on the object (called a saccade). This occurs because the vestibulo-ocular reflex is deficient. [head impulse test video]
- Central vertigo - the eyes do not move off the object with head rotation [1,3]
- Nystagmus test
- To test for nystagmus, the examiner moves his finger from right to left while the patient follows it with his eyes. The patient should not turn his head during the test
- Nystagmus occurs when the eyes slowly drift away from the finger and then correct with a fast movement in the opposite direction. This drift and correction occurs over and over again giving the appearance of a beat.
- Peripheral vertigo - in peripheral vertigo, the nystagmus is horizontal and may contain a torsional component; it is never purely vertical or torsional. The direction of the fast phase remains the same regardless of the patient's gaze. The amplitude and frequency of the fast component increases when gazing toward the direction of the fast phase and may completely disappear when gazing away from it. The fast phase beats away from the side where the vestibular system is abnormal. [peripheral nystagmus video]
- Central vertigo - in central vertigo, the nystagmus may beat in any direction. The direction of the fast phase may also change with different gazes. [central nystagmus video] [1,3]
- Test of skew
- To perform the test of skew, the patient looks straight ahead while the examiner covers one eye. After covering the eye for several seconds, the examiner quickly removes the cover and observes the eye to see if it shifts vertically to realign with the other eye. The test is then repeated on the opposite eye.
- Peripheral vertigo - no vertical shift is noted when the eye is uncovered
- Central vertigo - vertical shift is noted when the eye is uncovered. [test of skew video] [1,3]
|Peripheral vs Central Vertigo|
|Head impulse test||
|Test of skew||
|Other neurologic deficits||
- Dix-Hallpike maneuver
- When vertigo is episodic and triggered by head movement, the Dix-Hallpike maneuver can be useful for diagnosing posterior BPPV. BPPV is believed to occur when otoliths enter one of the semicircular canals (semicircular canal illustration). The posterior canal is affected in 85 - 95% of cases, and the lateral canal (also called horizontal canal) accounts for the rest; anterior canal BPPV is believed to be very rare. A positive Dix-Hallpike maneuver is strongly suggestive of posterior canal BPPV. If the test is negative, a supine head roll test should be performed to look for lateral canal BPPV.
- The Dix-Hallpike maneuver is performed with the following steps:
- Patient sits upright on the exam table
- The examiner takes the patient's head in their hands and rotates it 45° to the right
- While maintaining the head at 45°, the examiner moves the patient from the seated to the supine position and then extends the neck below the horizontal plane by 20 - 30°. The maneuver should be done fairly quickly, and the patient should keep their eyes open.
- The examiner holds the patient in this position and observes for nystagmus for at least 1 minute; there is typically a delay of 5 - 20 seconds between the completion of the maneuver and the onset of nystagmus and vertigo. After the patient's vertigo and nystagmus (if present) resolve, the patient can sit upright. If the right side is negative, the test should be repeated to the left side. [Dix-Hallpike demonstration video]
- Posterior BPPV - the Dix-Hallpike maneuver is considered positive for posterior canal BPPV when the following two criteria are met: (1) patient reports symptoms of vertigo with the maneuver, (2) vertical up-beating (towards forehead) nystagmus is observed that may also include a torsional component. There is typically a delay of 5 - 20 seconds between the completion of the maneuver and the onset of nystagmus and vertigo. Once nystagmus and vertigo start, they often increase in intensity and then resolve within 60 seconds. The direction of the nystagmus may reverse when the patient sits up, and the maneuver is fatigable, meaning that symptoms decrease when it is repeated. If the test is positive on the patient's right side, then the right posterior canal is affected and vice versa. [positive Dix-Hallpike maneuver video] [7,11]
- Supine head roll test
- When vertigo is episodic and triggered by head movement, the supine head roll test can be useful for diagnosing lateral BPPV. BPPV is believed to occur when otoliths enter one of the semicircular canals (semicircular canal illustration). The posterior canal is affected in 85 - 95% of cases, and the lateral canal (also called horizontal canal) accounts for the rest; anterior canal BPPV is believed to be very rare. The Dix-Hallpike maneuver should be performed first to test for posterior BPPV. If it is negative, the supine head roll test is performed to look for lateral canal BPPV.
- The supine head roll test is performed with the following steps:
- Patient lies supine on the exam table while examiner holds head at about 30° above the horizontal
- Examiner then turns the head from right to left while examining the eyes for nystagmus. Nystagmus usually occurs within seconds of turning the head. [supine head roll test video]
- Lateral BPPV - the supine head roll test is considered positive for lateral canal BPPV when horizontal nystagmus occurs. The horizontal nystagmus in lateral BPPV changes direction when the head is turned and is either geotropic (beating towards the ground) or apogeotropic (beating towards the sky). Determining the affected side can be difficult, but in general, the following is true: (1) with geotropic nystagmus, the side with the strongest nystagmus is the affected side, (2) with apogeotropic nystagmus, the side opposite the strongest nystagmus is the affected side [7,11]
- Imaging and labs
- One of the most difficult decisions in evaluating vertigo is determining which patients should have brain imaging. While ≥ 95% of patients presenting to the ER with dizziness do not have a stroke, it is also true that about 33% of strokes that present with dizziness are initially missed. In general, it is recommended that patients with signs of central vertigo have brain imaging. MRI with diffusion-weighted images is more sensitive than CT and is preferred. In cases where it is difficult to differentiate central from peripheral vertigo, patient risk factors for stroke should be considered when deciding who to image.
- Laboratory testing is not helpful in identifying the etiology of vertigo [3,4]
- Disequilibrium is an impairment of one's balance, but unlike vertigo, there is no illusion of movement. Disequilibrium most commonly affects older patients. As people age, the organs and pathways that sense and control balance deteriorate. Common age-related effects on the vestibular system include the following: (1) motion-sensing hair cells in the vestibular apparatus are lost, (2) visual acuity declines, (3) proprioceptors become less sensitive, (4) cerebellar and brainstem pathways degenerate. Other medical problems that can contribute to disequilibrium include Parkinson's disease, peripheral neuropathy (e.g. diabetic), and motor deficits from previous strokes.
- Disequilibrium usually has a slow, progressive onset, but it may be exacerbated or become more apparent after an acute event (e.g. fall). Patients with a sudden onset of disequilibrium should be evaluated for a stroke. [2,6]
- The evaluation of patients with presyncope is discussed here - presyncope evaluation
- Lightheadedness is a catch-all category for patients who give nonspecific and vague symptoms. The term "lightheadedness" is sometimes used synonymously with feeling faint, so it is important to consider presyncope when evaluating these patients. Other conditions to consider when evaluating lightheadedness include hyperventilation, anemia, metabolic disorders (e.g. hypoglycemia), psychiatric disorders (e.g. depression, anxiety, panic disorder, dissociative disorder), carbon monoxide poisoning, and head trauma. [2,9]
- Medications that can cause dizziness
- One of the first steps in evaluating dizziness is to review the patient's medication list to see if a drug may be contributing to or causing their symptoms. Medications have been implicated in up to 23% of dizziness cases. The table below gives a list of drugs that are known to cause dizziness in some patients. It's important to note that a large number of drugs list dizziness as a potential side effect. This is because dizziness is a common complaint in the general population so it is likely that a fair amount of people will report dizziness while taking any medication..
|Medications associated with dizziness|
Central nervous system agents
- PERIPHERAL VERTIGO
- Benign paroxysmal positional vertigo (BPPV)
- Epidemiology: BPPV is by far the most common cause of vertigo, and it is diagnosed in up to 42% of patients with dizziness. The lifetime risk of BPPV in people who live to be 80 years old is up to 10% in some studies. The peak incidence occurs between the ages of 50 and 60 years, and women are affected more than men.
- Symptoms: BPPV typically presents as a sudden onset of vertigo that lasts < 1 minute and is induced by changes in head position (e.g. getting out of bed, rolling over in bed, leaning forward, head turning). Nausea and vomiting may also be present, and spontaneous remissions and recurrences are common.
- Pathology: The vestibular system is composed of two vestibular apparatuses that are encased in the temporal bone next to the ear on each side of the head. Each apparatus contains three semicircular canals and an utricle and saccule. [vestibular system illustration] The semicircular canals contain endolymph fluid that flows through the canal with head movement. At the base of each canal there is an ampulla that contains cells with cilia on their surface (hair cells). The cilia detect fluid movement across the surface of the cell, and this causes the cell to send a signal to the vestibular nerve. The utricle and saccule are sac-like structures that are lined with sensory hair cells similar to the ones in the ampullas of the semicircular canals. Above the cells, calcium carbonate crystals called otoliths are suspended in a gel matrix. When a person moves forward, the otoliths are displaced and this causes the cilia on the hair cells to move. The hair cells then send a signal to the vestibular nerve. BPPV is believed to occur when clumps of otoliths are shed from the saccule or utricle into one of the semicircular canals. The clumps cause abnormal fluid movement in the canal that is interpreted by the central nervous system as motion. The posterior canal is affected in 85 - 95% of cases, and the lateral canal (also called horizontal canal) accounts for the rest; anterior canal BPPV is believed to be very rare.
- Diagnosis: For patients with short episodes of vertigo triggered by head movement, a positive Dix-Hallpike maneuver is diagnostic for posterior canal BPPV. If the Dix-Hallpike maneuver is negative, the supine head roll test should be performed to look for lateral BPPV.
- Posterior canal BPPV
- Observation - BPPV typically resolves without treatment with 20% of affected individuals having spontaneous resolution at 1 month and 50% by 3 months. Patients with milder, less bothersome symptoms may choose observation over other treatments.
- Canalith repositioning procedures (CRP) - CRP are highly effective at treating posterior canal BPPV. Success rates after one session are up to 80%, and they increase to almost 100% with repeated sessions. The Epley maneuver is the most widely used CRP. A video demonstration of the maneuver is available here - Epley maneuver demonstration, and a handout that describes how to perform the maneuver at home is available here - home Epley maneuver instructions (pdf). The maneuver should be performed to the same side that elicited a positive Dix-Hallpike test. Some patients who do not have nystagmus on the Dix-Hallpike maneuver still benefit from CRP.
- Medications - in general, vestibular suppressant medications (e.g. antihistamines, benzodiazepines) are not recommended for BPPV. [7,11]
- Lateral (horizontal) canal BPPV
- Observation - BPPV typically resolves without treatment with 20% of affected individuals having spontaneous resolution at 1 month and 50% by 3 months. Lateral canal BPPV may resolve faster than posterior canal BPPV. In one study, the average time to resolution was 39 days for posterior BPPV and 16 days for lateral BPPV. Patients with milder, less bothersome symptoms may choose observation over other treatments.
- Canalith repositioning procedures (CRP) - Two CRPs have been developed to treat lateral canal BPPV. The Gufoni maneuver is demonstrated here - Gufoni maneuver video, and the right and left Lempert 360° roll maneuvers (also called barbecue roll) are demonstrated here - Right Lempert (barbecue roll) and Left Lempert (barbecue roll). A major challenge in treating lateral BPPV is determining which side is affected (see supine head roll test). [7,11]
- Medications - in general, vestibular suppressant medications (e.g. antihistamines, benzodiazepines) are not recommended for BPPV. [7,11]
- Recurrence: Recurrence of BPPV is common. In studies, recurrence rates were 5 - 13.5% at 6 months, 10 - 18% at 1 year, and up to 50% at 5 years. [3,7]
- Vestibular neuritis
- Epidemiology: Vestibular neuritis (also called vestibular neuronitis) is a clinical diagnosis that has no pathognomonic finding or objective test. This makes it difficult to estimate a true incidence. Further compounding the issue is the fact that it is sometimes considered synonymous with labyrinthitis, and the two syndromes are lumped together. In studies, vestibular neuritis or labyrinthitis has been diagnosed in 5 - 6% of patients who present to the ER with dizziness.
- Symptoms: Vestibular neuritis presents with an acute onset (over several hours) of severe vertigo that is constant and may be worsened by head movement. Vertigo usually peaks within 48 hours and then resolves over days to weeks. Nausea and vomiting are common, and symptoms of a viral illness may precede the onset of vertigo. Vestibular neuritis differs from labyrinthitis in that there are no auditory symptoms (hearing loss, tinnitus) with vestibular neuritis.
- Pathology: Vestibular neuritis is believed to occur from inflammation of the vestibular portion of the 8th cranial nerve. The cause of inflammation is presumed to be a viral infection, but other etiologies (e.g. vascular, autoimmune) have been proposed.
- Diagnosis: There is no definitive test or finding that can be used to make a diagnosis of vestibular neuritis. Affected patients will have continuous vertigo and a HINTS exam that is consistent with a peripheral etiology (see central vs peripheral vertigo above). Unlike BPPV, the vertigo in vestibular neuritis is constant as opposed to intermittent and triggered. If auditory symptoms are present, labyrinthitis should be considered.
- Treatment: During the acute phase, most experts recommend vestibular suppressants including antihistamines (e.g. meclizine), antiemetics (e.g. prochlorperazine, promethazine), and/or benzodiazepines. These agents are not recommended for more than 3 days. Patients who continue to have significant symptoms may benefit from vestibular rehabilitation therapy. Corticosteroids have been used in the past, but there is no clear evidence in trials that they are beneficial. Antiviral agents have not been found to be helpful. [12,13,14]
- Recurrence: Recurrence of vestibular neuritis occurs in about 2 - 11% of patients [12,13,14]
- Epidemiology: In most cases, the diagnosis of labyrinthitis is based on subjective findings, and there are no widely recognized diagnostic criteria. This makes it difficult to estimate an incidence. Further compounding the issue is the fact that it is sometimes considered synonymous with vestibular neuritis, and the two syndromes are lumped together. In studies, vestibular neuritis or labyrinthitis has been diagnosed in 5 - 6% of patients who present to the ER with dizziness.
- Symptoms: Labyrinthitis presents with an acute onset (over several hours) of severe vertigo that is constant and may be worsened by head movement. Vertigo usually peaks within 48 hours and then resolves over days to weeks. Nausea and vomiting are common, and symptoms of a viral illness may precede the onset of vertigo. Labyrinthitis differs from vestibular neuritis in that auditory symptoms (hearing loss or tinnitus) are present in labyrinthitis and absent in vestibular neuritis.
- Pathology: The labyrinth is the part of the middle ear that contains the utricle, saccule, semicircular canals, and cochlea. The labyrinth is encased in the temporal bone which forms the outer part called the bony labyrinth. A collection of fluid filled tubes and chambers inside the bony labyrinth make up the membranous labyrinth. The membranous labyrinth is separated from the bony labyrinth by a narrow space that is filled with a fluid called perilymph. The inside of the membranous labyrinth is filled with a fluid called endolymph. [labyrinth illustration] Labyrinthitis occurs when the membranous labyrinth becomes inflamed. The etiology of the inflammation may be infectious (viruses, bacteria) or autoimmune. Viruses are believed to be the most common cause, and bacterial labyrinthitis is primarily seen in children with meningitis or otitis media. Autoimmune labyrinthitis is uncommon, but may be seen in Wegener granulomatosis and polyarteritis nodosa. A special form of viral labyrinthitis can occur with herpes zoster oticus, also called Ramsay Hunt syndrome. In Ramsay Hunt syndrome, herpes zoster affecting the facial nerve (cranial nerve 7) causes facial paralysis/weakness and a painful vesicular rash (shingles) of the inner and outer ear and/or mouth. In 25% of cases, the vestibular apparatus is also affected and patients may experience vertigo and/or hearing loss.
- Diagnosis: There is no definitive test or finding that can be used to make a diagnosis of labyrinthitis. Affected patients will have continuous vertigo and a HINTS exam that is consistent with a peripheral etiology (see central vs peripheral vertigo above). Unlike BPPV, the vertigo in labyrinthitis is constant as opposed to intermittent and triggered. Patients with labyrinthitis will have hearing loss and/or tinnitus; this feature distinguishes it from vestibular neuritis. Audiometry may be performed to confirm hearing deficits.
- Treatment: Viral labyrinthitis, which is the most common type, typically resolves over the course of days to weeks. A short course of antihistamines (e.g. meclizine), antiemetics (e.g. prochlorperazine, promethazine), and/or benzodiazepines may be beneficial in the initial few days. Bacterial labyrinthitis is a serious infection that must be treated with IV antibiotics. Autoimmune labyrinthitis is treated with corticosteroids and other immunosuppressants. Ramsay Hunt syndrome is treated with antivirals (e.g. acyclovir, valacyclovir) and steroids. Patients with persistent vestibular symptoms may benefit from vestibular rehabilitation therapy.
- Sequelae: Most patients with viral labyrinthitis recover fully. A small number of patients may have persistent symptoms that last for weeks to months. Depending on the severity, bacterial labyrinthitis can lead to hearing loss and vestibular damage. In Ramsay Hunt syndrome, some patients are left with some degree of facial paralysis and hearing loss. [7,15,16]
- Meniere's disease (MD)
- Epidemiology: Meniere's disease (also called endolymphatic hydrops) is a rare disease with an estimated prevalence of around 0.20%. MD occurs almost exclusively in adults and has a peak age of onset between 40 - 60 years.
- Symptoms: MD is characterized by random and episodic attacks of vertigo lasting minutes to hours that are accompanied by hearing loss, tinnitus, and/or ear fullness. MD typically affects one ear initially, but as the disease progresses, both ears may become involved. Nausea and vomiting are common, and most patients experience 6 - 11 attacks per year.
- Pathology: The labyrinth is the part of the middle ear that contains the utricle, saccule, semicircular canals, and cochlea. The labyrinth is encased in the temporal bone which forms the outer part called the bony labyrinth. A collection of fluid filled tubes and chambers inside the bony labyrinth make up the membranous labyrinth. The membranous labyrinth is separated from the bony labyrinth by a space that is filled with a fluid called perilymph. The inside of the membranous labyrinth is filled with a fluid called endolymph. [labyrinth illustration] The exact cause of Meniere's disease is unknown, but it is believed to occur when there is an excessive amount of endolymph within the membranous labyrinth. The excessive lymph causes distension of the labyrinth that leads to small tears in the membrane. The tears periodically allow potassium-rich endolymph fluid to bathe cochlear hair cells and the eighth cranial nerve. This causes episodic vertigo and auditory symptoms.
- The AAO-HNS gives the following diagnostic criteria for MD
- Definite MD
- Two or more spontaneous attacks of vertigo, each lasting 20 minutes to 12 hours
- Audiometrically documented fluctuating low- to midfrequency sensorineural hearing loss (SNHL) in the affected ear on at least 1 occasion before, during, or after 1 of the episodes of vertigo
- Fluctuating aural symptoms (hearing loss, tinnitus, or fullness) in the affected ear
- Probable MD
- At least 2 episodes of vertigo or dizziness lasting 20 minutes to 24 hours
- Fluctuating aural symptoms (hearing loss, tinnitus, or fullness) in the affected ear
- Other causes excluded by other tests
- Acute symptomatic treatment - symptomatic treatment for acute episodes includes antihistamines (e.g. meclizine, promethazine, diphenhydramine), benzodiazepines, and anticholinergics (e.g. scopolamine)
- Lifestyle/dietary - lifestyle and dietary modifications may help prevent MD attacks; although, there is little to no evidence from randomized controlled trials supporting these measures. Recommendations often include the following: (1) sodium-restricted diet (< 1500 mg/day), (2) caffeine reduction/elimination, (3) alcohol reduction/elimination, (4) stress reduction, (5) nicotine reduction/elimination, (6) allergy testing and treatment.
- Diuretics - thiazide diuretics with or without a potassium-sparing diuretic (e.g. triamterene) are often prescribed to prevent MD episodes. It is hypothesized that diuretics reduce MD attacks by altering the electrolyte composition of endolymph, which in turn, reduces its volume. There are no good trials that have evaluated the efficacy of diuretics in preventing MD.
- Intratympanic steroids - steroids can be injected into the middle ear through the tympanic membrane using a needle. This procedure is sometimes used to treat active MD that is unresponsive to noninvasive treatments.
- Intratympanic gentamicin - gentamicin can be injected into the middle ear through the tympanic membrane using a needle. Gentamicin is toxic to the sensory cells of the vestibular system as well as the hair cells within the cochlea. Gentamicin injections work by chemically ablating the vestibular system. Intratympanic gentamicin injections appear to be very effective at improving vertigo symptoms, but up to 35% of patients may experience some hearing loss.
- Surgical labyrinthectomy - in severe, refractory cases, surgical labyrinthectomy may be performed. In several case series, surgical labyrinthectomy has been found to be > 95% effective at relieving vertigo symptoms.
- Prognosis: MD has a highly variable course with some patients worsening over time and others experiencing a resolution of symptoms. In the early stages of the disease, vertigo attacks typically worsen over the first several years before abating and sometimes resolving. Hearing loss may worsen or stabilize. In most patients, MD attacks cease over the course of 2 - 8 years, but permanent balance and hearing issues remain. [18,19]
- Acoustic neuroma (vestibular schwannoma)
- Acoustic neuroma is a rare tumor of the Schwann cells that surround the vestibulocochlear nerve. Acoustic neuromas typically present with unilateral hearing loss that may be accompanied by disequilibrium and vertigo. Acoustic neuromas are benign, but as the tumor enlarges, it can cause debilitating symptoms (e.g. tinnitus, hearing loss, disequilibrium, headaches, facial weakness). Treatment options include surgical excision, radiation therapy, and observation for smaller tumors.
- Perilymph fistula
- Perilymph fistula is a rare condition where a connection (fistula) forms between the middle ear and the space between the membranous labyrinth and bony labyrinth. The fistula allows perilymph fluid to drain into the middle ear. Perilymph fistulas present with hearing loss, tinnitus, ear fullness, and vestibular symptoms. Risk factors for perilymph fistulas include middle ear and/or mastoid surgery, brain trauma, cholesteatoma, temporal skull fractures, and barotrauma. Some perilymph fistulas heal on their own, but others require surgical repair.
- CENTRAL VERTIGO
- Central vertigo arises from conditions that affect the brain, primarily the cerebellum and brainstem. While > 90% of vertigo cases are from a peripheral cause, some of the more serious and emergent etiologies are central. Causes of central vertigo are listed below.
- Vertebrobasilar arterial stroke/TIA - the vertebrobasilar arteries supply blood to the brainstem and cerebellum (vertebrobasilar arteries illustration). Vertebrobasilar artery strokes account for 25% of all strokes, and vertigo is the presenting symptom in about half of these cases. See stroke and TIA for more.
- Multiple sclerosis - multiple sclerosis with demyelinating lesions of the brainstem and cerebellum can cause vertigo. See multiple sclerosis for more.
- Vestibular migraine - the definition of vestibular migraine varies in the medical literature, but in general, it is episodic vertigo that occurs in someone with a history of migraines. The vertigo is usually associated with other common migraine symptoms (e.g. headache, photophobia, auras), but not always. The treatment of vestibular migraine is similar to other types of migraines with an emphasis on avoiding triggers and early preventive medications in people who have frequent attacks. See migraine headache for more.
- Head trauma and concussions - patients with head trauma/concussions may experience vertigo symptoms
- Medications with CNS activity - see central nervous system agents above
- Posterior fossa brain tumors [1,2,10]
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