Vertigo (from the Latin vertere, to turn, and the suffix -igo, a condition, i. e., "a condition of turning about") is a specific type of dizziness, a major symptom of a balance disorder. It is the sensation of spinning or swaying while the body is actually stationary with respect to the surroundings.
There are two types of vertigo: subjective and objective. There is a subjective vertigo when a person has a false sensation of movement. In the case of objective vertigo, the surroundings appear to move past a person's field of vision.
The effects of vertigo may be slight. It can cause nausea and vomiting and, in severe cases, it may give rise to difficulties with standing and walking.
Causes
Vertigo is usually associated with a problem in the inner ear balance mechanisms (vestibular system), in the brain, or with the nerve connections between these two organs.
Vertigo can be a symptom of an inner ear infection or of an underlying harmless cause. The most common cause of Vertigo is benign paroxysmal positional vertigo, or BPPV; however, vertigo can indicate the existence of more serious problems, including drug toxicities (specifically gentamicin), strokes or tumors (though these are much less common than BPPV), and syphilis.
Vertigo can also be a symptom of multiple sclerosis (MS). People with MS can feel off balance or lightheaded.
Vertigo can also be brought on suddenly through various actions or incidents, such as skull fractures or brain trauma, sudden changes of blood pressure, or as a symptom of motion sickness while sailing, riding amusement rides, aeroplanes or in a motor vehicle. Vertigo can also be caused by carbon monoxide poisoning. It is also one of the more common symptoms of superior canal dehiscence syndrome and Meniere's disease.
Vertigo-like symptoms may also appear as paraneoplastic syndrome (PNS) in the form of opsoclonus myoclonus syndrome, a multi-faceted neurological disorder associated with many forms of incipient cancer lesions or viruses.
Vertigo is typically classified into one of two categories depending on the location of the damaged vestibular pathway. These are peripheral or central vertigo. Each category has a distinct set of characteristics and associated findings.
Vertigo can also occur after long flights or boat journeys where the mind gets used to turbulence, resulting in a person's feeling as if he is moving up and down. This usually subsides after a few days.
Pathophysiology
The pathophysiology of vertigo includes 6 primary neurotransmitters that have been identified between the 3-neuron arc that drives the vestibulo-ocular reflex (VOR). Many others play more minor roles.
Three neurotransmitters that work peripherally and centrally include glutamate, acetylcholine, and GABA.
Glutamate maintains the resting discharge of the central vestibular neurons, and may modulate synaptic transmission in all 3 neurons of the VOR arc. Acetylcholine appears to function as an excitatory neurotransmitter in both the peripheral and central synapses. GABA is thought to be inhibitory for the commissures of the medial vestibular nucleus, the connections between the cerebellar Purkinje cells and the lateral vestibular nucleus, and the vertical VOR.
Three other neurotransmitters work centrally. Dopamine may accelerate vestibular compensation. Norepinephrine modulates the intensity of central reactions to vestibular stimulation and facilitates compensation. Histamine is present only centrally, but its role is unclear. It is known that centrally acting antihistamines modulate the symptoms of motion sickness.
The neurochemistry of emesis overlaps with the neurochemistry of motion sickness and vertigo. Acetylcholine, histamine, and dopamine are excitatory neurotransmitters, working centrally on the control of emesis. GABA inhibits central emesis reflexes. Serotonin is involved in central and peripheral control of emesis but has little influence on vertigo and motion sickness.
Diagnosis
Tests of vestibular system (balance) function include electronystagmography (ENG), rotation tests, Caloric reflex test, and Computerized Dynamic Posturography (CDP).
Tests of auditory system (hearing) function include pure-tone audiometry, speech audiometry, acoustic-reflex, electrocochleography (ECoG), otoacoustic emissions (OAE), and auditory brainstem response test (ABR; also known as BER, BSER, or BAER).
Other diagnostic tests include magnetic resonance imaging (MRI) and computerized axial tomography (CAT or CT).
Treatment
Treatment is specific for underlying disorder of vertigo:
- vestibular rehabilitation
- anticholinergics
- antihistamines
- benzodiazepines
- calcium channel antagonists, specifically Verapamil and Nimodipine
- GABA modulators, specifically gabapentin and baclofen
- neurotransmitter reuptake inhibitors such as SSRI's, SNRI's and tricyclics
- benign paroxysmal positional vertigo (BPPV), a special kind of vertigo, is treated with the Epley maneuver (performed by a doctor or physical therapist, or with a BPPV maneuver at home)
Benign Paroxysmal Positional Vertigo
BPPV is the most common form of vertigo in adult patients. Within the labyrinth of the inner ear lie collections of calcium crystals known as otoconia. In patients with BPPV, the otoconia are dislodged from their usual position within the utricle and they migrate over time into one of the semicircular canals (the posterior canal is most commonly affected due to its anatomical position). When the head is reoriented relative to gravity, the gravity-dependent movement of the heavier otoconial debris within the affected semicircular canal causes abnormal (pathological) fluid endolymph displacement and a resultant sensation of vertigo. This more common condition is known as canalithiasis.
In rare cases, the crystals themselves can adhere to a semicircular canal cupula rendering it heavier than the surrounding endolymph. Upon reorientation of the head relative to gravity, the cupula is weighted down by the dense particles thereby inducing an immediate and maintained excitation of semicircular canal afferents afferent nerve. This condition is termed cupulolithiasis.
Triggers may vary from person to person
- Changes in barometric pressure - patients often feel symptoms approximately two days before rain or snow
- Lack of sleep (required amount of sleep may vary widely)
- Visual exposure to nearby moving objects (examples - cars, snow)
- Tilting the head
- Differences between visual stimuli and the information received from the inner ear about one's location in space.
The primary symptom is the sudden onset of severe vertigo and nystagmus that occurs exclusively with head movement in the direction of the affected ear.
Patients often describe their first experience occurring while turning their head in bed.
The vertigo is brief in duration — 5 seconds to 30 seconds.
It is often associated with nausea.
Patients do not experience other neurological deficits such as numbness or weakness, and if these symptoms are present, a more concerning etiology such as posterior circulation stroke, must be considered.
The condition is diagnosed from patient history (feeling of vertigo with sudden changes in positions); and by performing the Dix-Hallpike maneuver which is diagnostic for the condition. The test involves a reorientation of the head to align the posterior canal (at its entrance to the ampulla) with the direction of gravity. This test stimulus is effective in provoking the symptoms in subjects suffering from archetypal BPPV. These symptoms are typically a short lived vertigo, and observed nystagmus. In some patients, the vertigo can persist for years.
The treatment of choice for this condition is the Epley canalith repositional maneuver which is effective in approximately 80% of patients. The treatment employs gravity to move the calcium build-up that causes the condition. The particle repositioning maneuver (Epley's maneuver) can be performed during a clinic visit by specially trained otolaryngologists, neurologists, chiropractors, physical therapists, or audiologists. The maneuver is relatively simple but few general health practitioners know how to perform it. A method known as the Semont maneuver in which patients themselves are able to achieve canalith repositioning has been shown to be effective.
Devices such as a head over heels "rotational chair" are available at some tertiary care centers Home devices, like the DizzyFIX, are also available for the treatment of BPPV and vertigo.
The Epley maneuver (particle repositioning) does not address the actual presence of the particles (otoconia), rather it changes their location. The maneuver moves these particles from areas in the inner ear which cause symptoms, such as vertigo, and repositions them into areas where they do not cause these problems.
Meclizine is a commonly prescribed medication, but is ultimately ineffective for this condition, other than masking the dizziness. Other sedative medications help mask the symptoms associated with BPPV but do not affect the disease process or resolution rate. Serc is available in some countries and is commonly prescribed but again it is likely ineffective. Particle repositioning remains the current gold standard treatment for most cases of BPPV.
Surgical treatments, such as a semi-circular canal occlusion, do exist for BPPV but carry the same risk as any neurosurgical procedure. Surgery is reserved for severe and persistent cases which fail particle repositioning and medical therapy.
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