Vertigo

Vertigo is classified into either peripheral or central depending on the location of the dysfunction of the vestibular pathway, although it can also be caused by psychological factors. Vertigo can also be classified into objective, subjective, and pseudovertigo. Objective vertigo describes when the person has the sensation that stationary objects in the environment are moving. Subjective vertigo refers to when the person feels as if they are moving. Peripheral Vertigo that is caused by problems with the inner ear or vestibular system, which is composed of the semicircular canals, the vestibule (utricle and saccule), and the vestibular nerve is called "peripheral", "otologic", or "vestibular" vertigo. The most common cause is benign paroxysmal positional vertigo (BPPV), which accounts for 32% of all peripheral vertigo. Any cause of inflammation such as common cold, influenza, and bacterial infections may cause transient vertigo if it involves the inner ear, as may chemical insults (e.g., aminoglycosides) or physical trauma (e.g., skull fractures). Motion sickness is sometimes classified as a cause of peripheral vertigo. People with peripheral vertigo typically present with mild to moderate imbalance, nausea, vomiting, hearing loss, tinnitus, fullness, and pain in the ear. Central vertigo may have accompanying neurologic deficits (such as slurred speech and double vision), and pathologic nystagmus (which is pure vertical/torsional). cervical spine disorders such as cervical spondylosis, degenerative ataxia disorders, migraine headaches, lateral medullary syndrome, Chiari malformation, multiple sclerosis, parkinsonism, as well as cerebral dysfunction. Central vertigo may not improve or may do so more slowly than vertigo caused by disturbance to peripheral structures. Alcohol can result in positional alcohol nystagmus (PAN). ==Signs and symptoms==

Vertigo is a sensation of spinning while stationary. It is commonly associated with nausea or vomiting, falls, changes to a person's thoughts, and difficulties in walking. Recurrent episodes in those with vertigo are common and frequently impair the quality of life. Persistent onset vertigo is characterized by symptoms lasting for longer than one day Additionally, there is a degeneration of the ampulla and otolith organs with an increase in age. Persistent onset is commonly paired with central vertigo signs and symptoms. The characteristics of an episodic onset vertigo are indicated by symptoms lasting for a smaller, more memorable amount of time, typically lasting for only seconds to minutes. ==Genetics==

A large meta-analysis of genome-wide association study (GWAS) associated six genes with vertigo and implicated the proteins they encode in the biology of the inner ear. ==Pathophysiology==

The neurochemistry of vertigo includes six primary neurotransmitters that have been identified between the three-neuron arc that drives the vestibulo-ocular reflex (VOR). Glutamate maintains the resting discharge of the central vestibular neurons and may modulate synaptic transmission in all three neurons of the VOR arc. Acetylcholine appears to function as an excitatory neurotransmitter in both the peripheral and central synapses. Gamma-Aminobutyric acid (GABA) is thought to be inhibitory for the commissures of the medial vestibular nucleus, the connections among the cerebellar Purkinje cells, 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. Dopamine, histamine, serotonin, and acetylcholine are neurotransmitters thought to produce vomiting. ==Diagnosis==

Tests for vertigo often attempt to elicit nystagmus and to differentiate vertigo from other causes of dizziness such as presyncope, hyperventilation syndrome, disequilibrium, or psychiatric causes of lightheadedness. and computerized dynamic posturography (CDP). The HINTS test, which is a combination of three physical examination tests that may be performed by physicians at the bedside, has been deemed helpful in differentiating between central and peripheral causes of vertigo. The HINTS test involves the horizontal head impulse test, observation of nystagmus on primary gaze, and the test of skew. CT scans or MRIs are sometimes used by physicians when diagnosing vertigo. Benign paroxysmal positional vertigo Benign paroxysmal positional vertigo (BPPV) is the most common vestibular disorder This is the most common cause of vertigo. Ménière's disease Ménière's disease is an inner ear disorder of unknown origin, but is thought to be caused by an increase in the amount of endolymphatic fluid present in the inner ear (endolymphatic hydrops). As the disease worsens, hearing loss will progress. Vestibular neuritis Vestibular neuritis presents with severe vertigo Individuals with vestibular neuritis do not typically have auditory symptoms, but may experience a sensation of aural fullness or tinnitus. however, one hypothesized cause is that the stimulation of the trigeminal nerve leads to nystagmus in individuals with migraines. Decompression sickness Vertigo is recorded as a symptom of decompression sickness in 5.3% of cases by the U.S. Navy as reported by Powell, 2008 For example, after using a very helium-rich trimix at the deepest part of the dive, a diver will switch to mixtures containing progressively less helium and more oxygen and nitrogen during the ascent. Nitrogen diffuses into tissues 2.65 times slower than helium, but is about 4.5 times more soluble. Switching between gas mixtures that have very different fractions of nitrogen and helium can result in "fast" tissues (those tissues that have a good blood supply) increasing their total inert gas loading. This is often found to provoke inner ear decompression sickness, as the ear seems particularly sensitive to this effect. Stroke A stroke (either ischemic or hemorrhagic) involving the posterior fossa is a cause of central vertigo. ==Management==

Definitive treatment depends on the underlying cause of vertigo. Common drug treatment options for vertigo may include the following: • Anticholinergics such as hyoscine hydrobromide (scopolamine) • Anticonvulsants such as topiramate or valproic acid for vestibular migraines • Antihistamines such as betahistine, dimenhydrinate, or meclizine, which may have antiemetic properties • Beta blockers such as metoprolol for vestibular migraine • Corticosteroids such as methylprednisolone for inflammatory conditions such as vestibular neuritis or dexamethasone as a second-line agent for Ménière's disease All cases of decompression sickness should be treated initially with 100% oxygen until hyperbaric oxygen therapy (100% oxygen delivered in a high-pressure chamber) can be provided. Several treatments may be necessary, and treatment will generally be repeated until either all symptoms resolve, or no further improvement is apparent. ==Etymology==

Vertigo is from the Latin word, vertō, which means "a whirling or spinning movement". ==See also==