Vertigo (medical)

Vertigo, a specific type of dizziness, is a major symptom of a balance disorder. It is the sensation of spinning or swaying while the body is stationary with respect to the earth or surroundings. With the eyes shut, there will be a sensation that the body is in movement, called subjective vertigo; if the eyes are open, the surroundings will appear to move past the field of vision, called objective vertigo.

The effects of vertigo may be slight. It can cause nausea and vomiting or, if severe, may give rise to difficulty with standing and walking.

The word "vertigo" comes from the Latin "vertere", to turn + the suffix "-igo", a condition = a condition of turning about.

Causes of Vertigo
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.

The most common cause of vertigo is benign paroxysmal positional vertigo, or BPPV. Vertigo can be a symptom of an underlying harmless cause, such as in BPPV or it can suggest more serious problems. These include drug toxicities (specifically gentamicin), strokes or tumors (though these are much less common than BPPV).

Vertigo can also be brought on suddenly through various actions or incidents, such as skull fractures or or brain trauma, sudden changes of blood pressure, or as a symptom of motion sickness while sailing, riding amusement rides or in a vehicle.

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.

Peripheral vertigo
The lesions, or the damaged areas, affect the inner ear or the vestibular division of the auditory nerve or (Cranial VIII nerve). Vertigo that is peripheral in origin tends to be felt as more severe than central vertigo, intermittent in timing, always associated with nystagmus in the horizontal plane and occasionally hearing loss or tinnitus (ringing of the ears).

Peripheral vertigo can be caused by BPPV, labyrinthitis, Ménière's disease, perilymphatic fistula or acute vestibular neuronitis. Peripheral vertigo, compared to the central type, though subjectively felt as more severe, is usually from a less serious cause.

Central vertigo
The lesions in central vertigo involve the brainstem vestibular nerve nuclei. Central vertigo is typically described as constant in timing, less severe in nature and occasionally with nystagmus that can be multi-directional. Associated symptoms include motor or sensory deficits, dysarthria (slurred speech) or ataxia.

Causes include things such as migraines, multiple sclerosis, posterior fossa tumors, and Arnold-Chiari malformation. Less commonly, strokes (specifically posterior circulation stroke), seizures, trauma (such as concussion) or infections can cause also central vertigo.

Vertigo in context with the cervical spine
In some cases ligamental injuries of the upper cervical spine result in head-neck-joint instabilities which can cause vertigo. Instabilities of the head neck joint are affected by rupture or overstretching of the alar ligaments and/or capsule structures mostly caused by whiplash or similar biomechanical movements. If patients describe prolonged vertigo after a whiplash trauma, professionals should think about ligamental damage of head-neck-joint structures.

Symptoms during damaged alar ligaments besides vertigo often are
 * dizziness
 * reduced vigilance, such as somnolence
 * seeing problems, such as seeing "stars", tunnel views or double contures.
 * Some patients tell about unreal feelings that stands in correlation with:
 * depersonalization and attentual alterations

Many medical professionals don't know about the disease complex of head-neck-joint instabilities. Often the patients are having an odyssey of medical consultations without any clear diagnosis and are then sent to psychiatrist because doctors think about depression or hypochondria. Standard imaging technologies such as CT Scan or MRI are not capable of finding instabilities without taking functional poses.


 * The multitude of problems occurring after whiplash injury

Neurochemistry of Vertigo
The neurochemistry 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. Acetylcholinc, 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.

Diagnostic Testing
Tests of vestibular system (balance) function include electronystagmography (ENG), rotation tests, Computerized Dynamic Posturography (CDP), and Caloric reflex test. 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