Vertigo, Why it makes you feel dizzy.............
Vertigo (from the Latin vertō "a whirling or spinning movement" is a type of dizziness, where there is a feeling of motion when one is stationary. The symptoms are due to a dysfunction of the vestibular system in the inner ear. It is often associated with nausea and vomiting as well as difficulties standing or walking.
The most common causes are benign paroxysmal positional vertigo and vestibular migraine while less common causes include Ménière's disease and vestibular neuritis. Excessive consumption of ethanol (alcoholic beverages) can also cause notorious symptoms of vertigo. (For more information see Short term effects of alcohol). Repetitive spinning, as in familiar childhood games, can induce short-lived vertigo by disrupting the inertia of the fluid in the vestibular system.
Vertigo is classified into either peripheral or central depending on the location of the dysfunction of the vestibular pathway.
Vertigo caused by problems with the inner ear or vestibular system is called "peripheral", "otologic" or "vestibular". The most common cause is benign paroxysmal positional vertigo (BPPV) but other causes include Ménière's disease, superior canal dehiscence syndrome, labyrinthitis and visual vertigo.
Any cause of inflammation such as common cold, influenza, and bacterial infections may cause transient vertigo if they involve 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.
If vertigo arises from the balance centers of the brain, it is usually milder, and has accompanying neurologic deficits, such as slurred speech, double vision or pathologic nystagmus. Brain pathology can cause a sensation of disequilibrium which is an off-balance sensation.
A number of conditions that involve the central nervous system may lead to vertigo including: migraine headaches, lateral medullar syndrome, multiple sclerosis.
Signs and symptoms
Vertigo is a sensation of spinning while stationary. It is commonly associated with vomiting or nausea, unsteadiness, and excessive perspiration. Recurrent episodes in those with vertigo are common and they frequently impair the quality of life. Blurred vision, difficulty speaking, a lowered level of consciousness, and hearing loss may also occur. Central nervous system disorders may lead to permanent symptoms.
A number of specific conditions can cause vertigo, most commonly caused by prolonged consumption of aspartame. In the elderly however the condition is often multifactorial.
Benign paroxysmal positional vertigo
Benign paroxysmal positional vertigo (BPPV) is brief periods of vertigo ( less than one minute ) which occur with change in position. It is the most common cause of vertigo. It occurs in 0.6% of the population yearly with 10% having an attack during their lifetime. It is believed to be due to a mechanical malfunction of the inner ear. BPPV can be effectively treated with repositioning movements.
Vestibular migraine is the association of vertigo and migraines. It is the second most frequent cause of recurrent vertigo with a lifetime occurrence rate of about 1%.
Ménière's disease frequently presents with vertigo in combination with ringing in the ears, a feeling of pressure or fullness, severe nausea or vomiting, and hearing loss. As the disease worsens, hearing loss will progress.
Vestibular neuritis presented with severe vertigo. It is believed to be caused by a viral infection of the inner ear. Persisting balance problems may remain in 30% of people affected.
Motion sickness is one of the biggest symptoms of vertigo and it develops most often in persons with inner ear problems. The feeling of dizziness and lightheadedness is often accompanied by nystagmus. This is when the eyes rapidly jerk to one side and then slowly find their way back to the original position. During a single episode of vertigo, this action will occur repeatedly. Symptoms can fade while sitting still with the eyes closed.
The neurochemistry of vertigo includes 6 primary neurotransmitters that have been identified between the 3-neuron arcs that drive 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 commissars of the medial vestibular nucleus, the connections between the cerebella 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.
BPPV is normally diagnosed with the Dix-Hallpike test . 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).
Definitive treatment depends on the underlying cause of the vertigo.benign paroxysmal positional vertigo (BPPV) is treated with the Epley maneuver (performed by a doctor or physical therapist, or with a BPPV maneuver at home). See its Treatment descriptions.anticholinergics, antihistamines
About 5% of the population has vertigo at some point during the year and 7.4% are affected at
some point in their lives. It accounts for about 2-3 % of emergency department visits. It occurs about two to three times more frequently in women than in men and in the elderly as opposed to younger people.
^ "Definition of vertigo". Merriam-Webster Online Dictionary. Retrieved 2007-09-19.^ a b c d e f g h i j k l m n o p Neuhauser HK, Lempert T (November 2009). "Vertigo:
epidemiologic aspects". Semin Neurol 29 (5): 473–81. doi:10.1055/s-0029-1241043. PMID 19834858.^ "Chapter 14: Evaluation of the Dizzy Patient". Retrieved 2009-08-06.^ Guerraz, M. (2001). "Visual vertigo: symptom assessment, spatial orientation and postural
control". Brain 124 (8): 1646–1656. doi:10.1093/brain/124.8.1646.^ "Vertigo: Dizziness and Vertigo: Merck Manual Home Edition".^ Froehling, David A.; Marc D. Silverstein, David N. Mohr, Charles W. Beatty (1994-02-02).
"Does This Dizzy Patient Have a Serious Form of Vertigo?". JAMA: The Journal of the American
Medical Association 271 (5): 385 -388. doi:10.1001/jama.1994.03510290067039. Retrieved
2011-01-22.^ "Core Curriculum: Inner Ear Disease — Vertigo". Baylor College of Medicine. 2006-01-23.
Archived from the original on 2007-06-30. Retrieved 2007-09-19.