View source for Lightheadedness and vertigo pathophysiology

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{{Lightheadedness and vertigo}}
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==Overview==
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-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 virus. If conventional therapies fail, consult with a neuro-oncologist familiar with [[PNS]].

===Pathophysiology===
The neurochemistry of vertigo includes 6 primary [[neurotransmitter]]s 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 [[chemical synapse|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]].

==References==
{{Reflist|2}}
[[Category:Otolaryngology]]
[[Category:Neurology]]
[[Category:Signs and symptoms]]
[[Category:Emergency medicine]]
[[Category:Primary care]]
[[Category:Needs overview]]
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