Coma

=Objectives=

Understand the spectrum of consciousness

 * coma (comatose state)
 * "a state of unarousable unresponsiveness in which the eyes remain continuously closed and there is no understandable response to environmental or intrinsic stimulation"
 * "a deep sleeplike state from which the patient cannot be aroused"
 * arbitrarily defined as lasting at least an hour


 * vegetative state
 * signifies an awake but unresponsive state. Eyelids may be open, yawning, coughing, swallowing and limb movements may persist, but there are no meaningful responses to the external environment.


 * minimally conscious state
 * closely related to vegetative state, though a patient may make rudimentary vocal or motor reponses
 * "a condition of severely altered consciousness in which minimal but definite behavioral evidence of self or environmental awareness is demonstrated"
 * may gesture, reach for objects they see, eye movements in response to stimuli, etc.


 * persistent vegetative state
 * a vegetative state that has persisted for more than a few months (3+ months following non-traumatic injury, 12 months following traumatic injury. very poor prognosis.


 * locked-in-state
 * a type of pseudocoma in which an awake patient has no means of producing speech or volitional movement but retains voluntary vertical eye movements and has a clear, functioning mind
 * associated with ALS, Guillian-Barre, pharmacological neuromuscular blocade or infarction of the ventral ponds (transects descending corticospinal and corticobulbar pathways)
 * See The Diving Bell and the Butterfly for a popular culture case study


 * akinetic state
 * a partially or fully awake state in which the patient is able to form impressions and think but is immobile and mute


 * non-convulsive status epilepticus
 * a neurological emergency that can present as a pseudocoma. The patient is unresponsive due a continuous generalized electrical discharges of status epilepticus without myoclonus.
 * may have nystagmus, subtle limb twitching, will respond to antiepileptic medications (lorazepam)

Name the areas of the brain where focal pathologies can alter the degree of consciousness.

 * 1) Reticular Activating system (RAS): The RAS in the pons and midbrain is associated with coma.  A variety of mechanism encroach up on RAS function.
 * 2) Cerebral cortex: Large bilateral lesions of the cortex is required to produce coma.
 * 3) Basilar artery occlusion: Can produce a locked-in syndrome or comatose state
 * 4) Pontine Hemorrhage

Describe how breathing patterns and eye movement/pupillary disturbances associated with specific lesions
=References= 

=Links=
 * The Diving Bell and the Butterfly, an award winning movie about a man in a locked in state.