NMS
5/12/99

Pain
•	Spinothalamic pathway
•	Free nerve endings—all pain fibers
•	Found throughout our system
•	Two types of pain patterns 
•	A—myelinated, small, rapid, found in the acute situation, go to the cortex, somatotopically discriminated (sharp, localized, burning), adapt rapidly, not found in the viscera, found in the extremity—lateral spinothalamic pathway, decussates quickly, enters through the dorsal horn
•	Dorsal horn divided into laminae (1-8)
•	Many stop at laminae 1 and give rise to second order neurons which decussates
•	Goes up the spinothalamic pathway to thalamus
•	3rd order neuron to cortex—thalamocortical pathway
•	leads to immediate response
•	C—chronic, go to the thalamus, does not go to the cortex, dull, deep, achy, poorly localized (spreading), do not adapt
•	The two types can usually be found in similar places throughout the body
•	stop at laminae 2 or 3
•	substania gelatinosa
•	inhibits pain perception in some pain patterns when stimulated
•	interneuron—inhibits the second order neuron and blocks the message
•	goes up anterior spinothalamic or spinoreticulothalamic
•	do not generally make it to the cortex
•	2nd order neurons
•	C fibers do not cause dermatome pain
•	Causes referred pain
•	Sclerotome—will see about 99% of the time (sclero—connective tissue, bone, tendon, cartilage)
•	Send collaterals into brain stem nuclei
•	Stimulate an area—reticular formation
•	Reticular activation system—when activated makes you wake up
•	People w/dull, deep pain have a hard time sleeping
•	Limbic area—found in the brain stem near the reticular formation
•	Emotional area
•	Constant stimulation makes the person very emotional
•	Controlled by the cortex
•	Mechanoreceptors—found in muscle, tendon, ligament, joints
•	Pancinian
•	Muscle spindles
•	Golgi tendons
•	ruffini
•	Tear a ligament is a sprain
•	Substantia gelatinosa
•	Inhibits the transmission from the 2nd order neurons of C fibers
•	Stimulated by proprioception

Propioception
1.	dorsal column—highest level, high discrimination, "which way is your finger pointing" to test—we are only aware what this level is doing (unaware of the other two areas)
•	discrimination—kinesthesia (loss of conscious proprioception)
2.	spinocerebellar—goes up to cerebellum, help body coordinate muscular activity
•	difficult to explain
•	romberg test—rapid alternating motion
•	have pt stand w/feet slightly apart
•	close the eyes
•	hold hands out in front of them
•	look to see if pt sways 
•	differentiate cord from cerebellum
•	(+)  =  increase ataxia w/eyes closes = lesion in the cord
•	if loss the cerebellum one would be in a wheelchair—can't coordinate activity
3.	deep tendon—safety pin cycle—at cord level reflex, doesn't go up to the brain
•	annulospiral—sends info into the cord, wraps around

Gate Theory
•	motion and stimulation of these structures blocks some pain—segmentally related
•	strain suprospinatus—deep dull achy pain, fixation at C5/C6, adjust and the pain in the shoulder is less

Endorphins and enkephlains—non-segmental, can block any where in the body

•	fixated areas decrease proprioception
•	adjustment helps by restoring proprioception to the area (breaks the cycle)—somatosomatic reflex
•	this activates the interneurons which can help block some of the pain 
•	over the counter meds are affective in treating C fiber pain—these block substance P