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Pain
"The fifth Vital Sign"
Two pathological pathways:
1. nociceptive
2. neuropathic
Pain originates from the CNS or PNS. Nociceptors are nerve endings that detect pain in the periphery and transmit it to the CNS. These nerve endings are located in skin, joints, connective tissue, muscle, thoracic, abdominal and pelvic viscera.
Nociceptors carry the pain signal to the CNS via afferent nerve fibers, A delta and C fibers.
Nociception is divided into 4 phases: transduction, transmission, perception, and modulation. As tissue is injured initially it releases chemicals called substance P, histamine, prostaglandins, serotonin, and bradykinin. The fourth phases, modulation, stops the pain from continuing forever. More chemicals are released from the descending pathway from the brainstem to the spinal cord producing an analgesic effect. neurotransmitters include serotonin, norepinephrine, neurotensn, GABA, and endogenous opioids (B-endorphins, enkephalins, and dynorphins).
Neuropathic pain does not follow the of nociceptive pain. It is pain caused by a lesion or disease of the somatosensory nervous system. Conditions that may cause neuropathic include DM, herpes zoster, HIV/AIDS, sciatica, trigeminal neuralgia, phantom limb pain, and chemotherapy. CNS lesions such as stroke, MS, and tumors are also examples.
Sources of Pain:
1. somatic- MS tissues or body surface
2. Deep somatic- blood vessels, joints, tendons, muscles, and bone. described as aching, throbbing.
3. cutaneous- skin surface, subcutaneous tissue. described as superficial, sharp, or burning.
4. referred pain- pain felt at a certain site, but originates elsewhere. ex: inflamed appendix in RLQ of abd but can be felt in periumbilical area or pain from ACS may be felt in left arm or neck
Types of pain:
1. acute
2. chronic - greater than 6 mo.
3. breakthrough pain- transient spikes
Complex Regional Pain Syndrome (CRPS) or Reflexive Sympathetic Dystrophy (RSD)
chronic progressive nerve condition, characterized by burning, swelling, stiffness, and discoloration of affected extremity.
it occurs weeks to months after a nerve injury.
key feature is that a typically innocuous stimulus such as a light brush of cotton ball or clothing can cause a severe, intense, painful response.
Reference:Jarvis, C. (2016). Physical Examination and Health Assessment. (7th ed.)
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Cranial Nerves
I. olfactory
Sensory: sense of smell
II. Optic
Sensory: vision testing and visual fields
Sensory: Pupillary light reflex
Exam: use ophthalmoscope to examine fundus and optic disc.
III. Oculomotor
Sensory: pupillary constriction of light reflex
Motor: opening of eye lid, & extra ocular movements (superior, inferior, medial rectus, and inferior obliques)
Extraocular Muscles = 6 muscles attach the eyeball to its orbit. Movement by EOMs are innervated by CN III, IV, and VI.
When one eye is exposed to bright light, a direct light reflex (constriction of that pupil) and a consensual light reflex (simultaneous constriction of the other pupil) occurs.
IV. Trochlear
Motor: Innervates superior oblique muscle causing downward, internal rotation of the eye
V. Trigeminal
Motor - temporal and masseter muscles (jaw clenching), and lateral pterygoids (lateral jaw movement).
Sensory- carries afferent sensation into the brain. sensation of face and scalp, cornea, mm of mouth and nose. test corneal reflexes with wisp of cotton
VI. Abducens
Motor: lateral rectus muscle of the eye, which abducts the eye.
VII. Facial
Motor- facial expression, closing eye, closing mouth.
Test: smile, frown, close eyes, lift eyebrows, puff cheeks,
Sensory- taste for salty, sweet, sour, bitter on anterior 2/3 of tongue.
VIII. Acoustic
Sensory: hearing (cochlear) and balance (vestibular)
IX. glossopharyngeal
Motor-pharynx (phonation and swallowing)
Test: uvula midline
Sensory- taste on posterior 1/3 tongue, gag reflex
X. Vagus
Motor: pharynx and larynx (talking and swallowing)
Sensory:
XI. Spinal Accessory
Motor- sternomastoid and trapezius. turning face and shrugging shoulders
XII. Hypoglossal
Motor- sticking tongue out.
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Neurological System
I. CN - see CN note cards
II. CNS Anatomy
1. Cerebral cortex - outer layer of nerve cell bodies. called "gray matter" bc it lacks myelin. Myelin is the white insulation on the axon that increases the conduction velocity of nerve impulses. Each half of the cerebrum is called a hemisphere. The left side is dominant in most people, including those who are left handed. Each hemisphere is divided into 4 lobes: frontal, parietal, temporal, and occipital.
Frontal: personality, behavior, emotions, and intellect. Broca's area mediates motor speech. Expressive aphasia occurs and pt. can't talk. The person knows what they want to say, but can't get it out.
Parietal: postcentral gyrus is the primary center for sensation.
Occipital: vision
Temporal: auditory reception center, hearing, taste, and smell. Wernicke's area in temporal lobe is associated with language comprehension. Receptive aphasia occurs if this area is affected. The person hears sound, but it has no meaning.
2. Basal Ganglia
Deep gray matter in both hemispheres that forms the extrapyramidal system also called subcortical associated motor system. Initiates and coordinate movement and automatic movements of the body such as arm swinging with legs during walking.
3. Thalamus
Relay station where sensory pathways of spinal cord, cerebellum, basal ganglia, and brainstem from synapses on their way to cerebral cortex. Human emotion and creativity.
4. Hypothalamus
Respiratory center with vital functions such as temperature, appetite, sex drive, heart rate, and blood pressure; sleep center; pituitary gland regulator; and coordinator of ANS activity and stress response.
5. Cerebellum
located under the occipital lobe. Concerned with motor coordination of voluntary movements, equilibrium, and muscle tone. Doesn't initiate, but does coordinate muscles needed for piano, swimming, juggling.
6. Brainstem
Central core of brain. CN 3-12 originate here. Three parts: Midbrain, Pons, and Medulla.
7. Spinal Cord
Long, cylindric structure of nervous tissue located in vertebral canal from medulla to lumbar L1-L2. White matter bundles of myelinated axons. Mediates reflexes of posture control, unrination, and pain. Its nerve cell bodies or gray matter are butterfly shape with ant. and post. horns.
II. Peripheral Nervous System
A nerve is a bundle of fibers located outside the CNS. The peripheral nerves carry the impulses to the CNS via afferent fibers and deliver output from CNS via efferent fibers.
Reflexes
Basic defense mechanism of the nervous system. involuntary. Help to maintain balance and muscle tone and warn against pain or damage.
4 types: Deep tendon, superficial, visceral, and pathologic.
Spinal Nerves
31 pairs of spinal nerves
Dermal segmentation is the cutaneous distribution of the various spinal nerves.
A dermatome is an area of skin that is supplies by one spinal cord segment via a specific spinal nerve.
Useful Dermatome Landmarks:
*C6, C7, and C8 = thumb, middle finger, and fifth finger
*T1 = axilla
*T4 = nipple
*T10 = umbilicus
*L1 = groin
*L4 = knee
I. Cerebellar Function
A. Coordination and Skilled Movements
1. Rapid Alternating Movements (RAM)
Pt pats knees while flipping hands to front and back and does it faster as they go. A normal exam is done with equal turning and a quick, rhythmic pace.
A second RAM test includes the pt. touching the thumb to each finger on the same hand starting with index and then reversing. Normal exam can be done quickly and accurately.
2. Finger to Finger test
pt. has eyes open and touches index finger to your finger and his or her own nose, while you move your finger.
3. Finger to Nose
pt. closes eyes and stretches out arms. then touches the tip of his or her nose with index finger alternating hands.
4. Heel to shin
pt. is supine. place heel on opposite knee and run it down the shin from the knee to the ankle. should be able to move heel in a straight line down the shin.
B. Balance Tests
1. Gait
observe walking 10-20 feet.
2. Tandem Walking
heel to to walking in a straight line.
3. Romberg Test
pt. stands with feet together and arms at sides. closes eyes. holds for 20 seconds.
4. knee bend or hop
ask patient to stand with feet together and arms at side. then get pt. to bend one knee or hop in place.
II. Sensory Testing
Compare symmetric parts of the body.
You do not need to test the entire skin surface.
Draw results on a diagram.
Spinothalamic Tract
1. Pain
test for sharp and dull sensations with tongue blade or pin. Ask the pt. can they feel anything, then ask if it is dull or sharp.
2. Light touch
use a wisp of cotton and brush it over different sites including arms, forearms, hands, chest, thighs, and legs.
Posterior (dorsal) column tract
1. vibration
use tunning fork over bony prominences. strike tunning fork on your hand and hold the base on a body prominence of finger or great toe. pt. should be able to say when vibration starts and stops. If the lower parts are normal stop exam, if not, move proximally and test ulnar processes and ankles, patellae, and iliac crest. compare right and left side.
2. position (kinesthesia)
pt. closes eyes. You move finger or toe and ask pt. to tell you which way it is moved, up or down.
3. Tactile discrimination (fine touch)
4. Stereognosis
recognize objects by feeling with eyes closed. use paper clip, coin, etc.
5. Graphesthesia
ability to read a number that is traced on the skin with eyes closed.
6. Two-point discrimination
tests ability to determine two pin points on skin. finger is usually 2-8 mm.
7. Extinction
simultaneously touch both sides of body at the same point and ask person how many sensations are felt and where they are.
8. Point Location
touch the skin quickly and then remove hand. get pt. to point to where you were touching. You could do this test with light touch at the same time.
Reflexes
compare right and left side. responses should be equal. graded on a 4 point scale. This is a subjective test.
4+ = hyperactive
3+ = brisk
2+ = normal
1+ = diminished
0 = absent
Biceps (C5 to C6)
support pt. arm
place thumb on biceps tendon
strike hammer on your thumb
Triceps (C7 to C8)
suspend arm by holding
pt. needs to relax
strike triceps tendon above elbow
arm should extend
Brachioradialis (C5 to C6)
hold thumb and suspend forearms to relax
strike above the wrist
normal is flexion and supination of FA
Quadriceps (L2 to L4)
lower leg dangles
strike tendon directly below the patella
Achilles (L5 to S2)
knee flexed and hip externally rotated
hold food in dorsiflexion
strike achilles
foot should plantar flex against hand
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