Exam 1 Nerve Irritation vs Nerve Compression, Sensory LEs

5 components of Vertebral Subluxation Complex (VSC)

1. spinal kinesio-pathology

2. myopathology

3. histopathology

4. neuropathology

5. biomechanical changes

subluxation has ____________ as a component that contributes to S/S

nerve IRRITATION

what percent of the time is a subluxation a nerve irritation?

97% of the time

if a patient is experiencing nerve irritation what might they say? what would the sensory exam show?

"feels numb", but the sensory exam is WNL

what is the primary factor of nerve irritation?

EDEMA

-bathes the NR, irritating the tissue: prostaglandins, bradykinins, substance P, WBCs surround joint capsule

**edema does NOT compress the NR

a disc herniation at C4/C5 affects which NR?

C5 nerve root

hypertrophic changes of the uncinate processes of C5 will affect what NR?

C5 NR

hypertrophic changes of the T1 VB will affect which NR?

C8 NR

a patient with a documented anterior disc herniation that is not directly compressing the nerve root. could they still have neck pain? arm pain?

neck pain: even without direct, severe compression, a herniated disc causes localized neck pain due to tension in the annulus fibrosus, disc inflammation, or surrounding tissue irritation

arm pain: while classic radiculopathy arises from direct NR compression, arm pain can still occur via referred pain from the disc itself (chemical radiculitis) or irritation of nearby structures

*the pain is frequently a nociceptive response, where inflammation in the disc material, rather than just mechanical pressure, creates localized/radiating pain

if patient has unilateral dermatomal radiating pain, what should you suspect?

nerve root

if patient has unilateral multi-dermatomal radiating pain, what should you suspect?

plexus, peripheral nerve, or vascular

if patient has diffuse thigh pain that does NOT go beyond the knee, what should you suspect?

lumbar facet

if patient has radiating pain that goes beyond the knee and follows a dermatomal pattern, what should you suspect?

lumbar disc

if patient has pain 1" lateral to the L5 spinous process, what should you suspect?

L5 facet syndrome/irriation

myelopathy

dysfunction of the spinal cord

radiculopathy

dysfunction of a spinal nerve root

neuropathy

dysfunction of a peripheral nerve distal to the nerve root

myopathy

muscle abnormalities

dermatome

the area of skin innervated by cutaneous axons in the distribution of a single spinal nerve

myotome

refers to the muscle fibers innervated by the motor axons of a single spinal nerve

describe type A nerve fibers and characteristics of pain they carry

fast, lightly myelinated

acute, sharp, stinging sensation to nociceptive

usually localized

alerts to the presence of pain but does NOT contribute to the intensity of pain

describe type C nerve fibers and characteristics of pain they carry

slow, unmyelinated

aching, burning, lingering type of pain

usually diffuse

conduct information related to intensity of pain AND temperature

what are the three mechanistic types of pain?

1. nociceptive pain

2. neuropathic pain

3. nociplastic pain

nociceptive pain

pain arising from actual or threatened damage to non-neural tissue caused by activation of nociceptors

*pain from tissue injury and inflammation

key mediators of nociceptors

PGs, bradykinin, substance P, CGRP (calcitonin gene-related peptide), cytokines (IL-1, TNF-a)

what do the mediators of nociceptors do?

these chemicals lower nociceptor activation thresholds, producing peripheral sensitization

clinical examples of nociceptive pain

somatic pain: acute muscle sprain, ligament sprain, post-surgical pain, OA, inflammatory joint disease

radicular pain

visceral pain

neuropathic pain

pain caused by a lesion or disease of the somatosensory nervous system

*pain from nerve damage or disease

damage to peripheral or central nerves leads to

ectopic spontaneous firing

ion channel dysregulation

loss of inhibitory interneurons

central sensitization

clinical features of neuropathic pain

1. pain not necessarily proportional to injury

2. burning, electric shock-like, tingling

3. dermatomal or nerve distribution

4. may persist after healing

clinical examples of neuropathic pain

radiculopathy from disc herniation

diabetic neuropathy

post-herpetic neuralgia

carpal tunnel syndrome

trigeminal neuralgia

key pathophysiology of neuropathic pain

upregulation of voltage-gated sodium channels

microglial activation

NMDA receptor activation

increased glutatmate signaling

*these produce pathological neural firing independent of tissue injury

nociplastic pain

pain arising from altered nociception despite no clear evidence of tissue damage or nerve injury

*pain from central processing dysfunction

*CNS amplification of pain signals

-central sensitization

-reduced descending inhibition

-neuroimmune activation (microglia, astrocytes)

clinical examples of nociplastic pain

1. pain often disproportionate to injury

2. widespread, diffuse pain

3. fatigue, sleep, and mood problems

4. symptoms often persistent

-ex: persistent neck pain months after minor issues, central pain amplification despite healed tissues

-ex: fibromyalgia, chronic tension-type headache, chronic migraine, IBS, chronic non-specific low back pain

neurochemical changes in nociplastic pain

NMDA receptor activation

increased glutamate

reduced GABA inhibition

what is nociplastic pain often strongly influenced by?

stress, trauma, emotional factors, autonomic dysregulation

*the nervous system becomes hyper-responsive to normal input

pain vs nociception: which is subjective and which is objective?

pain = subjective

nociception = objective

define pain

the SUBJECTIVE, unpleasant, and often emotional experience that arises from processed neurological signals

-subjective, experiential, and highly influenced by biology, psychology, and social

**pain is biopsychosocial

pain example

Hurt back while playing basketball, now you can't work. You worry about social implications of not being able to work = increase intensity of pain

define nociception

the sensory detection and transmission of noxious (potentially damaging) stimuli

-objective, physiological, and measurable

-nociceptors detect a threat and send electrical signals up nerve fibers to the spinal cord and brain

nociception example

a pin pricks your finger, nociceptors fire and send signals to your CNS and you pull your hand away

*nociception is the transmission and modulation of noxious stimuli

which joint tissues are void of nociceptors?

articular cartilage

inner annulus of IVD

nucleus of IVD

synovial membranes

in a normal joint, the nociceptive system is?

INACTIVE

-to active the nociceptive fibers, you must first have a noxious stimuli (mechanical, thermal, or chemical)

nociceptive nerve endings are found within the annulus fibrosis. what does this mean?

annular tears can cause pain in the lower back, buttocks, SI region, and lower extremity

*this pain can occur WITHOUT nerve compression by a disc protrusion

disc protrusion that does not compress the nerve root directly can cause an inflammatory response and secondary radiculitis by?

chemically induced inflammatory neural pain leading to nerve irritation

what is the neuropathway for the patient to experience pain from a cervical disc bulge/herniation?

the sinuvertebral nerve (recurrent nerve of Luschka) conveys sensory fibers to the PLL, the dura, and the outer border of the annulus. sinuvertebral nerve re-enters the IVF, and innvervates the facet joints, the annulus fibrosus, the ligaments, and periosteum of the spinal canal, carrying pain and proprioception sensation

sensory deficit order of loss

lost 1st: light tough

sharp pain and temperature

lost last: vibration and position sense

when compression is removed, sensory is restored in

the OPPOSITE order

*light touch is first to go and last to return

always compare sensory ________ with the ________ side first

bilaterally, asymptomatic

with nerve irritation, the patient will say

they have sensory changes (ex: numbness) but the exam is WNL showing no sensory deficits

with nerve compression, the patient will say

they have sensory changes and the exam shows + paresthesia

paresthesia

abnormal sensations along dermatomes and described by the patient as: numbness, tingling, pins and needles, pain, prickling, aching, warmth (heat), cold, and burning

hyperesthesia

increased sensation to pain or other stimuli across dermatomal patterns

*typically seen with nerve IRRITATION, partial lesions, or secondary to healing

*typical in a chiro patient

hypoesthesia

diminished sensitivity to pain or other stimuli across dermatomal patterns

*typically seen with nerve root COMPRESSION

anesthesia

absence of sensation across dermatomal patterns

*typically seen with NR COMPRESSION

what is the MC cause of NR compression?

DISC

examples of space occupying lesions

1. disc

2. bone

3. tumor

4. ligament

5. muscle

6. hemorrhage

7. infection

if the patient does not feel the vibratory sensation equal from side to side, assume there is a deficit in the

posterior columns

if the patient does not feel the sensation at all, as in some neuropathies, you should

move up the leg to evaluate the extent of paresthesia and map it

if you find an area of hypo/hyperesthesia, then you need to determine ifit follows:

1. dermatome pattern

2. peripheral nerve pattern

3. lumbar/sacral plexus pattern

4. vascular insufficiency pattern

5. spinal stenosis

6. intermittent claudication

7. thrombophlebitis

8. visceral pain referral pattern

what is carried in the posterior columns?

position sense, vibration, pressure, texture, localization of touch, 2-pt discrimination, weight, and ability to decipher #s written on the skin

**lesions that affect these sensations while sparing light touch, pain, and temp are likely SPINAL CORD origin

for the most part, nociceptive (pain and temp) fibers travel along the lightly myelinated A delta fibers and unmyelinated C fibers of the __________

lateral spinothalamic tract

light touch is associated with which tract?

anterior spinothalamic

dermatomes with light touch deficits would indicate possible?

NR compression (along dermatomes) or possible peripheral nerve lesions (cross dermatomes)

if the pain is sharp with motion and constant, think

joint

if the pain is burning, sharp/lightning, tingling and/or numbness, think

nerve

if the pain is cramping/spasm or a dull ache with AROM and resisted PROM

muscle

if the pain is radiating dull or deep, heavy, boring, think

scleratogenous (facet, SI, disc)

if the pain is a dull ache/pain with PROM or a deep burning, think

bone/ligament

if the pain is pinpointed over paraspinal and has a crawling sensation, think

myofascial

if the pain is throbbing, think

vascular

if the pain is well localized, think

peripheral

if the pain is diffuse, think

central

if the pain is bilateral, think

CORD first

most common causes for radiculopathy include

disc herniation

synovial cyst

spinal stenosis

frequency of lumbar radiculopathy in men and women

men: 2-5%

women: 1-3%

*frequency peaks at age 44 for both sexes

why is venous congestion more common in the IVF?

because the radicular veins may be immediately compressed by reduction in foraminal diameter

-possibility of reflux from the segmental veins through pressure damaged valves

-venous congestion --> swelling within IVF --> contributes to compression of the other intra-foraminal structures, including the NR

where is circulation especially vulnerable to venous congestion?

dorsal root ganglia

why are nerve roots more vulnerable to mechanical effects than peripheral nerves?

location within the IVF makes NR vulnerable

NRs lack protection of epineurium and perineurium

NRS are dependent on a single radicular artery entering via the foramen, the margin of safety provided by collateral pathways is minimal

your patient has numbness and tingling down the right side of the neck and into the right shoulder traveling distally down into the middle finger. instrumentation break to the right at C6 with static and motion palpation fixation at C6. the sensory exam revealed a hypoesthesia to light touch and sharp pinprick along the right anterior lateral aspect of the forearm and the middle finger. what's the diagnosis?

SOL at C6 causing nerve root compression C7 on the right

thoracic spine landmarks

T4, T7, T10, T12

when the upper limb is by the side, the SP of T3 is level with the _____, and the T7 SP is level with the _____

spine of the scapula, inferior angle

T1 nerve root motor, sensory, and reflexes

motor: interosseous

sensory: hand, medial arm

reflexes: none

T2, T3, T4 motor, sensory, and reflexes

motor: intercostal

sensory: same as rib (nipple)

reflexes: none

T5, T6, T7 motor, sensory, and reflexes

motor: rectus abdominus superior

T5-T6 sensory: same as rib (epigastric)

T5-T6 reflexes: none

T7 sensory: same as rib (xiphoid)

T7 reflexes: superficial

T8-T10 motor, sensory, and reflexes

T8-T9 motor: rectus abdominus superior

T8-T9 sensory: same as rib (umbilicus)

T8-T10 reflexes: superficial (on abdomen)

T10 motor: rectus abdominus inferior

T10 sensory: umbilicus (follow around to back)

T11-T12 motor, sensory, and reflexes

T11-T12 motor: rectus abdominus inferior

T11 sensory: inferior abdomen (groin)

T12 sensory: pubic region (above pubic symphysis) (groin)

T11-T12 reflexes: superficial (abdomen)

what is a positive light touch thoracic sensory exam associated with?

anterior spinothalamic tract

what does a positive sharp touch thoracic sensory exam indicate?

hypo or hyperesthesia's nociceptive (pain and temp) fibers travel along the lightly myelinated A delta fibers and unmyelinated C fibers of the lateral spinothalamic tract

name two additional tests for a sensory exam of the thoracic spine

motor test of the same NR

DTR test of same NR

describe the LE dermatomes L1-S2

L1: inguinal

L2: anterior thigh (high)

L3: anterior thigh (low)

L4: anterior knee, medial lower leg, medial foot

L5: top of foot, anterior lateral lower leg

S1: lateral foot, lateral calf, posterior thigh

S2: posterior medial thigh, medial calf

what does a positive LE vibration sensory test indicate?

patient does NOT feel the vibratory sensation equal from side to side = assume there is a deficit of the posterior columns

2 additional tests for LE vibration sensory exam

sensory exam of LE, temperature and sharp/light touch

L4 herniated nucleus pulposus with compression

A. affects the medial aspect of the foot

B. affects the top of the foot

C. affects the lateral aspect of the foot

D. affects the anterior aspect of the thigh

B. affects the top of the foot

describe L5 posterior facet referral pain (scleratogenous referred pain)

dully achy unilateral pain found on active or passive extension

lateral to the SP of L5, radiates into posterior glute and thigh -- but NOT below the knee

what direction do lumbar discs most commonly herniate in?

posteriorly

known as: subarticular disc herniation or paracentral/lateral recess herniation

why is the exiting NR in the lumbars usually not involved in any herniations of the disc within its space?

exiting NR takes a 45 degree angle turn around the pedicle of its vertebra

-exiting NR almost never crosses the disc space below it and therefore is usually not involved

a lumbar NR is most commonly involved in herniations of the disc located ______ its point of exit

ABOVE

**traversing NR is most commonly affected in lumbars

3 locations of disc herniations in order of MC to least common

1. subarticular (MC)

2. foraminal/extraforaminal

3. central (rare)

which articulations have the greatest motion in the lumbar spine?

L4-L5 and L5-S1

**therefore, the incidence of herniated discs is greater at these areas than any other lumbar space