Nerve entrapment

classifications of acute nerve injuries

• neurapraxia

• axonotmesis

• neurotmesis

define neuropraxia

a temporary loss of motor and sensory function due to blockage of nerve conduction

What is considered a mild form of nerve injury

neurapraxia

what is damaged in neurapraxia

myelin sheath

symptoms of neurapraxia

pain

minimal atrophy

numbness or greater loss of motor and sensory function

diminished proprioception

when does recovery occur for neurapraxia

4-6 weeks

define axonotmesis

reversible injury to damaged fibers since they maintain anatomical relationship to each other

Where is the damage for axonotmesis

axons and myelin sheath

What classification of nerve injury is associated with Distal Wallerian degeneration

neurotmesis and potentially axonotmesis

when does recovery occur for axontmesis

1mm/day

define wallerian degeneration

degeneration that occurs distally, specifically to the myelin sheath and axon

define neurotmesis

irreversible injury due to severing of the nerve and nerve sheath

What categories of nerve injuries require surgery for repair

axonotmesis and neurotmesis

What subjective questioning triggers thinking of nerve injury

burning pain, numbness, tingling

parts of the neuroscreen

dermatomes

myotomes

reflexes

parts of the dermatome screening

light touch and pinprick

parts of the myotome screening

strong and weak

parts of the reflexes screening

hypo/hyper and normal

draw the dermatomes for nerve roots

draw the dermatomes for peripheral nn

step 1 of neuroscreen algorithum

reflexes

step 2 of neuroscreen algorithum

dermatomes

step 3 of neuroscreen algorithum

myotomes

what pathology is considered when reflexes are abnormal on the neuroscreen algoithum

central

hyperreflexia indicates…

UMN lesion

hyporeflexia indicates…

LMN lesion

what pathology is considered when entire dermatome is abnormal on the neuroscreen algoithum

central

what pathology is considered when patchy distribution of dermatomes is abnormal on the neuroscreen algoithum

peripheral

what pathology is considered when myotome is weak on the neuroscreen algoithum

central

what pathology is considered when myotome is strong on the neuroscreen algoithum

peripheral

what muscle is chosen for myotome testing for neuroscreen algorithum

another muscle along same central level, but different peripheral nerve

how do we differentiate brachial plexus vs cervical spine

screening the neck

Dx classifications for plexus injuries

• peripheral mononeuropathy

• peripheral polyneuropathy

• spinal roots and nerves

common name for peripheral mononeuropathy

single nerve entrapment

common name for peripheral polyneuropathy

brachial plexus/thoracic outlet

What type of injury would a spinal roots and nerve classification be

cervical radiculopathy

peripheral mononeuropathy effects on sensory

loss along the nerve route

peripheral mononeuropathy effects on motor

weakness and atrophy in a peripheral distribution

• may have fasciculations

peripheral polyneuropathy effects on sensory

“stocking glove” distribution

peripheral polyneuropathy effects on motor

weakness and atrophy (weaker distally)

may have fasciculations

peripheral polyneuropathy effects on reflexes

decreased

spinal roots and nerve injury effects on sensory

dermatomal deficits

spinal roots and nerve injury effects on motor

weakness in an innervated pattern

• may have fasciculations

spinal roots and nerve injury effects on reflexes

decreased

what is the most common UE nerve injured

axillary

What may cause an Axillary n injury

fx of humeral neck

anterior dislocation of the shoulder

use of crutches

What may cause an Musculocutaneous n injury

fx of the clavicle

What may cause a Radial n injury

compression of radial tunnel

fx of humerus

What may cause a Median n injury

compression in carpal tunnel

pronator teres entrapment

What may cause an Ulnar n injury

compression in cubital tunnel

entrapment in Guyon’s canal

What objective assessment tools can we use to correlate dx

clinical electromyography (EMG)

nerve conduction velocity (NCV)

purpose of EMG

evaluate the score of a neuromuscular disorder through assessment of muscle activity/recruitment

purpose of NCV

determines the speed with which a peripheral motor or sensory n conducts an impulse

process of EMG

1. needle electrode inserted into muscle

2. patient contacts and relaxes muscle

3. needle records muscle activity during rest and movement

general abnormal reading for EMG

spontaneous potentials when at rest

decrease/same size action potential with increase in strength of contraction

Spontaneous Abnormal findings on EMG

fibrillation potentials

positive sharp wave

fasciculation

repetitive discharges

what do fibrillation potentials indicate on EMG

LMN disease

what do positive sharp wave indicate on EMG

denervated muscle disorder at rest

primary muscle disease such as muscular dystrophy

what do fasciculations indicate on EMG

irritation/degeneration of anterior horn cell, nerve root compression, or muscle spasm

what do repetitive discharcges indicate on EMG

myopathies, lesion of anterior horn cells, and peripheral nerves

Voluntary abnormal findings for EMG

polyphasic potentials

what do polyphasic potentials indicate on EMG

myopathies, muscle or peripheral nerve involvement

process for NCV

1. stimulating electrodes placed over nerve

2. recording electrodes placed over muscle the nerve controls

3. low-level electrical shock applied through stimulating electrodes

4. recording electrodes measures speed of impulse

5. impulses appear as waves on monitor

motor definitions for NCV

M-wave

response latency

conduction velocity

another name for M wave

the motor action potential (MAP)

What is the M wave

representation of the summated activity of all motor units in the muscle that responsed to stimulation of the nerve trunk

what is response latency

the point at which the M wave leaves the baseline (time between stim and reading)

What does response latency indicate

the time elapsed from the initial propagation of nerve impulse to the depolarization of the muscle fibers beneath the electrodes

how is conduction velocity found

dividing the distance between the 2 points by the difference between the proximal and distal latencies

sensory definitions for NCV

the H reflex

antidromic conduction

purpose of the H reflex

measuring for radiculopathy and peripheral neuropathy

what is a normal H reflex

+/- 5.5 msec

What is a slow latency on the H reflex indicative of

abnormal dorsal root function

what is antidromatic conduction

conduction reading is taken backwards (distal to prox) to prevent inaccurate reading from motor input

What factors are better for recover of nerve impingement

• earlier repair

• children

• more distal lesion

what classification is thoracic outlet syndrome (TOS)

polyneuropathy

what is the thoracic outlet

anatomical space occupied by the 1st rib, clavicle, and superior border of the scapula, through which great vessels and nerves pass to the UE

risk factors for TOS

• occupational activities (overhead and heavy lifting)

• poor posture

• sleeping with arms elevated

• acute injuries

• wearing tight clothing

• backpacks

What type of athletes are at higher risk for TOS

overhead (swimming, tennis, volleyball, baseball)

Vascular s/s of TOS

• swelling throughout UE

• report of heaviness/fatigue

• throbbing pain

• cyanotic/cold

• difference in DBP between sides >10 mmHg

neurologic s/s of TOS

• N/T

• atrophy of hand muscles and difficulty with fine motor skills

• stabbing/cutting/burning/electric pain

what nerve distribution is typically affected by TOS

ulnar

What is unique about dxing TOS

its a dx of exclusion and you must rule out all other dxs

test item cluster for TOS

• wright

• adson’s

• hyperabduction

• Roos

• tinel’s

How many of the TOS cluster is needed to rule in TOS

5/5

procedure for hyperabduction test

• palp radial pulse at rest

• pt places arm above 90 degrees abduction and full ER

• hold position for 1 min

• note changes in pulse and paresthesia

What test is this

hyperabduction

Procedure for Wright test

• palp radial pulse at rest

• pt places arm above 90 degrees abduction and full ER

• pt rotate head opp of testing side

• hold position for 1-2 min

• note changes in pulse and paresthesia

What test is this

wright

What test is this

roos

procedure for roos test

• patient abd and ER arms to 90 degrees

• pt rapidly opens/closes hands

• perform for 1 min

procedure for Adson’s test

• arms in 15 degrees of abduction and full extension

• head rotated towards testing side

• patient inhales deeply and holds breath

• note paresthesia. pulse changes, or symptom reproduction

What test is this

adson’s

procedure for tinel’s sign for TOS

• patient sits with arms at side

• PT taps the supraclavicular fossa with reflex hammer

• noting tenderness

What test is this

tinels

purpose of cervical rotation and lateral flexion test

assess 1st rib hypomobility

procedure for cervical rotation and lateral flexion test

• patient seated

• passive rotation away from affected side

• gentle side flex (ear to chest)

• note mobility restrictions

What test is this

cervical rotation and lateral flexion test

Procedure for 1st rib MET

• patient unaffected arm supported on PT knee

• place hand on pts head and gently sidebend toward affected side

• locate 1st rib with 2nd MCP

• have patient to gently sidebend into contralateral hand for 3-5 seconds then relax

• perform 3 times before reassessing