ICL 4.6: UE Entrapment Neuropathies Flashcards Preview

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Flashcards in ICL 4.6: UE Entrapment Neuropathies Deck (46)
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what are the 3 types of nerve connective tissue?

1. endoneurium

2. perineurium

3. epineurium


what is the endoneurium?

a type of nerve connective tissue

connective tissue surrounding each individual axon and its mylin sheath


what is the perineurium?

strong, protective connective tissue

it surrounds bundle or fascicles of myelinated and unmyelinated nerve fibers; middle layer --> so it's a bundle of axons covered in endoneurium

it strengthens the nerve and acts as diffusion barrier --> individual axons may cross from one bundle to another along its course


what is the epineurium?

loose connective tissue surrounding entire nerve; most outside layer

it holds fascicles together

protects nerve from compression


what's the most common nerve entrapment syndrome?

carpal tunnel syndrome


what are the 3 classifications of nerve injuries?

1. neurapraxia

2. axonotmesis

3. neurotmesis


what is the etiology and description of neurapraxia?

aka conduction block

the nerve gets compressed so it can't relay the message down the axon

so like when you fall asleep and your nerve gets pinched and you wake up and your hand is tingling

axon is intact; might have local myelin injury

you'll recover within a few hours; pretty mild injury


what is the etiology and description of axonotmesis?

nerve crush injury

you do have disruption of the axon and protective tissue damage

endoneurium and perineurium is intact but axon and myelin are effected so axons will start to die = Wallerian degeneration occurs

you won't be able to conduct any type of signal down the nerve

takes 1 mm a day to heal the nerve between the nerve to the muscle it innervates


what is the etiology and description of neurotmesis?

nerve transection injury

your nerve is totally cut --> epineurium is fine but endoneurium and perineurium are damaged

axon is interrupted, connective tissue is damaged and no conduction down the nerve

regrowth is really difficult so patients will have to have surgery to reattach nerves


what are the 5 places of entrapment of the median nerve?

1. ligament of struthers (LOS)

2. bicipital aponeurosis (lacertus fibrosis)

3. pronator teres (PT) Syndrome

4. AIN syndrome

5. carpal tunnel


how does the median nerve get entraped at the ligament of struthers? what effects will you see if that happens?

there is a 2 cm bone spur 3-6 cm proximal to medial epicondyle connected by a ligament to the medial epicondyle in 1% of population and the median nerve passes under the ligament and can get entrapped there

the nerve becomes entrapped with brachial artery under ligament; so pulse might be diminished and patients might complain of dull achy sensation in forearm from nerve entrapment

rehab or surgery is how you fix it

1. FDP and FDS weakness = grip weakness

2. FCR weakness = wrist flexion weakness

3. FDP weakness = 2nd and 3rd digit flexion weakness


how does the median nerve get entraped at the lacertus fibrosis? what effects will you see if that happens?

when there's thickening of the antebrachial fascia that attaches your biceps to ulna --> the antebrachial fascia overlies the median nerve in the proximal forearm in the elbow region

you could also get a hematoma that compresses the nerve if someone punctures the veins in the area

treat with rehab or surgical release or stretching the ligament

1. FDP and FDS weakness = grip weakness

2. FCR weakness = wrist flexion weakness

3. FDP weakness = 2nd and 3rd digit flexion weakness

looks just like LOS entrapment!


how does the median nerve get entraped at the pronator teres? what effects will you see if that happens?

so your median nerve actually passes between the 2 heads of the pronator teres muscle on its way down to the FDS and it can get compressed inside the muscle or by the fascial bands that connect to the FDS

patients will complain of dull ache in proximal forearm exacerbated by forceful pronation or finger flexion (FDS)

weakness = all median innervated muscles in forearm and hand except pronator teres*


how does the median nerve get entraped at the AIN? what effects will you see if that happens?

pure motor syndrome

can be caused by idiopathic, fracture, laceration, compression

Exam: +ve OK sign, difficulty forming a fist d/t inability to approximate thumb and index finger

FDP and FDL will flex distal portion of fingers so they should be able to make OK sign but if they can't they'll compensate with the ulnar nerve and will extend at the DIP and have a more flattened OK sign

they also won't be able to fully flex when you ask them to make a fist because they won't be able to flex DIP so they're finger will be sticking out


what are some of the causes of carpal tunnel?

1. Idiopathic

2. Increased volume within the carpal tunnel

ex. thyroid disease, CHF, renal failure, mass (tumor, hematoma), and pregnancy (usually occurs at 6 mos and resolves postpartum)

3. decreased volume within the carpal tunnel

ex. fracture, arthritis, rheumatoid tenosynovitis

4. Double crush syndrome from DM, Cervical Radiculopathy, and TOS


what's the clinical presentation of carpal tunnel?

1. gradual and often at night

2. first 3 digits often effected: night pain or aching, numbness, tingling pain in hand, pain in forearm toward shoulder

3. feels need to ”shake it off”

4. weakness LOAF muscles

**severity of CTS symptoms does not necessarily correlate with severity of EDX findings


what structure is not within the carpal tunnel?


2. FDP

3. FCR

4. FPL

5. median nerve

flexor carpi radialis


what 5 tests can you do to test for carpal tunnel?

1. Tinel's

2. Phalen's

3. Tourniquet's test = inflate BP cuff reproduction of symptoms at 1 minute

4. carpal compression test aka Durken's compression test

5. reverse Phalen's test

you usually want 2 positive tests to diagnose with CTS


how do you treat carpal tunnel syndrome?

1. rehab

- orthotics: neutral resting hand splints overnight

- medications: NSAIDS, oral steroids, steroid injection, diuretic, vitamin B6

- ergonomic modifications

- treat underlying medical disorder

2. surgery

indications = muscle atrophy, severe pain and failure of conservative treatment

limited symptomatic relief and return of muscle strength with severe median nerve damage and profound muscle atrophy


what are the 3 sites of entrapment of the ulnar nerve?

1. arcade of struthers

2. cubital tunnel

3. Guyon's cannal


what's the path of the ulnar nerve?

it descends along medial head of triceps within Arcade of Struthers

then it continues posteriorly through the retrocondylar groove and through the cubital tunnel in the forearm

it then passes into the hand via Guyon's canal


how does the ulnar nerve get entrapped at the arcade of struthers? what effects will you see if that happens?

there's a fascial band in the medial arm that connects brachialis to tricep brachii and the ulnar nerve can get compressed under this fascial band

interventions may include rehab or surgical release of AOS

clinical presentation:
1. involvement of ALL ulnar nerve innervated muscles; since this is very proximal all the ulnar muscles will be effected

2. wrist flexion w/ radial deviation (FCU weakness)

3. abnormal sensation in all sensory braches of ulnar nerve

4. ulnar claw hand: unopposed pull of EDC causes partial finger flexion of 4th and 5th PIP and DIP joint d/t MCP extension


what is the Froment's sign?

Inability to hold piece of paper by thumb and index finger with pure thumb adductions (APL)

the patient will instead substitute the median innervated FPL causing flexion of DIP joint


what is Wartenberg's sign?

inability to aduct the pinky because interossei is weakened


how does the ulnar nerve get entrapped at the cubital tunnel? what effects will you see if that happens?

this is the most common site of elbow entrapment

the ulnar nerve gets compressed beneath the proximal edge of FCU aponeurosis or arcuate ligament --> the cubital tunnel is bordered by medial epicondyle and olecranon with overlying aponeurotic band

treat with rehab or surgical release

clinical presentation:

1. all ulnar nerve innervated muscles +/- FCU are effected

2. similar complaints as AOS entrapment

3. Tinel’s sign at ulnar groove


how does the ulnar nerve get entrapped at Guyon's canal? what effects will you see if that happens?

proximal extent of the transverse carpal ligament and ends at the aponeurotic arch of the hypothenar muscles

different branches of ulnar nerve can be injured at wrist

can be caused by cyclist's palsy, wrist ganglions, RA, or trauma

clinical presentation depends on the type you have (there are 3)


what are the 3 types of Guyon's canal ulnar compressions?

1. involvement of the deep ulnar branch, hypothenar and sensory

2. involvement of deep ulnar motor branches

3. involvement of the superficial ulnar sensory branch


what are the 5 entrapment sites of the radial nerve?

1. crutch palsy

2. 2. Spiral groove – Honeymooner’s palsy

3. radial tunnel

4. PIN syndrome

5. 5. Cheiralgia Paresthetica


what is crutch palsy?

when you're compressing on the posterior cord of brachial plexus; most commonly affecting radial nerve

you will see weakness in ALL radially innervated muscles including triceps brachii

sensation is decreased over posterior arm and forearm

interventions: focus on rehab, discontinue crutch use, static cock-up splint or dynamic splinting


what is spiral groove/honeymooner's palsy?

Arm positioned over a sharp ledge like a chair back or head on humerus when you're cuddling with someone --> you can also get them from injections, compression, or fracture

you will see weakness in radial innervated muscles below the spiral groove -- triceps and anconeus are spared though!

weakness of elbow flexion (Brachialis**), supination (supinator), wrist drop (ECRL, ECRB, ECU) finger extension (EDC)

sensory deficits in dorsal aspect of hand and posterior forearm