OPP 3 - Peripheral Nerve Entrapment (Lect. & Lab)

General Nerve compression MOI

Brief compression primarily affects myelinated fibers, and classically spares unmyelinated fibers (except in cases of severe acute compression). Acute compression compromises axoplasmic flow which can reduce membrane excitability. Chronic compression affects both myelinated and unmyelinated fibers and can produce segmental demyelination in the former, and if the insult persists, axolysis and wallerian degeneration will occur in both types. The issue of ischemia is more controversial.

Some contend that simultaneous venous stasis at the site of compression can produce ischemia which can lead to edema outside the axonal sheath which may further exacerbate the ischemia. Eventually, fibrosis, neuroma formation, and progressive neuropathy can occur.

Occipital nerve entrapment

A sensory branch of C2

Entrapment presents as occipital neuralgia: pain in the occiput usually with a trigger point near the superior nuchal line. Pressure here reproduces pain radiating up along back of head towards vertex. 

More common in women.

ddx:

1. headache (may mimic migraine or part of tension HA)

2. myofascial pain: pain widely separated from trigger point

3. rare: vertebrobasilar disease, cervical spondylosis, chiari malformation

Possible causes of occipital nerve entrapment

1. trauma

• direct trauma (including iatrogenic placement of suture through the nerve during surgical procedures, e.g. in closing a posterior fossa craniectomy)

• following traumatic cervical extension which may crush the C2 root and ganglion between the C1 arch and C2 lamina

• fractures of the upper cervical spine”

2. atlanto-axial subluxation (AAS) (e.g. in rheumatoid arthritis) or arthrosis

3. entrapment by hypertrophic C1–2 ligament

4. neuromas

5. arthritis of the C2–3 zygapophyseal joint

Occipital N entrap Tx

For idiopathic occipital neuralgia: available evidence is from small, retrospective, case series studies and is insufficient to conclude that either local injection or surgery are effective.

Nerve blocks at trigger points with steroids and local anesthetics provide only temporary relief. ex: greater occipital N

• usually point at near superior nuchal line, may also block @ point where N. emerges from dorsal neck muscles

Surgical procedures such as nerve root decompression or neurectomy may provide effective pain relief for some patients; however, patient-selection criteria for these procedures have not been defined, and recurrence is common. In idiopathic cases with no neurologic deficit, the condition is usually self limited.

• ex: C2 nerve root decompress b/t C1 & C2; in cases of AAS, decompress and atlanto-axial fusion may work

Surgical tx’s for idiopathic occipital neuralgia

• release of the nerve within the trapezius muscle. Immediate results: relief in 46%, improvement in 36%. Only 56% reported improvement at 14.5 mos

• intradural division of the C2 dorsal route via a posterior intradural approach

• occipital neurectomy: relief only occurs in ≈ 50%, and recurrence, usually within a year, is common

Median Nerve neuropathy

• C5-T1 nerve roots

• Purely motor anterior interosseous nerve which supplies all but 2 muscles of finger and wrist flexion

• + phalens, reverse phalens, tinel’s, and opponens pollicus

• 2 most common entrapment sites:

  • wrist @ transverse carpal lig (carpal tunnel syndrome)

  • Upper forearm @ pronator teres muscle

struther’s ligament

anatomical variant, bridges SCP to medial epicondyle

pronator teres syndrome

From direct trauma or repeated pronation with tight hand-grip.

Nocturnal exacerbation is absent. Pain in palm distinguishes this from carpal tunnel syndrome (CTS)

• pain is distal and moves proximal

Carpal Tunnel Syndrome (CTS)

• onset over months to years

• usually as result of repetitive activity, frequent grasping, ulnar deviation, direct pressure over carpal tunnel, and vibrating hand tools.

• systemic causes: pregnant, diabetes, RA

• most common compression neuropathy

• sx: tingling in the hand, worse at night and with elevation of hands

• PE: decreased pinprick in digits 1–3 and the radial half of 4, +Tinels/Phalens/Reverse Phalens, Electrodiagnostics —> Prolonged NCV on EMG

• tx: mild —> NSAIDs + neutral positioning

  • severe —> surgical nerve decompression

Ulnar Nerve Entrapment sites

C7, C8 and T1 nerve roots.

Second most prevalent entrapment neuropathy

Potential sites of compression:

• above elbow by the arcade of Struthers

• at the elbow in the ulnar groove process.

• under the aponeurosis between the heads of the flexor carpi ulnaris 

• Guyon’s canal Etiologies: structural, mechanical or idiopathic.

• May also be due to chronic subluxation out of the ulnar groove

@ elbow = numb in palm AND backside of hand

@ wrist = numb in palm only

Ulnar nerve entrapment sx

Motor/sensory findings include:

• Wasting of the interossei

  • most evident in the first dorsal interosseous (in the thumb web space)

• Wartenberg’s sign: one of the earliest findings of ulnar nerve entrapment

  • abducted little finger due to weakness of the third palmar interosseous muscle--patient may complain that the little finger doesn’t make it in when they reach into their pocket

• Sensory findings involving the little finger and ulnar half of the ring finger.  Sensory loss over the ulnar side of the dorsum of the hand.

  • This will be spared in ulnar nerve entrapment at the wrist (dorsal ulnar cutaneous nerve branches proximal to the wrist) Injury above elbow

Meralgia Paresthetica

compression of the lateral femoral cutaneous nerve (L2 and L3 nerve roots) - Erupts medial to ASIS and below inguinal ligament

risk factors: obesity, tight belt/scrub strings

Signs and Symptoms

• Burning dysesthesias of lateral thigh

• Increased/altered sensation of touch and clothing

• Pts may constantly rub lateral thigh

• Symptoms to not go past the knee

Disc herniation patterns of pain/numbess

pain —> proximal (thigh, arm)

numbness —> distal (shin, forearm)

Piriformis syndrome

More common in women

Pain in the gluteal region that travels down

Increases with sitting longer than 15-20 minutes and improves with ambulation

Contralateral SI pain

Parasthesias in posterior thigh and/or foot

Signs:

• Ipsilateral leg externally rotated

• Ipsilateral leg short

• Tenderness in the greater sciatic notch with/without palpable mass

• Reproducible with active contraction or passive stretch

• Straight leg raise may be positive

• In most cases: sacrum is anteriorly rotated to contralat. side

Tx: OMM (ME, CS- peeing dog, HVLA, artic, Still, consider sacrum/pelvis)

• untreated can result in chronic pain, parasthesias, or weakness

Piriformis Syndrome - FADIR test

Patient in lateral recumbent position

Affected side up

Hip flexed to 60 degrees

Knee flexed to 60-90 degrees

Examiner induces internal rotation and

Adduction of the hip

Downward pressure on the knee

Piriformis Syndrome - Piriformis Sign

While patient is supine

Ipsilateral external rotation of the lower extremity

Piriformis Syndrome - Lesegue Sign (seated straight leg raise)

“worthless” lol

Piriformis Syndrome - Freiberg’s sign

Patient supine

Thigh extended

Passive internal rotation of the leg

Positive if pain is reproduced

Piriformis Syndrome - Pace’s sign

Patient seated

Patient attempts to abduct the thighs against resistance

Positive if pain is reproduced

Fibular nerve/Common peroneal nerve compression

• may be seen w/ knee or fibular fx’s, also assoc with crossing legs while seated

• sx: parasthesias of lat lower leg/dorsum of foot, may have painful dysesthesia

• signs: weakness of dorsiflexors, + tinnel’s at some point along nerve course (ex tarsal tunnel), may have prolonged NCV on EMG

• tx: OMM for fib head, surgical decompression

• ddx: must differentiate from L5 radiculopathy, consider diabetic neuropathy if “painless footdrop”

Carpal tunnal - myofascial release (MFR)

Carpal tunnel - Still’s technique

carpal tunnel - BLT

dorsiflex and ulnar deviate

hold hand like MFR but flipped (thumbs on dorsum, fingers on their palm) and begin w/ them pronated, end with them supinated, dorsiflexing, and ulnar deviated

O/A & A/A

dx and tx

note: make sure to dx A/A while standing

PC1 inion - counterstrain (FStRa)

Inguinal Ligament - Articular release

Position – Supine

Contact the middle of the inguinal ligament with the hypothenar eminence. Force is in a superior, medial and posterior direction.

Maintain a steady pressure until a release is felt.