Entrapment neuropathy

Surat Tanprawate, MD, FRCP(T)Northern Neuroscience Center

Chiangmai University

Concept

• All of confusing problem come form plexus

• Entrapment level: root, plexus, nerve

• Concept to be remembered: muscle– Same nerve: different root– Same root: different nerve

• Step to remember– Muscle: nerve innervation– Muscle: root innervation

• Step approach1. Clarify symptom:

where’s drop?2. What’s muscle affected?3. What’s nerve and root

innervated that muscle?4. Test key muscle: muscle

innervated by : same nerve, different root : same root, different nerve

Musculocutaneous n.

5 6 7 8T1

5 6 78

Median n.

Ulnar n.

Axillary n. Radial n.

Proximal forearm

• Musculocutaneous nerve– Muscle: Bicep m.– Cutaneous: lateral

cutaneous of forearm

• Axillary nerve– Pass under axillar– Supply: deltoid m.

Radial nerve

• Radial n:– Run around radial

groove

• Form:– Posterior interosseous n. – Superficial radial n.

• Special test– Out stretch arm test

Tricep

Brachioradialis

ExtensorCarpi

ExtensorDigitorum

PollicisIndices

Median nerve

• Median n:– Run median of arm

• Form:• Median n.• Anterior interosseous n.• Special test

– Finger pinch or O.K. test: งอ distal ไม่�ได้�

– Benediction’s sign– Tinel’s and Phalen’s test

for CTS

Flexor carpi radialis

Flexor digitorum superficialis

Flexor digitorum profundus 1,2

Flexor Pollicis longus

LOAF

Pronator quadratus

Median nerve syndrome

• Carpal tunnel syndrome

Pronator teres syndrome

• Signs:

Ulnar nerve

• Ulnar n:– Run ulnar of arm

• Most intrinsic hand except LOAF

• Special test– Open your hand:

• Ulnar claw hand

– Prayer test

Flexor carpi ulnaris

Flexor digitorum profundus 3,4

Intrinsic hand muscle except

LOAF

Ulnar n syndrome

• Cubital tunnel syndrome• wrist

Entrapment of upper extremities

• Clinical approach– Proximal arm weakness– Wrist drop– Hand atrophy

Proximal arm weakness

• Proximal arm muscle: key muscle– Deltoid:C5,6- axillary n.– Bicep: C5, 6-

musculocutaneous n.– Tricep: C7,8- radial n.– Brachioradialis: C5, 6-

radial n.

• Pattern involved– Deltoid alone

• axillary n. lesion

– Deltoid, bicep, brachioradialis involved(spare tricep)• C5,6 root

– Involve alls muscle• Brachial plexus• Cord

Wrist drop

• Wrist drop– Extexsor carpi radialis

longus(C5, C6 and radial nerve)

– Extensor carpi ulnarlis( C7, C8 and posterior interosseous branch of radial nerve)

Key muscle: nerve, root

• Key muscle: radial distribution– Radial n: tricep,

brachioradialis– P.I.N: extensor

digitorum, extensor carpi ulnaris

• Key muscle: C5,6– Deltoid: axiallary n– Bicep:

musculocutaneous n.– Tricep: radial n.(C6,7,8)– FCR: median n.(C6,7)

Interprete

• Generalized weakness: esp. weakness of deltoid, tricep, wrist ext, finger ext.– UMN: corticospinal tract

lesion

• Selected weakness– C7,C8 root or plexus– Radial nerve lesion– Posterior interosseous

nerve lesion

Out stretch arm test

Tricep Brachioradialis

Wrist extension

Finger extension

Finger flexion

PIN lesion(finger drop with radial deviation)

Normal Normal Normal (radial

diviation)

Weak Normal

C7,8 or brachial

plexus lesion

Weak Normal Radial diviation

Weak Weak

Radial nerve lesion(radial

groove)(wrist drop)

Normal Weak Weak Weak Normal

C5,6 orBrachial plexus

Mild Weak

Weak Weak Normal Normal

Hand atrophy(wast hand)

Muscle of hand

Median nerve Ulnar nerve

LOAF Others than LOAF

APB ADM and 1 DI

Hand atrophy

• Muscle of hand– LOAF(median n.), other

than LOAF(ulnar n.)– Key muscle: 3 muscle

• APB(for LOAF), ADM and 1 DI(for other than LOAF)

• Root innervation– APB: C8 T1– 1DI: C8, T1– ADM: C8, T1

• Pattern of weakness– Only APB: median n.

lesion-test other flexor m. group

– Only ADM and 1DI: ulnar n. lesion

– Weak all 3 muscle: many causes

Weak all 3 key muscle

• 3 muscle plus finger extensor, tricep, finger flexor– C7,8,T1 root

• Fail arm+ all sensation– Brachial plexus

• Fail arm and cape distribution sensory loss– Spinal cord

• Generalized– MND– Polyneuropathy

C8 radiculopathy Brachial plexus,lower trunk

Brachial plexus, medial cord

Ulnar neuropathy

Wrist flexion Weak Weak Weak Weak

Finger flexion Normal Weak Weak Normal

Thumb flexion, opposision

Normal Weak Weak Normal

Interossei weakness, atrophy

Yes Yes Yes Yes(esp. atrophy of 1 dorsal interossei

Senseory loss Same as ulnar+ulnar aspect of forearm

Similar to medial cord

Same as ulnar+palmar aspect of hand and digit1-4

Ulnar aspect of hand, 5 digit and half of 4

Tricep reflex Partial No Partial No

Hand shape Either Simian hand Simian hand Claw hand

Horner syndrome Can occur Can occur Never Never

Causes Compression by cervical disc

Traumatic injury at birth

Traumatic, tumor, neuritis

Compression, ulnar groove

Lower extremities

• Lumbosacral plexus• Proximal– Anterior: obturator n., femoral n.– Posterior: gluteal n., sciatic n(hamstring m.)

• Distal – Anterior: peroneal nerve(deep VS superficial)– Posterior: tibial nerve

Entrapment neuropathy of lower extremities

L1 L2 L3 L4 L5 S1 S2

Femoral nerve- Iliopsoas(L1,2,3)- Quadricep(L2,3,4)Obturator nerve- Adductor group(L2,3,4)

Femoral n. Obturator n.

Entrapment neuropathy of lower extremities

L1 L2 L3 L4 L5 S1 S2

Glureal n.Superior gluteal nInferior gluteal n

Sciatic n.

Gluteal n.

Tibial n.TP. m.(L4,5)Gastroc m(S1,2) Deep peroneal n.

TA. M(L4,5)EHL m.(L5, S1)

Proximal weakness of legs

• Key muscle– Iliopsoas m: L1, 2-

femoral n.– Quadricep m: L2,3-

femoral n.– Adductor m: L3,4-

obturator n.– Hamstring m: L5, S1,2-

sciatic n.– Gluteus maximus m: L5,

S1,2- inferior gluteal n

• Weak • Iliopsoas+quadricep– Femoral n. lesion

• Iliopsoas+quadricep+ hip adduction– L2,3, 4 lesion

Foot drop

• Due to weakness of tibialis anterior• Key muscle– Tibialis anterior m: L4,5-DPN– EHL: L5, S1- DPN– Peroneus m: L5, S1- SPN– Tibialis posterior m: L4,5 - tibial n.– Gastrocnemius m: S1,2 - tibial n.

Pattern of foot drop

• weakness of• Dorsiflex+eversion+EHL– Common peroneal n.

lesion

• Dorsiflex+inversion+ hip abduction– L4, 5 root or plexus

lesion

• Alls movement of foot– Peripheral neuropathy– Sciatic n. lesion– Plexus lesion– Cauda equina lesion– Anterior horn cell

disease

Differential diagnosis of foot drop

L5 radiculopathy Lumbar plexopathy

Sciatic neuropathy

Peroneal neuropathy

Ankle inversion W W N or mildly weak N

Toe flexion W W N or mildly weak N

Plantar flexion N N N or mildly weak N

Ankle jerk N N or depress N or depress N

Sensory loss Big toe L5 dermatome Entire lateral leg and dorsum of foot

Distal 2/3 of lateral leg, dorsum of foot

Pain Rare, deep pain Radicular pain Can be severe Radicular pain

Causes Disc herniation Prolong labor, pelvic fracture

Hip surgery Compression

Good luck