Nerve Palsies

Question 1

Brachial plexus lesion - Erb-Duchenne paralysis

Answer 1

• DOWNWARD TRACTION e.g. FALL ON SIDE of NECK
• INCREASED TRACTION DURING BIRTH/ACCIDENT
• C5, C6 DAMAGE = DELTOID & SHOULDER MUSCLES, BRACHIALIS & BICEPS
• ARM “PORTER’S TIP” = SHOULDER ADDUCTED, ELBOW EXTENDED, FOREARM PRONATED, WRIST FLEXED

SENSORY ANAESTHESIA OVER C5, C6 DERMATOME

Question 2

Brachial plexus lesion - Klumpke’s paralysis

Answer 2

• UPWARD TRACTION of C8/T1 e.g. BREECH DELIVERY
• T1 DAMAGE = INTRINSIC MUSCLES
• “CLAWED” HAND
• RARER

Question 3

Axillary nerve (at risk complication of, presentation)

Answer 3

• AT RISK: SURGICAL NECK of HUMERUS
• COMPLICATION of: # HUMERAL NECK, SHOULDER DISLOCATION, SATURDAY NIGHT PALSY (PRESSURE on POSTERIOR CORD of BRACHIAL PLEXUS)

PRESENTATION:

* SENSORY DEFICIT = BADGE AREA
* MOTOR DEFICIT = LOSS of SHOULDER ABDUCTION - DELTOID; MUSCLE WASTING can occur - can SEE HUMERUS

• Check BADGE PATCH AREA SENSATION BEFORE + AFTER CORRECTING SHOULDER DISLOCATION

Question 4

Radial nerve (closely ass. w/, at risk complication of, presentation)

Answer 4

• ROOTS: C5 - T1; POSTERIOR CORD
• SUPPLIES EXTENSORS of ARM + FOREARM
• IN ARM, CLOSELY ASS. W/: PROFUNDA BRACHII ARTERY
• ENTERS FOREARM by PASSING BWTN: BRACHIORADIALIS & BRACHIALIS (& posterior interosseous branch of radial nn. passes bwtn 2 planes of supinator)
• AT RISK: SPIRAL GROOVE of HUMERUS & LATERAL INTERMUSCULAR SEPTUM (& POSTERIOR INTEROSSEOUS BRANCH at RADIAL NECK)

• COMPLICATION of: # HUMERAL SHAFT, SATURDAY NIGHT PALSY (pressure on posterior cord of brachial plexus), EXPOSURE of PROXIMAL RADIUS

PRESENTATION:

* SENSORY DEFICIT = 1ST WEBSPACE DORSALLY
* MOTOR DEFICIT = WRIST DROP (EXTENSORS not contracting - so wrist flexion appears)

Question 5

Median nerve (closely ass. w/, at risk complication of, presentation)

Answer 5

• ROOTS = C7 - T1
• IN ARM, CLOSELY ASS. W/: BRACHIAL ARTERY
• ENTERS FOREARM by PASSING BWTN: 2 HEADS of PRONATOR TERES
• AT RISK: VOLAR ASPECT WRIST & CUBITAL FOSSA
• COMPLICATION of: CARPAL TUNNEL SYNDROME, WRIST LACERATIONS & SUPRACONDYLAR #, STRUTHER’S LIGAMENT

PRESENTATION:

* SENSORY DEFICIT = VOLAR ASPECT THUMB
* MOTOR DEFICIT = THENAR WASTING, POINTING FINGER

Question 6

Ulnar nerve (closely ass. w/, at risk complication of, presentation)

Answer 6

• ROOTS: C7 - T1
• IN ARM, CLOSELY ASS. W/: SUPERIOR ULNAR COLLATERAL ARTERY (& ulnar artery & nn. v. closely interwoven at wrist
• ENTERS FOREARM by PASSING BWTN: 2 HEADS of FLEXOR CARPI ULNARIS
  
  • AT RISK: BEHIND MEDIAL EPICONDYLE of HUMERUS (& WRIST, CANAL of GUYON)
  • COMPLICATION of: # HUMERAL CONDYLES (& WRIST LACERATIONS)

PRESENTATION:

* SENSORY: LITTLE FINGER
* MOTOR DEFICIT: CLAW HAND, HYPOTHENA & 1ST DORSAL INTEROSSEOUS WASTING

Question 7

Femoral nerve (passage, purpose)

Answer 7

• ROOTS: L2 - L4
• LARGEST BRANCH of LUMBAR PLEXUS
• PASSES THROUGH PSOAS MUSCLE - EXITS PELVIS UNDER INGUINAL LIGAMENT; LATERAL to FEMORAL ARTERY VEIN & LYMPHATIC CHANNELS in FEMORAL TRIANGLE
• SUPPLIES QUADRICEPS MUSCLES in ANTERIOR THIGH
• TERMINATES in LONG FINE SENSORY BRANCH = SAPHENOUS NN. (accompanies femoral artery in subsartorial canal of thigh & long saphenous vein in lower leg & in front of medial malleolus at ankle to supply great toe)

Question 8

Lateral femoral cutaneous nerve

Answer 8

• ROOTS: L2 - L3
• Lies on SURFACE of ILIACUS MUSCLE
• Usually EXITS PELVIS UNDER LATERAL END of INGUINAL LIGAMENT - VARIABLE
• PURELY SENSORY to LATERAL THIGH
• COMPRESSION = causes MERALGIA PARAESTHETICA

Question 9

Sciatic nerve

Answer 9

• ROOTS: L4 - S3
• LARGEST NN. IN BODY = MAIN BRANCH of SACRAL PLEXUS = BROAD + FLAT w/ ACCOMPANYING ARTERY
• EXITS PELVIS through SCIATIC FORAMEN BELOW PIRIFORMIS MUSCLE
• RUNS DEEP to GLUTEUS MAXIMUS MUSCLE
• SUPPLIES HAMSTRING MUSCLES in POSTERIOR THIGH + PART of ADDUCTOR MAGNUS + ALL LOWER LEG & FOOT MUSCLES via TERMINAL BRANCHES (common fibular nn. & tibial nn.)
• AT RISK from POSTERIOR DISLOCATION of HIP, INTRA-MUSCULAR INJECTIONS & DURING SURGERY = DIVISION is DEVASTATING

Question 10

Common fibular nerve

Answer 10

• ROOTS: L4 - S2
• SMALLER & LATERAL BRANCH of SCIATIC NN.
• Passes ~ LATERAL ASPECT of FIBULA NECK (AT RISK! - DEFICIT causes FOOT DROP & SLAPPING GAIT - MOST COMMONLY INJURED NN. in LOWER LIMB)
• COMMUNICATING BRANCH to SURAL NN.
• DIVIDES in SUPERFICIAL & DEEP FIBULAR NN.