Peripheral Nerve Injury Flashcards
1
Q
Learning Outcome:
A
- Median nerve injury
- Ulnar nerve injury
- Radial nerve injury
- Sciatic nerve injury
- Femoral nerve injury
- Principles of management
2
Q
Median nerve injury pathology
A
- Pathway:
- From medial and lateral cords of brachial plexus (all roots)
- lateral to brachial artery -> medial to brachial artery (half arm) -> medial area in cubital fossa -> between FDS and FDP (give AIN and Palmar cutaneous branch) -> enters carpal tunnel -> divided into recurrent branch, palmar digital branch - Function:
i. Median - superficial and middle layer of anterior compartment
i. AIN - deep layer of anterior compartment
ii. Palmar cutaneous - skin of radial palm (not in carpal tunnel)
iii. Recurrent branch - thenar muscles (OAF)
iv. Palmar digital branch - lateral two lumbricals and sensory (palm, lateral two half digits) - Level of injury
i. low (wrist distally)
- Carpal tunnel syndrome
- Carpal dislocation
- Wrist cut
ii. high (proximal tu wrist)
- Pronator tunnel syndrome
- Elbow dislocation
- Fracture of forearm
- Supracondylar fracture of humerus
3
Q
Median Nerve Injury diagnosis
A
High lesion
i. inspection:
- benedict sign
- loss of thumb abduction
- wasting of forearm
- pronator mass
- thenar eminence
ii. motor:
- loss of pronation
- weak wrist flexion (FCU, Palmaris brevis by ulnar)
- loss of PIP, DIP flexors in index, middle
- loss of thumb opposition and abduction
- ochner’s test +ve
ii. sensory
- loss on thenar eminence (palmar cut. branch)
- loss on lateral 2 and a half digits (digital cut.)
AIN lesion only
i. inspection: benedict sign, pinched ok sign
ii. motor:
- weak pronation
- loss thumb IPJ flexion
- loss index, middle DIPJ flexion
iii. sensory: none
Low lesion
i. inspection: thenar wasting, loss of thumb abduction
ii. motor
- weak thumb oppostion (lost OP, FPB)
- weak thumb abduction (APB lost)
- weak MCP flexion (Lumbricals)
iii. sensory
- lateral 2 and a half digits lost (digital cutaneous branch)
- radial palm spared (palmar cutaneous branch)
iv. special test
- tinel’s test
- compression test
- phalen’s test
4
Q
Pronator Syndrome
A
.
5
Q
Carpal Tunnel Syndrome
A
.
6
Q
Ulner Nerve Injury pathology
A
- Pathway:
- from medial cord (C8, T1)
- medial side of arm -> posterior to medial epicondyle -> pierce two heads of FCU in forearm -> along ulnar side of forearm (muscular branch) -> at wrist (2 branch: palmar cut., dorsal cut) -> superficial to flexor retinaculum -> Guyon’s canal in hand -> superficial, deep branch) - Function:
i. muscular branch (FCU, medial FDP)
ii. deep branch (medial Lumbricals, Adductor pollicis, Interossei, Palmaris brevis)
iii. palmar cut. branch: hypothenar palm
iv. sup. branch: palmar medial one half fingers
iv. dorsal cut. branch: dorsal hand and medial one half fingers - Level of injury:
i. High lesion (proximal to wrist)
- cubital tunnel compression
- elbow dislocation
- ulnar subluxation
- cubitus valgus
- brachial plexus
- medial epicondyle fracture
ii. Low lesion (distal to wrist)
- guyon’s canal compression
- wrist cut
7
Q
Ulner Nerve Injury diagnosis
A
- High level injury:
i. inspection:
- guttering between metacarpals
- hypothenar wasting
- minimal claw hand (loss of lumbricals + unopposed FDS)
- wartenberg sign (little finger deviation due to unopposed EDM)
- radial deviation (unopposed FCR)
ii. motor:
- loss of medial wrist flexion
- loss of fingers abduction
- loss of DIP flexion of ring and little fingers
- loss of thumb adduction (Froment’s test)
iii. sensory:
- loss of hypothenar sensation
- loss of palmar and dorsal medial one half fingers
iv. special test: - Low level injury:
i. inspection:
- ulnar claw (loss of lumbricals with unopposed FDP, FDS)
- metacarpals guttering
- hypothenar wasting
- wartenberg sign
ii. motor
- loss of fingers abduction
- loss of thumb adduction (Froment’s Test)
iii. sensory
- sparing of dorsal and palmar sensation
- same as high level injury
8
Q
Cubital tunnel syndrome
A
.
9
Q
Guyon’s Canal Syndrome
A
.
10
Q
Radial Nerve Injury pathology
A
- Pathyway:
- posterior cord (all roots) -> triangular space -> posterior of humerus shaft spiral groove (3 branches before spiral groove: post cut. arm, inferolateral cut. arm, post. cut. forearm) -> anterior to lateral epicondyle -> lateral cubital fossa -> (Deep branch, superficial branch)
- deep branch -> pierce supinator muscle -> PIN
- superficial branch -> dorsal lateral three and a half digits - Function
i. muscular branch: triceps, anconeus, brachioradialis, ECRL
ii. post. cut. arm: sensory
iii. inferolateral cut. arm: sensory
iv. post. cut. forearm: sensory
v. deep branch: ECRB, supinator
vi. PIN: posterior compartment forearm muscle
vii. superficial branch: sensory for dorsal hand lateral three and a half digits - Level of injury:
i. low (below elbow)
- radial head dislocation
- deep laceration wound
ii. high (above elbow to spiral groove)
- humeral shaft fracture
- prolonged arm tourniquet
- radial tunnel syndrome
iii. very high lesion (spiral groove to axilla)
- shoulder dislocation
- fracture of proximal humerus
- saturday night palsy
- crutch palsy - Compression
- Radial tunnel syndrome
- Posterior interosseus syndrome (FREAS)
11
Q
Radial Nerve Injury diagnosis
A
- very high lesion
i. inspection:
- wrist and finger drop
- radial deviation (no ECU)
- forearm extensors wasting
- triceps wasting
ii. motor:
- loss of thumb extension
- loss of fingers extension
- loss of wrist extension
(cogged wrist test)
- loss of elbow extension
iii. sensory:
- loss of posterior arm
- loss of inferolateral arm
- loss of posterior forearm
- loss of dorsum hand and lateral 3 and a half digits - high lesion
i. inspection:
- wrist and finger drop
- radial deviation (no ECU)
- forearm extensors wasting
ii. motor:
- loss of thumb extension
- loss of fingers extension
- loss of wrist extension
(cogged wrist test)
iii. sensory:
- loss of posterior forearm
- loss of dorsum hand and lateral 3 and a half digits - low lesion
i. inspection:
- finger drop
- radial deviation (no ECU)
- forearm extensors wasting
ii. motor:
- loss of thumb extension
- loss of fingers extension
- weak wrist extension (still supported by ECRL)
(cogged wrist test)
iii. sensory:
- if PIN only, no loss
- if sup. branch affected, loss of dorsum hand and lateral 3 and a half digits
12
Q
Posterior Interosseus Syndrome / Radial Tunnel Syndrome
A
.
13
Q
Sciatic Nerve Injury
A
- Pathway:
- Lumbosacral plexus (L4-S3) -> exits sciatic notch -> deep to piriformis -> posterior thigh -> distal third thigh (2 terminal branches: tibial, common peroneal)
- tibial -> between heads of gastroc -> posterior to medial malleolus-> into tarsal tunnel -> plantar (2 terminal branches: medial plantar, lateral plantar)
- common peroneal -> posteroinferior to biceps femoris-> around fibular neck (2 terminal branches: deep peroneal, superficial peroneal)
- deep peroneal-> anterior leg compartment behind anterior tibialis -> inferior extensor retinaculum -> motor, sensory
- superficial peroneal-> lateral compartment-> becomes anterior 12cm above lateral malleolus-> (2 terminal branches: medial dorsal cut., lateral dorsal cut/sural) - Function:
i. Sciatic nerve: Posterior thigh muscle
ii. Tibial nerve:
- muscular branch: posterior leg
- medial sural cutaneous: posterolateral leg
- medial calcaneal branch: medial hindfoot
- medial plantar: skin medial plantar foot, FDB, FHB, 1st lumbrical
- lateral plantar: skin lateral plantar foot, AbDM, AH, QP, Interossei, 4 lumbricals
iii. Common peroneal: short head biceps femoris
iv. Deep peroneal: anterior leg muscle, 1st web space
v. Sup. peroneal:
- muscular: lateral leg muscle
- sural/lateral dorsal cut: lateral dorsal skin
- medial dorsal cut: medial dorsal skin - Level of lesion
i. Sciatic nerve
- iatrogenic (injection to gluts)
- posterior hip dislocation
- acetabular fracture
- piriformis syndrome
- penetrating wound
ii. Tibial nerve
- ankle injury
- tarsal tunnel syndrome
- posterior compartment syndrome
iii. Common peroneal
- fibular neck fracture
- pressure from cast, bersila
- iatrogenic
- varus knee injury
iv. Deep peroneal
- anterior compartment syndrome
- ankle fracture injury
v. Superficial peroneal
- lateral compartment syndrome
- ankle injury
14
Q
Sciatic Nerve Injury diagnosis
A
- Sciatic nerve injury
i. inspection:
- high stepping gait
- foot drop
- wasting hamstring, leg muscle
ii. motor:
- loss of hip extension, knee flexion
- loss ankle dorsiflexion, plantar flexion, inversion, eversion
- loss of toe extension, flexion, adduction, abduction
iii. sensory
- loss of posterolatera, anterolateral leg
- loss of dorsum and plantar foot, 1st web space - Tibial nerve injury
i. inspection:
- sole, gastrocnemius wasting
- sole pressure sores
- toe clawing
ii. motor:
- loss of plantar flexion
- toes flexion, extension, adduction, abduction
iii. sensory:
- loss of heel sensation, medial plantar foot, lateral plantar foot - Deep peroneal nerve injury:
i. inspection:
- wasting over anterior leg compartment
- foot drop
- foot everted
ii. motor:
- loss of ankle dorsiflexion, inversion
iii. sensory:
- 1st web space loss - Superficial peroneal nerve injuries
i. inspection:
- lateral leg wasting
- foot inverted
ii. motor:
- loss of ankle eversion
iii. sensory:
- medial dorsum foot
- lateral dorsum foot
15
Q
Femoral nerve injury pathology
A
- Pathway
- from L2-L4
- behind midpoint of inguinal ligament (anterior cut. branch) -> femoral triangle -> (branch to hip and knee articular) -> adductor canal -> saphenous nerve - Function:
i. femoral nerve:
- hip flexors: pectineus, illiacus, sartorius
- knee extensors: quadriceps femoris
ii. anterior cutaneous: anteromedial thigh
iii. saphenous nerve: medial leg - Lesion:
- hip arthroplasty
- abdomiopelvic surgery
- thigh penetrating injury
- psoas abscess, haematoma
