Peggers’ Super Summary of Lower Limb Nerve Injuries
Lower Limb Nerve Injuries / compression:
Sciatic Nerve
 Hamstrings and all muscles below the knee are
paralysed
 Ankle jerk is absent
 All sensation lost below the knee except medially
(Medial side supplied by saphenous branch of
femoral nerve)
EXPLORE IF
 Total sciatic palsy
 Partial lesion with sever burning
 Strong evidence of reversible cause
o Cement
o Bone fragment
o Haematoma
Below knee Nerves
 Common peroneal nerve supplies lateral lower leg
and dorsum of foot
 Posterior tibial nerve supplies the sole of foot
o Motor branches are the medial and lateral
plantar nerves supplying intrinsic foot
muscles
 Anterior tibial nerve supplies 1st web space
Nerve conduction studies:
1. Motor Nerve Conduction
 Electrode placed in superficial nerve and
measures
o Measures CAMP – compound action
muscle potential, if halved patient has
lost half of nerve fibres
o Time to reach muscle
o Amplitude reaching muscle
o Nerve conduction velocity
 Conduction slowing along a whole nerve
suggests demyelination i.e. Charcot-MarieTooth syndrome
2. Sensory nerve Conduction
 Measures SNAPs – unable to measure smaller
myelinated nerves for pain and temperature
3. Electromyography (EMG)
 Hypodermic need inserted into muscle to
visualise and hear muscle recruitment
 At rest there is silence, during movement noise
and spikes
 Denervated muscles fire spontaneously (occur
7-12 days post injury)
 Chronic neuropathy shows polyphasic profile
Interpretation of Neurophysiological tests:
 Reduced motor or sensory potential suggest nonfunctioning nerves which at worse are transected
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Loss of sensory responses (SNAPs) suggest nerve
injury, presence of SNAPs suggests disc or
avulsion ie preganglionic
Conduction slowing / block suggest
NEUROPRAXIC thus potentially recoverable
Denervation on EMG 10 days post injury suggests
significant injury
Recruited motor units in a weak limbs suggest
recovery potential
Upper Limb Nerve injuries/Compressions:
MEDIAN NERVE
Carpal tunnel syndrome
 Wasting of thenar muscles
 Sensory dullness in median nerve
 Weak thumb abduction
 Phalens test > 60s of wrist flexion and tinel’s tap
test
Proximal median nerve compression
 Compression by Pronator teres or aponeurosis
 FOREARM pain
 Altered sensation in region of palmar cutaneous
branch of median nerve (exits proximal to CT)
 Phalens and tinel’s are negative
 Resisted elbow flexion in supination increases
symptoms
Anterior interosseous nerve syndrome
 MOTOR WEANKESS no sensory symptoms
 Unable to make OK sign
ULNAR NERVE
Cubital tunnel
 Facial/tunnel/FCU compression
 Hypothenar muscle wasting
 Ulnar nerve dullness
 Weakness in abductor digiti minimi or froments
sign
Guyon’s Canal
 Can be pure motor / sensory / mixed pictures
 Sensory division of ulnar nerve leave in 1st part of
Guyons canal
RADIAL NERVE
 Compression can occur at Supinator / ECRB /
radiocapitellar joint
Posterior interosseous syndrome
 Pure motor with weakness of MCPjs
 Wrist extension preserved as nerves to ECRL arise
proximal to supinator
Radial tunnel syndrome
 Mimics tennis elbow with lateral elbow pain and
painful resisted elbow extension
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