Peripheral nerve examination
Sciatic nerve
Common Peroneal nerve
Supervisor: Miss Liau
CLASSIFICATION OF
PERIPHERAL NERVE INJURY
CLASSIFICATION
SEDDON’S
CLASSIFICATION
1. Neuropraxia:
• a reversible block to nerve conduction in which
there is loss of sensation & muscle power,
followed by spontaneous recovery after a few
days or weeks.
• The nerve is intact but there is demyelination
of axons in some segments
• seen in ‘Saturday night palsy’, torniquet palsy
2. Axonotmesis :
- seen typically after closed fractures and dislocations.
-axonal interruption.
- loss of conduction but the nerve is in continuity and the
neural tubes are intact.
- Wallerian degeneration. Distal to the lesion, and for a few
millimetres retrograde, axons disintegrate and are resorbed by
phagocytesproliferation of Schwann cells and fibroblasts
lining the endoneurial tubes.
-The denervated target organs (motor end-plates and sensory
receptors) gradually atrophy, and if they are not reinnervated
within 2 years they will never recover.
-Axonal regeneration starts within hours of nerve damage
- These axonal processes grow at a speed of 1–2 mm per day.
3. Neurotmesis :
• disruption on the continuity of axon &
supporting structures (nerve trunk)
• usually in open wound
• some recovery possible but much more likely
with surgical nerve repair
• Rapid wallerian degneration also occur, but
damage to endoneural tube is extensive and
multiple segments,so regenerated fibres
usually mingles with proliferated schwann cells
and fibroblast to form Neuroma.
Treatment Principles
Nerve Exploration
Closed injuries usually recover spontaneously and it is worth waiting
until the most proximally supplied muscle have regained function.
Exploration is indicated:
▪ (1) if the nerve was seen to be divided and needs to be repaired
▪ (2) if the type of injury (e.g. a knife wound or a high energy injury)
suggests that the nerve has been divided or severely damaged
▪ (3) if recovery is inappropriately delayed and the diagnosis is in
doubt.
Primary Repair
▪ A divided nerve is best repaired as soon as
possible
▪ Primary suture at the time of wound toilet
has considerable advantages:
– the nerve ends have not retracted much
– their relative rotation is usually undisturbed
– there is no fibrosis.
Delayed repair
▪ Late repair, i.e. weeks or months after the injury, may be indicated
because: (1) a closed injury was left alone but shows no sign of
recovery at the expected time; (2) the diagnosis was missed and the
patient presents late; or (3) primary repair has failed.
▪ The options must be carefully weighed: if the patient has adapted to
the functional loss, if it is a high lesion and re-innervation is unlikely
within the critical 2-year period, or if there is a pure motor loss which
can be treated by tendon transfers, it may be best to leave well
alone.
Nerve Grafting
▪ Free autogenous nerve grafts can be
used to bridge gaps too large for direct
suture. The sural nerve is most
commonly used; up to 40 cm can be
obtained from each leg. Because the
nerve diameter is small, several strips
may be used (cable graft).
▪ The graft should be long enough to lie
without any tension, and it should be
routed through a well-vascularized bed.
The graft is attach at each end either by
fine sutures or with fibrin glue.
Nerve transfer
▪ In root avulsions of the upper brachial plexus,
too proximal for direct repair, nerve transfer can
be used. The spinal accessory nerve can be
transferred to the suprascapular nerve, and
intercostal nerves can be transferred to the
musculocutaneous nerve.
▪ If biceps has failed because too much time has
passed since the injury, an entire muscle (gracilis
or latissimus dorsi) can be transferred as a free
flap, attached between elbow and shoulder and
then innervated by joining intercostal nerves or
the spinal accessory nerve to the stump of the
original nerve supplying that muscle.
Peripheral nerve examination
Sciatic nerve
Common Peroneal nerve
Supervisor: Miss Liau
SCIATIC NERVE INJURY
Click icon to add picture
L4-L5, S1-S3
Click icon to add picture
Causes
▪ Gunshot wounds
▪ Operative (iatrogenic) accidents
– Complication of hip replacement
– Usually partial lesion
▪ Misdiagnosed as a common peroneal compression injury
▪ Traction and compression are more common and
occur with local trauma
▪ Fractures
– Acetabulum fracture
– Lumbar spine injury
– Fracture dislocation of hip
– femur
Signs & Symptoms
▪ Foot drop
▪ Numbness and parasthesia in the leg and foot
▪ Painful limb (direct injury to nerve)
▪ Muscles below the knee are paralysed and sensation is absent in most
of the leg
▪ If only the deep peroneal component of the nerve is affected, paralysis
is incomplete and the signs are easily mistaken for common peroneal
nerve injury
▪ Late features : wasting of calf muscles and trophic ulcers
Treatment
▪ Iatrogenic lesions
– Direct injury : the nerve should be explored
– Otherwise : wait for spontaneous recovery
– In all cases : foot should be splinted to prevent a
permanent equinus deformity
PERONEAL NERVE INJURY
L4-S3
▪ Part of sciatic nerve (L4, L5, S1, S2)
▪ Supplies short head of biceps femoris in thigh, crosses post to lateral
head of gastrocnemius and becomes subcutaneous behind head of
fibula
▪ Divides into superficial & deep peroneal nerves
▪ Gives off lateral sural cutaneous branch which joins with medial sural
cutaneous nerve a sural nerve
Causes
▪ Trauma or injury to the knee
▪ Injury during knee surgery
▪ Lateral ligament injuries
– Knee forced into varus
– Pressure from a splint or a plaster cast
– Lying with the leg externally rotated
Signs & Symptoms
▪ Foot drop
– Both dorsiflexion and eversion are weak. Causing a tendency to trip and fall while
walking
▪ Loss of sensation over the front and outer half of the leg and dorsum of
the foot
▪ Superficial branch
– Peroneal muscles are paralysed, eversion are lost, loss of sensation over the outer
side of leg and foot
▪ Deep branch
– Threatened in anterior compartment syndrome
– Pain, abnormal sensation and weakness of dorsiflexion, sensory loss around the
first web space on the dorsum of foot
Treatment
▪ Threatened compartment syndrome
– Treat as emergency and may need immediate decompression
▪ Open wound : explore nerve and suture
▪ Apply splint to control foot drop while recovery is awaited
▪ Protect skin against ulceration
▪ No recovery :
– Improve disability by transferring the tibialis posterior tendon to the
dorsum of the foot ( acts as dorsiflexor)
– alternative : operative stabilization of hindfoot
– Permanent splintage
Examinations
1. Neurological examination
2. Special test
– Straight leg test – lumbar radiculopathy
– FAIR test – Piriformis syndrome
– FABER test – SI Joint pathology, iliopsoas tightness
