Ses 6 Msk Flashcards
Severity of nerve diseases Seddon classification
Neurapraxia - block of conduction at area of injury so sensory and motor dysfunction distal to the area.
No loss of axonal continuity. The endo, peri and epineurium are intact. No Wallerian degeneration.
Full recovery in days to weeks.
Axonotmesis
Loss of continuity of the axons. Endo, peri and epineurium are preserved.
Wallerian degeneration commences within 24hrs distal to site of injury.
Axonal regeneration (1-3 mm/day) so no surgical intervention. Time to recovery= distance from injury to the target organ.
Neurotmesis
partial or complete division of the axons, endo, peri and epineurium.
Wallerian degeneration.
sensory, motor and autonomic defects are severe.
scar tissue between the divided fascicles prevents regeneration so Surgical intervention.
Wallerian degeneration notion and traumatic neuroma
After injury, distal axon disintegrates.
macrophages and Schwann cells phagocytose the debris.
Schwann cells proliferate and by three weeks they form lines called “Bands of Bunger” that guide the direction of axon regeneration.
During this time, the denervated muscle undergoes atrophy but if axonal regeneration is successful muscle restored - months.
However
if the severed ends are not surgically reapposed unregulated regeneration occurs.
Disordered proliferation of axons from the severed end leads to traumatic neuroma = painful.
muscle is replaced by fibrous tissue and fat.
Piriformis syndrome
compression of the sciatic nerve by the piriformis muscle (not spinal nerve roots).
Symptoms:
• A dull ache in the buttock
• Typical sciatica pain in the thigh, leg and foot
• Pain when walking up stairs or inclines
• Increased pain after prolonged sitting
• Reduced range of motion of the hip joint
Causes:
spasm of the piriformis muscle, usually due to overuse (e.g. in athletes, cyclists)
direct trauma
Treatment:
activity modification
NSAIDs
Physio
Meralgia paraesthetica
compression of the lateral cutaneous nerve of the thigh.
Comes from posterior abdominal wall to pierce the lateral part of the inguinal ligament and becomes compressed.
Causes:
Obesity(compression by abdominal fat)
Pregnancy
Tool belt, tight clothing
Symptoms(aggravated by standing and relieved by lying down with hip flexed):
Supplies anterolateral part of thigh so stinging sensation there.
Reduced sensation
Positive Tinel’s sign - percussing at site of compression causes parathesisa in nerve distribution.
Diagnosis:
No motor problems
Exclude tumour causing compression
Treatment:
Don’t wear tight clothes
Local nerve blocks
Surgery to release the trapped nerve
Tibial nerve injury notion
Pathway:
In thigh - crosses popliteal fossa
In leg - Posterior to soleus and between FDL and FHL
In ankle - behind medial malleolus
In sole - medial calcaneal branch, medial and lateral plantar branches
Patient presents with calcaneovalgus foot as these actions are unapposed.
Weakened inversion (T. ant can still do some) and no plantarflexion
Loss of flexion of toes
Sensory loss in sole and heel of foot
Superficial peroneal nerve injury
Pathway:
From neck between peoneous longus and brevis and lateral border of EDL.
Then cutaneous
Then dorsum
Fracture of proximal fibula and penetrating injury to lateral leg would cause:
Loss of eversion
Sensory loss in distal anterolateral leg and dorsum of foot
Lateral approach to ankle joint surgery causes:
Sensory loss of dorsum of foot
Deep peroneal nerve injury
Pathway:
Neck of fibula
Pierces EDL
Next to A.tibial artery
In ankle divides into medial and lateral branches
Causes:
Most common mononeuropathy - Motor neurone disease, vasculitis, diabetes
Total knee replacement
Loss of sensation in 1st webspace in dorsum of foot
Loss of dorsiflexion (foot drop)
Loss of extension of toes
Common peroneal nerve injury
Pathway:
L4-S2
Superior popliteal fossa
Medial border of biceps femoris
Gives off cutaneous brach
Pierces peroneus longus and divides into 2
Causes:
Prolonged bed rest
Pressure from tight cast
Fractures of neck of fibula
Loss of sensation in lateral leg and lateral border of foot.
Loss of eversion (so present with inverted ankle) and dorsiflexion (foot drop)
Loss of toe extension
Femoral nerve injury
Causes:
Trauma to hip eg hip dislocation or fracture
Hip replacement surgery
Penetrating wound to groin
Weakened hip flexion as psoas major can still function
No knee extension
Loss of sensation in anteromedial thigh and medial leg and medial border of foot
Saphenous nerve injury
Causes:
Surgery to distal tibia or medial malleolus
Cut-down for emergency access
Harvest for bypass surgery
Branches from femoral nerve in femoral triangle
Goes through adductor canal
Pierces fascia lata in medial leg so loss of sensation in medial leg
Goes till ball of foot - 1st MTPJ
Superior gluteal nerve injury
Pathway:
dorsal divisions of L4, L5 and S1.
leaves the pelvis through the greater sciatic foramen above the piriformis muscle.
accompanied by the superior gluteal artery and vein.
Superior - loss of innervation to G.med and min (also tensor fascia lata) so pelvis drops to unaffected side when standing on the leg of affected side.
In Trendelenberg gait patient will use trunk muscles to lift pelvis so lurches to affected side.
Sural nerve injury
From lateral cutaneous branch of tibial nerve and medial cutaneous branch of common peroneal nerve.
Posterior to lateral malleolus
Loss of sensation in posterolateral leg and lateral border of foot.
Harvested for nerve grafting and reconstructive surgery
