S6: lower limb consolidation Flashcards
Describe the Seddon classification
Class I neurapraxia: mildest type of nerve injury & temporary physiological block of conduction in the affected axons without loss of axonal continuity – sensory and motor dysfunction distal to the site of injury
Class II axonotmesis: loss of continuity of the axons & myelin sheath, endometrium, perineurium and epineurium are preserved, Wallerian degeneration takes place distal to the site of injury
Class III neurotmesis: partial/complete division of axons, endoneurium, perineurium & epineurium, sensory, motor & autonomic defects are severe – surgical intervention is always required
Describe the clinical presentation of nerve root injury due to prolapsed intervertebral disc
Most common sites for slipped disk are L4/L5 and L5/S1
L4 root compression – weakness of ankle dorsiflexion & paraesthesia in medial leg & medial ankle
L5 root compression – weakness of extension of great toe & paraesthesia in lateral leg & dorsum of foot
S1 root compression – weakness of ankle plantarflexion & paraesthesia in the lateral border of foot, sole of foot & heel (ankle reflex will be diminished/absent)
Describe the clinical presentation of the Trendelenburg sign
Superior gluteal nerve injury = pelvis on the contralateral side will drop and foot will catch the ground on walking unless the patient lurches their trunk towards the affected side
Describe the clinical presentation of Piriformis syndrome
Compression of the sciatic nerve by the piriformis muscle
Symptoms: dull ache in the buttock, typical sciatica pain in thigh, leg & foot, pain when walking stairs/inclines, increased pain after prolonged sitting & reduced range of motion of the hip joint
Caused by spasm of piriformis muscles usually due to overuse
Describe the clinical presentation of meralgia paraesthetica
Compression of the lateral cutaneous nerve as it pierces the inguinal ligament or as it pierces the fascia lata in the thigh
Patient experiences burning/stinging sensation over the anterolateral aspect of the thigh
Describe the clinical presentation of femoral nerve injury
Uncommon - may result from penetrating wounds to the groin or hip/pelvis fractures
Weakness and wasting of quads, sartorius, iliacus and pectineus
Hip flexion is compromised, extension of the knee will be lost and knee jerk reflex will be absent
Paraesthesia on the anteromedial thigh & medial leg, sometimes extending down the medial border of the foot
Describe the clinical presentation of tibial nerve injury in the popliteal fossa
Patient will have paralysis of gastrocnemius & soleus -> will not be able to plantarflex
Flexion of toes will be lost, inversion of midfoot will also be compromised
Calcaneovalgus posture
Loss of sensation on the sole of the foot (except for small parts supplied by sural & saphenous nerves)
Describe the clinical presentation of injury to common peroneal (fibular) nerve or its deep or superficial branches
Common fibular nerve: paralysis of ankle evertors & dorsiflexors, loss of sensation of lateral leg & dorsum of the foot
Superficial fibular nerve: loss of active eversion, sensory loss of most of the dorsum of the foot & anterolateral leg, sparing the 1st dorsal web space
Caused by ankle surgery & ankle arthroscopy portal placement
Deep fibular nerve: loss of active ankle dorsiflexion (FOOT DROP), sensory loss in the 1st dorsal web space
Describe the clinical presentation of injury to the saphenous nerve
Loss of sensation to medial leg and ankle (+ sometimes medial border of the foot)
Injured in venous cutdown & vein harvest for bypass surgery
Describe the clinical presentation injury to the sural nerve
Paraesthesia of the lateral ankle and lateral border of the foot
Note: the sural nerve can be harvested for nerve grafting & reconstructive surgery (relatively minor sensory deficit)
