Footdrop
Approach
• Bilateral
• LMN
• Peripheral neuropathy (see peripheral neuropathy)
• UMN
• Cord lesion
• Unilateral
• Once dorsiflexion impaired
• Check eversion (Common peroneal nerve = dorsiflex and eversion)DEC
• Check inversion and plantarflex = posterior tibial nerve
• If foot drop and inversion and eversion is lost with normal plantarflexion, then L5 nerve root
• If all gone = posterior tibial+common peroneal, sciatic nerve or plexus/roots
• Knee flexion intact
• Go to sensory
• Peripheral neuropathy
• Common peroneal nerve palsy (sensory loss over dorsum of the foot)
• Determine if common peroneal nerve or
• Deep branch only or
• The superficial branch only
• If knee flexion weak, test hip abduction and internal rotation and intact
• Go to sensory
• Sciatic nerve
• If hip abduction and internal rotation is weak
• Go to sensory
• Nil = anterior horn cell
• L4 and L5 dermatome = plexus or root
• Once site is located, go for the cause
• Note walking aids
Questions
• Common peroneal nerve palsy (L4 and L5)
• Anatomy
• the sciatic nerve divides at the popliteal fossa into the tibial and common peroneal nerves
• The posterior tibial nerves effects plantar flexion and inversion of the foot
• The common peroneal nerves winds round the neck of the fibula, covered by s/c tissue and skin only and prone to extrinsic compression
• It then divides into the
• Superficial branch: foot everters and sensation to lateral calves and dorsum of the foot
• Deep branch : toe dorsiflexors and dorsiflexion of the ankle and sensation to the first interdigital web space
• Therefore wasting of the peroneous and anterior tibialis muscles; weakness of dorsiflexion of the foot and eversion; foot drop and high steppage gait and loss of sensory over the lateral aspect of the calf and dorsum of the foot
• Causes of mononeuropathy (3 Sx and 3 Medical causes)
• Trauma
• Surgical
• Compression at the neck of the fibula (habitual leg crossing, cast, brace)
• Infection – Leprosy
• Inflammatory – CIDP
• Ischaemic - Vasculitis
• Part of mononeuritis multiplex (Endo, AI, infection, infiltrative and cancer)
• Ix = NCT and EMG
• Mx
• PT/OT – 90 degrees splint at night
• Sx – for severed nerve or excision of ganglion
• Sciatic nerve (L4 L5 S1 S2)
• Weakness of the knee flexion also
• Knee jerk is intact but ankle jerks affected and plantar response absent (for common peroneal nerve, all reflexes intact)
• L5 nerve root
• Weakness of hip abduction and internal rotation as well as loss of foot inversion (cf with common peroneal nerve)
C
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