Foot Drop

Always a difficult one, make sure its clear in your head

First, you will notice the foot drop when they walk – it will still be necessary to do the full lower limb exam.

Think about it using the following flow chart;

SINGLE LEG

FOOT DROP (L4,5)

Ankle Jerk Present Ankle Jerk Absent

(S1, S2 intact)

Inversion Present Inversion Absent Complete loss of sensation/ power below knee

Loss of sensation in dermatome(s)

Sensory Loss L5 root lesion Sciatic nerve

(big toe extension should be weak)

Cauda Equina lesion

Lumbosacral plexus

Sensory loss between 1^st and 2^nd toe Lateral foot/leg

Deep peroneal branch Common Peroneal nn

Of Common Peroneal (look/ feel the fibular head)

The common peroneal splits into superficial and deep peroneal branches. The superficial supplies the peronei and the deep supplies tibialis anterior, EDL, EHL and the deep sensory branch to the thong area.

Also remember that weak hip abduction and knee flexion also indicate L5 weakness.

BOTH LEGS

Reflexes normal Reflexes Increased

Consider myopathy, distal neuropathy ?Pretectal gyrus

Spinal cord (Conus meduallaris)

The signs of the conus medullaris and cauda equina syndromes can be asymmetrical and you must remember to examine the buttocks and back of legs looking for sensory change.