Approach to Foot Drop

Question 1

Unilateral foot drop

Answer 1

Clinical manifestation of weakened tibialis anterior muscle leading to ankle dorsiflexion weakness and 1st dorsal webspace numbness
“All foot drops lead to tibialis anterior muscle”

Also look at extensor digitorum brevis (muscle bulk)
- Also innervated by deep peroneal nerve

Innervating nerves and muscles (bottom to top)
- Offer distal myopathy, NMJ disease as cause
- Deep peroneal nerve
- Branch of common peroneal nerve
- Sciatic nerve
- Lumbar roots and sacral plexus
- Cortical foot drop

Question 2

Three milestones

Answer 2

Hip extension - sacral plexus (very high)
Knee flexion - sciatic nerve
Hip abduction - L4/L5 level

?? - attach picture and matrix table

Question 3

Very high level foot drop
- Sacral plexopathy

Answer 3

Localising features
1. Hip extension weakness - gluteus maximus
- Innervated by inferior gluteal nerve (from L5, S1, S2)

2. Hip abduction weakness - gluteus medius and minimus
   - Innervated by superior gluteal nerve (from L4/L5)
3. Variable sensory deficit, commonly L4/L5

Question 4

High level foot drop
- Sciatic nerve
- Tibial nerve

Answer 4

Localising features
1. Knee flexion weakness - hamstrings
- Innervated by sciatic nerve

2. Plantar flexion and inversion weakness - gastrocnemius, soleus, tibialis posterior
   - Innervated by tibial nerve
   - Inversion by L4/L5 and plantarflexion by S1
   (Tibialis anterior inverts ankle too, thus plantarflexion determines tibial nerve involvement)
3. Sensory deficit over common peroneal and tibial nerve

Question 5

Common peroneal foot drop

Answer 5

Localising features
1. Ankle eversion weakness - peroneus longus and brevis
- Innervated by superficial peroneal nerve (branch of common peroneal nerve)

2. Sensory deficit over lateral aspect of calf and dorsum of foot

Question 6

Cortical foot drop and gait

Answer 6

1. Differentiating UMN vs LMN
2. Significant gait difference
   - UMN - circumduction gait (spasticity, pyramidal pattern of weakness over hip and knee flexors - difficult clearing foot off the ground)
   (Strumpell’s tibialis phenomenon)

• LMN - high stepping gait and flexing hip to elevate dropped foot off the ground