FANDOM



Approach to footdrop:


1) determine if unilateral or bilateral


If lesion is unilateral:


a) Determine site of lesion i.e. common peroneal nerve / sciatic nerve / L5 radiculopathy or anterior horn cell*/ cortical lesion.

  • foot drop is not an uncommon presentation of motor neurone disease.


b) If weak ankle dorsiflexion and foot eversion, but strong ankle plantarflexion and foot inversion; numb dorsum of the foot; ankle jerk intact.... lesion is at the common peroneal nerve (usually compression at fibula neck) and NOT sciatic nerve or L5 nerve root.



c) L5 segment lesion: weak ankle dorsiflexion, foot eversion, AND foot inversion. Proceed to test hip internal rotation / abduction. Weak hip internal rotation / abduction indicates L5 radiculopathy. 'Vague subjective numbness over dorsum of foot and lateral part of leg- 'present in L5 radiculpathy but not in L5 anterior horn cell disorder.

d) For SCIATIC nerve: weak ankle dorsiflexion/plantarflexion, foot inversion/eversion; absent ankle jerk, numb whole leg and foot .

Knee flexion is often weak; but hip abduction, and internal rotation should be strong.


d) In a cortical lesion, UMN signs are present,e g Babinski reflex.

e) Clinical discriminative utility of ankle jerk is not high because many patients with any of the above lesions may have co-existent peripheral neuropathy with loss of ankle jerks on both sides.

Common peroneal nerve

Sciatic nerve

L5 radiculopathy/ant horn cell dysfunction

Cortical lesion

Ankle dorsiflexion

Weak

Weak

Weak

Weak

Ankle plantarflexion

Strong

Weak

Foot inversion

Strong

Weak

Foot eversion

Weak

Weak

Weak Weak

Hip internal rotation

Strong

Weak

Hip abduction

Strong

Weak

Ankle DTR

Present

Absent

Bilateral footdrop (causes): 1) Peripheral neuropathy


2) Bilateral radiculopathy- Bil L5 radiculopathy OR more usually..


3) Cauda equina syndrome (LMN lesion) / Conus medullaris syndrome (mixed UMN/LMN lesion)

4) Motor neurone disease

5) Spastic paraplegia--not just foot drop..and examintion will reveal more extesnive involvement of both LL.

6) Infrequently distal myopathy...not important cause as it is rare.

Community content is available under CC-BY-SA unless otherwise noted.