Differential Diagnosis for Acute Foot Drop
- Single most likely diagnosis
- Peroneal nerve compression or injury: This is often due to compression of the peroneal nerve as it wraps around the fibular head, leading to weakness or paralysis of the muscles it supplies, which are primarily responsible for foot dorsiflexion (lifting the foot up).
- Other Likely diagnoses
- L5 radiculopathy: This refers to damage or irritation of the L5 nerve root, which can cause foot drop among other symptoms. It's a common cause due to the nerve root's involvement in controlling the muscles responsible for foot dorsiflexion.
- Stroke or cerebral vasculature issues: Although less common than peripheral causes, a stroke affecting the motor areas of the brain responsible for lower limb control can lead to foot drop.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cauda equina syndrome: This is a serious condition where the nerves in the spinal canal are compressed, leading to potential loss of bladder and bowel control, as well as lower limb weakness, including foot drop. It requires urgent medical attention.
- Spinal cord injury or compression: Similar to cauda equina syndrome, any injury or compression affecting the spinal cord can lead to acute foot drop and is a medical emergency.
- Rare diagnoses
- Guillain-Barré Syndrome: An autoimmune disorder where the body's immune system mistakenly attacks part of its peripheral nervous system, potentially leading to muscle weakness, and in some cases, foot drop.
- Neuropathies (e.g., diabetic neuropathy, if presenting acutely): While more commonly associated with gradual onset, certain neuropathies can present with acute symptoms, including foot drop, especially in the context of diabetes or other systemic diseases.
- Tumors (e.g., schwannoma, neurofibroma): Rarely, tumors affecting the nerves can cause foot drop, either by direct compression of the nerve or by affecting the surrounding tissues.