What is Foot Drop?
Foot drop is the clinical diagnosis for a patient who is unable to dorsiflex, or pick up the ankle, when walking. Additionally, the patient may be unable to bring the ankle outward, resulting in rolling of the foot. It is called "foot drop" because the foot literally drops due to the inability to lift the ankle.
Causes of Foot Drop
Foot drop can stem from various causes, such as a herniated disc in the spine that compresses the nerve root at a very high level. It can also originate from more rare conditions, like a tumor in the brain or spinal cord. The condition might arise from issues with the sciatic nerve or the common peroneal nerve branch of the sciatic nerve when these nerves are pinched, compressed, or injured. Sometimes, a ganglion cyst pressing on the nerve along its pathway can lead to foot drop. Diabetes can also increase the risk of nerve compression due to swelling, particularly in the common peroneal nerve, which, when swollen, may get pinched right below the knee at the fibular head.
Symptoms and Diagnosis
Patients with foot drop often experience numbness that affects the top of the foot. Notably, the numbness typically does not extend to the sole of the foot if the issue is due to the common peroneal nerve. A key symptom many patients notice is difficulty walking, often hearing their foot flap against the ground or catching their toes on door jambs and carpet edges.
When diagnosing foot drop, a comprehensive history is crucial. Common diagnostic tools include MRI scans of the lumbar spine, pelvis, sciatic nerve, and sometimes the knee. Ultrasound may also be used to trace the sciatic nerve from the buttock to the leg. Electromyography (EMG) and nerve conduction studies performed by neurologists or electrophysiologists can help pinpoint whether the lesion is in the spine, buttock, leg, or at the level of the knee.
The physical exam is an invaluable diagnostic tool, especially for peripheral nerve surgeons. Evaluating previous surgical incisions or injuries, such as hip or knee replacements or fractured femurs, is also critical for identifying the location of nerve injury or entrapment.
Treatment Options
The treatment for foot drop largely depends on the diagnosis and where the nerve is pinched. If the nerve is compressed, decompression surgery may be necessary. If a ganglion cyst or lesion is causing the compression, these will need to be removed to relieve pressure on the nerve.
Time is of the essence for treating foot drop. Once paralysis sets in, there is a window of about one year to 18 months to recover function. Early referral to a specialist is crucial for the best outcomes.
Recovery From Foot Drop Treatment
Recovery from foot drop can vary widely based on the cause and severity of the injury. If the nerve compression is relieved promptly, recovery can occur within minutes to hours after surgery. However, if the nerve has been pinched for an extended period and severely damaged, it may take months to recover, and in some cases, full recovery may not be possible.
Expertise in Foot Drop Treatment
As peripheral nerve specialists, we treat many patients with foot drop. We encourage early consultation, especially if you notice changes in your gait or experience foot slapping but still retain some motor function. Early intervention can significantly improve the chances of a full recovery before the nerve deteriorates completely.
If you have experienced foot drop for a prolonged period, we are still available to evaluate your condition and determine if any further action can be taken from a peripheral nerve standpoint.
