When you have foot drop, your foot drops down during walking, increasing the likelihood of your toes catching the ground, which can cause you to trip or fall. There are several underlying causes of foot drop, which can be identified based on certain tests.

EMG

Electromyography (EMG) is a test that is used to test muscle function. The test involves placing fine needles through the skin until they reach the appropriate muscle that needs to be tested. Insertion of the needle can be painful depending on the exact location of placement and whether the area is especially sensitive. After the needles are inserted, the muscle is stimulated. This can identify whether there is abnormal muscle function, such as those that might occur while the muscle is relaxed or a lack of function when the muscle is contracted. A problem with muscle function might indicate issues like paralysis or autoimmune diseases that affect the muscles. In the instance of foot drop, the muscles responsible for dorsiflexion of the foot may be paralyzed or otherwise not work correctly.

Nerve Conduction Study

Usually, a nerve conduction study is paired with an EMG and done first. The study involves testing the nerves to determine whether they are continuing to transmit stimuli and if they are transmitting stimuli, whether the transmission is slower than normal. Since the probe used triggers a reaction in the affected nerve, the test can feel awkward because the appendage being tested may jump. The specific nerve is tested at different places along its pathway to determine if there is any damage at a certain place along the nerve. Some issues that can be detected with this test include a pinched nerve or neuropathy. If there is a problem with nerve conduction, it could also be the result of chronic disease processes like multiple sclerosis. Typically, foot drop occurs because of damage or compression of the peroneal nerve, at the lateral aspect of the knee.

MRI

Magnetic resonance imagery (MRI) might be used in some cases if the problem is assessed to be higher up in the nerve. In this situation, the doctor might expect to see a tumor near the base of the spine or damaged vertebrae that are pressing on the sciatic nerve. The test involves taking many image slices of the targeted area. In the case of foot drop, the targeted area will likely be the low back to see if there is anything pressing on the spine. Another underlying cause of foot drop that may be detected is damage in the brain, such as a stroke, or other degenerative diseases of the brain and spine.

When foot drop occurs, there are several tests that can be used to identify whether the problem is a weak muscle or a nerve injury, and the exact cause and location of the injury. Once the problem is identified, the doctor can prescribe a course of treatment, such as surgery, physical therapy, or bracing to reduce the impact on gait. Talk to a neurology specialist to learn more.