Raj N. Sureja, MD
When we hear the term “pinched nerve”, we typically think of the neck or lower back. But pinched or compressed nerves can occur anywhere in the body and the foot or ankle are no exception. When a bone, tendon or ligament presses against a nerve, pain and dysfunction can result.
Common Types of Nerve Compression in the Foot or Ankle
When a nerve in the foot is compressed or irritated, it responds by thickening the tissue around it, so that it forms a tiny nodule, called a neuroma. Neuromas are also described as nerve tumors. A common neuroma in the foot is the Morton’s Neuroma, which normally occurs in the ball of the foot, in area between the bones of the third and fourth toes. The pain is often described as feeling like you have a pebble in your shoe under the ball of your foot, and your toes can burn, sting or feel numb.
Another common nerve compression of the foot is Plantar Nerve Entrapment. The pain is often confused with that of Plantar Fasciitis, but there are differences. Plantar Fasciitis usually is a stabbing pain in the heel that is worse first thing in the morning upon rising and weight bearing, but diminishes with stretching and use. Plantar Nerve Entrapment causes chronic burning heel pain that doesn’t diminish when not weight bearing, is worse at night and the pain worsens with stretching and standing.
Tarsal Tunnel Syndrome occurs when the posterior tibial nerve is compressed within the tarsal tunnel (a channel containing nerves, veins, arteries and tendons, covered by a thick ligament) in the ankle. It is comparable to what happens in Carpal Tunnel Syndrome in the wrist. The nerve can be compressed due to a cyst, varicose vein or bone spur, from an injury or disease or because a person has flat feet. The pain can be sharp, like an electric shock, accompanied by numbness, burning or tingling. It is typically felt on the inside of the ankle and the bottom of the foot, but may refer elsewhere on the foot and even the calf.
Diagnosis of Nerve Compression Issues in the Foot
Patients are typically x-rayed to see if there are any structural/mechanical issues with their bones, like arthritis, bone spurs or fractures. A physical exam will be done and the patient will be asked to walk, flex and rotate their foot. The physician will touch and press different areas of your foot to illicit a pain response. The patient will be asked many questions, like “when did the pain start? When is it worse or better? What at home remedies have you tried?”
Your physician may also try to rule out a condition to make a definitive diagnosis of another. You may be injected with a steroid/numbing agent to see if it alleviates or doesn’t decrease the pain. This is called a diagnostic injection.
When nerve compression is diagnosed, the first rule of treatment is to eliminate the compression on the nerve. Conservative treatment will be tried first for non-structural issues. Anti-inflammatory medications may be given orally or by injection. Activity modification will be needed to allow the irritation to subside and the nerve to heal. Physical Therapy will be recommended. Buying more supportive and better fitting shoes may be suggested. Orthotic devices can also be very helpful in providing padding, bracing or lift to the foot within the shoe, so that the angry nerve can heal without more irritation.
Neuromas can be treated by radio frequency ablation, which is a simple, minimally-invasive, in-office procedure. This procedure uses a high frequency to heat the protein sheath covering the nerve until it breaks down. When this happens, the nerve fibers stop transmitting pain signals. Done under local anesthetic, the patient can go home immediately after the procedure.
If the nerve is being compressed by a cyst, the cyst may need to be drained or surgically removed. Mechanical issues, caused by bone spurs from arthritis, will need to be surgically addressed so that the nerve can decompress. If a tendon is pressing on the nerve, the physician may need to release it to relieve pressure on the tendon.