What is tarsal tunnel syndrome and what causes it
Tarsal tunnel syndrome results from chronic compression of the posterior tibial nerve — the largest nerve that enters the foot and branches out across the bottom of the foot toward the toes. It passes from the lower leg, along the inner side of the ankle, just below the bony protrusion (the medial malleolus), and through a passage of bone and muscle called the tarsal tunnel. When functioning properly, the posterior tibial nerve provides sensations to the underside of the foot.
The most common cause of tarsal tunnel syndrome is when the arch of the foot flattens excessively (cavus or flat foot) when walking. Typically the problem progresses slowly over decades, resulting in the posterior tibial nerve stretching and flattening as it passes through the tarsal tunnel. Other causes may include soft tissue formations or varicose veins along the tarsal tunnel pressing against the nerve and causing changes to sensations in the foot.
Common tarsal tunnel syndrome symptoms
The typical symptoms of tarsal tunnel syndrome include burning or numb sensations along the bottom of the foot, most often along the edge. However, the exact location of the symptoms may vary from patient to patient due to how the nerve branches out to multiple areas of the foot. Most patients experience a slow, progressive burning sensation developing over many years.
Any tingling, numbness, or changes in sensation in the feet, whether in one foot or both, should be evaluated by a podiatrist as soon as possible. Tarsal tunnel syndrome shares similar symptoms with diabetic or alcoholic neuropathy, nerve compression higher in the body, or poor circulation — all of which could lead to a number of serious complications if left untreated. Your podiatrist is well equipped to differentiate between the conditions and start you on an appropriate treatment plan.
Diagnosis of tarsal tunnel syndrome begins with your podiatrist discussing your symptoms and medical history, as well as with a physical examination of the affected foot and ankle.
Your podiatrist will likely ask you when your symptoms began, what you were doing at the time, and how the symptoms have changed over time. You may also be asked if anything makes the symptoms better or worse.
Your podiatrist will examine your lower legs, ankles, and feet, with the focus the inner side of the ankle, the bottom of the foot, and the arch. You may be asked to walk a short distance in order for your podiatrist to observe the movement of your feet and ankles while walking to evaluate cavus (flat foot) or over-pronation, which may exacerbate tarsal tunnel syndrome. Your podiatrist may also feel and look for swelling on the inner side of the ankle, just below the medial malleolus on the inner side of the ankle. Slight swelling in this region is common with tarsal tunnel syndrome. Part of your examination may also include your podiatrist tapping the affected area with either fingers or a neurological hammer (sometimes called a reflex hammer) to see if the tingling sensations are reproducible.
Depending on your podiatrist’s findings during your examination, you may be sent for x-rays, an MRI or other studies of your feet and ankles to rule out other conditions that may or may not be contributing to your symptoms. However, neither nerves nor soft tissue masses are visible on x-rays and while an MRI may show soft tissue masses, it is not a good diagnostic tool for evaluating nerve damage. In some cases, a nerve conduction study may be ordered to investigate damage to the posterior tibial nerve; however, if you are in the early stages of tibial tendon syndrome, a nerve conduction study may not show any damage.
Tarsal tunnel syndrome treatment
Treatment of tarsal tunnel syndrome is typically conservative with a focus on correction abnormal foot motion. The first line of defense is custom-made orthotics — prescription inserts for your shoes that correct abnormal pronation, often combined with a careful regimen of calf stretching. Tight calves may add to the tension on the posterior tibial nerve and tarsal tunnel. Depending on the degree of discomfort, some patients may also gain some relief from non-steroidal anti-inflammatory medications, corticosteroids, or certain B-vitamin supplements. In rare cases surgical intervention to remove soft tissue masses may be necessary. In more advanced stages where nerve damage is already present, treatment may be focused on pain management and comfort measures.
If you have experienced any burning, tingling, or numbness in your feet, call Kansas City Foot Specialists right away at (913) 338-4440 to schedule an evaluation. Our podiatrists are here to evaluate your foot-related needs and to keep you going, step-by-step.