As promised, our next topic is Tarsal Tunnel Syndrome. Most people have heard of Carpal Tunnel Syndrome of the hand. It's common in people who work with their hands; whether it be checkers at the grocery store or people who type on the computer. Tarsal Tunnel Syndrome occurs in the foot, and is not necessarily the result of overuse.
People experiencing TTS complain of numbness, tingling, burning or cramping of the sole of the foot. Occasionally symptoms will radiate in to the toes as well. The symptoms will typically worsen as the day or activity goes on, and can be at their worst in the evening. These nerve symptoms are caused by irritation of the tibial nerve as it courses behind the medial malleoulus (the "inside" ankle bone). Symptoms may occur anywhere along the path of the tibial nerve as it divides and innervates the bottom of the foot. Causes of TTS vary, and include a mass in the tarsal tunnel impinging on the nerve, direct trauma to the nerve, and commonly a flattened, overpronating foot. An unstable flat foot can cause traction on the nerve which, over time, may lead to TTS. If the area behind the medial malleolus feels "full", a mass may have developed which can press on the nerve and cause symptoms.
Because of similar symptoms, TTS may be misdiagnosed as Morton's Neuroma (see previous blog post) or radiculopathy (nerve impingement in the low back). We can distinguish TTS from these other concerns by pressing or tapping on the nerve behind the medial malleolus. Patients with TTS will generally experience discomfort with these maneuvers. Occasionally an MRI will be ordered if a mass (such as a ganglion cyst or varicosities) is suspected. In our nearly 40 combined years in practice, we've never seen a malignant tumor in the tarsal tunnel region. We have, however, diagnosed a malignant tumor near the spine that was causing only foot symptoms. We may only treat the foot and ankle, but we're trained to evaluate the entire body. When our examination still leaves the diagnosis in question, nerve conduction studies may be necessary to confirm our suspicion of TTS.
If the patient has a collapsing unstable flat foot, the initial treatment will be mechanical. Taping, over-the-counter, or custom foot orthotics will be tested. Often symptoms resolve without requiring any further treatment. If mechanical control fails, we try physical therapy and/or steroid injections. Injections are geared toward reducing the inflammation around the nerve. If theses measures fail, surgery is recommended. If TTS is left untreated, the nerve irritation may progress to scarring of the nerve, at which point the symptoms may be permanent. It's this permanent nerve damage that will lead us to suggest surgery sooner rather than later.
Tarsal Tunnel Syndrome can really put a damper on your running, hiking, dancing or skiing. Don't wait if you're concerned about numbness burning, or cramping in your foot. Don't let this hobble you permanently!