Interdigital Neuroma

Interdigital neuroma (sometimes called a Morton's neuroma) is the medical term for a painful condition of the digital nerves of the foot. The pain is most commonly felt between the third and fourth toes but can also occur in the area between the second and third toes. The exact cause of this problem is not clear. Some studies suggest that it is due to swelling, scarring, or a noncancerous tumor in one of the small nerves of the foot. It is not entirely understood why an interdigital neuroma forms.

Interdigital neuroma is characterised by pain and irritation of a nerve in the foot. Several nerves run into the forefoot and out to the toes between the long metatarsal bones of the feet. Each nerve splits at the end of the metatarsal bone and continues out to the end of the toe. Each nerve ending supplies feeling to two different toes. Interdigital neuroma occurs in the digital nerve, just before it divides into the two branches at the web space between the toes.

Symptoms of Interdigital Neuroma

Symptoms of interdigital neuroma typically manifest as a burning or tingling sensation in the forefoot. The pain radiates toward the lesser toes and is aggravated by shoe wear. The pain is relieved when the shoe is removed and the forefoot is massaged. Sometimes the symptoms involve specific toes. The third and fourth toes are commonly affected. Although, the second toes may be affected, if the neuroma is in the second web space.

Some patients have vague symptoms and may describe midfoot pain, pain radiating from the forefoot up the anterior ankle and leg, or a sense of pressure or numbness that is aggravated by shoe wear and exercise activities.

Interdigital neuroma may cause pain in the ball of the foot when weight is placed on the foot. Some people with this condition report feeling a painful catching sensation while walking, and many report sharp pains that radiate out to the two toes where the nerve ends. Morton's neuroma can sometimes feel like electric shocks, similar to hitting the funny bone on your elbow.

Diagnostic Procedures for Interdigital Neuroma

The diagnosis of interdigital neuroma is usually made by physical examination and review of the patient's medical history. X-rays are only useful to make sure the pain is not coming from something else. In some cases, an injection of lidocaine and cortisone into the area may help decide if the diagnosis of an interdigital neuroma is correct. However, the injection of lidocaine and cortisone is only a diagnostic procedure that results in a temporary reduction of the symptoms.

Presense of Tarsal Tunnel Syndrome

It is important to identify the presence of any nerve-related symptom, particularly tarsal tunnel syndrome. Some patients may have a combination tibial nerve irritation (a tarsal tunnel syndrome) and individual focal neuritis. In these patients, the symptoms of interdigital neuroma may become exacerbated as a result of the pressure on the tibial nerve resulting in a double crush syndrome.