Morton neuroma (interdigital neuroma), first described in 1876, is a perineural fibrosis and nerve degeneration of the common digital nerve. Morton neuroma, or Morton's neuroma, is not a true neuroma, although it results in neuropathic pain in the distribution of the interdigital nerve secondary to repetitive irritation of the nerve. The most frequent location is between the third and fourth metatarsals (third webspace). Other, less common locations are between the second and third metatarsals (second webspace) and, rarely, between the first and second (first webspace) or fourth and fifth (fourth webspace) metatarsals.
Pronation of the foot can cause the metatarsal heads to rotate slightly and pinch the nerve running between the metatarsal heads. This chronic pinching can make the nerve sheath enlarge. As it enlarges it than becomes more squeezed and increasingly troublesome. Tight shoes, shoes with little room for the forefoot, pointy toeboxes can all make this problem more painful. Walking barefoot may also be painful, since the foot may be functioning in an over-pronated position.
Patients with a Morton's neuroma typically experience a sharp, shooting or burning pain, usually at the base of the forefoot or toes, which radiates into the two affected toes. Sometimes the pain may also radiate into the foot. The pain is often associated with the presence of pins and needles and numbness.
A thorough subjective and objective examination from a physiotherapist is usually sufficient to diagnose a Morton's neuroma. Investigations such as an X-ray, ultrasound, MRI, CT scan or bone scan may sometimes be used to assist with diagnosis, assess the severity of the injury and rule out other conditions.
Non Surgical Treatment
Common treatments involve wearing different shoes or using arch supports. Resting the foot, massaging the toes and using an ice pack may work for some people. A GP or a podiatrist (foot specialist) may also recommend anti-inflammatory painkillers or a course of steroid injections. Numbing injections, in which alcohol and a local anaesthetic are injected into the affected area of the foot, may also be effective. In extreme cases, when the condition does not respond to treatment, day case surgery may be needed.
Surgery for Morton's neuroma is usually a treatment of last resort. It may be recommended if you have severe pain in your foot or if non-surgical treatments haven't worked. Surgery is usually carried out under local anaesthetic, on an outpatient basis, which means you won't need to stay in hospital overnight. The operation can take up to 30 minutes. The surgeon will make a small incision, either on the top of your foot or on the sole. They may try to increase the space around the nerve (nerve decompression) by removing some of the surrounding tissue, or they may remove the nerve completely (nerve resection). If the nerve is removed, the area between your toes may be permanently numb. After the procedure you'll need to wear a special protective shoe until the affected area has healed sufficiently to wear normal footwear. It can take up to four weeks to make a full recovery. Most people (about 75%) who have surgery to treat Morton's neuroma have positive results and their painful symptoms are relieved.