A Morton’s neuroma, or interdigital neuroma, is a painful condition which involves a nerve on the plantar aspect (bottom) of the foot. Occasionally a neuroma develops following a bruising injury to the sole of the foot, such as might be caused by jumping onto a rock or other objects, but in general, the origin of the condition is unknown.
The exact cause of Morton’s neuroma is not known. However, it is thought to develop as a result of long-standing (chronic) stress and irritation of a plantar digital nerve. There are a number of things that are thought to contribute to this. Some thickening (fibrosis) and swelling may then develop around a part of the nerve. This can look like a neuroma and can lead to compression of the nerve. Sometimes, other problems can contribute to the compression of the nerve. These include the growth of a fatty lump (called a lipoma) and also the formation of a fluid-filled sac that can form around a joint (a bursa). Also, inflammation in the joints in the foot next to one of the digital nerves can sometimes cause irritation of the nerve and lead to the symptoms of Morton’s neuroma.
A Morton’s neuroma causes a “burning” sharp pain and numbness on the bottom of the foot in the involved area, and this pain and numbness can radiate to the nearby toes. The pain is usually increased by walking or when the ball of the foot is squeezed together and decreased with massaging. It may force a person to stop walking or to limp from the pain.
Morton’s neuroma is usually diagnosed by your doctor listening to your symptoms and examining your foot. Sometimes your doctor can feel the ‘neuroma’, or an area of thickening in your foot, which may be tender. Sometimes, your doctor may suggest an ultrasound scan or MRI scan to confirm the diagnosis but this is not always necessary. Some doctors inject a local anaesthetic into the area where you are experiencing pain. If this causes temporary relief of pain, burning and tingling, it can sometimes help to confirm the diagnosis and show the doctor where the problem is.
Non Surgical Treatment
Depending on your overall health, symptoms and severity of the neuroma, the condition may be treated conservatively and/or with surgery. Non-surgical methods for neuroma are aimed at decreasing and/or eliminating symptoms (pain). Wear proper supportive shoes. Use an arch support. Wear shoes with a wide toe box. Modify your activities. Lose weight. Wear shoes with cushion. Prescribe an oral anti-inflammatory medication. Anti-inflammatory medication is useful to significantly reduce pain and inflammation. A physical therapist may perform ultrasound and other techniques to reduce inflammation. You will also be instructed how to stretch your foot and leg properly. Padding and/or cushioning of the ball of the foot is an effective method of preventing physical irritation with shoes. A custom foot orthotic is a doctor prescribed arch support that is made directly from a casting (mold) of your feet, and theoretically should provide superior support compared to shoe insert that you would purchase from a pharmacy. A cortisone injection is a powerful anti-inflammatory medication that is used to rapidly reduce the pain associated with an inflamed nerve. The pain relief that you may experience from the injection(s) is often temporary. Typically injection(s) are administered once every 2 months for a total of 3 injections or until the pain is resolved. A sclerosing alcohol injection is placed around the involved nerve to weaken its capacity to report pain. In other words, the alcohol injection will ?deaden? the affected nerve. The pain relief that you may experience from the injection(s) can be permanent. Typically injection(s) are administered once every week for a few weeks until the pain is resolved.
If pain persists with conservative care, surgery may be an appropriate option. The common digitial nerve is cut and the Mortons neuroma removed. This will result is numbness along the inside of the toes affected, and there is a small chance the end of the nerve will form a Stump Neuroma. Approximately 75% of people receive symptom resolution for Mortons Neuroma with conservative care.
While Morton?s Neuroma has been an ongoing topic of clinical investigation, the condition is in some cases difficult to either treat or prevent. Experimental efforts involving the injection of muscle or bone with chemicals such as alcohol, as well as suturing, and covering affected areas with silicone caps have been attempted, with varying success.