Morton’s neuroma is one cause of metatarsalgia – pain in the ball of the foot. It is due to inflammation and thickening of a digital nerve in the foot. “Neuroma” means nerve tumour, which is this instance simply means a benign enlargement of the nerve, and not malignancy.
The cause of nerve enlargement is thought to be repeated injury. The nerve becomes compressed in between the metatarsal heads when standing and walking. This most often occurs in tight shoes, high heels or thin hard soles. It usually occurs most commonly between the 3rd and 4th toes or 2nd and 3rd toes, and can occur in both feet. The incidence is 8-10 times more common in women.
Symptoms of Morton’s Neuroma
The symptoms are pain and numbness in a specific spot in the ball of the foot, sometimes radiating into the toes. At times, the pain may be absent and at other times severe enough to cause you to stop and take off the shoe. It may feel like a marble or a stone under the foot moving around and sometimes causing a sharp “snap” to be felt. The examining orthopaedic surgeon can sometimes feel this by pressing on the foot. Testing with a pin may reveal numbness in the toes.
Treatment of Morton’s Neuroma
Diagnosis can be difficult at first and several examinations may be necessary as the condition tends to get worse over time. With repeated injury the nerve becomes larger, and as it becomes larger it is more easily injured. Ultrasound or MRI scans can help to identify the “growth”.
The first step in treatment is to modify the shoes. A pad or orthotic in the shoe, and an extra wide soft shoe will help. Also a cortisone injection around the nerve may help reduce swelling and inflammation, this will also help to localise the problem.
Surgery to remove the neuroma can also be carried out. It is has an 80% success rate. Since the inflamed nerve is removed there is numbness in the toes and in the ball of the foot afterwards. This is not usually a problem and becomes less so with time.
There are a couple of post surgery risks, that of persisting pain which may be due to irritation at the cut end of the nerve and if this is the case then additional surgery may be required. Infection is also a possible complication as the foot is prone to post-operative swelling and bleeding. An adequate period of rest and elevation following surgery is required to help prevent this complication.