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Morton's Neuroma
Definition:
A neuroma is a benign enlargement of tissue around a nerve. Although it is sometimes referred to as a benign tumor, it is not a cancer and will not spread to other parts of your body. A Morton’s neuroma affects a nerve that leads to your toes and is usually found in the space between the third and fourth toes. It is sometimes called an intermetatarsal neuroma due to its location. Irritation, caused by compression of the nerve, can lead to the development of a neuroma. Women are much more likely to develop a Morton’s neuroma than men, probably due to the types of shoes that women tend to wear.
Causes:
Any situation that constricts and irritates the nerves leading to the toes increases the risk of a neuroma forming.
The most common cause is the wearing of certain types of shoe. Heels that are higher than 1 inch place more weight and pressure on the ball of the foot, and toe boxes that taper to a narrow point force the toes together in a way that compresses the nerves.
Certain irregularities in the structure of the foot can predispose a person to develop a Morton’s neuroma. Examples of such irregularities are flat feet, overly flexible feet, bunions and hammertoes.
Some activities, for instance sports that involve running or repeated pushing off from the balls of the feet, may trigger the formation of a neuroma, as can a direct injury to the foot.
Symptoms:
Symptoms often appear gradually and can first be felt as an occasional pain on wearing certain shoes or doing a particular activity. In the early stages the irritation lessens with rest. Over time the symptoms become more constant and more severe as the condition develops and the damage becomes permanent.
These symptoms may include:
- A feeling as though there is something small and hard in your shoe, or as though your sock is bunched up. It may feel as though the object is inside the ball of your foot.
- Pain at the location of the nerve damage, made worse when putting pressure on the ball of the foot, or wearing high heels or shoes with a tapered toe box
- Extreme pain on pressing the space between the third and fourth toes
- A numbness, or sometimes a tingling or burning sensation in the affected area
Diagnosis:
The sooner you make an appointment to see your doctor, the more likely it is that conservative treatment of a Morton’s neuroma will be successful. Delaying diagnosis and treatment increases the chances of permanent nerve damage and subsequent surgery.
Your doctor will examine your foot carefully and palpate it in ways to elicit a pain response in order to determine the exact location of the damage. He or she will attempt to feel if any mass is present between the toes, or if there is an audible click on palpating the intermetatarsal space while squeezing the whole foot (Mulder’s sign). Testing the range of motion of the toes will help to rule out arthritis or other joint conditions.
X-rays might be taken to look for stress fractures or arthritis of the metatarsophalangeal joints (joints between the metatarsals and the toe bones). Ultrasound can show thickening of the nerve and if such thickening measures greater than 0.1 inch, a Morton’s neuroma is indicated. An MRI scan may be used to assess the size of the neuroma, especially if surgery is necessary.
Treatment:
Initial treatment is nonsurgical and usually involves the following measures:
- Avoiding high-heeled, tight or narrow shoes. This allows the toes to spread out, relieving pressure on the nerve and giving it a chance to heal.
- Applying ice, crushed in a bag and covered with a towel, to the affected area for as long as is comfortable, several times a day.
- Taking NSAIDs (non-steroidal anti-inflammatory drugs) will reduce inflammation and pain.
- Using inserts or pads in the shoes. A typical pad might be made of foam and is positioned under the space between the two affected toes. The effect is to keep the bones separate, which relieves pressure on the nerve. Pads and inserts are available over the counter, or custom-made orthotics can be ordered.
- A corticosteroid injection into the affected area can provide rapid and long-lasting pain relief, but can only be administered a few times a year as they can cause damage to tendons and ligaments.
- Increasingly, injections of diluted alcohol into the affected area relieve symptoms by poisoning the nerve tissue. Injections normally have to be repeated at intervals for several weeks, but success rates in clinical studies are high. This treatment is becoming a viable alternative to surgery.
Over 80% of people suffering from a Morton’s neuroma find that the above treatments provide relief from their symptoms. If, however, conservative treatment fails, surgery can be performed to cut away a portion of the nerve, a procedure known as a neurectomy. The neuroma can be approached surgically from the top or bottom of the foot, according to the surgeon’s preference. Recovery times can therefore vary. As with all surgery, there are risks involved that should be discussed with your surgeon prior to making a decision.
Another possible treatment is cryogenic neuroblation, where nerve axons are destroyed so that painful impulses cannot be transmitted. Although this procedure retains more of the original nerve than surgery or alcohol injection, results show that over the longer term, symptoms of neuroma recur more often.
Prevention:
To avoid a recurrence of painful symptoms, make sure that your footwear is properly fitted. Shoes should have soft soles, heels no higher than 1 inch, and a wide and high toe box.
Avoid activities that cause you to place repeated stress on the balls of your feet. Consider doing low-impact exercise such as swimming or bicycling instead of running.
Maintain a healthy weight and use orthotics in your shoes if necessary.
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