Morton’s Neuroma
A Morton’s Neuroma is a benign tumor of a nerve that develops in the ball of the foot. It occurs as the nerve passes under the ligament connecting the toe bones (metatarsals) in the forefoot. The nerve becomes sandwiched in his location between the ligament in the foot and the ground. A Morton’s Neuroma most frequently develops between the third and forth toes but is also quite common between the second and third toes.
Morton’s Neuromas develop due to pressure on the nerve. Certain activities and shoes can cause a Morton’s Neuroma to develop. Most notably, high heel shoes, especially pointy toe high heel shoes can cause a Morton’s Neuroma to develop. High heel shoes concentrate all of the body weight onto the ball of the foot where neuromas develop.
Certain activities can also increase your chances of developing a Morton’s Neuroma. Any activity that results in increased pressure on the ball of your foot can potentialy cause a neuroma to develop. Occupations that require a lot of crouching on your toes such as carpenters and certain types of construction work. Certain sporting activities such as basketball and tennis that put a lot of pressure on the ball of the foot can also cause a Morton’s Neuroma to develop.
Morton’s Neuromas present as a pain in the ball of the foot. While the neuroma is located at a specific area between the toes, patients often can’t exactly tell where the pain is coming from and complain of generalized pain in ball of their foot. Since a Morton’s Neuroma is a nerve, the nerve cells can send any signal imaginable back to the brain, so symptoms vary. Symptoms may include; burning, tingling, stabbing, or numbness. Many patients describe the sensation of walking on a bunched-up sock in the area.
How is Morton’s Neuroma diagnosed?
Morton’s Neuromas can usually be diagnosed clinically by your podiatrist. There are telltale clinical signs with a Morton’s Neuroma. One of which is a positive “lateral squeeze test." The lateral squeeze test is performed by pinching the interspace where the neuroma is suspected with the thumb and index finger while at the same time applying lateral compression to the forefoot. This test applied direct pressure to the nerve and will cause pain at the site.
In addition to point tenderness at the site during the lateral squeeze test there may also be a clicking sensation felt by the patient and examiner. This is called a “Mulder’s Sign” or “Mulder’s Click” and represents the Morton’s Neuroma snapping over the plantar ligament.
While a Morton’s Neuroma won’t show up on an X-ray, X-rays are usually taken to rule out other causes of pain in the ball of the foot such as a stress fracture or arthritis. There is also something called the “Sullivan’s Sign” that can be seen on X-ray. A Sullivan’s Sign occurs when the Morton’s Neuroma causes the adjacent toes on either side of where the Morton’s Neuroma is located to splay apart from one another.
As far as home remedies go, the best thing you can do is protect the ball of the foot from undue pressure. This can be accomplished with proper shoes. Look for shoes with a thick cushiony sole. An arch support is also very effective because this will take weight off the ball of the foot and transfer it to the arch. There is also something called a metatarsal pad or metatarsal bar that can be added to a shoe or insert that takes off weight from the ball of the foot. There are also adhesive backed metatarsal pads available to apply directly to the bottom of the foot. These pads can be purchased from your local drugstore.
If you have changed your shoes and lifestyle to protect the ball of the foot, and the pain persists, it is time to visit the doctor. Conservative treatment usually involves a series of cortisone injections and oral anti-inflammatories. Custom molded orthotics are also very effective and can be designed to specifically off weight the inflamed nerve.
If conservative treatment fails to alleviate symptoms, a Morton’s Neuroma may need to be removed. Generally speaking, if a patient has had symptoms longer than a few months the nerve has probably already grown into a large tumor. Once a Morton’s Neuroma develops into a large fibrotic tumor, conservative care is usually temporary at best.
Surgical excision of a Morton’s Neuroma is a relatively simple procedure. A 1 ½-2 inch incision is made over the top of the foot in the area of pain and the nerve is removed. There is some residual numbness that may result because the nerve is a sensory nerve, but it is a small price to pay to get rid of the pain.
Initial identification of the Morton’s Neuroma
The proximal nerve root is cut and the Morton’s Neuroma is followed distally to where it splits into two branches that extend out into the toes. These two distal branches are then cut and the Morton’s Neuroma is removed.
After Morton’s Neuroma surgery patients are allowed to weight bear in a post-op shoe/boot but should keep ambulation to a minimum for the first several days. Stitches are removed in 2 weeks, and patients are back in shoes at around 2-3 weeks.
Morton’s Neuroma surgery is a relatively safe and quick surgical procedure, and complications are uncommon. Beyond the list of regular possible surgical complications such as infection or hematoma, there is a rare possibility of developing something called a stump neuroma. A stump neuroma occurs when the cut end of the nerve attempts to regenerate and develops into a painful bulb shaped growth.
Stump neuromas have much the same symptoms as a Morton’s Neuroma. If caught early they can be relieved with the same treatments used to treat the Morton’s Neuroma such as NSAIDS, cortisone injections, etc. If a stump neuroma fails to respond to these conservative measures, they are surgically excised in a manor very similar to removing a Morton’s Neuroma.
Once the Morton’s Neuroma is removed it is sent to pathology for microscopic evaluation.