Podiatrists @ Placentia-Linda Foot & Ankle Grou

NEUROMA CAUSES AND TREATMENT

When foot pain and tenderness occurs under the ball of the foot, usually the podiatry presentation is either a metatarsal stress fracture, a nerve is being entrapped or a painful callus is present. A callous is usually the cause of the ball of the foot pain if the bone does not hurt with compression from top and bottom but the skin is tender. A nerve problem is present if the pain is between the metatarsal bones in the ball of the foot and the skin and metatarsal heads do not hurt with squeezing the bones. Review the Corn and Callous Page or the Metatarsal Stress Fracture Page if you think your problem is a painful callus or a stress fracture and not a neuroma.

A Morton's Neuroma is a name given to a scared and enlarged nerve that is between the two lesser metatarsal heads. The most common place for a neuroma to occur is between the third and fourth metatarsal heads. The third and fourth metatarsal heads connect to different bones in the middle of the foot and with twisting of the forefoot during gait, these two bones rotate in separate directions causing the nerve to become pinched. A neuroma is a condition that occurs from repetitive injury to the nerve that is running under and between the metatarsal heads in that the nerve enlarges with scar tissue. The primary cause of the nerve injury is from a twisting of the forefoot while walking that is associated with flattening of the foot or pronation. The nerve innervates the inside bottom area of the two toes that the nerve passes between. With injury to the nerve, the typical pain that is experienced is an electrical burning pain that may leave the toes numb intermittently. Usually the pain is not subtle but very obvious and occurs on and off during weight bearing. The pain can also continue into the night even after the foot is rested. The clinical examination is classic for radiating pain when the nerve is pushed on from below and between the metatarsal heads. Sometimes there is even a click that occurs or a marble feeling to the bottom of the foot with walking as the nerve becomes enlarged with repeated injury. With each injury to the nerve the nerve enlarges with scar tissue that is a mixture of scar and nerve tissue. It is the repeated scarring that is the cause of the pain as the nerve tissue has no where go when you are standing on your foot and the metatarsal bones are above and around the nerve.

Treatment with a new nerve injury is aimed at changing the way in which you stand by changing shoes to more supportive motion control athletic shoe or the Podiatrist can fabricate custom molded foot orthotics. Cortisone injection therapy is the first line of treatment to try to reduce the amount of inflammation around the nerve and to relieve pain. Without any other intervention to improve the alignment of the foot while weight bearing, the cortisone shots have little long-term affet for curing the neuroma condition. If treatment is quickly administered upon the onset of the formation of the neuroma that includes anti-inflammatory medications, the prognosis is excellent for resolving the nerve injury condition. If cortisone therapy is partially affective in the pain is improved but not resolved, alcohol injection therapy is typically the next tretment.  The alcohol therapy uses a diluted alcohol solution to demyelinate the nerve to stop the nerve from sending pain messages and then the nerve will regenerate over time and in doing so a new healthy nerve will reform. In many patients, up to three ahcohol injections are needed to completely resolve the patient's neuroma pain.  If the nerve injury has progressed too far with repeated compression injuries, the nerve will increase in size from a normal diameter of a 1/16th of an inch to over a half inch from the scar formation. In half the cases, where a patient has a severe neuroma, half resolve the problem without surgery and half go on to surgery. Surgery entails either repositioning the nerve or removing the scarred nerve and placing the cut nerve end into a small muscle next to the metatarsal. If the nerve is not implanted into the interosious muscle adjacent to the shaft of the metatarsal, there is a 60% re-occurrence rate of having the neuroma return. Extremity nerves that go to the skin will regenerate unless the nerve end is placed into a tissue that already has a nerve innervation such as a muscle belly. For this reason, patients who have had neuroma surgery and not had the nerve implanted into muscle have a much higher rate of re-occurrence after surgery. Although rare, if the nerve is implanted into muscle, the nerve can still develop a painful mushroom at the end of the nerve where the nerve was cut and implanted into muscle. The recovery from neuroma surgery is usually minimally painful if tissues are respected and the podiatric surgeon closes the tissues in layers and lets down the tourniquet prior to closing the skin and not after the skin is closed. The patient should not need to take more that a few pain pills in the first couple days after neuroma surgery and typically will use anti-inflammatory medications for the next two weeks to control the amount of swelling in the area.

Ultimately, early treatment of a neuroma is important in preventing the progressing of the scaring of the nerve.  Surgery should be reserved for those patients who have not responded to changing shoe gear, foot orthotics, cortisone injection therapy, rest and anti-inflammatory medications. In the hands of a good Podiatric Surgeron, if euroma surgery is needed, the surgery should go smooth with a rare chance that the neuroma will return.