CONSERVATIVE AND SURGICAL OPTIONS FOR FOOT NEUROMA

A variety of foot ailments can befall the average citizen in modern society. Trapped inside a shoe for a majority of our waking hours, foot pain is experienced by many. Part of this frequency  is that we are walking on perfectly flat surfaces the great majority of our day. This exaggerates many orthopedic issues and one of the most common is a trapped nerve in the ball of the foot.

This condition is called by many things, most commonly a neuroma, although that specific term can be applied to any nerve that has become trapped. Still, the word has become synonymous with entrapment of a sensory nerve between the third and fourth metatarsal bones of the foot. Alternate terminology includes a neurofibroma, a nerve entrapment syndrome, or a Morton’s neuroma (after a physician who first described it in medical journals).

Before a discussion of treatment, a relevant question concerns the cause of a neuroma, which can vary. Anything which affects an individual’s biomechanics, the manner in which the human body functions in stance and gait, can result in irritation and compression of the structure in question. Some key issues include the tightness of one’s Achilles tendon-calf muscle complex, as well as their foot architecture. Poorly fitting shoes or broken down shoes can all result in repetitive compression of the nerve as it courses under the arch out towards the toes.

But the gist of this article does not concern the etiology, aka the cause, of an intermetatarsal nerve entrapment problem. Instead, this is a discussion of some of the standard treatments and the problems that are associated with certain specific techniques. It is a common pathology and not a rarity, allowing therapies to be studied and success rates measured. Consequently, guidelines have been developed for treatment.

Initial therapy generally consists of one to three steroid injections (colloquially known as cortisone). For some, administering a corticosteroid will help to shrink the scar tissue which forms around the nerve and symptoms are resolved. Should there be recurrence of pain, a third has a poor success rate. A cortisone injection is a simple process and inexpensive, at least relative to the expense of modern medical care, and nearly always a covered service by insurers. But the long term success rate is not great with many experiencing only transient improvement.

Another frequently utilized approach involves altering foot mechanics in such a way as to reduce the pinching of the nerve in question. This method of care can have multiple benefits, aiding a variety of musculoskeletal issues, including the resolution of neuroma pain. How best to do this is an important question and the answer complex.

Commonly, a piece of rigid material is shaped so as to support precisely the weight bearing structures of the body, referred to as a foot orthotic. This can function to reduce excessive motion of the metatarsal bones. Although challenging, with a detailed analysis and appropriate prescription, this device, placed under the foot inside the shoe, can provide an efficacious solution to better support and optimal function of the foot, leg, and spine. Numerous sufferers turn to generic foot supports, i.e. off the shelf products, typically providing only mild relief if any.

Another method listed in the guidelines is one typically associated with vein problems. It’s termed a sclerosing technique, indicating some structure is chemically induced to shrink up. This has a good success rate for an intermetatarsal neuroma and entails rare complications when applied judiciously. A series of injections is always performed with the goal being destruction of the nerve. Because it is only a sensory nerve, the technique produces no weakness, often some mild numbness of the skin between the toes.

Depending on the person, and the care brought to bear, some individuals will continue to experience symptoms. Many are told at some point in this process that surgery is their best option, which traditionally has consisted of cutting out the diseased section of nerve. Interestingly, this is the only place in the human body where a section of nerve is cut out and removed. Elsewhere we may move a nerve but it is never removed entirely.

A relevant issue in this discussion should be the success rate of this technique but just as important is the complication rate. Every single procedure has the potential for problems. Of the many surgical procedures performed, some have a low rate and others not so. Although it is commonly performed, this older procedure of nerve removal entails an uncomfortably high risk for certain problems. Consequently, in the next issue, a discussion of nerve changes with trauma and some exciting new approaches to safer neuroma surgery.

Dr. Conway McLean, a board certified podiatric physician, is the Director of Superior Foot and Ankle Centers in Marquette Michigan.