– Morton’s Neuroma – Causes, Diagnosis and Treatment

Morton’s neuroma is thought to be caused from irritation to the nerve travelling between the metatarsals of the feet, near the toes.  This irritation can result in the nerve forming a painful nodule called a neuroma.  Patients with this problem have a constellation of symptoms which can range from the sensation of walking on a rock or marble to painful shooting pains in the toes or other symptoms of nerve irritation, such as electrical type pain or burning pain.

Causes

The actual cause of Morton’s neuroma is not exactly known.  We do know it is most common between the third and fourth metatarsals and tends to be relieved with flat, wide shoe wear.  Often patients prefer to go shoeless as this allows the metatarsals to spread out as much as possible and relieve pressure on the irritated nerve.  Since many patients with this problem present after years of wearing high-heeled shoes or pointed/tight toe box shoes, one of the prevailing thoughts is that Morton’s neuroma results from chronic compressive trauma to the nerve.

Diagnosis

Diagnosis of Morton’s neuroma can often be made clinically based on the patient’s symptoms (described above) and the physical exam findings.  Findings consistent with a Morton’s neuroma often include decreased or altered sensation in the area supplied by the nerve, usually the opposing sides of the third and fourth toes or the sole of the foot directly under the painful area.  The doctor will also test for a Mulder’s Click, where the foot is compressed from side to side and then the metatarsals are moved up and down.  This test is positive if the physician feels a ‘click’ and/or the patient has a painful clicking.  Another diagnostic test often used is a lidocaine injection (‘numbing medicine) into the area.  If this relieves the pain then it is considered a positive test and suggests the pain is truly coming from the nerve.  Finally, ultrasound or MRI can be useful in identifying the nodule or swelling of the nerve.  Other tests such as x-rays may be necessary to rule out other diagnoses, such as a stress fracture or arthritis, as part of your evaluation.

Treatment

Treatment of Morton’s neuroma usually proceeds in two stages.  The first is non-operative treatment and has several facets.  The first (and possibly most helpful) is to change shoe wear to avoid high heels and change to shoes with a wide toe box.  Additionally, orthotics or shoe inserts can be fabricated to help spread the metatarsals out in the painful area in an attempt to relieve pressure on the nerve.  Some studies have also shown that a single or series of cortisone injections into the area can provide lasting relief, especially when shoe modification is also done.  Physical therapists can also play a helpful role as they can provide manual therapy, heat/ice therapy and other exercises to make sure the heel cord (Achilles tendon) is appropriately stretched out.  A tight heel cord can cause the patient to walk more on the ball of the foot and therefore put more pressure on the affected area.  Finally, there have been some recent reports suggesting that Shock Wave Therapy may help with Morton’s neuroma.   There is no consensus as to whether Shock Wave may help but it is a non-invasive procedure with very low theoretical side effects.  There have been several studies showing that non-operative treatment for Morton’s neuroma is successful in 80% of cases.

For those patients who do not have relief from the non-operative measures listed above, surgery is an option.  The surgery generally involves releasing a ligament between the metatarsals, which may be causing some or all of the pressure on the nerve and removing the neuroma itself.  There have been several different surgical approaches described in the medical literature and vary from an incision on the top of the foot to an incision on the sole of the foot to an incision between the toes.  Generally, surgical treatment of Morton’s neuroma results in a 90% satisfaction rate.  The most important thing to know about the surgery is that when the nerve is removed, the patient will have permanent numbness on the side of the toes supplied by the nerve and possibly on a small area of the ball of the foot.  However, many patients would rather trade some numbness of a part of the toe for pain relief.

Is there a permanent solution for Morton’s neuroma?

The answer is probably (90%) when the solution is surgery.  However, at Specialty Orthopedic Surgery we always advocate trying non-operative treatment when there is a reasonable chance that will cure the problem.  I would recommend make an appointment to see our Foot and Ankle Specialist, Dr. Brimacombe for a complete evaluation.  Appointments can be made online or by calling 602-258-8500.

Written by Dr. Matthew Seidel

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