A neuroma is a condition where the plantar nerve, which branches between the metatarsal bones, becomes inflamed and enlarged in a benign tumor-like growth. This leads to nerve entrapment by the metatarsal bones.
Morton’s neuroma most commonly affects the third interdigital nerve in the third webspace between the third and fourth toes, and next commonly, the 2nd common digital nerve in the second webspace.
Symptoms include pain, often described as a burning sensation with tingling and numbness, located under the forefoot and into the toes. It is more common in a foot with a dropped metatarsal arch (transverse arch). Symptoms are worse with prolonged activity on hard surfaces and with heeled or tight shoes. However, not all pain in the forefoot is a Morton’s neuroma. In fact, most chronic pain in the forefoot is NOT the result of a Morton’s neuroma, but rather is from inflammation like metatarsalgia. The symptoms of Morton’s neuroma are due to irritation of one or more of the small nerves, just before they travel into the toes
Treatment is primarily conservative and includes custom soft orthotics to offload the MTP joints and avoid pressure over the neuroma. Patients should avoid walking barefoot as much as possible. Oral and topical anti-inflammatories can help reduce the swelling around the nerve and reduce symptoms. Injections including both corticosteroids and PRP can help reduce swelling around the nerve and MTP joint as well as shrink the size of the neuroma.
Operative treatment of Morton’s neuroma should be considered only after failure of non-operative management and only if it can be ascertained that the symptoms are not primarily due to any other pathology such as synovitis or metatarsalgia. Standard operative treatment involves identifying the nerve and cutting (resecting) it above the point where it is irritated/injured. This is usually done through an incision on the top (dorsal) aspect of the foot. Forefoot pain is often complex in nature and although a Morton’s neuroma may be identified on ultrasound or MRI, it may not be the only source of pain. If the neuroma is the only source of pain surgery is very successful, but if there are other factors involved your success with surgery can vary. For this reason, it is highly recommend exhausting all conservative therapy prior to considering surgical excision of any neuroma.
Potential operative complications include:
- Delayed healing. It is not unusual for mild residual swelling at the surgical site to cause persistent discomfort for 2-3 months. Occasionally up to 6 months.
- Infection as with any surgical procedure
- Post-operative scar tissue can be quite uncomfortable, especially if the incision is made on the plantar aspect of the foot.
- Stump Neuroma. Where the nerve regrows where it has been cut causing recurrence of symptoms.
- Continued pain. This is not uncommon as the nerve maybe only a part of the pain generating complex.