When someone complains that they feel like they're "walking on a marble" or that their sock feels like it's wadding up under the ball of the foot, that's often the sign of a Morton's neuroma. Morton's neuroma is a condition characterized by pain in the ball of the foot emanating from the space between the third and fourth metatarsal heads. Patients may notice numbness, tingling, burning, electrical shock sensations or simply stabbing pain beginning in the forefoot and radiating into the third and fourth toes. Neuromas may occur in other intermetatarsal spaces, but are most common in the third due to its unique anatomy.
Treatment is, as always, preceded by making the diagnosis. Your podiatrist will compress the foot, pushing the first and fifth metatarsal heads together. When this maneuver produces a "clunk" it's a positive test and is known as a Mulder's click. An enlarged nerve is popping against a ligament which induces the clunk. If a neuroma is still suspected but there's no Mulder's click, an MRI or ultrasound will occasionally be ordered. MRIs are expensive and are somewhat fallible in detecting neuroma in the forefoot. It may be a necessary test, though, if some other type of pathology is suspected, or the patient has a history of cancer or trauma.
Once the diagnosis is made, conservative care is attempted first. Over 80% of neuromas will resolve without requiring surgical intervention. Wide, supportive shoes need to replace narrow or high heeled dress shoes. Metatarsal padding can splay the bones and reduce irritation of the nerve. Patients with structural issues may require custom foot orthotics. Steroid injections can alleviate the inflammation and thus reduce the pain. Sclerosing alcohol injections have been tried with variable success.
If conservative measures fail, the next alternative is surgery. Surgery may include simply releasing the ligament that binds the nerve or removal of the enlarged section of nerve. Surgery in general is very successful. In rare cases, however, the nerve regrows in somewhat of a tangle, referred to as a "stump" neuroma. This unusual complication is exceptionally difficult to relieve. Combined with the success rate of conservative care, this complication is the primary reason surgery is considered a final alternative.
Compared to many foot surgeries, neuroma resection is relatively easy to recover from . Patients are bandaged and have sutures in place for two weeks. A gradual transition to regular shoes is then attempted over the next two weeks. It's typically close to a month before regular activity can slowly be reintroduced. Pain-free activity can resume at two to three months.
A condition that causes similar symptoms but is the result of a quite different cause is Tarsal Tunnel Syndrome. Stay tuned to our blog for the next post on TTS!