Morton's Neuroma

Also known as Morton's metatarsalgia or Morton's neuroma, although Morton described neither (Morton thought this was a problem in the 4th MTP joint and Betts described the "neuroma" 70 years later).

The "neuroma" consists of degenerative and fibrotic changes in the common digital nerve near its bifurcation. However, there may be similar changes in adjacent unaffected nerves and it is not known why one becomes symptomatic. A number of causative factors have been suggested:

• tethering of the 3rd space nerve by the anastomotic branch between medial and lateral plantar nerves

• traction on the nerve by hindfoot valgus, interdigital bursitis or forced toe dosiflexion in high-heeled shoes

The symptoms may be quite non-specific:

• neuralgic pain in a toe and/or interdigital space

• tingling of a toe

• colour changes

• numb or "dead" toe

• vague forefoot tingling

• pain usually worse on walking and sometimes at night

• relief on removing shoes

Symptoms are commonest in the 3rd interdigital space, then the 2nd. Symptoms in the 4th space are rare and should make one doubt the diagnosis. Symptoms in the first space are virtually unknown.

The condition may remain undiagnosed for many years