Morton's neuroma; Morton's entrapment; intergidital or intermetatarsal neuroma

Etiology

• running
• tight shoes, high heels
• bunion
• hammertoe
• high arched feet

Epidemiology

• uncommon
• women affected 4-fold more often than men

Pathology

• repetitive microtrauma of the common digital nerves
• cycle of inflammation, accumulation of perineural fibrosis, & enlargement of neurilemma
• nerve entrapment

Clinical manifestations

• burning pain at the 2nd or 3rd web space between the toes
  • most commonly in the web space between the 3rd & 4th toes but may be found in the 2nd web space
• pain may radiate to the tips of the involved toes
• unilateral in most cases
• tenderness to palpation at the involved webspace
• symptoms reproduced by compression of the involved metatarsals
• weight-bearing exacerbates symptoms
  • runners may feel pain as they push off from the starting block
• removal of shoes may relieve symptoms
• generally, not palpable
• pain may be described as cramping or walking on a pebble

Radiology

• X-ray of foot may show widening of the metatarsal space
• magnetic resonance imaging (MRI) for soft tissue visualization

Differential diagnosis

• metatarsalgia

Management

• metatarsal pads to spread the metatarsal heads & decompress the nerve
• injection of glucocorticoid & local anesthetic
  • effective for some patients
  • multiple injections may be needed (see joint injection)
• surgery involves resection of a small portion of involved nerve or release of tissue around the nerve
• common plantar digital nerve decompression

More general terms

• neuroma
• entrapment neuropathy; nerve entrapment syndrome; pinched nerve

Additional terms

• metatarsalgia (forefoot pain)
• Morton's foot