Morton's neuroma differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2]

Overview

Morton's neuroma must be differentiated from other causes of pain in the forefoot such as capsulitis, intermetatarsal bursitis, arthritis of intermetatarsal joints, calluses, stress fractures, and Freiberg's disease.

Differentiating Morton's Neuroma from other Diseases

• Morton's neuroma must be differentiated from other causes of pain in the forefoot because too often all forefoot pain is categorized as neuroma
• Since a neuroma is a soft tissue condition, an MRI should be helpful in diagnosis, however, often an MRI will be inconclusive for neuroma even though a neuroma exists
• Other conditions to consider are:
  • Metatarsophalangeal joint capsulitis/metatarsalgia
  • Intermetatarsal bursitis between the third and fourth metatarsal bones will also give neuroma type symptoms because it too puts pressure on the nerve
  • Inflammatory arthritis of joints that join the toes to the foot
  • Calluses
  • Metatarsal stress fracture
  • Freiberg's disease
  • Osteomyelitis
  • Localized vasculitis
  • Ischemia or lack of blood flow through plantar digital artery, it precedes the fibrous thickening around the nerve known as perineural fibrosis
  • Tarsal tunnel syndrome
  • Rheumatoid arthritis
  • Peripheral neuritis
  • Synovitis
  • Tendonitis
  • Avascular necrosis

Differentiating Morton's neuroma from other diseases

Disease/Condition	Underlying Etiology	Pathophysiology	Clinical presentation	Other associated features
Morton's neuroma	Improper footwear or tight shoes with tapered toe box Abnormal positioning of toes Flat feet Overpronation High foot arches High heels Gait abnormalities Forefoot problems such as: Bunions Hammer toes High-impact sports such as: Rock-climbing Ballet dancing Jogging Running Snow skiing Racquet sports Court sports	On gross pathology, characteristic findings of morton's neuroma, include: Adherent fibrofatty tissue Small, firm, oval, yellowish-white, slowly growing, palpable nodule on skin (no discoloration of skin on the top of nodule) </=2cm in size On microscopic histopathological analysis, characteristic findings of morton's neuroma include: Extensive fibrosis around and within the nerve Digital artery Thrombosis Epineural and endoneural arterial thickening/vascular hyalinization Degenerated/demyelinated axons	Symptoms of morton's neuroma include: Feeling like ''walking on a marble'' or a pebble in the shoe or bunched-up sock Most common symptom is pain in the affected area caused by pressure on the enlarged section of nerve where it passes between the metatarsal heads, and is squeezed between them Pain is persistent & has the following characteristics: Occurs mostly on weight bearing while walking or wearing shoes that squeeze the feet Occurs frequently after only a short time Affects the contiguous halves of two toes Pain tends to ease off at the night time Nature of pain maybe any of the following: Shooting Burning Stabbing Raw Gnawing Sickening sensations Numbness Parasthesia Dysesthesia (painful hypersensitivity to normal light tactile stimuli) Functional impairment Psychological distress (severely decreasing the quality of life)	Usually located at the following sites: Third intermetatarsal space most commonly (between third and fourth metatarsals) Second or fourth interspaces At the bifurcation of the fourth plantar digital nerve Fifth interspace (rarely) (first toe is usually not involved)
Metatarsophalangeal joint capsulitis/Metatarsalgia	Abnormal foot mechanics (putting excessive amount of weight bearing pressure on the ball of the foot beneath the toe joint) Repetitive foot motion exerting pressure on the ball of foot resulting in connective tissue degeneration High level of activity Tight Achilles tendon Severe foot deformities such as: Bunion Hammer toe Second toe longer than the big toe Structurally unstable high arch of foot Prominent metatarsal heads Tight toe extensor muscles Weak toe flexor muscles Hypermobile first foot bone Improper fitting footwear (women’s dress shoes, other restrictive footwear with narrow toe box) High heels High impact activities/sports without proper footwear/orthotics such as track & field running, tennis, football, baseball, & soccer Older age (thinning of foot fat pad leads to more susceptibility to pain in the ball of the foot)	Inflammation of capsule/ligaments that surround two bones, at the level of the joint (in this case, ligaments that attach the toe bone to the metatarsal bone) Inflammation from this condition will put pressure on an otherwise healthy nerve and give neuroma type symptoms	Pain, particularly on the ball of the foot Feeling like: A ''marble'' in the shoe A bunched up sock Standing on a "pea'' Swelling at the base of the toe Difficulty wearing shoes Pain while walking barefoot Crossover toe (end-stage of capsulitis)	Also referred to as ''ball-of-foot-pain'' Colloquially known as ''stone bruise'' Usually located under the 2nd, 3rd, & 4th metatarsal heads
Intermetatarsal bursitis	Trauma Rheumatoid arthritis Gout	Irritation, inflammation and secondary fibrosis of intermetatarsal bursa located distal to transverse metatarsal ligament and close to neurovascular bundles	Between the third and fourth metatarsal bones will give neuroma type symptoms because it too puts pressure on the nerve Lateral foot compression squeezes the inflammed bursa between the metatarsal heads leading to pain mimicing neuroma Mulder's sign of physical examination (squeezing the metatarsals produces the click due to enlarged & inflammed bursa)
Inflammatory arthritis of metatarsophalangeal joints (join the toes to the foot)
Calluses
Metatarsal stress fracture
Freiberg's disease
Osteomyelitis
Localized vasculitis
Tarsal tunnel syndrome
Rheumatoid arthritis
Peripheral neuritis
Synovitis
Tendonitis
Avascular necrosis	Permanent or temporary lack of blood supply to the bones due to: Trauma Non-traumatic etiologies include: Alcoholism Excessive steroid use Caisson disease (decompression sickness) Vascular compression Hypertension Vasculitis Thrombosis Damage from radiation Bisphosphonates (particularly the mandible) Sickle cell anaemia (very rarely) Idiopathic (no cause is found in some cases)			Also known as: Osteonecrosis Aseptic bone necrosis Ischemic bone necrosis

References

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