What are the differences in diagnosis and treatment between Morton's neuroma and metatarsalgia?

Morton's Neuroma vs. Metatarsalgia: Diagnosis and Treatment Differences

Morton's neuroma and metatarsalgia are distinct forefoot conditions with different diagnostic criteria and treatment approaches, with Morton's neuroma being a mechanically-induced degenerative neuropathy while metatarsalgia is a broader term for pain in the metatarsal head region with multiple potential causes.

Diagnostic Differences

Morton's Neuroma

• Characterized as a perineural fibrosis (not a true neuroma) affecting the common plantar digital nerves, most commonly between the third and fourth metatarsal heads 1
• Presents with paroxysmal neuralgia and severe intermittent pain in the web spaces of the toes 2
• Clinical diagnosis primarily relies on a positive compression test of the affected web space, which is highly specific 3
• Imaging studies:
  • Ultrasound and MRI are the preferred imaging modalities with high sensitivity (US: 90%, MRI: 93%) 4
  • Ultrasound has the advantage of allowing clinical correlation during examination 5
  • Radiographs are insensitive for diagnosis but useful to exclude other causes of webspace pain 5

Metatarsalgia

• Broader term referring to pain in the metatarsal head region, existing in three forms: first metatarsal head region pain, fourth/lateral metatarsal head region pain, and generalized metatarsalgia 3
• Multiple potential causes including sesamoiditis, stress fractures, and plantar plate injuries 5
• Sesamoiditis specifically presents with pain under the first metatarsophalangeal joint 6
• Imaging studies:
  • Radiographs are the initial imaging study but have limited sensitivity 5
  • MRI without contrast is recommended for persistent pain after negative radiographs 5
  • For sesamoiditis, MRI can show bone marrow edema and stress-related changes 6

Treatment Differences

Morton's Neuroma

• Conservative treatment options:

  • Corticosteroid injections placed beside (not into) the neuroma using small volumes (0.05-0.1 mL) of triamcinolone acetonide at multiple points around the neuroma 7
  • Orthotic devices to reduce pressure on the affected nerve 2
  • Mechanical Diagnosis and Therapy (MDT) using repeated end-range movements has shown preliminary effectiveness 8

• Surgical options (when conservative treatment fails):

  • Surgical excision of the nerve (neurectomy) through dorsal or plantar approach 1
  • Transposition of the transected plantar digital nerve may yield better long-term results than standard resection 9
  • Dorsal incisions may result in less symptomatic post-operative scars compared to plantar excision 9

Metatarsalgia

• Treatment depends on the specific underlying cause 3
• For sesamoiditis:
  • Conservative measures including rest, padding, and anti-inflammatory medications 6
  • CT can help distinguish between sesamoiditis, stress fractures, and bipartite sesamoids 6
• For general metatarsalgia:
  • Specific surgical operations are effective when conservative measures fail 3
  • SPECT/CT has been found useful for investigating persistent heel pain with increased specificity compared to bone scintigraphy alone 5

Common Pitfalls and Caveats

• Failing to differentiate Morton's neuroma from other causes of forefoot pain can lead to misdiagnosis and inappropriate treatment 6
• Direct injection into a Morton's neuroma (rather than around it) may cause higher risk of fat and dermal atrophy 7
• Radiographs alone are insufficient for diagnosis of Morton's neuroma but should be performed to rule out other causes 5
• For Morton's neuroma, careful patient selection, pre-operative counseling, and proper surgical technique are key to successful outcomes 1
• The evidence base for both surgical and non-surgical interventions for Morton's neuroma remains limited, requiring well-designed trials 9