Interdigital neuroma

Disease Description (Causes and Symptoms)

• Definition: Interdigital neuroma (Interdigital/Morton neuroma) is a condition in which the interdigital nerve running from the metatarsophalangeal region (the front part of the foot) to the toes becomes thickened (fibrotic) due to repeated compression and friction, causing pain and sensory disturbances. It is not a true tumor but a pathological change in the nerve.
• Pathophysiology: The nerve is compressed by structures such as the deep transverse metatarsal ligament between the metatarsal bones. Chronic irritation in this area causes progressive fibrosis around the nerve, making it thicker. As a result, the nerve may become pinched or shift while walking, causing pain and clicking.
• Main symptoms:
  • Burning or tingling pain in the forefoot (especially when walking or wearing shoes)
  • Tingling or numbness in the toes
  • Symptoms improve when shoes are removed or when wearing shoes with a wide toe box
  • Pain or clicking (Mulder's click) may be elicited during the web-space compression test (compressing the metatarsal heads from the medial and lateral sides and pressing the metatarsophalangeal space)
• Differential diagnoses: Lipoma, ganglion, synovial cyst, metatarsal stress lesion, peripheral neuropathy (such as diabetes), hallux valgus, etc.

Treatment Methods

• Conservative treatment (first-line choice)
  • Shoe modification: Shoes with a wide toe box and low heels; soft materials are recommended
  • Reduce pressure with functional insoles (metatarsal pads/supports) or metapads (which spread the space between the metatarsals)
  • Activity modification: Avoid standing for long periods or wearing narrow dress shoes
  • Medication: Nonsteroidal anti-inflammatory drugs (NSAIDs) for temporary pain relief
  • Physical therapy/manual therapy: Forefoot stretching, massage, and other treatments may help relieve symptoms
• Injection treatment and nonsurgical procedures
  • Intralesional (or ultrasound-guided) local steroid injection: Reduces inflammation and pain in the short term, but the number of repeated injections is limited (the duration of effect varies between individuals)
  • Nonsurgical nerve ablation procedures, such as alcohol neurolysis: Performed at some centers; results vary
  • Diagnostic injection using a local anesthetic: Improvement in pain supports diagnostic confirmation
  • Ultrasound-guided procedures (e.g., RFA [radiofrequency ablation]) are used in some cases (evidence and indications vary by institution)
• Surgery
  • Selective indications: Failure of conservative treatment or substantial disruption to daily life
  • Surgical methods: Neurectomy or incision of the deep transverse metatarsal ligament (decompression), etc.
  • Benefits/limitations: Symptoms may improve, but there is a possibility of decreased sensation (which may be permanent), recurrence (stump neuroma after excision), and surgical complications (infection and delayed healing). Reported satisfaction varies by institution, and some studies have reported satisfaction rates in the approximately 60% range.
• Precautions and self-care
  • Even during conservative treatment, carefully modify footwear and activities
  • Repeated steroid injections require limits because of risks such as fat-pad atrophy and infection
  • After surgery, wound care, weight-bearing control, and rehabilitation (stretching and maintaining muscle strength) are important
  • If comorbidities such as diabetes or peripheral vascular disease are present, the risks of delayed healing and infection increase → consultation with a doctor is essential

Outpatient Visit Checklist (Including Preparation and Sample Questions)

• Items to bring (recommended)
  • A list of current medications (including prescription drugs, over-the-counter medicines, and supplements)
  • Previous test results (X-rays, ultrasound, MRI, etc.) or captured images
  • Pain and symptom records: Onset, aggravating factors (shoes and activities), relieving factors, pain intensity (e.g., 0–10), and symptom frequency
  • Photos of shoes (types of shoes usually worn) or the actual shoes
  • Previous treatment history (whether insoles, injections, physical therapy, or surgery were used)
  • Information about allergies and medical conditions (especially diabetes, blood-clotting disorders, and infectious diseases)
• Tests that may be performed during the outpatient visit
  • Physical examination (web-space compression test/Mulder’s test)
  • Ultrasound or MRI (if necessary) — to identify the lesion and guide procedures
  • Diagnostic local injection (can support the diagnosis if pain improves)
• Information useful to show the doctor during the outpatient visit
  • Specific examples of shoes or activities that worsen the pain
  • When the pain began and response to treatment (if applicable, which treatment was effective)

General Sample Questions to Ask the Doctor

• Can you confirm that this condition is definitely an interdigital neuroma? Are any additional tests needed?
• What conservative treatment do you recommend, and how long might it take to expect an effect?
• What are the advantages and disadvantages of steroid injections (complications and limits on the number of injections)?
• If surgery is needed, what is the expected recovery time and what possible side effects (such as loss of sensation and recurrence) may occur?
• How would the treatment plan change if I have diabetes or another medical condition?

Sample Condition-Specific Questions

• Do my symptoms (such as pain when wearing specific shoes or tingling in specific toes) fit the typical findings of an interdigital neuroma?
• Do you recommend an ultrasound-guided steroid injection or alcohol neurolysis? What are the advantages and disadvantages?