Neuroma
Further Information for Healthcare Professionals
Definition of Condition
Morton’s Neuroma
Morton's neuroma (also known as Morton's metatarsalgia, Morton's neuralgia, plantar neuroma and inter-metatarsal neuroma) is a benign neuroma of the inter-digital plantar nerve. This problem is characterised by numbness and pain, relieved by removing footwear. Despite the name, the condition was first correctly described by a chiropodist named Durlacher, and although it is labelled a "neuroma", many sources do not consider it a true tumour, but rather a perineural fibroma (fibrous tissue formation around nerve tissue).
Symptoms and signs
Symptoms include: pain on weight bearing, frequently after only a short time; the pain is felt as a shooting pain affecting the contiguous halves of two toes. Burning, numbness and paraesthesia may also be experienced. Classically the 3rd digital space between the 3rd and 4th toes is affected, but the condition can occasionally occur in the 2nd and 3rd inter-digital space. The pain is caused by pressure on the enlarged section of nerve where it passes between the metatarsal heads, and is squeezed between them. The first toe is usually not involved. Neuroma in the 4th/5th inter-digital space is described, but is extremely rare.
Diagnosis/differential diagnosis
Negative signs include no obvious deformities, erythema, signs of inflammation or limitation of movement. Direct pressure between the metatarsal heads will replicate the symptoms, as will compression of the forefoot between the finger and thumb so as to compress the transverse arch of the foot. This is referred to as Mulder’s Sign.
There are other causes of pain in the forefoot. Too often all forefoot pain is categorized as neuroma. Other conditions to consider are capsulitis, which is an inflammation of ligaments that surrounds two bones, at the level of the joint. In this case it would be the ligaments that attach the phalanx (bone of the toe) to the metatarsal bone. Inflammation from this condition will put pressure on an otherwise healthy nerve and give neuroma type symptoms. Additionally, an inter-metatarsal bursitis between the third and fourth metatarsal bones will also give neuroma type symptoms because it too puts pressure on the nerve. Freiberg's disease, which is an osteochondritis of the metatarsal head, causes pain on weight bearing or compression.
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.
Pathophysiology
Common Symptoms
•Cramping pain
•Burning
•Numbness / tingling
Clinical Classification
Neuromas do not have a classification system as such other than their size which can be a weak predictor of response to treatment.
Initial Management Options
1 Advice on footwear
2 Cortisone (Ultrasound guided injections are probably more effective)
Surgical Management Options
1 Decompression of the nerve by releasing the transverse metatarsal ligament
2 Excision of the damaged portion of the nerve
Initial Advice
There is little to be gained by active early intervention. Patients should try to wear appropriate footwear and seek intervention when symptoms dictate.
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