Morton’s neuroma is diagnosed primarily through a physical exam that includes specific hands-on tests of the forefoot, supported by ultrasound or MRI when the clinical picture is unclear. Most cases can be identified in an office visit without imaging, but scans help confirm the diagnosis, rule out other conditions, and guide treatment decisions.
What the Pain Feels Like
The hallmark of Morton’s neuroma is sharp, burning pain in the ball of the foot, most commonly between the third and fourth toes or the second and third toes. These two spaces account for nearly all cases, each representing about 50% of diagnosed neuromas. Pain in the first or fourth intermetatarsal spaces is extremely rare, making up less than 1% combined.
People often describe the sensation as feeling like they’re walking on a marble or a stone, or like a sock is bunched up under the ball of the foot. The pain is typically stabbing, shooting, or burning, and it tends to worsen with walking, standing, or wearing tight or narrow shoes. Removing your shoes and rubbing the foot usually brings relief. Numbness or tingling in the affected toes is also common. These descriptions alone can point a clinician strongly toward the diagnosis.
The Physical Exam
The most important diagnostic tool is a clinical maneuver called the Mulder test. Your doctor squeezes the metatarsal heads (the bones at the ball of your foot) together while pressing on the space between them from below. When a neuroma is present, this compression pushes the thickened nerve tissue downward, producing a palpable and sometimes audible click. That click, combined with reproduction of your typical pain, is highly suggestive of Morton’s neuroma.
Your doctor will also press directly on the intermetatarsal spaces to locate the point of maximum tenderness, check for numbness between the toes, and assess whether the pain changes with different footwear. The exam helps distinguish Morton’s neuroma from other causes of forefoot pain like joint inflammation, capsule tears, or stress fractures, all of which produce tenderness in slightly different locations.
When Imaging Is Needed
If the physical exam is convincing, imaging isn’t always necessary. But when symptoms are atypical, when more than one web space hurts, or when an injection or surgery is being considered, ultrasound or MRI helps confirm the diagnosis and measure the size of the neuroma.
Both modalities are effective, but they have different strengths. A systematic review in Clinical Radiology that pooled data from over 450 patients found ultrasound had 90% sensitivity and 88% specificity, while MRI had 93% sensitivity but only 68% specificity. In practical terms, MRI is slightly better at detecting neuromas but more likely to flag something that isn’t actually a neuroma. Ultrasound is better at confirming that what’s there is truly the problem.
Ultrasound has an additional advantage: it’s dynamic. The examiner can perform the Mulder maneuver during the scan and watch the neuroma pop into view in real time. A neuroma appears as a solid, non-compressible mass that shifts toward the sole of the foot when the metatarsals are squeezed. This movement pattern helps distinguish it from a fluid-filled bursa, which compresses under pressure rather than displacing.
Size Matters for Diagnosis
Not every thickening of an intermetatarsal nerve causes symptoms. Small neuromas are common incidental findings on imaging, which is one reason the diagnosis can’t rely on scans alone. Research comparing symptomatic and asymptomatic groups found a meaningful size difference: neuromas averaging 5.3 mm across tended to cause pain, while those averaging 4.1 mm generally did not. The widely used clinical threshold is 5 mm in transverse diameter. Below that, a neuroma visible on MRI may be irrelevant to your symptoms.
This is why correlation between imaging findings and clinical symptoms is essential. A scan that shows a 3 mm thickening in a patient with classic Mulder-positive pain might still support the diagnosis, while a 6 mm neuroma in someone with no forefoot symptoms is likely meaningless. Your doctor weighs both together.
Conditions That Mimic Morton’s Neuroma
Several other forefoot problems produce overlapping symptoms, and part of the diagnostic process is ruling them out.
- Intermetatarsal bursitis: A fluid-filled sac between the metatarsal heads can cause similar pain in the same location. The key difference is anatomical. A bursa sits above the ligament that runs across the metatarsal heads, while a neuroma sits below it. On ultrasound, a bursa compresses when pressed, whereas a neuroma does not. Small fluid collections of 3 mm or less between the metatarsals can be entirely normal.
- Stress fracture: A stress fracture of a metatarsal bone produces pain that worsens with activity but tends to be more localized over the bone itself rather than in the web space. Initial X-rays can look completely normal. MRI is the best way to catch an early stress fracture, which shows up as swelling within the bone marrow before any visible fracture line appears.
- Metatarsophalangeal joint problems: Inflammation or tears of the joint capsule at the base of a toe can mimic neuroma pain but typically produce tenderness directly over the joint rather than between the metatarsal heads. Swelling at the base of the toe is another distinguishing feature.
What the Diagnostic Process Looks Like
For most people, the path to diagnosis is straightforward. You describe the classic “walking on a marble” sensation, your doctor performs the Mulder test and gets a positive click with pain reproduction, and the diagnosis is made clinically. The entire exam takes a few minutes.
If there’s any ambiguity, an ultrasound is typically the next step. It’s fast, widely available, doesn’t involve radiation, and can be done in the same office visit at many orthopedic or podiatric practices. MRI is reserved for cases where ultrasound is inconclusive, where multiple conditions are suspected, or when surgical planning requires a detailed anatomical map of the forefoot.
A diagnostic injection is sometimes used as a final confirmation tool. Your doctor injects a small amount of local anesthetic into the affected intermetatarsal space. If your pain disappears temporarily, it strongly supports the neuroma diagnosis and also gives you a preview of the relief that a corticosteroid injection or other treatment might provide.