Morton’s neuroma (MN) is a painful condition characterized by the thickening of tissue around a nerve between the metatarsal bones in the forefoot. This typically occurs between the third and fourth toes, causing sharp, burning pain, tingling, or numbness that can feel like stepping on a small stone or a bunched-up sock. Because the discomfort is centered in the ball of the foot, MN symptoms often overlap with those of many other common foot ailments. Structural and inflammatory issues can mimic the localized irritation of a neuroma. Distinguishing these conditions is important because their treatments differ significantly from those used for nerve compression.
Conditions Involving Joint and Ligament Inflammation
Pain in the forefoot that is not MN often stems from instability or inflammation in the joints near the toes, such as capsulitis and plantar plate tears. Capsulitis refers to inflammation of the joint capsule and its surrounding ligaments, most frequently affecting the second toe. This condition creates a painful, aching sensation directly beneath the toe joint, easily confused with the deep discomfort of a neuroma. The pain is often a dull ache or throbbing, intensifying when bearing weight or when the affected toe is pushed upward.
Unlike the electrical, shooting pain of a neuroma, capsulitis symptoms are primarily mechanical, centered on the joint itself. Movement or manipulation of the toe joint will typically reproduce the pain in capsulitis, whereas MN pain is usually only triggered by compressing the nerve between the metatarsal heads. If the condition progresses, the inflammation can destabilize the joint, sometimes causing the toe to drift out of alignment or even cross over an adjacent toe.
A plantar plate tear is a significant injury to the strong ligament structure that stabilizes the toe and prevents it from shifting upward. An injury here often presents with localized pain and swelling at the base of the toe, which can feel like the forefoot is unstable. The tear occurs due to repetitive stress, which weakens the ligament until it partially or completely ruptures.
The pain from a plantar plate tear is usually described as an intense, localized pain under the ball of the foot, increasing sharply during the toe-off phase of walking. While both MN and a tear can cause pain when pushing off, the tear often involves a feeling of instability or a feeling that the toe is loose in its socket. Imaging, such as an MRI or ultrasound, is often necessary to confirm the presence of a ligament tear and differentiate it from the nerve thickening characteristic of a neuroma.
Forefoot Pain Caused by Bone Stress and Trauma
Another class of forefoot pain that mimics MN symptoms involves issues with the structural integrity of the bones, most notably metatarsal stress fractures. These are tiny cracks in the long bones of the foot, usually caused by repetitive impact or overuse, such as from running or prolonged standing. The location of the pain, often in the second or third metatarsal, puts it right in the same general area as a neuroma, leading to diagnostic confusion.
The quality of the pain, however, provides a reliable differentiation. Stress fracture pain is typically continuous and dull, intensifying significantly when the foot bears weight or is subjected to impact. Unlike the intermittent, sharp, and burning sensation of MN, which often resolves quickly upon removing footwear or resting, fracture pain tends to linger for hours or days after the activity is stopped. Furthermore, stress fractures often cause localized tenderness and visible swelling on the top (dorsum) of the foot, symptoms that are rare in cases of MN.
Diagnosis of a stress fracture often relies on imaging, beginning with X-rays, although early-stage fractures may not be visible for several weeks. In contrast, MN diagnosis relies on the patient’s description of nerve-related symptoms like tingling, confirmed using ultrasound or MRI to visualize the thickened nerve tissue. Because the conditions involve nerve irritation versus bone trauma, their respective treatments—rest for a fracture and orthotics or injections for a neuroma—are not interchangeable.
Nerve Compression Issues Originating Outside the Toes
It is also possible for nerve-related pain to be mistakenly attributed to a localized neuroma when the actual compression occurs much higher up the leg or ankle. Tarsal Tunnel Syndrome (TTS) is the primary example of this, involving the entrapment of the posterior tibial nerve as it passes through a narrow space near the ankle bone. This nerve is responsible for sensation in the sole of the foot, meaning its compression can cause symptoms that radiate into the forefoot, simulating the burning and tingling of MN.
The symptoms of TTS typically include a burning, tingling, or numb sensation that affects the heel, arch, and sole of the foot, and sometimes extends to the toes. This broader distribution of symptoms is the main feature that distinguishes it from MN, which causes highly localized pain focused between two specific toes. Patients with TTS often report that their pain is worse at night or after prolonged activity, and it can be triggered by tapping over the nerve behind the inner ankle bone.
MN is a localized irritation of digital nerve branches in the forefoot, while TTS is a proximal entrapment of the main nerve trunk at the ankle. This anatomical difference means that a treatment aimed at the forefoot, such as an alcohol injection for a neuroma, will not alleviate TTS symptoms. A proper diagnosis requires a detailed neurological examination to map the area of pain and potentially nerve conduction studies to confirm the entrapment. The presence of symptoms affecting the heel or a wider area of the sole strongly suggests a more proximal issue like TTS rather than a localized neuroma.