Morton’s neuroma is a common foot condition causing discomfort in the forefoot. It is not a true tumor, but a benign thickening of nerve tissue, which is why the idea of “regrowth” after treatment is often misunderstood. Successful management requires understanding the condition’s structure, treatment goals, and the specific reasons why pain might return following a procedure.
Pathology and Location
Morton’s neuroma (MN) is defined as symptomatic perineural fibrosis, meaning fibrous tissue has thickened around a common plantar digital nerve. This thickening occurs most frequently in the third intermetatarsal space, between the heads of the third and fourth long bones of the foot. The nerve is susceptible to chronic compression and irritation, particularly by the transverse intermetatarsal ligament. Continuous mechanical stress leads to degenerative changes, including damage to the protective myelin sheath and the formation of disorganized nerve fibers and scar tissue. Patients typically experience a sharp, burning pain that radiates into the toes, often described as walking on a marble or a crumpled sock.
Treatment Goals and Interventions
The primary goal of Morton’s neuroma treatment is to decompress the irritated nerve or eliminate the painful segment entirely. Treatment begins with conservative, non-surgical measures aimed at reducing mechanical irritation and inflammation. This includes wearing shoes with a wide toe box, using custom orthotics, or placing metatarsal pads to redistribute weight away from the forefoot.
If modifications fail, injection therapies are introduced. Corticosteroid injections reduce inflammation and swelling, offering successful relief for approximately 50-82% of patients. Chemical neurolysis, involving a series of alcohol sclerosing injections, is another option used to intentionally damage the nerve fibers and silence the pain signal.
When conservative treatments are ineffective, surgical excision, or neurectomy, is considered the definitive step, boasting an 80-95% initial success rate. The procedure involves removing the diseased segment of the nerve, usually through a dorsal approach. This eliminates the source of pain but intentionally leaves the patient with permanent numbness in the adjacent toes.
Recurrence: Why Nerve Pain Returns
The original Morton’s neuroma cannot technically “grow back,” as it is a degenerative thickening, not a tumor that regenerates. However, pain often returns due to the formation of a secondary neuroma called a “stump neuroma,” a well-recognized complication following surgical neurectomy.
A stump neuroma develops when the body’s natural repair mechanism attempts to regenerate the cut nerve end in a disorganized manner. The nerve sprouts new fibers that become entangled in surrounding scar tissue, forming a hypersensitive, bulb-like mass. Pain from a stump neuroma is often more intense than the original condition because the disorganized tissue is easily irritated by mechanical pressure.
The incidence of unacceptable post-surgical pain requiring a second intervention ranges from 5 to 20% of cases. Returning pain can also result from an incomplete surgical removal, failure to identify a second neuroma in an adjacent web space, or an incorrect initial diagnosis.
Identifying and Treating New Symptoms
When pain returns after a neurectomy, a thorough clinical evaluation is necessary. A physical exam often reveals local tenderness further back in the foot compared to the original site, a tell-tale sign of a stump neuroma. Diagnostic imaging, such as high-resolution ultrasound or MRI, confirms the presence and size of this secondary nerve mass. A diagnostic nerve block, using an anesthetic injected near the suspected stump, offers temporary confirmation of the pain source.
Treatment typically starts with non-surgical options, including specialized nerve blocks or radiofrequency ablation to desensitize the tissue. For persistent pain, revision surgery is the final option. This involves removing the stump neuroma and burying the remaining nerve end deep into muscle or bone, a technique called nerve transposition, which shields the nerve from pressure.