Forefoot Pain: Neuromas Beyond Morton's

Purpose or Learning Objective: (1) Demonstrate the sonographic features of common and uncommon neuromas of the forefoot; (2) illustrate the role of dynamic maneuvers to demonstrate neuromas of the forefoot; and (3) describe ultrasonography (US)-guided interventions in the management of neuromas.

Methods or Background: Forefoot pain radiating to the midfoot while walking is one the common presentation of neuromas of the forefoot. The term forefoot neuroma is a misnomer because the abnormality is non-neoplastic and does not represent a true neuroma; rather, it is a perineural fibrosis. The location and appearance of neuroma on US and dynamic maneuvers leads us to the specific diagnosis. In failed conservative cases of neuroma, US-guided intervention is a viable alternative to surgery.

Results or Findings: The most common forefoot neuroma is the so-called Morton's neuroma that commonly occurs along the plantar digital nerve deep to the intermetatarsal ligament in the third intermetatarsal space proximal to the metatarsal head, followed by the second intermetatarsal space. Narrow space of the third intermetatarsal space leads to entrapment of the third plantar digital nerve, formed by both the medial and lateral plantar nerves.

Heuter's neuroma in the first intermetatarsal space and Iselin's neuroma in the fourth intermetatarsal space that occur along the respective plantar digital nerves are rare. Entrapment and perineural fibrosis leading to focal fusiform swelling of the medial digital nerve along the medial surface of the great toe is known as Joplin's neuroma. The fusiform, noncompressible hypoechoic swelling in the characteristic location on US is the diagnostic feature of these forefoot neuromas. A sonographic Mulder's sign is the dynamic maneuver used to elicit Morton's neuroma. A US-guided steroid injection into the neuroma in failed conservative cases offers short- to medium-term relief. In recalcitrant cases, radiofrequency ablation or alcohol ablation of these neuromas have been proven to provide long-term relief.

Conclusion: The commonly known neuroma of the forefoot is Morton's neuroma. However, Heuter's neuroma, Iselin's neuroma, and Joplin's neuroma are uncommon neuromas that occur in the forefoot at their characteristic locations. A specific diagnosis and ensuing interventional management can relieve the patient with forefoot pain.

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Artikel online veröffentlicht:
26. Mai 2023