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AI-Generated response:

what causes morton neuroma?

Answer generated on June 4, 2024

The AI-generated responses are for illustration purposes only and should not be used for medical purposes.

Morton's neuroma is primarily caused by compression and irritation of the interdigital nerve, typically in the third intermetatarsal space.

  • The condition is considered an entrapment neuropathy where the common digital plantar nerve is compressed between the metatarsal heads or by the transverse metatarsal ligament.[1]

  • Histological studies of Morton's neuroma show hyperplasia within the nerve, demyelination, intraneural fibrosis, and thickened endoneurial capillaries, indicating chronic irritation and damage.[1]

  • Anatomical variations, such as a thicker nerve formed by the joining of branches from the medial and lateral plantar nerves, make the nerve more susceptible to compression and trauma, particularly in the third interspace.[1]

  • External factors like wearing narrow shoes or high heels can exacerbate the compression of the nerve, leading to the symptoms associated with Morton's neuroma.[2]

  • Other potential causes include soft tissue masses like plantar lipomas that may compress the nerve against the ligament.[1]

Additional info

Understanding the etiology of Morton's neuroma is crucial for effective management. The condition involves both biomechanical factors, such as the anatomical positioning and susceptibility of the nerve to compression, and external factors like footwear that can exacerbate the nerve compression. This knowledge aids in guiding treatment options, which may include changes in footwear, orthotic supports, or more invasive procedures like injections or surgery if conservative measures fail. Awareness of the detailed anatomy and typical sites of compression can also assist in diagnostic imaging techniques, such as ultrasound, which is highly accurate but operator-dependent.[3] This comprehensive understanding helps in both diagnosing and formulating a tailored treatment plan for patients suffering from Morton's neuroma.

References

Reference 1

1.

Morton Neuroma, Elsevier ClinicalKey Derived Clinical Overview

• While the exact etiology of Morton neuroma is uncertain, most histologic studies show evidence of hyperplasia within the nerve. • The neuroma is further considered to be an entrapment neuropathy of the affected common digital plantar nerve (Fig. E1) between adjacent metatarsal heads or by the transverse metatarsal ligament. • The common plantar digital nerves are branches of the medial and lateral plantar nerve that course distally to supply the digits of the foot, passing just beneath the deep transverse intermetatarsal ligament. Within the third intermetatarsal space, a communicating branch of the medial plantar nerve often joins with a communicating branch of the lateral plantar nerve to supply the third and fourth digits. This anatomic variation results in a thicker nerve that is more prone to trauma between the constrictive metatarsal heads, a reason often cited to explain the prevalence of Morton neuroma specifically within the third interspace. • The deep transverse intermetatarsal ligament may also be implicated in the cause of a neuroma. If it is thickened or has aberrant bands, it may cause compression of the affected nerve. • Soft tissue masses such as a plantar lipoma may also cause compression of the nerve against the ligament, leading to the formation of a neuroma. • Histologic examination of resected Morton neuroma exhibits increased neural width, demyelination, intraneural fibrosis, and thickened endoneurial capillaries. FIG. E1On the plantar surface of the foot, the interdigital nerve is compressed below the transverse metatarsal ligament and not between the metatarsal heads (plantar view).From Hochberg MC:Rheumatology,ed 7, Philadelphia, 2019, Elsevier.

Reference 2

2.

Biundo, Joseph J., Canoso, Juan J. (2024). Bursitis, Tendinopathy, Other Periarticular Disorders, and Sports Medicine. In Goldman-Cecil Medicine (pp. 1742). DOI: 10.1016/B978-0-323-93038-3.00242-2

Morton neuroma (Fig. 242-8) is a prominent cause of forefoot pain and paresthesia in individuals who wear shoes that are too narrow for the width of their metatarsal arches and high heels that drive the forefeet into those limited spaces. The compressed nerve, surrounded by reactive fibrous tissue, supplies the opposing halves of two contiguous toes, generally the third and the fourth. Multiple nerves may be involved.Typically, symptoms do not appear wearing sandals.

Reference 3

3.

Mak MS, Chowdhury R, Johnson R. Morton's Neuroma: Review of Anatomy, Pathomechanism, and Imaging. Clinical Radiology. 2021;76(3):235.e15-235.e23. doi:10.1016/j.crad.2020.10.006. Publish date: March 1, 2021

Morton's neuroma is a commonly encountered cause of forefoot pain, which may limit weight-bearing activities and footwear choices. Although the aetiology and pathomechanism of this condition is controversial, the histological endpoint is well established as benign perineural fibrosis of a common plantar digital nerve, typically within the third intermetatarsal space. The diagnosis of Morton's neuroma is mainly based on characteristic symptoms and clinical findings, but may be confirmed by ultrasonography. Although ultrasound is a highly accurate diagnostic tool for Morton's neuroma, it is subject to interoperator variability due to differences in technique and level of experience. In this paper, the authors review the anatomy of the common plantar digital nerves and surrounding structures in the forefoot, which are deemed relevant to the understanding of Morton's neuroma, especially from a sonographic point of view. Several theories of the pathomechanism of Morton's neuroma are briefly discussed. The main purpose of this article is to illustrate the ultrasound techniques for evaluating Morton's neuroma and performing ultrasound-guided corticosteroid injections.

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