eMedicine Specialties > Physical Medicine and Rehabilitation > Lower Limb Musculoskeletal Conditions
Morton Neuroma
Updated: May 26, 2009
Introduction
Background
Morton neuroma (interdigital neuroma), first described in 1876, is a perineural fibrosis and nerve degeneration of the common digital nerve.1 Morton neuroma, or Morton's neuroma, is not a true neuroma, although it results in neuropathic pain in the distribution of the interdigital nerve secondary to repetitive irritation of the nerve. The most frequent location is between the third and fourth metatarsals (third webspace). Other less common locations are between the second and third metatarsals (second webspace) and, rarely, between the first and second (first webspace) or fourth and fifth (fourth webspace) metatarsals. (See images below and Images 1, 4.)
Plantar view showing the relationships between the metatarsal heads, the intermetatarsal ligament, and the neuroma.
Neuroma and adherent fibrofatty tissue.
Episodes of pain are intermittent. Patients may experience 2 attacks in a week and then none for a year. Recurrences are variable and tend to become more frequent. Between attacks, no symptoms or physical signs occur. Two neuromas coexist on the same foot about 2-3% of the time. Other diagnoses should be considered when 2 or more areas of tenderness are present.
Pathophysiology
Interdigital nerves are composed of communicating branches from the lateral and medial plantar nerves. At the level of the metatarsal heads, the interdigital nerve traverses inferior to the intermetatarsal ligament. At this site, the nerve may be compressed or stretched from repetitive toe flexion and extension. Other studies have shown perineural fibrosis and demyelination at the level of the metatarsal heads, indicating that the damage in Morton's neuroma may be more distal than the intermetatarsal ligament.2
Frequency
United States
Morton's neuroma is a common disease entity of the foot.
International
The incidence of Morton's neuroma is presumed to be the same internationally as in United States.
Sex
The female-to-male ratio for Morton's neuroma is 5:1.
Age
The highest prevalence of Morton's neuroma is found in patients aged 15-50 years, but the condition may occur in any ambulatory patient.
Clinical
History
Obtaining an accurate history is important to making the diagnosis of Morton's neuroma. Possible reported findings provided by the patient with Morton's neuroma include the following:- The most common presenting complaints include pain and dysesthesias in the forefoot and corresponding toes adjacent to the neuroma.
- Pain is described as sharp and burning, and it may be associated with cramping.
- Numbness often is observed in the toes adjacent to the neuroma and seems to occur along with episodes of pain.
- Pain typically is intermittent, as episodes often occur for minutes to hours at a time and have long intervals (ie, weeks to months) between a single or small group of multiple attacks.
- Some patients describe the sensation as "walking on a marble."
- Massage of the affected area offers significant relief.
- Narrow tight high-heeled shoes aggravate the symptoms.
- Night pain is reported but is rare.
Physical
Many sources acknowledge that the examination of patients with Morton's neuroma frequently is negative. Most often, sensation is wholly intact and maneuvers are unsuccessful in reproducing the characteristic pain. Palpation of the actual neuroma seldom is successful. Most clinicians focus on the history and on the lack of additional findings that might suggest other disorders.
- Firm squeezing of the metatarsal heads with one hand while applying direct pressure to the dorsal and plantar interspace with the other hand may elicit radiating neuropathic pain. Pain localized only to the plantar aspect of the webspace also may be consistent with Morton's neuroma.
- The squeeze test may also result in a "click" (Mulder click) as the neuroma moves between the metatarsals in the dorsal direction.3
- Passive and active toe dorsiflexion may aggravate symptoms.
- Sensory abnormalities may be observed, although motor deficits are not consistent with an interdigital neuroma because these are sensory nerves exclusively. Weakness would raise concerns for another diagnosis.
- Careful palpation of the metatarsal heads and shafts may help to differentiate stress fractures or metatarsal head osteonecrosis from Morton's neuroma.
- Palpation of the tarsometatarsal joint and metatarsophalangeal (MTP) joints may reveal tenderness, indicating midfoot arthritis or metatarsalgia (eg, when the tenderness is primarily on the plantar surface only) or MTP synovitis (eg, when the joint is tender with palpation).
- Pain from MTP synovitis is aggravated with forced toe flexion. Subtle joint swelling also may coexist with MTP synovitis. Tenderness localized to the second MTP joint, along with swelling and warmth, may be, in rare cases, an early presentation of Freiburg osteochondrosis.
- Inspection of the foot and evaluation of foot and ankle mechanics should be performed as part of the physical examination, looking for callus formation, hallux valgus, first-ray flexibility, hyperpronation, integrity of the medial arch, and gastrocnemius-soleus flexibility.
Causes
Various factors have been implicated in the precipitation of Morton's neuroma.
- Morton's neuroma is known to develop as a result of chronic nerve stress and irritation, particularly with excessive toe dorsiflexion.
- Poorly fitting and constricting shoes (ie, small toe box) or shoes with heel lifts often contribute to Morton's neuroma. Women who wear high-heeled shoes for a number of years or men who are required to wear constrictive shoe gear are at risk.
- A biomechanical theory of causation involves the mechanics of the foot and ankle. For instance, individuals with tight gastrocnemius-soleus muscles or who excessively pronate the foot may compensate by dorsiflexion of the metatarsals subsequently irritating of the interdigital nerve.
- Certain activities carry increased risk of excessive toe dorsiflexion, such as prolonged walking, running, squatting, and demi-pointe position in ballet.3
See the History and Pathophysiology sections.
More on Morton Neuroma |
 Overview: Morton Neuroma |
| Differential Diagnoses & Workup: Morton Neuroma |
| Treatment & Medication: Morton Neuroma |
| Follow-up: Morton Neuroma |
| Multimedia: Morton Neuroma |
| References |
| Further Reading |
| Next Page » |
References
Morton TG. Peculiar painful affection of fourth metatarsophalangeal articulation. Am J Med Sci. 1876;71:37.
Kim JY, Choi JH, Park J, et al. An anatomical study of Morton's interdigital neuroma: the relationship between the occurring site and the deep transverse metatarsal ligament (DTML). Foot Ankle Int. Sep 2007;28(9):1007-10. [Medline].
O'Connor FG, Wilder RP, Nirschl R. Foot Injuries in the Runner. In:Textbook of Running Medicine. New York: McGraw-Hill; 2001;258-260.
Lee MJ, Kim S, Huh YM, Song HT, Lee SA, Lee JW, et al. Morton neuroma: evaluated with ultrasonography and MR imaging. Korean J Radiol. Mar-Apr 2007;8(2):148-55. [Medline].
Zanetti M, Weishaupt D. MR imaging of the forefoot: Morton neuroma and differential diagnoses. Semin Musculoskelet Radiol. Sep 2005;9(3):175-86.
Akermark C, Saartok T, Zuber Z. A prospective 2-year follow-up study of plantar incisions in the treatment of primary intermetatarsal neuromas (Morton's neuroma). Foot Ankle Surg. 2008;14(2):67-73. [Medline].
Monacelli G, Cascioli I, Prezzemolo G, Spagnoli A, Irace S. [Surgical treatment of Morton's neuroma: our experience and literature review]. Clin Ter. May-Jun 2008;159(3):165-7. [Medline].
Valente M, Crucil M, Alecci V. Operative treatment of interdigital Morton's neuroma. Chir Organi Mov. May 2008;92(1):39-43. [Medline].
Villas C, Florez B, Alfonso M. Neurectomy versus neurolysis for Morton's neuroma. Foot Ankle Int. Jun 2008;29(6):578-80. [Medline].
Title CI, Schon LC. Morton neuroma: primary and secondary neurectomy. J Am Acad Orthop Surg. Sep 2008;16(9):550-7. [Medline].
Markovic M, Crichton K, Read JW, et al. Effectiveness of ultrasound-guided corticosteroid injection in the treatment of Morton's neuroma. Foot Ankle Int. May 2008;29(5):483-7. [Medline].
Betts LO. Morton's Metatarsalgia. Med J Aust. 1940;1:514.
Clanton TO, Butler JE, Eggert A. Injuries to the metatarsophalangeal joints in athletes. Foot Ankle. Dec 1986;7(3):162-76. [Medline].
Cyriax J. Diagnosis of soft tissue lesions.In: Textbook of Orthopaedic Medicine. 8th ed. Philadelphia, Pa:. The Curtis Center;1982.
Guiloff RJ. Carbamazepine in Morton''s neuralgia. Br Med J. Oct 13 1979;2(6195):904. [Medline].
Jahss MH, Kummer F. Non-inflammatory synovitis of the second metatarsophalangeal joint and its surgical management. Paper read at: 16th Annual Meeting of American Orthopaedic Foot Ankle Society, New Orleans, La. February 1986.
Logan PM, Janzen DL, O''Connell JX, et al. Magnetic resonance imaging and histopathologic appearances of benign soft-tissue masses of the foot. Can Assoc Radiol J. Feb 1996;47(1):36-43. [Medline].
Mizel MS, Miller RA, Scioli MW. Orthopaedic knowledge update. In: Foot and Ankle. Rosemont, Ill:. American Academy of Orthopaedic Surgeons;1998.
Snyder RK. In: Essentials of Musculoskeletal Care. Rosemont, Ill:. American Academy of Orthopedic Surgeons;1997.
Terk MR, Kwong PK, Suthar M, et al. Morton neuroma: evaluation with MR imaging performed with contrast enhancement and fat suppression. Radiology. Oct 1993;189(1):239-41. [Medline].
Vazquez-Abad D, Tian L, Monteon V, et al. CRI-EM is a human idiotype highly specific for scleroderma. Ann N Y Acad Sci. Apr 5 1997;815:512-5. [Medline].
Wu KK. Morton neuroma and metatarsalgia. Curr Opin Rheumatol. Mar 2000;12(2):131-42. [Medline].
Yocum LA. In: Clinics in Sports Medicine. Vol 7. Philadelphia, Pa:. WB Saunders Co;1988.
Further Reading
Related eMedicine topics:
Acute Nerve Injury
Metatarsalgia
Morton Neuroma [Orthopedic Surgery]
Morton Neuroma [Radiology]
Nerve Entrapment Syndromes
Nerve Entrapment Syndromes of the Lower Extremity
Clinical guidelines:
ACR Appropriateness Criteria Chronic Foot Pain
Ankle and Foot Complaints
Clinical studies:
Comparison of Alcohol and Steroid Injection for Treating Morton's Neuroma
Is Ultrasonography Comparable to MRI for the Detection of Morton Neuroma of the Foot?
Keywords
Morton neuroma, Morton's neuroma, neuroma, metatarsal, foot surgery, foot pain, feet pain, metatarsals, neuroma surgery, foot neuroma, neuromas, neuroma treatment, metatarsalgia, plantar nerve, interdigital nerve, Morton's metatarsalgia, interdigital neuroma, plantar neuroma, Morton metatarsalgia
