Portal de Periódicos da CAPES

Diagnosis and Treatment of Forefoot Disorders. Section 3. Morton's Intermetatarsal Neuroma

2009; Elsevier BV; Volume: 48; Issue: 2 Linguagem: Inglês

10.1053/j.jfas.2008.12.005

1542-2224

James L. Thomas, Edwin L. Blitch, D. Martin Chaney, Kris A. Dinucci, Kimberly Eickmeier, Laurence G. Rubin, Mickey D. Stapp, John V. Vanore,

Musculoskeletal synovial abnormalities and treatments

This clinical practice guideline (CPG) is based upon consensus of current clinical practice and review of the clinical literature. The guideline was developed by the Clinical Practice Guideline Forefoot Disorders Panel of the American College of Foot and Ankle Surgeons. The guideline and references annotate each node of the corresponding pathways. Nerve pathologies are a common cause of forefoot pain and include diverse conditions with similar symptoms. The symptoms are characteristic of sensory nerve disorders and differ from other musculoskeletal conditions. Morton's intermetatarsal neuroma is a compression neuropathy of the common digital nerve (Fig. 1). It is most commonly seen in the third intermetatarsal space, but it also can be seen in other intermetatarsal spaces (Fig. 2). A neuroma may occur in more than one intermetatarsal space and may be bilateral. Neuromas are more prevalent in adults beginning in the third decade of life, and are more common in females than males (1Keh R.A. Ballew K.K. Higgins K.R. Odom R. Harkless L.B. Long-term follow-up of Morton's neuroma.J Foot Surg. 1992; 31: 93-95PubMed Google Scholar, 2Mann R.A. Reynolds J.C. Interdigital neuroma: a critical clinical analysis.Foot Ankle. 1983; 3: 238-243Crossref PubMed Scopus (168) Google Scholar, 3Bradley N. Miller W.A. Evans J.P. Plantar neuroma: analysis of results following surgical excision in 145 patients.South Med J. 1976; 69: 853-854Crossref PubMed Scopus (48) Google Scholar, 4Friscia D.A. Strom D.E. Parr J.W. Surgical treatment for primary interdigital neuroma.Orthopedics. 1992; 14: 669-672Google Scholar, 5Gauthier G. Thomas Morton's disease: a nerve entrapment syndrome A new surgical technique.Clin Orthop Relat Res. 1979; 142: 90-92PubMed Google Scholar, 6Karges D.E. Plantar excision of primary interdigital neuromas.Foot Ankle. 1988; 9: 120-124Crossref PubMed Scopus (29) Google Scholar, 7Miller S.J. Nakra A. Banks A.S. Downey M.S. Martin D.E. Miller S.J. McGlamry's Comprehensive Textbook of Foot and Ankle Surgery. Lippincott Williams and Wilkins, Philadelphia2001: 231-252Google Scholar).FIGURE 2The reported frequency of intermetatarsal space neuromas has varied among investigators, although the third intermetatarsal space predominates in all series.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The subjective history reported by the patient is usually characteristic for this entity. The patient may complain of numbness and tingling, and/or radiating, burning pain. The pain often is localized at the plantar aspect of the respective intermetatarsal space, but it can radiate into the adjacent toes. Patients frequently describe a “lump” on the bottom of their foot or a feeling of walking on a rolled-up or wrinkled sock. The symptoms may increase with weightbearing and activity. Closed-toed shoes and especially tight-fitting footwear can increase the symptoms. Patients report relief of symptoms upon removing or changing their shoes. They also may get relief from massaging the foot and moving the toes. Objective findings are unique to Morton's neuroma and can provide further insight to aid the clinician in the diagnostic process. Although patients frequently describe numbness, a sensory deficit may or may not be present on examination. The clinical presentation may demonstrate a splaying or divergence of the digits (8Sullivan J.D. Neuroma diagnosis by means X-ray evaluation.J Foot Ankle Surg. 1967; 6: 45-46Google Scholar). Usually little to no edema or inflammation is seen clinically. Reproduction of the pain with palpation to the intermetatarsal space is typical. Care must be taken to press in the intermetatarsal space and avoid the metatarsal heads. Various clinical maneuvers have been described to assist the clinician in the diagnosis of Morton's neuroma. The patient may demonstrate a Mulder's sign (9Betts L.O. Morton's metatarsalgia neuritis of the fourth digital nerve.Med J Aust. 1940; 1: 514-515Google Scholar, 10Mulder J.D. The causative mechanism in Morton's metatarsalgia.J Bone Joint Surg Br. 1951; 33B: 94-95Google Scholar), elicited by squeezing the forefoot and applying plantar and dorsal pressure. A positive test result consists of a click or pop that can be felt or heard; this can be painful to the patient. Symptoms of Morton's neuroma may be replicated through the Gauthier' test, in which the forefoot is squeezed and medial to lateral pressure is applied (5Gauthier G. Thomas Morton's disease: a nerve entrapment syndrome A new surgical technique.Clin Orthop Relat Res. 1979; 142: 90-92PubMed Google Scholar). Bratkowski described a test that involves hyperextending the toes and rolling the thumb of the examiner in the area of symptoms. This maneuver may reveal a tender, thickened, longitudinal mass (11Bratkowski B. Differential diagnosis of plantar neuromas: a preliminary report.J Foot Ankle Surg. 1978; 17: 99-102Google Scholar). Patients with Morton's neuroma also may demonstrate Tinel's sign and Valleix phenomenon. Diagnostic testing for a Morton's neuroma may include plain radiography, ultrasound, and magnetic resonance imaging (MRI) (12Alexander I.J. Johnson K.A. Parr J.W. Morton's neuroma: a review of recent concepts.Orthopedics. 1987; 10: 103-106PubMed Google Scholar). Radiographs should be routinely ordered to rule out musculoskeletal pathology. Neuromas will not be visible on radiographs. Although increased proximity of the adjacent metatarsal heads has been thought to result in more pressure on the intermetatarsal nerve, Grace and colleagues found no statistically significant relationship between radiographic findings and the clinical presence of neuromas (13Grace T.S. Sunshein K. Jones R. Harkless L. Metatarsus proximus and digital divergence Association with intermetatarsal neuromas.J Am Podiatr Med Assoc. 1993; 83: 406-411Crossref PubMed Scopus (6) Google Scholar). Ultrasound also has been recommended for diagnostic evaluation of the interspaces (14Kaminsky S. Griffin L. Milsap J. Page D. Is ultrasonography a reliable way to confirm the diagnosis of Morton's neuroma?.Orthopedics. 1997; 20: 37-39PubMed Google Scholar). A neuroma will appear as an ovoid mass with hypoechoic signal (15Beggs I. Sonographic appearances of nerve tumors.J Clin Ultrasound. 1999; 27: 363-368Crossref PubMed Scopus (100) Google Scholar, 16Pollak R.A. Bellacosa R.A. Dornbluth N.C. Strash W.W. Devall J.M. Sonographic analysis of Morton's neuroma.J Foot Surg. 1992; 31: 534-537PubMed Google Scholar). This mass will be parallel to the long axis of the metatarsals and is best observed on the coronal view (17Kankanala G. Jain A.S. The operational characteristics of ultrasonography for the diagnosis of plantar intermetatarsal neuroma.J Foot Ankle Surg. 2007; 46: 213-217Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar, 18Redd R.A. Peters V.J. Emery S.F. Branch H.M. Rifkin M.D. Morton neuroma: sonographic evaluation.Radiology. 1989; 171: 415-417PubMed Google Scholar, 19Hassouna H. Singh D. Morton's metatarsalgia: pathogenesis, aetiology and current management.Acta Orthop Belg. 2005; 71: 646-655PubMed Google Scholar). MRI can be a useful diagnostic tool, but it should be reserved for atypical presentations or to rule out multiple neuromas. The neuroma is best identified on T1 weighted images. It will be revealed as a well-demarcated mass with low signal intensity (20Mendicino S.S. Rockett M.S. Morton's neuroma Update on diagnosis and imaging.Clin Podiatr Med Surg. 1997; 14: 303-311PubMed Google Scholar). The diagnosis of Morton's neuroma requires a careful clinical history correlated with the condition's unique set of characteristics found on examination. Care must be taken to rule out other possible etiologies of symptoms in this area of the forefoot (19Hassouna H. Singh D. Morton's metatarsalgia: pathogenesis, aetiology and current management.Acta Orthop Belg. 2005; 71: 646-655PubMed Google Scholar, 21Sharp R.J. Wade C.M. Hennessy M.S. Saxby T.S. The role of MRI and ultrasound imaging in Morton's neuroma and the effect of size of lesion on symptoms.J Bone Joint Surg Br. 2003; 85: 999-1005Crossref PubMed Scopus (106) Google Scholar, 22Rosenberg G.A. Sferra J.J. Morton's neuroma Primary and recurrent an their treatment.Foot Ankle Clin. 1998; 3: 473-484Google Scholar). The differential diagnosis of Morton's neuroma includes:•Stress fracture (23Zanetti M. Weishaupt D. MR imaging of the forefoot: Morton neuroma and differential diagnoses.Semin Musculoskelet Radiol. 2005; 9: 175-186Crossref PubMed Scopus (54) Google Scholar)•Neoplasm (eg, rheumatoid nodule) (24Hofbauer P.G. Rheumatoid nodule in Morton's neuroma A case report.J Am Podiatry Assoc. 1974; 64: 424-426Crossref PubMed Scopus (4) Google Scholar, 25Morris M.A. Morton's metatarsalgia.Clin Orthop Relat Res. 1977; 127: 203-207PubMed Google Scholar, 26Perini L. Del Borrello M. Cipriano R. Cavallo A. Volpe A. Dynamic sonography of the forefoot in Morton's syndrome: correlation with magnetic resonance and surgery.Radiol Med (Torino). 2006; 111: 897-905Crossref PubMed Scopus (17) Google Scholar, 27Zielaskowski L.A. Kruljac S.J. DiStazio J.J. Bastacky S. Multiple neuromas coexisting with rheumatoid synovitis and a rheumatoid nodule.J Am Podiatr Med Assoc. 2000; 90: 252-255Crossref PubMed Scopus (3) Google Scholar)•Bursitis (23Zanetti M. Weishaupt D. MR imaging of the forefoot: Morton neuroma and differential diagnoses.Semin Musculoskelet Radiol. 2005; 9: 175-186Crossref PubMed Scopus (54) Google Scholar, 25Morris M.A. Morton's metatarsalgia.Clin Orthop Relat Res. 1977; 127: 203-207PubMed Google Scholar, 28Iagnocco A. Coari G. Palombi G. Valesini G. Sonography in the study of metatarsalgia.J Rheumatol. 2001; 28: 1338-1340PubMed Google Scholar)•MPJ pathology (27Zielaskowski L.A. Kruljac S.J. DiStazio J.J. Bastacky S. Multiple neuromas coexisting with rheumatoid synovitis and a rheumatoid nodule.J Am Podiatr Med Assoc. 2000; 90: 252-255Crossref PubMed Scopus (3) Google Scholar, 28Iagnocco A. Coari G. Palombi G. Valesini G. Sonography in the study of metatarsalgia.J Rheumatol. 2001; 28: 1338-1340PubMed Google Scholar, 29Vainio K. Morton's metatarsalgia in rheumatoid arthritis.Clin Orthop Relat Res. 1979; 142: 85-89PubMed Google Scholar)•Metabolic neuropathy•Fibromyalgia and other chronic pain syndromes The diagnosis of Morton's neuroma is primarily a clinical diagnosis that is reached after examination and diagnostic testing have ruled out other possible etiologies of symptoms. Nonsurgical care of Morton's neuroma is centered on alleviating pressure and irritation of the nerve. Initially, patients should wear shoes that have a wide toe box to allow the metatarsals to spread out. High-heel shoes should be avoided. Metatarsal pads also can be beneficial. These pads, placed proximal to the metatarsal heads, help alleviate pressure on the nerve and assist in spreading out the metatarsals. Injection therapy includes a variety of alternative approaches to nonsurgical treatment. A local anesthetic block can be used to provide some diagnostic information, but it has not been shown to be therapeutic (30Okafor B. Shergill G. Angel J. Treatment of Morton's neuroma by neurolysis.Foot Ankle Int. 1997; 18: 284-287Crossref PubMed Scopus (55) Google Scholar). Corticosteroid injection is cited as having an 11% to 47% success rate, with multiple injections obtaining better results (31Bennett G.L. Graham C.E. Mauldin D.M. Morton's interdigital neuroma: a comprehensive treatment protocol.Foot Ankle Int. 1995; 16: 760-763Crossref PubMed Scopus (130) Google Scholar, 32Greenfield J. Rea Jr, J. Ilfeld F.W. Morton's interdigital neuroma Indications for treatment by local injections versus surgery.Clin Orthop Relat Res. 1984; 185: 142-144PubMed Google Scholar, 33Rassmussen M.R. Kitaoka H.B. Pantzer G.L. Nonoperative treatment of plantar interdigital neuroma with single corticosteroid injection.Clin Orthop Relat Res. 1996; 326: 188-193Crossref PubMed Scopus (88) Google Scholar, 34Saygi B. Yildirim Y. Saygi E.K. Kara H. Esemenli T. Morton neuroma: comparative results of two conservative methods.Foot Ankle Int. 2005; 26: 556-559PubMed Google Scholar, 35Strong G. Thomas P.S. Conservative treatment of Morton's neuroma.Orthop Rev. 1987; 16: 343-345PubMed Google Scholar). Care should be taken to avoid overusing corticosteroid injections; the literature contains reports of atrophy of the plantar fat pad secondary to cortisone injections, as well as joint subluxation (36Basadonna P.T. Rucco V. Gasparini D. Onorato A. Plantar fat pad atrophy after corticosteroid injection for an interdigital neuroma: a case report.Am J Phys Med Rehabil. 1999; 78: 283-285Crossref PubMed Scopus (51) Google Scholar). Dilute alcohol injections (3-7 injections of 4% alcohol administered at 5-10 day intervals) has been associated with an 89% success rate, with 82% of patients achieving complete relief of symptoms (37Dockery G.L. The treatment of intermetatarsal neuromas with 4% alcohol sclerosing injections.J Foot Ankle Surg. 1999; 38: 403-408Abstract Full Text PDF PubMed Scopus (63) Google Scholar). Several other investigators have verified the efficacy of sclerosing injections as a nonsurgical treatment alternative (38Fanucci E. Masala S. Fabiano S. Perugia D. Squillaci E. Varrucciu V. et al.Treatment of intermetatarsal Morton's neuroma with alcohol injection under US guide: 10-month follow-up.Eur Radiol. 2004; 14: 514-518Crossref PubMed Scopus (66) Google Scholar, 39Hyer C.F. Mehl L.R. Block A.J. Vancourt R.B. Treatment of recalcitrant intermetatarsal neuroma with 4% sclerosing alcohol injection: a pilot study.J Foot Ankle Surg. 2005; 44: 287-291Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar, 40Masala S. Fanucci E. Ronconi P. Sodani G. Taormina P. Romagnoli A. et al.Treatment of intermetatarsal neuromas with alcohol injection under US guide.Radiol Med (Torino). 2001; 102: 370-373PubMed Google Scholar). Another injection modality involves injecting the nerve with vitamin B12 (cyanocobalamin); this has been discussed in the literature, but the effects observed may have been due to the preserving agent, benzyl alcohol (41Steinberg M.D. The use of vitamin B-12 in Morton's neuralgia.J Am Podiatr Med Assoc. 1955; 45: 566-567Google Scholar). Phenol also has been reported as a safe and effective injection modality (42Magnan B. Marangon A. Frigo A. Bartolozzi P. Local phenol injection in the treatment of interdigital neuritis of the foot (Morton's neuroma).Chir Organi Mov. 2005; 90: 371-377PubMed Google Scholar). Excision of the affected portion of the nerve is perhaps the most common approach to neuroma surgery (1Keh R.A. Ballew K.K. Higgins K.R. Odom R. Harkless L.B. Long-term follow-up of Morton's neuroma.J Foot Surg. 1992; 31: 93-95PubMed Google Scholar, 7Miller S.J. Nakra A. Banks A.S. Downey M.S. Martin D.E. Miller S.J. McGlamry's Comprehensive Textbook of Foot and Ankle Surgery. Lippincott Williams and Wilkins, Philadelphia2001: 231-252Google Scholar, 19Hassouna H. Singh D. Morton's metatarsalgia: pathogenesis, aetiology and current management.Acta Orthop Belg. 2005; 71: 646-655PubMed Google Scholar, 43Kitting R.W. McGlamry E.D. Removal of an intermetatarsal neuroma.J Am Podiatry Assoc. 1973; 63: 274-276Crossref PubMed Scopus (3) Google Scholar). Excision requires identifying the common digital portion of the nerve and following the structure to the proper digital branches. Care must be taken to avoid other structures in the area. Various surgical approaches have been used, the most common of which is a dorsal incision over the involved intermetatarsal space (44Dereymaeker G. Schroven I. Steenwerckx A. Stuer P. Results of excision of the interdigital nerve in the treatment of Morton's metatarsalgia.Acta Orthop Belg. 1996; 62: 22-25PubMed Google Scholar, 45Ruuskanen M.M. Niinimaki T. Jalovaara P. Results of the surgical treatment of Morton's neuralgia in 58 operated intermetatarsal spaces followed over 6 (2-12) years.Arch Orthop Trauma Surg. 1994; 113: 78-80Crossref PubMed Scopus (20) Google Scholar) (Fig. 3). Plantar incisional approaches are most often used in revisionary procedures, although they also have been described as an initial surgical approach (19Hassouna H. Singh D. Morton's metatarsalgia: pathogenesis, aetiology and current management.Acta Orthop Belg. 2005; 71: 646-655PubMed Google Scholar, 22Rosenberg G.A. Sferra J.J. Morton's neuroma Primary and recurrent an their treatment.Foot Ankle Clin. 1998; 3: 473-484Google Scholar, 46Wu K.K. Morton's interdigital neuroma: a clinical review of its etiology, treatment, and results.J Foot Ankle Surg. 1996; 35 (discussion 187-188.): 112-119Abstract Full Text PDF PubMed Scopus (136) Google Scholar, 47Johnson J.E. Johnson K.A. Unni K.K. Persistent pain after excision of an interdigital neuroma: results of reoperation.J Bone Joint Surg Am. 1988; 70A: 651-657Google Scholar). Excision may also be elected when prior decompression surgery has failed to resolve symptoms (48Jarde O. Trinquier J.L. Pleyber A. Meire P. Vives P. Treatment of Morton neuroma by neurectomy Apropos of 43 cases.Rev Chir Orthop Reparatrice Appar Mot. 1995; 81: 142-146PubMed Google Scholar). Decompression of the intermetatarsal nerve through the use of endoscopic and minimally invasive techniques has been reported in recent years (49Barrett S.L. Walsh A.S. Endoscopic decompression of intermetatarsal nerve entrapment: a retrospective study.J Am Podiatr Med Assoc. 2006; 96: 19-23Crossref PubMed Scopus (23) Google Scholar, 50Shapiro S.L. Endoscopic decompression of the intermetatarsal nerve for Morton's neuroma.Foot Ankle Clin. 2004; 9: 297-304Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar, 51Zelent M.E. Kane R.M. Neese D.J. Lockner W.B. Minimally invasive Morton's intermetatarsal neuroma decompression.Foot Ankle Int. 2007; 28: 263-265Crossref PubMed Scopus (38) Google Scholar). Open decompression of the nerve by releasing the deep transverse intermetatarsal ligament and performing an external neurolysis has been described (52Dellon A.L. Treatment of Morton's neuroma as a nerve compression The role for neurolysis.J Am Podiatr Med Assoc. 1992; 82: 399-402Crossref PubMed Scopus (58) Google Scholar). In addition, transposition with nerve release has been shown to be useful (53Vito G.R. Talarico L.M. A modified technique for Morton's neuroma Decompression with relocation.J Am Podiatr Med Assoc. 2003; 93: 190-194Crossref PubMed Scopus (29) Google Scholar, 54Colgrove R.C. Huang E.Y. Barth A.H. Greene M.A. Interdigital neuroma: intermuscular neuroma transposition compared with resection.Foot Ankle Int. 2000; 21: 206-211PubMed Google Scholar). Cryogenic neuroablation is a minimally invasive procedure that applies a temperature of -50°C to -70°C to the nerve. This results in Wallerian degeneration of the axons and myelin, while leaving the epineurium and perineurium intact. Preserving these structures helps prevent stump neuromas during nerve regeneration; this is the greatest advantage of cryogenic ablation. There are limitations of this procedure. The results are not permanent, and it is not as effective on larger neuromas or in the presence of thick fibrosis. Several investigators have advocated this technique (55Hodor L. Barkal K. Hatch-Fox L.D. Cryogenic denervation of the intermetatarsal space neuroma.J Foot Ankle Surg. 1997; 36: 311-314Abstract Full Text PDF PubMed Scopus (36) Google Scholar, 56Caporusso E.F. Fallat L.M. Savoy-Moore R. Cryogenic neuroablation for the treatment of lower extremity neuromas.J Foot Ankle Surg. 2002; 41: 286-290Abstract Full Text PDF PubMed Scopus (32) Google Scholar). All treatments may have complications, with either ineffective relief of symptoms or worsening of the condition. Careful reassessment in failed surgical management may reveal tarsal tunnel or other proximal nerve pathology. Complications of surgical procedures include infection, hematoma, stump neuroma formation, and chronic pain syndromes. Surgical failures may require more aggressive surgical intervention including plantar approach and implantation of the proximal portion of nerve into muscle (57Wolfort S.F. Dellon A.L. Treatment of recurrent neuroma of the interdigital nerve by implantation of the proximal nerve into muscle in the arch of the foot.J Foot Ankle Surg. 2001; 40: 404-410Abstract Full Text PDF PubMed Scopus (61) Google Scholar, 58Banks A.S. Vito G.R. Giorgini T.L. Recurrent intermetatarsal neuroma A follow-up study.J Am Podiatr Med Assoc. 1996; 86: 299-306Crossref PubMed Scopus (19) Google Scholar).