Sonographic evaluation of interdigital neuromas

Sonographic anatomy and technique to image the plantar digital nerves and aid identification of a Morton's neuroma

Introduction

The anatomy of the forefoot is complex, and the sonographic assessment to image the plantar digital nerves and exclude, diagnose or discriminate between a Morton's neuroma and intermetatarsal bursitis can be challenging.

Topic description and discussion

A good appreciation of the sonographic anatomy, technique, normal and abnormal appearances is required to undertake a sonographic assessment of the forefoot and its interspaces, particularly the plantar digital nerves. This is unpacked in this paper with associated pictorial aids. Muscles, tendons, and ligaments of the interspaces and the nearby metatarsophalangeal joints and their associated soft-tissue structures are helpful sonographic landmarks to guide imaging and assessment of the common and proper plantar digital nerves and the intermetatarsal bursa. These need to be appreciated from both dorsal and plantar sonographic approaches, in both short- and long-axis imaging planes.

Conclusion

Improved understanding of the anatomy and sonographic appearances of the interspace structures can enhance the sonographic assessment of the forefoot and improve diagnosis of a Morton's neuroma and/or intermetatarsal bursitis when present to guide patient management.

A problem-based approach in musculoskeletal ultrasonography: central metatarsalgia

Ultrasonography (US) is a useful diagnostic method that can be easily applied to identify the cause of metatarsalgia. The superficial location of structures in the foot, dynamic capability of US, and the ability to perform direct real-time evaluations of the pain site are also strong advantages of US as a modality for examining the foot. Moreover, knowing the possible pain sources to investigate when a patient has a specific site of pain will enhance the diagnostic quality of US, and will help radiologists to perform US efficiently and effectively. The purpose of this article is to review the common etiologies of metatarsalgia including Morton’s neuroma, plantar plate injury, synovitis, tenosynovitis, bursitis, and metatarsal fractures, and to discuss their US features.

Imaging in metatarsalgia

Metatarsalgia is a common clinical conundrum that requires careful assessment. There are a variety of causes and understanding these can help manage the pain. These causes have different imaging characteristics and require specific imaging. By understanding core imaging principles and how they apply to causes of metatarsalgia, pathology can be more efficiently investigated. This article covers primary, secondary and iatrogenic causes of metatarsalgia with the most appropriate imaging modalities for each and the salient imaging findings. This article reviews the common forefoot pathologies and how they may be optimally radiologically investigated, with an emphasis on the key imaging findings.

Morton's neuroma: review of anatomy, pathomechanism, and imaging

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.

The effectiveness of shoe modifications and orthotics in the conservative treatment of Civinini-Morton syndrome: state of art

Civinini Morton’s Syndrome (CMS), better known as Morton’s Neuroma, is a benign enlargement that typically affects the third common digital branch of the plantar nerve. It is a common cause of metatarsalgia leading to debilitating pain. It prefers the female gender, with a female to male ratio of 5:1 and an average age of 50 years at time of surgery. Precise aetiology remains under debate, with four etiopathogenetic theories often cited in the literature. Clinical symptoms, physical exam and instrumental evidence are important in assessing and grading the disease. Biomechanics seem to play an important role, especially regarding the usefulness of correct footwear. The first approach in the early stages of this condition usually begins with shoe modifications and orthotics, designed to limit the nerve compression. In order to prevent or delay the development of CMS, shoes should be sufficiently long, comfortable, broad toe-boxed, should bear a flat heel and a sufficiently thick external sole which should not be excessively flexible. Most authors suggested that an insole with medial arch support and a retrocapital bar or pad, just proximal to the metatarsal heads, displaces the pressure sites and can be beneficial to relieve the pain from the pinched nerve. A threshold period of 4.5 months appears to emerge from the results of the analysed studies, indicating that, beyond this period and in neuromas larger than 5-6 mm, orthotics and/or shoes modifications do not seem to give convincing results, proving to be more a palliation for the clinical condition to allow an acceptable life with pain rather than a real treatment. (www.actabiomedica.it)

Dorsal suspension for Morton's neuroma: A comparison with neurectomy

BACKGROUND

The purpose of this study was to investigate and compare the clinical outcomes of dorsal suspension with those of neurectomy for the treatment of Morton's neuroma.

METHODS

We conducted a retrospective study of dorsal suspension and neurectomy group. The dorsal suspension was performed by dorsal transposition of neuroma over the dorsal transverse ligament after neurolysis. The visual analog scale (VAS), the Foot and Ankle Ability Measure (FAAM), postoperative satisfaction, and complications were evaluated.

RESULTS

Both groups reported significant pain relief, and there were no significant differences between the groups with respect to postoperative pain. The postoperative FAAM outcomes showed no significant between-group differences. Satisfaction analysis showed 'excellent' and 'good' results in the dorsal suspension and neurectomy groups (95% and 77.7%, respectively). Complications of numbness and paresthesia reported in the dorsal suspension group (5% and 5%, respectively) were significantly fewer than those of neurectomy group (61.1% and 33.3%, respectively) (both, p<.05).

CONCLUSIONS

With its favorable results, dorsal suspension can be another operative option for the treatment of Morton's neuroma.

LEVEL OF EVIDENCE

Level III, retrospective comparative case series.

Sclerosing alcohol injections for the management of intermetatarsal neuromas: A systematic review

An intermetatarsal neuroma is a plantar digital neuritis causing metatarsalgia of the affected inter-metatarsal space. At present the evidence to support the management of the condition is poor with only some quality evidence supporting the short-term management of intermetatarsal neuromas using steroid injections. Some authors have supported the use of alcohol sclerosing intra-lesional injections to treat intermetatarsal neuromas. Following a search of the evidence 11 articles were identified. The systematic review found that alcohol injections appear to be safe although some papers report a short-term side effect of a flogistic reaction and there are variances in the alcohol concentration used and guiding verses not guiding the injection using ultrasound imaging. Some of the evidence may suggest a sclerosing histological effect of the nerve. However, all the studies reviewed present a research design offering a low level of evidence that is open to methodological biases and interpretation. Thus, this review found insufficient high-quality research evidence to afford conclusions on the management of intermetatarsal neuromas with alcohol sclerosing agent injections.

Ultrasound Evaluation of Morton Neuroma Before and After Laser Therapy

OBJECTIVE

The objective of our study was to retrospectively assess for differences in imaging appearances of Morton neuromas before and after laser therapy using diagnostic ultrasound (US).

MATERIALS AND METHODS

A retrospective review was performed to identify patients who underwent US imaging to evaluate for Morton neuroma during the study period (June 1, 2013-July 1, 2014); of the 42 patients identified, 21 underwent US evaluations before and after laser therapy. US reports and images were reviewed and correlated with clinical history. The final study group consisted of 21 patients who had a total of 31 Morton neuromas evaluated using US after treatment. A retrospective review was then performed to characterize the appearances of these lesions before and after therapy followed by an analysis of variables.

RESULTS

Retrospective US review of 31 pretreatment Morton neuromas showed fusiform, heterogeneously hypoechoic masses with well-defined borders in most cases and that pain was reported when transducer pressure was applied in 97% (30/31) of cases. After treatment, lesions showed ill-defined borders (23/31), and pain with application of transducer pressure was either significantly decreased or absent (29/31); these findings were concordant with the clinical findings. Both of these characteristics were statistically significant (p < 0.0001). In addition, more Morton neuromas occurred in the second intermetatarsal space than in the third intermetatarsal space (p < 0.0001).

CONCLUSION

US may be used to identify posttreatment changes after laser therapy of Morton neuromas. Posttreatment changes include ill-defined borders and less pain or the absence of pain with the application of transducer pressure. These criteria may be applied in future clinical studies evaluating the efficacy of laser therapy for Morton neuroma.

Diagnostic Value of Elastography in the Diagnosis of Intermetatarsal Neuroma

The objective of the present study was to characterize the ultrasound and elastographic properties of intermetatarsal neuroma (interdigital neuroma) and their contribution to diagnosis. Eighteen patients with metatarsalgia, who had presented to an orthopedic clinic from April 2013 to February 2015, were diagnosed with 25 intermetatarsal neuromas (11 unilateral [61.11%], 7 bilateral [38.89%]). These patients underwent evaluation with ultrasonography and simultaneous ultrasound strain elastography to assess the elastographic properties of the tissues in the intermetatarsal space. The intermetatarsal neuroma diagnosis was confirmed by histopathologic inspection. The lesion contours, localization, dimensions, and vascularization were evaluated before surgical excision. The elasticity and strain ratio values were compared between the neuroma and adjacent healthy intermetatarsal space. Of the 25 intermetatarsal neuromas, 1 (4%) was not detected by ultrasonography (incidence of detection of 96%). The mean neuroma width was 6.35 (range 3.7 to 13) mm in the coronal plane, and the mean elasticity and strain ratio values were 3.44 (range 1.1 to 5.1) and 9.47 (range 2.3 to 19.3), respectively. The elasticity and strain ratio values were significantly greater in the presence of an interdigital neuroma than in the adjacent healthy intermetatarsal spaces (Z = -3.964, p = .0001 and Z = -3.927, p = .0001, respectively). The diagnostic cutoff values were calculated as 2.52 for elasticity and 6.1 for the strain ratio. Four neuromas (16%) were not demarcated, and the elasticity and strain ratio values for these were lower than those for neuromas with demarcated contours but were greater than those for healthy intermetatarsal spaces (p < .006 and p < .005, respectively). Patients with clinically suspected intermetatarsal neuromas that do not show demarcation and with smaller lesions might benefit from the use of ultrasound elastography for diagnosis.

Diagnostic Accuracy of Clinical Tests for Morton's Neuroma Compared With Ultrasonography

The aim of the present study was to assess the diagnostic accuracy of 7 clinical tests for Morton's neuroma (MN) compared with ultrasonography (US). Forty patients (54 feet) were diagnosed with MN using predetermined clinical criteria. These patients were subsequently referred for US, which was performed by a single, experienced musculoskeletal radiologist. The clinical test results were compared against the US findings. MN was confirmed on US at the site of clinical diagnosis in 53 feet (98%). The operational characteristics of the clinical tests performed were as follows: thumb index finger squeeze (96% sensitivity, 96% accuracy), Mulder's click (61% sensitivity, 62% accuracy), foot squeeze (41% sensitivity, 41% accuracy), plantar percussion (37% sensitivity, 36% accuracy), dorsal percussion (33% sensitivity, 26% accuracy), and light touch and pin prick (26% sensitivity, 25% accuracy). No correlation was found between the size of MN on US and the positive clinical tests, except for Mulder's click. The size of MN was significantly larger in patients with a positive Mulder's click (10.9 versus 8.5 mm, p = .016). The clinical assessment was comparable to US in diagnosing MN. The thumb index finger squeeze test was the most sensitive screening test for the clinical diagnosis of MN.

The accuracy of ultrasonography and magnetic resonance imaging for the diagnosis of Morton's neuroma: a systematic review

AIM

To determine the accuracy of MRI versus ultrasound for Morton's neuroma.

MATERIALS AND METHODS

A search was undertaken for clinical studies published in any language in PubMed up to the date of December 2013. Studies assessing the accuracy of the ultrasound or MRI for the diagnosis of Morton's neuroma were included. Data were pooled for meta-analysis. Study selection, data collection, and extraction were performed independently by two authors. Meta-disc 1.4 and Revman 5.2 software were applied for statistical analysis.

RESULTS

The study included 12 studies; 217 patients underwent MRI and 241 underwent ultrasound examinations. There appeared greater diagnostic accuracy for ultrasound than MRI for the diagnosis of Morton's neuroma (ultrasound sensitivity 90%, specificity 88%, positive likelihood ratio 2.77, negative likelihood ratio 0.16 versus MRI sensitivity 93%, specificity 68%, positive likelihood ratio 1.89, negative likelihood ratio 0.19).

CONCLUSIONS

The available evidence suggests that ultrasound can provide better accuracy for the diagnosis of Morton's neuroma than MRI.

Contribution of a new electrophysiologic test to Morton's neuroma diagnosis

BACKGROUND

Morton's neuroma causes metatarsalgia due to the interdigital neuropathy. The small nerve diameter compromises their evaluation in image studies. To overcome this problem we propose a new electrophysiological test.

METHODS

We conducted a prospective case-control study performing a orthodromic electroneurography using subdermal electrodes in controls and patients to assess the validity. Additionally all patients were tested with magnetic resonance. Some patients required surgery and subsequent histological evaluation.

RESULTS

The new ENG procedure showed higher sensitivity and specificity. Methodological standardization was easy and the test was well tolerated by the subjects.

CONCLUSIONS

Our test demonstrated remarkable diagnostic efficiency, and also was able to identify symptomatic patients undetected by magnetic resonance, which underlines the lack of correlation between the size and intensity of the lesion. This new electrophysiological method appears to be a highly sensitivity, well-tolerated, simple and low-cost for Morton's neuroma diagnosis.

Simple electrodiagnostic method for Morton neuroma

INTRODUCTION

We describe a simple and quickly applied electrodiagnostic method for confirming the diagnosis of interdigital neuropathy caused by Morton neuroma (MN).

METHODS

Interdigital nerves II-III and III-IV were stimulated with surface electrodes simultaneously touching the lateral side of 1 toe and the medial side of the other. Recording was also made with surface electrodes. The results of 20 normal controls and 14 patients with MN were evaluated.

RESULTS

The amplitude and peak latency values elicited in the patients as well as the interside differences revealed an acceptable abnormality rate between 57.1% and 71.4%.

CONCLUSIONS

Although the most popular and effective method of MN diagnosis is clinical evaluation supported by imaging, electrophysiological studies can, in selected patients, provide valuable information.

A case of subcutaneous neuroma presenting with intractable pain and allodynia over the anteromedial aspect of the knee

INTRODUCTION

With the exception of interdigital neuromas, cutaneous neuromas are relatively rare and often present a diagnostic challenge.

CASE REPORT

We describe a case of a 30-year-old man with a 9-month history of intractable pain and touch allodynia on the medial side of his proximal left leg. Although the exact focus of the pain and allodynia was initially difficult to detect, a subsequent thorough physical examination revealed touch allodynia in a 1×1-cm area overlying the proximal tibia, immediately below the left patella. Ultrasonography of this site with a 7.5-MHz linear probe showed a 2×4-mm round hypoechoic mass with smooth margins that was suspected to be a neuroma arising from the infrapatellar branch of the saphenous nerve. An excisional biopsy was then performed, the pathology of which revealed perineurial thickening, inflammatory cells in the perineurium, and neovascularization, consistent with neuroma. All symptoms disappeared immediately after an excisional biopsy.

CONCLUSIONS

The diagnosis of cutaneous neuroma should be considered in all patients who have intractable pain and allodynia at unusual locations and in atypical patterns. In addition, ultrasonography can prove very useful in the detection of small cutaneous neuromas if the site of symptoms can be precisely localized.

Painful neuromas

OBJECTIVES

To perform a topical review of the published literature on painful neuromas.

METHODS

A MEDLINE search was performed using the MESH terms "neuroma", "pain", "diagnosis", and "treatment" for all dates.

RESULTS

Acoustic neuromas and intraabdominal neuromas were excluded from a total of 7616 articles. The reference lists from these articles were further reviewed to obtain other relevant articles.

DISCUSSION

Neuromas develop as part of a normal reparative process following peripheral nerve injury. Painful neuromas can induce intense pain resulting in immense suffering and disability. MRI aids the diagnosis, but, ultrasound imaging allows cost effective accurate diagnosis and localization of neuromas by demonstrating their direct contiguity with the nerve of origin. Management options for painful neuromas include pharmacotherapy, prosthetic adjustments, steroid injection, chemical neurolysis, cryoablation, and radiofrequency ablation. Ultrasound imaging guidance has improved the success in localizing and targeting the neuromas. This review discusses the patho-physiology and accumulated evidence for various therapies and the current percutaneous interventional management options for painful neuromas.

Ultrasonography and magnetic resonance imaging in the diagnosis of Morton's neuroma

BACKGROUND

Magnetic resonance imaging (MRI) and ultrasonography are used widely for the diagnosis of Morton's neuroma. The aim of this study was to assess the accuracy of these two modalities as diagnostic tools in Morton's neuroma.

METHODS

Fifty feet of 47 consecutive patients (39 women and 8 men; mean age, 46 years; age range, 36-64 years) who presented between January 1, 2005, and June 30, 2008, were included in the study. Twenty-five feet were investigated with ultrasonography and 25 with MRI. Morton's neuroma was confirmed surgically and histologically in all of the patients. A Student unpaired t test was applied.

RESULTS

Twenty-two MRIs were diagnostic (sensitivity, 88%). Three patients with negative MRI findings underwent ultrasonography and were found to have a neuroma smaller than 5 mm. Twenty-four ultrasound scans demonstrated the neuroma (sensitivity, 96%), with five neuromas being smaller than 5 mm.

CONCLUSIONS

Ultrasonography has a slightly higher sensitivity in the diagnosis of Morton's neuroma, particularly of neuromas smaller than 5 mm, and should be the preferred imaging modality in suspected cases, and MRI should be reserved for cases with equivocal diagnosis.

The use of surgeon-performed ultrasound assessment in a foot and ankle clinic

BACKGROUND

We describe the first reported use of ultrasound examination performed by an orthopaedic surgeon in the setting of a foot and ankle clinic.

METHODS

The senior author attended a course in musculoskeletal ultrasound and performed 100 examinations each checked against the results from a consultant radiologist. Records were kept of all examinations performed in the clinic over a 6-month period with results.

RESULTS

Of the 622 patients seen, 91 had an ultrasound scan and 36 had guided injections. All patients had one hospital attendance spared, for most two. Time saved on the treatment pathway per patient was on average 6 weeks.

CONCLUSION

Ultrasound assessment performed by a clinician during an outpatient clinic appointment reduces delay in treatment and cuts costs by reducing patient episodes.

Efficacy of corticosteroid injection versus size of plantar interdigital neuroma

BACKGROUND

The aim of this prospective study was to assess the effectiveness of a single ultrasound-guided steroid injection in the treatment of Morton's neuromas and whether the response to injection correlates with the size of the neuroma.

METHODS

Forty-three patients with clinical features of Morton's neuroma underwent ultrasound scan assessment. Once the lesion was confirmed in the relevant web space, a single corticosteroid injection was given using 40 mg of methylprednisolone along with 1% lidocaine. All scans and injections were performed by a single musculoskeletal radiologist. Patients were divided into two groups on the basis of the size of the lesion measured on the scan. Group 1 included patients with neuromas of 5 mm or less and group 2 patients had neuromas larger than 5 mm. A visual analog scale (VAS) for pain (scale 0 to 10), the American Orthopaedic Foot and Ankle Society (AOFAS) score, and the Johnson satisfaction scale were used to assess patients before injection and then at 6 weeks, 6 months, and 12 months following the injection. Thirty-nine patients had confirmed neuromas. Group 1 (lesion ≤ 5 mm) included 17 patients (mean age, 30 years) (7 males, 10 females) and group 2 (lesion >5 mm) had 22 patients (mean age, 33 years) (8 males, 14 females).

RESULTS

VAS scores, AOFAS scores, and Johnson scale improved significantly in both groups at 6 weeks (p < .0001). At 6 months postinjection, this improvement remained significant only in group 1 with all scores (p < . 001). At 12 months, there was no difference between both groups and outcome scores nearly approached preinjection scores. At the final review, two patients in group 1 and four patients in group 2 had severe recurrent symptoms and therefore underwent surgical excision of the neuroma after they rejected the offer for a repeat injection (p = 0.6).

CONCLUSION

A single ultrasound-guided corticosteroid injection resulted in generally short-term pain relief for symptomatic Morton's neuromas. The effectiveness of the injection appears to be more significant and long-lasting for lesions smaller than 5 mm.

Patient's assessment of discomfort during ultrasound-guided injection of Morton's neuroma: selecting the optimal approach

PURPOSE

Assess patient discomfort during two different methods of injection of Morton's neuroma.

METHODS

Sixty-eight patients referred for ultrasound-guided injection of Morton's neuroma had punctures performed dorsal or plantar to the interdigital skin crease, with and without preliminary subcutaneous local anesthesia (LA). Patients rated discomfort during skin puncture (SP) and needle advancement (NA) using a visual analog scale.

RESULTS

Average pain score was 4.4 ± 2.3 (1 SD) for the plantar approach and 2.9 ± 2.0 for the dorsal approach. This difference was statistically significant during SP (p < 0.01) and NA (p < 0.05). During the plantar approach with LA, mean pain score during SP was 4.4 (± 2.1) and 3.9 (± 2.8) during NA. This plantar approach without LA resulted in a pain score of 4.3 (± 2.6) and 3.8 (± 3.1), respectively. Mean pain scores for patients injected from the dorsal approach with LA during SP were 3.8 (± 2.7) and NA were 2.2 (± 2.0) and without LA were 2.6 (± 1.9) and 3.0 (± 2.1). There was no statistical significance in mean pain score difference during SP and NA, with and without LA for either the plantar (p > 0.05) or the dorsal (p > 0.05) approach.

CONCLUSIONS

Injection of Morton's neuroma was better tolerated via a dorsal approach and use of preliminary LA did not confer any benefit.

Prevalence of interdigital nerve enlargements in an asymptomatic population

BACKGROUND

Morton's neuroma is a common primary diagnosis for referral to foot and ankle surgeons. On presentation, many patients have had an ultrasound reporting the presence of Morton's neuroma, which may not correlate with the clinical examination findings. The prevalence of such sonographic findings in the general population remains unknown.

METHODS

In this observational prospective study, patients with asymptomatic forefeet who were seen by two foot and ankle surgeons for unrelated mid- or hind foot pathology were examined clinically and sonographically for the presence of interdigital nerve thickening. Forty-eight volunteers participated in the study (96 feet). For the purpose of this study, asymptomatic thickenings greater than 5 mm in diameter were termed sonographic neuromas. Ultrasound examination was performed by two specialist musculoskeletal radiologists.

RESULTS

Fifty-four percent of the volunteers (26 of 48) had sonographic nerve thickening and in 17 cases (35.4%) enlarged nerves were found bilaterally. Differences for gender, original diagnosis or side of original pathology were not significant. Older subjects were more likely to have a sonographic neuroma (p = 0.018). Feet with a positive Mulder's click were more likely to have a sonographic neuroma (p = 0.015).

CONCLUSION

Ultrasound, even in highly skilled hands, has a high rate of incidental finding of an asymptomatic interdigital nerve enlargement, which can lead to a false diagnosis of a Morton's neuroma. Sonographic evidence of Morton's neuroma per se is unreliable unless it is correlated with an equivocal clinical examination. Clinical examination is still the gold standard for the diagnosis of a Morton's neuroma.

MRI and ultrasonography in Morton's neuroma: Diagnostic accuracy and correlation

BACKGROUND

The diagnosis of Morton's neuroma is based primarily on clinical findings. Ultrasonography (US) and magnetic resonance image (MRI) studies are considered complementary diagnostic techniques. The aim of this study was to establish the correlation and sensitivity of both techniques used to diagnose Morton's neuroma.

MATERIALS AND METHODS

Thirty seven patients (43 intermetatarsal spaces) with Morton's neuroma operated were retrospectively reviewed. In all cases MRI or ultrasound was performed to complement clinical diagnosis of Morton's neuroma. In all cases, a histopathological examination confirmed the diagnosis. Estimates of sensitivity were made and correlation (kappa statistics) was assessed for both techniques.

RESULTS

Twenty seven women and 10 men participated with a mean age of 60 years. Double lesions presented in six patients. The second intermetatarsal space was affected in 10 patients and the third in 33 patients. An MRI was performed in 41 cases and a US in 23 cases. In 21 patients, both an MRI and a US were performed. With regard to the 41 MRIs performed, 34 were positive for Morton's neuroma and 7 were negative. MRI sensitivity was 82.9% [95% confidence interval (CI): 0.679-0.929]. Thirteen out of 23 US performed were positive and 10 US were negative. US sensitivity was 56.5% (95% CI: 0.345-0.768). Relative to the 21 patients on whom both techniques were carried out, the agreement between both techniques was poor (kappa statistics 0.31).

CONCLUSION

Although ancillary studies may be required to confirm the clinical diagnosis in some cases, they are probably not necessary for the diagnosis of Morton's neuroma. MRI had a higher sensitivity than US and should be considered the technique of choice in those cases. However, a negative result does not exclude the diagnosis (false negative 17%).

Ultrasound guided alcohol ablation of Morton's neuroma

BACKGROUND

Morton's neuroma is a common cause of metatarsalgia. This study evaluated the efficacy of ultrasound guided alcohol injection as a treatment for this condition.

METHOD

Data from 87 treatment courses were included in this study with a mean follow of 14.3 months.

RESULTS

Technical success was 100%. One patient developed symptoms consistent with an allergic reaction to the injection and one patient declined further injection because of periprocedural pain. Partial or total treatment response was achieved in 66%, with 32% of patients having complete resolution of pain. The median visual analogue score (VAS) decreased from 8 pre-procedure to 4 post-procedure (p < 0.0001). Procedural success was greater in patients under 55 years old and in those with solitary neuromas. Seventeen patients (20%) went on to have surgery due to continuing pain.

CONCLUSION

Ultrasound guided alcohol ablation for the treatment of Morton's neuroma was a safe procedure that significantly reduced pain and may offer an alternative therapy to surgery.

Morton's neuroma: A clinical versus radiological diagnosis

BACKGROUND

The aim of our study was to compare the clinical versus radiological diagnosis of patients suffering from a Morton's neuroma.

METHODS

Clinical assessments and pre-operative radiological imaging of patients who had excision of a Morton's neuromas were retrospectively compared.

RESULTS

43 neuromas were excised from 36 patients over 68 months. The commonest clinical symptoms were tenderness on direct palpation (100%), pain on weight bearing (91%) which was relieved by rest (81%). The most sensitive clinical sign was a Mulder's click. Clinical assessment had a sensitivity of 98% (42/43). Ultrasonography had a sensitivity of 90% (28/31) and magnetic resonance imaging had a sensitivity of 88% (14/16).

CONCLUSION

There is no absolute requirement for imaging patients who clinically have a Morton's neuroma. The two main indications for imaging are (a) an unclear clinical assessment and (b) cases when more than one web space is affected. Ultrasonography should be the investigation of choice.

Alcohol sclerosing therapy is not an effective treatment for interdigital neuroma

BACKGROUND

Alcohol sclerosing therapy has been reported as a safe and effective means of treating interdigital neuromas, both with or without ultrasound. The use of ultrasound introduces beside the ultrasound device, increased cost, and the need for skilled technicians and may reduce usability, especially in the outpatient clinic. We report a series of patients with interdigital neuroma treated using ethanol sclerosing therapy in a clinic setting without the use of ultrasound.

MATERIALS AND METHODS

We retrospectively reviewed charts of 32 consecutive patients who were enrolled to receive a series of sclerosing ethanol injections from June 2009 to April 2010 for the treatment of a painful interdigital neuroma. Plain radiographs and MRI scans were obtained if clinically indicated to assistance with the diagnosis. Duration and quality of symptoms were recorded and current pain levels were evaluated on a visual analog pain scale. Previous treatments, including orthotic use, corticosteroid injection, or prior neuroma resection were reported. A solution of 1 ml consisting of 20% ethanol and 0.25% bupivacain solution was injected without the use of ultrasound into the affected webspace. The mixture was provided by the local pharmacy. Technical success was confirmed by the temporary resolution of pain following local anesthetic infiltration. If still symptomatic, an injection was repeated every 2 weeks, with most patients receiving a series of four injections. Pain was evaluated on a visual analog pain scale at each visit. Treatment success was defined as resolution of pain as expressed by the patient.

RESULTS

Of the 32 patients successful relief of symptoms was only achieved in seven patients, while 25 showed no significant reduction of symptoms and considered or underwent a surgical excision.

CONCLUSION

Alcohol sclerosing therapy administered in the clinic setting without alcohol is not an effective treatment in the nonoperative management of painful interdigital neuromas and has been abandoned in our clinic.

Interdigital neuralgia

Interdigital neuralgia affects a significant number of individuals, with an average age of presentation in the sixth decade and a 4- to 15-fold increased prevalence in women. Historical descriptions date back to the 19th century. Nonoperative treatment with shoe modifications, metatarsal pads, and injections provides relief for most, but long term, 60% to 70% of patients eventually elect to have surgery. Although excision can be performed through a dorsal or plantar approach, we prefer the dorsal incision to prevent scar formation on the plantar aspect of the foot. Satisfactory results are common but not certain with reports of excellent or good ranging from 51% to 93%.

The Use of Ultrasound in Diagnosing Morton's Neuroma and Histological Correlation

This was a retrospective study examining 60 surgically excised Morton's neuromas from 53 patients over a period of three years at Southend University Hospital, Essex. The initial diagnosis of Morton's neuroma was based on history and examination findings. In only one-third of cases was the neuroma palpable. However, many patients had difficulty localizing the pain and had atypical presentation. We attempted to assess the reliability of ultrasound in diagnosing Morton's neuroma in the 60 histologically confirmed cases. Our second objective was to assess whether size estimate of a neuroma seen on ultrasound correlated with subsequent real specimen measurement. In our study, preoperative ultrasound reliably diagnosed Morton's neuroma in 97% of the cases. In contrast, there was poor correlation in real specimen size measurements when compared with ultrasound reports.

Abnormal dip phenomenon: a characteristic electrophysiological marker in interdigital neuropathy of the foot

OBJECTIVE: The nerve conduction findings in interdigital neuropathy of the foot (IDN; Morton's neuroma) have rarely been reported. We analyzed the nerve conduction data in 23 patients with suspected IDN studied between 1982 and 2002. METHOD: Diagnosis of IDN was made on the basis of clinical features. All patients underwent routine nerve conduction studies and a near-nerve needle sensory nerve conduction study of the interdigital nerves by Oh's method in the symptomatic foot. RESULTS:Of the 23 patients, the diagnosis of definite IDN was made in 13 cases and of possible NDN in the others cases. Nineteen were females. Twenty two patients had only one nerve affected. One patient had two nerves affected. The III-IV interdigital nerve was affected in 17 cases and the II-III interdigital nerve in 7 cases. The near-nerve needle nerve conduction showed abnormality in the affected interdigital nerves in all definite IDN cases and confirmed the diagnosis of IDN in 10 cases by the abnormal dip phenomenon (a selective decrease of 50% or more in the sensory CNAP amplitude of the affected nerve compared with that of the preceding interdigital nerve). In 11 possible IDN cases, IDN was identified by the abnormal dip phenomenon. CONCLUSION: The near-nerve needle sensory nerve conduction of the interdigital nerves is a highly sensitive diagnostic test, and abnormal dip phenomenon is the most characteristic electrophysiological marker for the diagnosis of IDN.

The operational characteristics of ultrasonography for the diagnosis of plantar intermetatarsal neuroma

A retrospective study was carried out on 48 patients to correlate preoperative ultrasound findings with postoperative histopathology findings and to assess the sensitivity, specificity, positive predictive values, and negative predictive values of ultrasound in the diagnosis of Morton's interdigital neuroma. All case sheets of 48 patients operated on between 1997 and 2005 were reviewed in the medical record section of Ninewells Hospital, Dundee, Scotland, so that preoperative ultrasound reports were compared with the postoperative histopathological reports. A statistical analysis of the results was performed. Ultrasonography showed 43 true-positive cases, 1 true-negative case, and 4 false-negative cases out of 48 cases. Histopathology showed 47 true-positive cases and 1 true-negative case; statistical analysis performed on the results showed a sensitivity of 91.48%, a specificity of 100%, and 100% positive and 20% negative predictive values, respectively. In our analysis, the probability that ultrasound will confirm the presence of plantar intermetatarsal neuroma is 91.67%.

Morton neuroma: evaluated with ultrasonography and MR imaging

Objective

The purpose of this study was to compare the diagnostic accuracy of both ultrasonography (US) and magnetic resonance imaging (MRI) for the assessment of Morton neuroma.

Materials and Methods

Our study group was comprised of 20 neuromas from 17 patients, and the neuromas were confirmed on surgery following evaluation with US, MRI, or both US and MRI. The diagnostic criterion for Morton neuroma, as examined by US, was the presence of a round or ovoid, well-defined, hypoechoic mass. The diagnostic criterion, based on MR imaging, was a well defined mass with intermediate to low signal intensity on both the T1- and T2-weighted images. The retrospective comparison between the sonographic and MR images was done by two experienced radiologists working in consensus with the surgical and pathologic correlations.

Results

The detection rate of Morton neuroma was 79% for 14 neuromas from 11 patients who had undergone US followed by an operation. The detection rate was 76% for 17 neuromas from 15 patients who had undergone MRI and a subsequent operation. The mean size of the examined neuromas was 4.9 mm on the US images and it was 5.1 mm on the MRI studies. Ten neuromas (71%) were 5 mm or less as measured by US, and three neuromas were not detected, whereas on the MRI analysis, 10 neuromas (59%) were 5 mm or less and four neuromas were not visualized. Among the patients examined during postoperative follow-up, symptoms were completely relieved in 85% and the symptoms were partially relieved in 15%.

Conclusion

US and MR imaging are comparable modalities with high detection rate for the evaluation of Morton neuroma.

Treatment of Morton's neuroma with alcohol injection under sonographic guidance: follow-up of 101 cases

OBJECTIVE

Morton's neuroma is a common cause of forefoot pain. For this study, we assessed the efficacy of a series of sonographically guided alcohol injections into the lesion.

SUBJECTS AND METHODS

One hundred one consecutive patients with Morton's neuroma were included in this prospective series. An average of 4.1 treatments per person were administered, and follow-up images were obtained at a mean of 21.1 months after the last treatment (range, 13-34 months).

RESULTS

Technical success was 100%. Partial or total symptom improvement was reported by 94% of the patients, with 84% becoming totally pain-free. The median visual assessed pain score decreased from 8 before treatment to 0 after treatment (p < 0.001). Transitory increased local pain occurred in 17 cases (16.8%). There were no major complications. Thirty patients underwent sonography at 6 months after the last injection and showed a 30% decrease in the size of the neuroma.

CONCLUSION

We conclude that alcohol injection of Morton's neuroma has a high success rate and is well tolerated. The results are at least comparable to surgery, but alcohol injection is associated with less morbidity and surgical management may be reserved for nonresponders.

Neuropathies of the foot

Compared with the common neuropathies affecting the hands (carpal tunnel syndrome and ulnar neuropathy), neuropathies of the feet have received less attention in the past. This is partly because of the rarity of these disorders as well as the lack of reliable electrophysiological tests for them. Over the years, nerve conduction tests for various nerves of the feet have been reported, and at this time techniques for all the nerves of the feet are available to the electromyographer. This review will provide up-to-date information on the current status of the research and issues relating to the neuropathies of the foot, with an emphasis on the most useful tests and the caveats for clinical neurophysiologists.

Ultrasound-guided interdigital neuroma injections: short-term clinical outcomes after a single percutaneous injection--preliminary results

PURPOSE

To describe the procedure of ultrasound-guided Morton's neuroma and recurrent stump neuroma injections and early clinical outcomes after a single injection.

MATERIALS AND METHODS

Retrospective review of 44 percutaneous ultrasound-guided neuroma injections in 24 patients who had completed clinical outcomes questionnaires. A 10-point pain scale [scale of 1 (no pain) to 10 (severe pain)] in a 7-day pain log format was distributed to patients at the time percutaneous neuroma injection was performed.

RESULTS

Neuromas were clearly visualized with sonography as hypoechoic nodules and were distinguishable from other causes of forefoot pain, such as metatarsophalangeal joint synovitis and intermetatarsal bursae. The sizes of the neuromas injected ranged between 4 and 19 mm. Postinjection, all neuromas displayed increased echogenicity and/or the appearance of fluid surrounding it, confirming localization of the therapeutic mixture. We arbitrarily subdivided the pain ratings into symptomatic (greater than 4) and asymptomatic (less than or equal to 4) for statistical analysis. Average pain level pre injection was 5.2 and average pain level was 3.7 at 7 days post single injection, with 62% of the initially symptomatic patients asymptomatic on day 7 (p < 0.000001). Overall, 76% of the total number of neuromas injected once were asymptomatic on day 7.

CONCLUSION

Ultrasound can be used to accurately target Morton's neuromas and, therefore, appropriately direct therapeutic interventions, with good short-term clinical results.

Tratamento do neuroma de Morton via plantar: avaliação retrospectiva dos resultados cirúrgicos

Com a finalidade de avaliar a eficácia da técnica cirúrgica, envolvendo a neurectomia por via plantar, transversa, fora da zona de carga, em portadores de neuroma de Morton, 217 pacientes foram submetidos a este tratamento.Um total de 264 pés foram observados, sendo 32,2% no pé direito, 46,1% no pé esquerdo e 21,7% bilateralmente.Quanto ao sexo, foram observadas ocorrências de 86,6% no sexo feminino e 13,4% masculino.Quanto a localização, 83,5% (220 neuromas) estavam presentes no terceiro espaço interdigital, 7,5% no segundo espaço, com presença de bilateralidade em 47 pacientes.O tempo médio de acompanhamento foi de 7,5 anos, variando de 4 a 216 meses, com resultado satisfatório e regulares em 95,8% dos pacientes no total, com apenas 11 pacientes (4,2%) insatisfeitos com o tratamento de forma global.Os autores concluem, por tanto, que a neurectomia por via plantar transversa é uma opção satisfatória, com boa visibilização anatômica do neuroma, evoluindo com boa cicatrização, retorno precoce às atividades e satisfação do paciente com o resultado alcançado.

Endoscopic nerve decompression

Endoscopic decompression for forefoot nerve entrapments is discussed in this article from not only the perspective of preoperative indications, intraoperative technique, and postoperative management, but with reference to the changing paradigm for management of this condition. Surgical results are discussed and compared with other published reports. Complications of the surgical technique are also discussed, which will give the operating surgeon a frame of reference when comparing decompression procedures to those techniques involving nerve resection. There is also a valuable discussion of current methods of diagnosis that may help the practitioner improve patient outcomes.

Régression du névrome de Morton après infiltration de corticostéroïdes

Morton neuroma is a non neoplastic lesion corresponding to perineural fibrosis encircling the common interdigital plantar nerve. Several therapeutic approaches are possible: conservative treatment or surgery. We report a case treated by local steroid injection where follow-up MR showed near complete regression of the lesion. Although local injection of steroid is a classical treatment, it is the first time to our knowledge that resolution or such a striking diminution of size is reported after infiltration.

Interdigital neuromas: current state of the art--surgical

Several reports demonstrated that the interdigital neuroma is a form of entrapment neuropathy. Nonoperative measures may provide satisfactory results to some patients, but surgical treatment seems to provide more predictable results and lasting pain relief. Neurectomy remains the most commonly used procedure for the treatment of interdigital neuritis through a plantar or a dorsal approach. Outcome results after neurectomy note a failure rate of 2% to 35%.

High-resolution sonography of the peripheral nervous system - a review of the literature

High-resolution sonography is capable of depicting peripheral nerves and the brachial plexus. In this study we review the literature on this subject. Normal peripheral nerves have a characteristic echotexture. Most nerves are readily visualized, although this is not always the case with the nerves of the lower extremity. The main pathological changes that can be demonstrated are nerve enlargement and increased hypoechogenicity. In order to demonstrate nerve enlargement, measurements should be performed and compared with a set of reference values. Several neuropathies have been studied by means of ultrasonography. However, many studies concern case reports and show methodological shortcomings. The best studied peripheral neuropathy is the carpal tunnel syndrome in which ultrasonography seems to have an additional value when combined with nerve conduction studies. Nerve enlargement has also been demonstrated in radial neuropathy at the humerus and in ulnar neuropathy at the elbow. The role of sonography in various hereditary and inflammatory neuropathies is uncertain although diffuse nerve thickening could be demonstrated. Further systematic studies are needed to determine the role of sonography in the diagnostic process of the various neuropathies. It would be important to study the subcategories of patients in whom electrodiagnostic studies are normal or show equivocal findings.

Nerves in a pinch: imaging of nerve compression syndromes

Nerve compression is a common entity that can result in considerable disability. Early diagnosis is important to institute prompt treatment and to minimize potential injury. Although the appropriate diagnosis is often determined by clinical examination, the diagnosis may be more difficult when the presentation is atypical, or when anatomic and technical limitations intervene. In these instances, imaging can have an important role in helping to define the site and etiology of nerve compression or in establishing an alternative diagnosis. MR imaging and ultrasound provide direct visualization of the nerve and surrounding abnormalities. For both modalities, the use of high-resolution techniques is important. Bony abnormalities contributing to nerve compression are best assessed by radiographs or CT. For the radiologist, knowledge of the anatomy of the fibro-osseous tunnels, familiarity with the causes of nerve compression, and an understanding of specialized imaging techniques are important for successful diagnosis of nerve compression.

Interdigital neuroma: clinical examination and histopathologic results in 63 cases treated with excision

Between November 1993 and September 1999, 60 patients (three bilateral) were consecutively treated with excision of interdigital neuroma. The clinical examination was preoperatively performed and a personal interview, physical examination, and routine radiographs were included. A specific clinical rating system was developed. The clinical results were excellent or good in 49 (78%) feet, fair in 12 (19%), and poor in two (3%). Prior to surgery, the clinical evaluation score was an average of 16 points. Postoperative average score was 67 points, with an average improvement of 50 points. Histopathologically, intraneural fibrosis and sclerohyalinosis were observed, as in the interstitium; furthermore, an increase of the elastic fibers in the stroma was also observed. The precise etiology of interdigital neuroma remains obscure.

Ultrasound in the detection and treatment of a painful stump neuroma

Ultrasound is an established modality for the evaluation of neuromas, particularly Morton's neuromas. It has also had success in the assessment of amputation stump neuromas. While ultrasound localization for steroid injection has proven useful in the conservative treatment of Morton's neuromas, it has not yet been established as a localization technique for steroid injection to successfully treat amputation stump neuromas.

Compression neuropathies of the lower extremity

Compression neuropathies of the lower extremity can be just as disabling as compression neuropathies in the upper extremity. The most common compression neuropathies encountered in the lower extremity affect the lateral femoral cutaneous nerve, the peroneal nerve, the saphenous nerve, the sural nerve, and the tibial nerve (including their branches). These are discussed in terms of anatomy, etiologies, manifestations, and surgical treatment.