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

The role of high-resolution ultrasound and MRI in the evaluation of peripheral nerves in the lower extremity

Lower extremity peripheral neuropathy is a commonly encountered neurologic disorder, which can lead to chronic pain, functional disability, and decreased quality of life for a patient. As diagnostic imaging modalities have improved, imaging has started to play an integral role in the detection and characterization of peripheral nerve abnormalities by non-invasively and accurately identifying abnormal nerves as well as potential causes of neuropathy, which ultimately leads to precise and timely treatment. Ultrasound, which has high spatial resolution and can quickly and comfortably characterize peripheral nerves in real time along with associated denervation muscle atrophy, and magnetic resonance neurography, which provides excellent contrast resolution between nerves and other tissues and between pathologic and normal segments of peripheral nerves, in addition to assessing reversible and irreversible muscle denervation changes, are the two mainstay imaging modalities used in peripheral nerve assessment. These two modalities are complimentary, and one may be more useful than the other depending on the nerve and location of pathology. Imaging must be interpreted in the context of available clinical information and other diagnostic studies, such as electrodiagnostic tests. Here, we offer a comprehensive overview of the role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of the peripheral nerves of the lower extremity and their associated neuropathies.

Complications of alcohol injections for Morton’s neuroma

Introduction

Morton’s neuroma (MN) is a neuropathic metatarsalgia that causes pain in the plantar aspect of the forefoot generally between the third and fourth metatarsal heads. Treatment can be nonoperative or surgical. Among nonoperative procedures, alcohol injections are still commonly used as considered simple, relatively safe and well-tolerated treatment. However, they present transient and minor complications.

Methods

Two hundred patients with a diagnosis of MN underwent ultrasound-guided injections with a 47.5% alcohol solution between 2013 and 2020. We reviewed the current literature to highlight the known complications of this treatment, comparing them to the complications developed by our patients.

Results

Three patients out of 200 patients, developed necrosis of skin and subcutaneous tissue not described in previous studies about MN.

Conclusions

Our study focuses attention on the complications subsequent to the alcohol injection therapy for MN. Patients and surgeons should be aware that in a small number of cases this therapy can be burdened by necrotic complications of the skin.

Isolated Intermetatarsal Ligament Release as Primary Operative Management for Morton's Neuroma: Short-term Results

BACKGROUND

Although the precise pathoetiology of Morton's neuroma remains unclear, chronic nerve entrapment from the overlying intermetatarsal ligament (IML) may play a role. Traditional operative management entails neuroma excision but risks unpredictable formation of stump neuroma.

MATERIALS AND METHODS

Medical records were examined for adult patients who failed at least 3 months of conservative treatment for symptomatic and recalcitrant Morton's neuroma and who then underwent isolated IML decompression without neuroma resection.

RESULTS

A total of 12 patients underwent isolated IML decompression for Morton's neuroma with an average follow-up of 13.5 months. Visual Analog Pain Scale averaged 6.4 ± 1.8 (4-9) preoperatively and decreased to an average of 2 ± 2.1 (0-7) at final follow-up (P = .002). All patients reported significant improvement.

CONCLUSION

Isolated IML release of chronically symptomatic Morton's neuroma shows promising short-term results regarding pain relief, with no demonstrated risk of recurrent neuroma formation, permanent numbness, or postoperative symptom exacerbation.

LEVEL OF EVIDENCE

Level IV: Case series.

Effectiveness of corticosteroid injections in Civinini-Morton's Syndrome: A systematic review

BACKGROUND

The aim of this paper is to analyze the effectiveness of corticosteroid injections (CI), in combination with or without a local anaesthetic, for Civinini-Morton's Syndrome to determine which protocol could be the most appropriate among conservative treatments.

METHODS

All selected articles were screened using a thorough database search of PubMed, EMBASE and SCOPUS to assess their suitability to the research focus.

RESULTS

Selection produced 10 articles as full-text, for a total of 590 patients, with a mean follow-up of 14 ± 14.2 (range 3-48) months. Johnson satisfaction scale, resulting from 6 studies, scored 25.6% (range 5-38) and 39.4% (range 15-51.8), respectively completely satisfied and satisfied with minor reservations. Mean VAS, declared in 5 studies, decreased from 70.7 ± 16.5 (range 67-89) to 33.4 ± 7.6 (26-42.5) points (p < 0.01). Most common complication was skin depigmentation in 7 (2.6%) cases.

CONCLUSIONS

CI appear to be a safe treatment allowing good results with a very low complications rate. A neuroma of 6.3 mm seems to be the cut-off size; below which CI could have best indications and be considered as an intermediate treatment between shoe modifications and more invasive procedures such as percutaneous alcoholization or surgery.

LEVEL OF EVIDENCE

Level II, systematic review.

First webspace Morton's neuroma case report with literature review

Morton's neuromas are benign lesions of the inter-digital nerves within the foot. They are most commonly found in the second and third webspace. Morton's neuroma of the first webspace is very rare. A case of a 42-year-old female who presented complaining of long standing forefoot pain is presented. The patient was diagnosed with a soft tissue tumor in the 1st webspace. An excisional biopsy of the tumour confirmed a Morton's neuroma. Very few cases of Morton's neuroma in the first webspace have been reported in the literature.

The effects of a combined physical therapy approach on Morton's Neuroma. An N-of-1 Case Report

INTRODUCTION

There is a lack of supporting evidence for conservative treatments involving Morton's Neuroma, which has often a clinical presentation with many associated complications such as functional impairment and chronic pain. This case study assessed the effects of a combined physical therapy treatment for Morton's Neuroma, an injury often referred for surgery.

METHODS

The patient suffered a long-standing Morton's Neuroma and received 6 combined physical therapy sessions that included soft-tissue massage, joint mobilization, strengthening therapeutic exercises and pain education. Values for pain with deep pressure, pain maladaptive beliefs and functionality were taken using clinical testing and questionnaires.

RESULTS

After the intervention was successfully completed, pain when applying deep pressure resolved. Functionality involving the toe-to-wall test showed an improvement in ankle dorsiflexion and better results were found in both the LEFS and FAAM questionnaires. Pain maladaptive beliefs, assessed with the Pain Catastrophizing Scale and the Pain Awareness Questionnaire also reflected an improvement.

CONCLUSION

A combined physical therapy approach shows encouraging results in the treatment of Morton's Neuroma.

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)

Improved Injection Technique of Ethanol for Morton's Neuroma

BACKGROUND

Morton's neuroma is a common cause of forefoot pain. Various conservative methods (injections of various pharmacologic agents) have been published with an outcome of 6%-75% success rate (free of pain in daily life) per injection. The aim of the present study was to assess the outcome of an improved localization technique, a higher dosage, and a higher percentage of ethanol.

METHODS

Using fluoroscopic and electroneurographic guidance, 2.5 mL of 70% ethanol were injected into 33 feet with a magnetic resonance imaging (MRI)-verified neuroma. We evaluated patients at up to 5-year follow-up.

RESULTS

A "success rate" of more than 82% per single injection (defined as free of pain in daily life) was achieved and no recurrence was seen over 5 years. All scores (visual analog scale; Short Form-36 subscales, American Orthopaedic Foot & Ankle Society ankle-hindfoot score) showed significant improvement (P < .0001). Mean 1.2 injections were necessary. No significant side effects were seen. However, some mild pain persisted in some patients who participated in sports.

CONCLUSION

The injection of 2.5 mL of 70% ethanol under fluoroscopic and electroneurographic guidance was a safe method for the treatment of MRI-verified Morton's neuromas. Combining the effect of a higher percentage of alcohol and a higher dosage and an improved localization technique resulted in a high rate of patients without pain.

LEVEL OF EVIDENCE

Level IV, cases series, prospective.

Mallet Toes, Hammertoes, Neuromas, and Metatarsophalangeal Joint Instability: 40 Years of Development in Forefoot Surgery

BACKGROUND

Today's foot and ankle surgeon has an enhanced understanding of forefoot pathology and treatment options compared to surgeons who practiced in previous decades. This paper summarizes developments in forefoot surgery in the past 40 years, specifically in treatments for mallet toe, hammertoe, neuroma, and metatarsophalangeal joint instability.

MATERIALS AND METHODS

A review of the literature was conducted using the PubMed search engine, with key terms including, "mallet toe," "hammertoe," "neuroma," "metatarsophalangeal joint instability," "plantar plate," and "forefoot surgery." Chapters in major orthopaedic textbooks covering these topics were also reviewed. We then chronicled the history of the diagnosis and treatment of these pathologies, with a focus on the past 40 years.

CONCLUSIONS

There have been major advances in understanding and treating forefoot pathologies in the past four decades; however, there remain areas for improvement both in the diagnosis and treatment of these problems.

LEVEL OF EVIDENCE

Level V, meta-synthesis.

Morton's neuroma - Current concepts review

Morton's neuroma is a common pathology affecting the forefoot. It is not a true neuroma but is fibrosis of the nerve. This is caused secondary to pressure or repetitive irritation leading to thickness of the digital nerve, located in the third or second intermetatarsal space. The treatment options are: orthotics, steroid injections and surgical excision usually performed through dorsal approach. Careful clinical examination, patient selection, pre-operative counselling and surgical technique are the key to success in the management of this condition.

Morton's interdigital neuroma of the foot: A literature review

Morton's neuroma is one of the most common causes of metatarsalgia. Despite this, it remains little studied, as the diagnosis is clinical with no reliable instrumental diagnostics, and each study may deal with incorrect diagnosis or inappropriate treatment, which are difficult to verify. The present literature review crosses all key points, from diagnosis to surgical and nonoperative treatment, and recurrences. Nonoperative treatment is successful in a limited percentage of cases, but it can be adequate in those who want to delay or avoid surgery. Dorsal or plantar approaches were described for surgical treatment, both with strengths and weaknesses that will be scanned. Failures are related to wrong diagnosis, wrong interspace, failure to divide the transverse metatarsal ligament, too distal resection of common plantar digital nerve, an association of tarsal tunnel syndrome and incomplete removal. A deep knowledge of the causes and presentation of failures is needed to surgically face recurrences.

Ultrasound-Guided Percutaneous Radiofrequency for the Treatment of Morton's Neuroma

PURPOSE

Morton's neuroma (MN) is a leading cause of disability. The purpose of this study was to investigate the effectiveness of radiofrequency (RF) in patients with chronic pain refractory to conservative therapies.

METHODS

Between September 2012 and December 2016, RF was performed on 52 patients. A sterile RF needle probe (22G, 5-cm needle with 10-mm electrode active tip) was inserted between the toes into the intermetatarsal space at the center of the lesion. Potential complications of the intervention and post-procedure care were examined. All patients provided written, informed consent. All percutaneous procedures were performed with the NeuroTherm^® NT1100 (Neurotherm Inc., M.) device and using ultrasound guidance (Philips IU22). Continuous RF was performed with one cycle of 90 s and with the probe tip maintaining a temperature of 85 °C (impedance 95-210 mΩ).

RESULTS

Mean VAS score before the procedures was 9.0 ± 0.6. A reduction of pain intensity was achieved after 1 week by RF (mean VAS scores 3.7 ± 0.9; p < 0.05), with a stabilization of the painful symptomatology in the following months and after 1 year of treatments (mean VAS scores 2.0 ± 0.4 after 12 months, p < 0.05). The FHSQ scores showed improved quality of life (QOL) in all patients at 6 months (p < 0.05) and 1 year (p < 0.05) of RF. No patients developed complications.

CONCLUSIONS

RF is a safe, efficient, and minimally invasive technique for the treatment of symptomatic MN.

Intraoperative Ultrasound for Peripheral Nerve Applications

Offering real-time, high-resolution images via intraoperative ultrasound is advantageous for a variety of peripheral nerve applications. To highlight the advantages of ultrasound, its extraoperative uses are reviewed. The current intraoperative uses, including nerve localization, real-time evaluation of peripheral nerve tumors, and implantation of leads for peripheral nerve stimulation, are reviewed. Although intraoperative peripheral nerve localization has been performed previously using guide wires and surgical dyes, the authors' approach using ultrasound-guided instrument clamps helps guide surgical dissection to the target nerve, which could lead to more timely operations and shorter incisions.

Corticosteroid Injection for the Treatment of Morton's Neuroma: A Prospective, Double-Blinded, Randomized, Placebo-Controlled Trial

BACKGROUND

The effectiveness of corticosteroid injection for the treatment of Morton's neuroma is unclear. In addition, most of the studies related to it are case-control or retrospective case series. The purpose of this study was to compare the effectiveness between corticosteroid injection associated with local anesthetic and local anesthetic alone (placebo control group) for the treatment of Morton's neuroma.

METHODS

Forty-one patients with a diagnosis of Morton's neuroma were randomized to receive 3 injections of either a corticosteroid plus a local anesthetic or a local anesthetic alone. The patients and the researcher who collected data were blinded to the treatment groups. The visual analog scale for pain and the American Orthopaedic Foot & Ankle Score (metatarsophalangeal/interphalangeal score) were obtained at baseline, after each injection, and at 3 and 6 months after the last injection.

RESULTS

There were no significant between-group differences in terms of pain and function improvement at 3 and 6 months after treatment completion in comparison with baseline values. At the end of the study, 17 (48.5%) patients requested surgical excision of the neuroma: 7 (44%) in the experimental group and 10 (53%) in the control group ( P = 1.0).

CONCLUSION

The injection of a corticosteroid plus a local anesthetic was not superior to a local anesthetic alone in terms of pain and function improvement in patients with Morton's neuroma.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

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.

The accuracy of diagnostic ultrasound imaging for musculoskeletal soft tissue pathology of the extremities: a comprehensive review of the literature

Musculoskeletal diagnostic ultrasound imaging (MSK-DUSI) has been growing outside the traditional radiology speciality. Increased use of this technology has been reported in several healthcare settings, however an apparent gap in the knowledge of the accuracy of this diagnostic technology indicated a review was warranted. We undertook a structured review of the literature to assess the accuracy of MSK-DUSI for the diagnosis of musculoskeletal soft tissue pathology of the extremities. An electronic search of the National Library of Medicine’s PubMed database (1972 to mid-2014) was conducted. All relevant systematic reviews of diagnostic studies, all diagnostic studies published after the date of the latest systematic reviews and relevant diagnostic studies outside the scope the systematic reviews that directly compared the accuracy of MSK-DUSI (the index test) to an appropriate reference standard for the target condition were included. A fundamental appraisal of the methodological quality of studies was completed. The individual sensitivity, specificity and likelihood ratio data were extracted and entered into diagnostic accuracy tables. A total of 207 individual studies were included. The results show that MSK-DUSI has acceptable diagnostic accuracy for a wide spectrum of musculoskeletal conditions of the extremities. However, there is a lack of high quality prospective experimental studies in this area and as such clinicians should interpret the results with some caution due to the potential for overestimation of diagnostic accuracy.

Ultrasound versus magnetic resonance imaging for Morton neuroma: systematic review and meta-analysis

OBJECTIVES

To compare ultrasound (US) and magnetic resonance imaging (MRI) in the diagnosis of Morton's neuroma.

METHODS

Studies that assessed the diagnostic accuracy of US and MRI for Morton's neuroma were retrieved from major medical libraries independently by two reviewers up to 1 April 2014. Predefined inclusion and exclusion criteria were adopted.

RESULTS

277 studies were initially found, and the meta-analysis was conducted on 14 studies. US sensitivity was studied in five studies, MRI sensitivity in three studies, and bothin six studies. All studies used surgery as the reference standard. A high sensitivity (SE) of diagnostic testing was observed for both US (SE (95 % CI) = 0.91 (0.83-0.96)) and MRI (SE (95 % CI) = 0.90 (0.82-0.96)) with no significant differences between the two modalities in diagnosis (Q test p = 0.88). For MRI, specificity of test was 1.00 with a pooled estimation of 1.00 (0.73-1.00), while the pooled specificity was 0.854 (95 % CI: 0.41-1.00) for US. No differences were observed between US and MRI in study design (p = 0.76).

CONCLUSION

This meta-analysis shows that the SE of US (0.91) is equal to (p = 0.88) that of MRI (0.90) for identification of Morton's neuroma.

KEY POINTS

• For Morton's neuroma, US sensitivity is equal to MRI. • US is as accurate as MRI in diagnosing Morton's neuroma. • US may be the most cost-effective imaging method for Morton's neuroma.

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.

Role of MRI in detection of Morton's neuroma

BACKGROUND

Distinguishing between patients with a true Morton's neuroma and other forefoot pathology can be difficult. The aim of this study was to evaluate the diagnostic accuracy of routine magnetic resonance imaging (MRI) when compared to clinical examination for Morton's neuroma.

METHODS

We retrospectively identified 71 patients who underwent operative treatment due to the diagnosis of Morton's neuroma between 2007 and 2013. All patients had a MRI preoperative. Our study group comprised 58 female and 13 male patients with a mean age of 57 (range, 38-92) years. We compared the results of preoperative MRI and the patient's clinical assessment with postoperative histopathological results.

RESULTS

Typical clinical signs were found in 65 cases. Most common symptoms were plantar pain (92%) and increased pain on walking (89%). A Morton's neuroma was detected on MRI in 59 of 71 cases. Its sensitivity was 0.84 and its specificity was 0.33. The positive and negative predictive values were 0.97 and 0.08, respectively. For the presence of main clinical symptoms we found a sensitivity of 0.94 and a specificity of 0.33. The positive predictive value was 0.97 and the negative predictive value was 0.20.

CONCLUSION

MRI under routine conditions had a good detection rate for the evaluation of Morton's neuroma. However, its accuracy was not as high as the accuracy of clinical assessment.

LEVEL OF EVIDENCE

Level IV, retrospective series.

Misdiagnosis of plexiform neurofibroma of the medial plantar nerve: case report

Plexiform neurofibromas are benign tumors of the peripheral nerve. Diagnosis may be challenging, if they present mimicking other peripheral nerve pathologies. We report the case of a patient who had severe foot pain, which progressively hampered her walking ability, erroneously attributed to recurrent Morton's neuroma. Diagnosis of plexiform neurofibroma of her right medial plantar nerve was made 15 years after the appearance of symptoms. Pain and function recovered after radical neurotomy of the medial plantar nerve. A correct diagnosis is an essential starting point in the treatment of neurofibromas and a misdiagnosis may lead to an inappropriate treatment.