Entrapment Neuropathies of the Foot and Ankle

Nerve entrapment syndromes of the lower limb: a pictorial review

Peripheral nerves of the lower limb may become entrapped at various points during their anatomical course. While clinical assessment and nerve conduction studies are the mainstay of diagnosis, there are multiple imaging options, specifically ultrasound and magnetic resonance imaging (MRI), which offer important information about the potential cause and location of nerve entrapment that can help guide management. This article overviews the anatomical course of various lower limb nerves, including the sciatic nerve, tibial nerve, medial plantar nerve, lateral plantar nerve, digital nerves, common peroneal nerve, deep peroneal nerve, superficial peroneal nerve, sural nerve, obturator nerve, lateral femoral cutaneous nerve and femoral nerve. The common locations and causes of entrapments for each of the nerves are explained. Common ultrasound and MRI findings of nerve entrapments, direct and indirect, are described, and various examples of the more commonly observed cases of lower limb nerve entrapments are provided.Critical relevance statement This article describes the common sites of lower limb nerve entrapments and their imaging features. It equips radiologists with the knowledge needed to approach the assessment of entrapment neuropathies, which are a critically important cause of pain and functional impairment.Key points• Ultrasound and MRI are commonly used to investigate nerve entrapment syndromes.• Ultrasound findings include nerve hypo-echogenicity, calibre changes and the sonographic Tinel's sign.• MRI findings include increased nerve T2 signal, muscle atrophy and denervation oedema.• Imaging can reveal causative lesions, including scarring, masses and anatomical variants.

Imaging of the Peripheral Nerves of the Lower Extremity

Continued advancements in magnetic resonance (MR) neurography and ultrasound have made both indispensable tools for the workup of peripheral neuropathy. Ultrasound provides high spatial resolution of superficial nerves, and techniques such as "sonopalpation" and dynamic maneuvers can improve accuracy. Superior soft tissue contrast, ability to evaluate both superficial and deep nerves with similar high resolution, and reliable characterization of denervation are strengths of MR neurography. Nevertheless, familiarity with normal anatomy, anatomic variants, and common sites of nerve entrapment is essential for radiologists to use both MR neurography and ultrasound effectively.

The diagnostic and therapeutic challenges of medial plantar neuropathy in jogger's foot: a case report

Jogger's foot is characterised by a neuropathic pain along the medial arch of the foot caused by compression of the medial plantar nerve. It is more common in runners, especially when there is an anatomical predisposition or some extrinsic factor that may exert compression on the nerve. This article presents the case of a 59-year-old man, who had pain and paraesthesia along the medial plantar arch of the left foot, lasting for several months. Despite having undergone some conservative treatments (plantar orthosis and physiotherapy) and minimal invasive procedures (cortico-anaesthetic injection and shockwave therapy) the symptoms persisted and amyotrophy of the abductor hallucis muscle became clinically evident. At this point, a magnetic resonance image was taken, showing compression of the medial plantar nerve at the intersection of the flexor hallucis longus and the flexor digitorum longus tendons. Ultrasound-guided treatment with pulsed radiofrequency of the medial plantar nerve was then proposed to try and modulate his chronic neuropathic pain. After the procedure, the patient reported immediate relief of the symptoms, which were maintained over 6 months of follow up after the procedure. This case report illustrates a rare and frequently misdiagnosed cause of midfoot pain and its management using electromagnetic modulation of peripheral nerves by pulsed radiofrequency. This seems to be an effective technique, with long-lasting results.

An update on imaging of tarsal tunnel syndrome

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the tibial nerve (TN) within the tarsal tunnel (TT) at the level of the tibio-talar and/or talo-calcaneal joints. Making a diagnosis of TTS can be challenging, especially when symptoms overlap with other conditions and electrophysiological studies lack specificity. Imaging, in particular MRI, can help identify causative factors in individuals with suspected TTS and help aid surgical management. In this article, we review the anatomy of the TT, the diagnosis of TTS, aetiological factors implicated in TTS and imaging findings, with an emphasis on MRI.

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.

An Update on Posterior Tarsal Tunnel Syndrome

Posterior tarsal tunnel syndrome (PTTS) is an entrapment neuropathy due to compression of the tibial nerve or one of its terminal branches within the tarsal tunnel in the medial ankle. The tarsal tunnel is formed by the flexor retinaculum, while the floor is composed of the distal tibia, talus, and calcaneal bones. The tarsal tunnel contains a number of significant structures, including the tendons of 3 muscles as well as the posterior tibial artery, vein, and nerve. Focal compressive neuropathy of PTTS can originate from anything that physically restricts the volume of the tarsal tunnel. The variety of etiologies includes distinct movements of the foot, trauma, vascular disorders, soft tissue inflammation, diabetes mellitus, compression lesions, bony lesions, masses, lower extremity edema, and postoperative injury. Generally, compression of the posterior tibial nerve results in clinical findings consisting of numbness, burning, and painful paresthesia in the heel, medial ankle, and plantar surface of the foot. Diagnosis of PTTS can be made with the presence of a positive Tinel sign in combination with the physical symptoms of pain and numbness along the plantar and medial surfaces of the foot. Initially, patients are treated conservatively unless there are signs of muscle atrophy or motor nerve involvement. Conservative treatment includes activity modification, heat, cryotherapy, non-steroidal anti-inflammatory drugs, corticosteroid injections, opioids, GABA analog medications, tricyclic antidepressants, vitamin B-complex supplements, physical therapy, and custom orthotics. If PTTS is recalcitrant to conservative treatment, standard open surgical decompression of the flexor retinaculum is indicated. In recent years, a number of alternative minimally invasive treatment options have been investigated, but these studies have small sample sizes or were conducted on cadaveric models.

Imaging of Entrapment Neuropathies in the Ankle

Entrapment neuropathies of the ankle and foot pose a major diagnostic challenge and thus remain underdiagnosed. Recent advancements in imaging modalities, including magnetic resonance neurography (MRN), have resulted in considerable improvement in the anatomical localization and identification of pathologies leading to nerve entrapment. MRN supplements clinical examination and electrophysiologic studies in the diagnosis of neuropathies, aids in assessing disease severity, and helps formulate management strategies. A comprehensive understanding of the anatomy and imaging features of the ankle is essential to diagnose and manage entrapment neuropathies accurately. Advancements in imaging and their appropriate utilization will ultimately lead to better diagnoses and improved patient outcomes.

Forefoot Injuries in Athletes: Integration of the Movement System

Despite the prevalence of forefoot related problems in athletes, there are few comprehensive summaries on examination and intervention strategies for those with forefoot related symptoms. While many factors may contribute to pathology and injury, the presence of abnormal foot alignment can negatively affect lower extremity biomechanics and be associated with injuries. Physical therapists may use the characteristics associated abnormal pronation or abnormal supination to describe the movement system disorder and serve as a guide for evaluating and managing athletes with forefoot pathologies. Athletes with an abnormal pronation movement system diagnosis typically demonstrate foot hypermobility, have decreased strength of the tibialis posterior muscle, and present with a medially rotated lower extremity position. Athletes with abnormal supination movement system diagnosis typically demonstrate foot hypomobility, decreased strength of the fibularis muscles, and a laterally rotated lower extremity position. Interventions of manual therapy, taping, strengthening exercises, and neuromuscular reeducation can be directed at the identified impairments and abnormal movements. The purpose of this clinical commentary is to integrate a movement system approach in pathoanatomical, evaluation, and intervention considerations for athletes with common forefoot pathologies, including stress fractures, metatarsalgia, neuroma, turf toe, and sesamoiditis. By applying a prioritized, objective problem list and movement system diagnosis, emphasis is shifted from a pathoanatomical diagnosis-based treatment plan to a more impairment and movement focused treatment.

LEVEL OF EVIDENCE

5.

Tarsal tunnel syndrome: current rationale, indications and results

Tarsal tunnel syndrome (TTS) is a neuropathy due to compression of the posterior tibial nerve and its branches. It is usually underdiagnosed and its aetiology is very diverse. In 20% of cases it is idiopathic. There is no test that diagnoses it with certainty. The diagnosis is usually made by correlating clinical history, imaging tests, nerve conduction studies (NCSs) and electromyography (EMG). A differential diagnosis should be made with plantar fasciitis, lumbosacral radiculopathy (especially S1 radiculopathy), rheumatologic diseases, metatarsal stress fractures and Morton’s neuroma. Conservative management usually gives good results. It includes activity modification, administration of pain relief drugs, physical and rehabilitation medicine, and corticosteroid injections into the tarsal tunnel (to reduce oedema). Abnormally slow nerve conduction through the posterior tibial nerve usually predicts failure of conservative treatment. Indications for surgical treatment are failure of conservative treatment and clear identification of the cause of the entrapment. In these circumstances, the results are usually satisfactory. Surgical success rates vary from 44% to 96%. Surgical treatment involves releasing the flexor retinaculum from its proximal attachment near the medial malleolus down to the sustentaculum tali. Ultrasound-guided tarsal tunnel release is possible. A positive Tinel’s sign before surgery is a strong predictor of surgical relief after decompression. Surgical treatment achieves the best results in young patients, those with a clear aetiology, a positive Tinel’s sign prior to surgery, a short history of symptoms, an early diagnosis and no previous ankle pathology.

Cite this article: EFORT Open Rev 2021;6:1140-1147. DOI: 10.1302/2058-5241.6.210031

An Update on Peroneal Nerve Entrapment and Neuropathy

Peroneal neuropathy is the most common compressive neuropathy of the lower extremity. It should be included in the differential diagnosis for patients presenting with foot drop, the pain of the lower extremity, or numbness of the lower extremity. Symptoms of peroneal neuropathy may occur due to compression of the common peroneal nerve (CPN), superficial peroneal nerve (SPN), or deep peroneal nerve (DPN), each with different clinical presentations. The CPN is most commonly compressed by the bony prominence of the fibula, the SPN most commonly entrapped as it exits the lateral compartment of the leg, and the DPN as it crosses underneath the extensor retinaculum. Accurate and timely diagnosis of any peroneal neuropathy is important to avoid progression of nerve injury and permanent nerve damage. The diagnosis is often made with physical exam findings of decreased strength, altered sensation, and gait abnormalities. Motor nerve conduction studies, electromyography studies, and diagnostic nerve blocks can also assist in diagnosis and prognosis. First-line treatments include removing anything that may be causing external compression, providing stability to unstable joints, and reducing inflammation. Although many peroneal nerve entrapments will resolve with observation and activity modification, surgical treatment is often required when entrapment is refractory to these conservative management strategies. Recently, additional options including microsurgical decompression and percutaneous peripheral nerve stimulation have been reported; however, large studies reporting outcomes are lacking.

Plantar Injuries in Runners: Is There an Association With Weekly Running Volume?

Running is an athletic activity that is increasingly gaining popularity. Despite its benefits, there are many suspected risk factors for running-related overuse injuries. The objective of this study is to describe injuries and clinical symptoms observed on the sole of the foot in runners, giving special attention to the weekly running volume. The literature presented in this narrative review is based on a non-systematic search of the Medline, Google Scholar, and ResearchGate databases and focuses on foot injuries (the full spectrum of the foot pathology from bones to tendons and plantar fascia, nerve, and joint disorders) in runners, which represents an important topic for both professional and recreational runners. The weekly running distance appeared to be one of the strongest predictors for future overuse injuries. Marathon training and average weekly running of over 20 km are possible predictive factors in the development of plantar foot injuries. The plantar medial aspect of the foot is the anatomic area of the foot that most frequently experiences pain, with numerous pathologic conditions. As a result, diagnosis is always a challenging task. The ability to obtain an accurate medical history and carefully perform a physical examination, together with good knowledge of the foot anatomy and kinesiology, are also proven to be key players in ensuring proper diagnosis.

Superficial peroneal nerve entrapment in ankle sprain in childhood and adolescence

Traumatic injuries of the ankle are the most common injuries in sports. Up to 40% of patients who have undergone inversion ankle sprain report residual symptoms. The primary purpose of the study is to evaluate the incidence of SPN entrapment as consequence of acute severe inversion ankle sprain in children and adolescents; the secondary is to report the diagnostic pathway and the results after surgical treatment. From 2000 to 2015 were reviewed to summarize patients under the age of 15 years treated for a first episode of severe inversion ankle sprain. Cases with persistent symptoms (more than 3 months) indicative for SPN neuropathy were then identified. Instrumental investigations were recovered and a pre-operative assessment of pain (VAS) was recorded. Patients were evaluated at minimum of 1-year post-operative follow-up. 981 acute ankle sprains have been evaluated. 122 were considered severe according to van Dijk criteria. 5 patients were considered affected by neuropathy of the SPN. All patients underwent surgery consisting in neurolysis and capsular retention and ligament reconstruction. At 25 months of follow-up AOFAS moved from 57.6 to 98.6. The study highlights a previously unreported condition of perineural fibrosis of the superficial peroneal nerve at the level of the ankle following first acute severe inversion ankle sprain in children.

Tarsal tunnel syndrome: Clinical-imaging analysis of a case series

BACKGROUND

Retrospective review of patients with a diagnosis of Tarsal Tunnel Syndrome (TTS) treated surgically.

METHODS

Retrospective series of patients with diagnosis of TTS operated between 2005 and 2020 in the same center. Variables such as age, sex, side, affected nerve or branch, classification, type of imaging study, biopsy result, infection rate, recurrence rate, sequelae, among others, were analyzed.

RESULTS

We included 8 men and 2 women with an average age of 47 years (range 34-67) and an average follow-up of 62.2 months (range 2-149). All cases were related to intrinsic compression. The most frequent cause was the presence of cyst (40%) followed by perineural adhesions (20%). The Posterior Tibial Nerve was the most affected (50%) and 30% the Medial Plantar Branch. Ultrasound (70%) and MRI (50%) were the most requested studies. There were no cases of postoperative infection. There were 3 patients who presented recurrence of the lesion requiring a new surgery.

CONCLUSIONS

TTS is a neuropathy involving the posterior tibial nerve or some of its branches. In general, it is caused by compression of the nerve by different structures such as accessory muscles and ganglions, among others. The diagnosis is eminently clinical, supported by imaging studies. Surgical treatment presents better results when the cause is an intrinsic compression, although variable recurrence rates are described.

Anomalous plantar intrinsic foot muscle attaching to the medial longitudinal arch: possible mechanism for medial nerve entrapment: a case report

Background

Muscular variations are potentially symptomatic and may complicate imaging interpretation. Intrinsic foot musculature and extrinsic tendon insertion variations are common. Distinct supernumerary muscles are rare. We report a novel anomalous intrinsic foot muscle on the medial longitudinal arch.

Case presentation

An accessory muscle was encountered on the medial arch of the right foot of a 78-year-old white male cadaver, between layers two and three of the foot intrinsics. It did not appear to be a slip or variant of a known foot muscle. This muscle consisted of two slips that ran transversely on the plantar aspect of the medial arch, crossing the medial transverse tarsal joint and attaching to the tuberosity of the navicular, the short and long plantar ligaments, and spring ligament.

Conclusions

The medial plantar vessels and nerve passed from deep to superficial between the two slips, and this suggests a possible location for medial nerve entrapment.

Clinico-radiological review of peripheral entrapment neuropathies - Part 2 Lower limb

PURPOSE

This review discusses the relevant anatomy, etiopathogenesis, current notions in clinical and imaging features as well as management outline of lower limb entrapment neuropathies.

METHODS

The review is based on critical analysis of the current literature as well as our experience in dealing with entrapment neuropathies of the lower limb.

RESULTS

The complex anatomical network of nerves supplying the lower extremities are prone to entrapment by a heterogenous group of etiologies. This leads to diverse clinical manifestations making them difficult to diagnose with traditional methods such as clinical examination and electrodiagnostic studies. Moreover, some of these may mimic other common conditions such as disc pain or fibromyalgia leading to delay in diagnosis and increasing morbidity. Addition of imaging improves the diagnostic accuracy and also help in correct treatment of these entities. Magnetic resonance imaging is very useful for deeply situated nerves in pelvis and thigh while ultrasound is well validated for superficial entrapment neuropathies.

CONCLUSION

The rapidly changing concepts in these conditions accompanied by the advances in imaging has made it essential for a clinical radiologist to be well-informed with the current best practices.

Lower extremity entrapment neuropathies

Entrapment neuropathies are frequently encountered by rheumatologists, not only because they are common but also because of their association with certain rheumatological and systemic disorders. Recognizing entrapment neuropathy early can help avoid progressive neurological deficits, as well as facilitate appropriate treatment measures, which can effectively minimize a patient's symptoms. Entrapment neuropathies may be distinguished from other musculoskeletal causes of lower extremity pain by identifying characteristic patterns of weakness and/or sensory loss, so a focused bedside neurological examination is key for diagnosis. In this chapter, we review the most common entrapment neuropathies that occur in the lower extremities, review the relevant neuroanatomy, outline a diagnostic approach to distinguish them from other mimics, and highlight appropriate management options.

Ultrasound Imaging of Cutaneous Innervations of the Lower Extremity

Ultrasound (US) is commonly used to evaluate the cutaneous innervation of the lower extremity, owing to the following advantages: (1) US is a high-resolution soft tissue imaging modality; (2) it is feasible in patients who are deemed unsuitable to undergo magnetic resonance imaging; and (3) it enables dynamic and real-time imaging. The evaluation of cutaneous nerves requires accurate knowledge of the anatomy as well as technical details. We present a review of the US anatomy of the cutaneous nerves in the lower extremity in addition to a description of a few pathologic conditions.

Injection Techniques for Common Chronic Pain Conditions of the Foot: A Comprehensive Review

Purpose of Review

This is a comprehensive literature review of the available evidence and techniques of foot injections for chronic pain conditions. It briefly describes common foot chronic pain syndromes and then reviews available injection techniques for each of these syndromes, weighing the available evidence and comparing the available approaches.

Recent Findings

Foot and ankle pain affects 20% of the population over 50 and significantly impairs mobility and ability to participate in activities of daily living (ADLs), as well as increases fall risk. It is commonly treated with costly surgery, at times with questionable efficacy. Injection therapy is challenging when the etiology is anatomical or compressive. Morton’s neuroma is a budging of the interdigital nerve. Steroid, alcohol, and capsaicin injections provide some benefit, but it is short lived. Hyaluronic acid (HA) injection provided long-term relief and could prove to be a viable treatment option. Achilles tendinopathy (AT) is most likely secondary to repeat tendon stress—platelet-rich-plasma (PRP) and prolotherapy have been trialed for this condition, but more evidence is required to show efficacy. Similar injections were trials for plantar fasciitis and achieved only short-term relief; however, some evidence suggests that PRP injections reduce the frequency of required therapy. Tarsal tunnel syndrome, a compressive neuropathy carries a risk of permanent neural injury if left untreated. Injection therapy can provide a bridge to surgery; however, surgical decompression remains the definitive therapy. When the etiology is inflammatory, steroid injection is more likely to provide benefit. This has been shown in several studies for gout, as well as osteoarthritis of the foot and ankle and treatment-refractory rheumatoid arthritis. HA showed similar benefit, possibly due to anti-inflammatory effects. Stem cell injections may provide the additional benefit of structure restoration.

Summary

Chronic foot pain is common in the general population and has significant associated morbidity and disability. Traditionally treated with surgery, these are costly and only somewhat effective. Injections provide an effective alternative financially and some evidence exists that they are effective in pain alleviation. However, current evidence is limited and the benefit described from injection therapy has been short-lived in most cases. Further studies in larger populations are required to evaluate the long-term effects of these treatments.

Chronic Lower Leg Pain in Athletes: Overview of Presentation and Management

BACKGROUND

Athletes with chronic lower leg pain present a diagnostic challenge for clinicians due to the differential diagnoses that must be considered.

PURPOSE/QUESTIONS

We aimed to review the literature for studies on the diagnosis and management of chronic lower leg pain in athletes.

METHODS

A literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The PubMed, Scopus, and Cochrane library databases were searched, and articles that examined chronic lower leg pain in athletes were considered for review. Two independent reviewers conducted the search utilizing pertinent Boolean operations.

RESULTS

Following two independent database searches, 275 articles were considered for initial review. After the inclusion and exclusion criteria were applied, 88 were included in the final review. These studies show that the most common causes of lower leg pain in athletes include medial tibial stress syndrome, chronic exertional compartment syndrome, tibial stress fractures, nerve entrapments, lower leg tendinopathies, and popliteal artery entrapment syndrome. Less frequently encountered causes include saphenous nerve entrapment and tendinopathy of the popliteus. Conservative management is the mainstay of care for the majority of cases of chronic lower leg pain; however, surgical intervention may be necessary.

CONCLUSIONS

Multiple conditions may result in lower leg pain in athletes. A focused clinical history and physical examination supplemented with appropriate imaging studies can guide clinicians in diagnosis and management. We provide a table to aid in the differential diagnosis of chronic leg pain in the athlete.

Extrinsic compression neuropathy of the tibial nerve secondary to accessory soleus muscle in a young teenager

Compression neuropathy of the tibial nerve or one of its terminal branches (tarsal tunnel syndrome) is relatively uncommon. Accessory musculature on the posteromedial aspect of the ankle is a rare extrinsic cause of compression. Therefore, it should be considered in patients with prolonged manifestations of tibial nerve compression. A detailed history and physical examination, together with proper radiological evaluation, allow for accurate diagnosis. In this case report, a 13-year old female teenager on history, physical examination, and imaging studies was diagnosed as compression neuropathy of the tibial nerve secondary to accessory soleus muscle. After surgical excision of the accessory soleus muscle with no tarsal tunnel release, the patient presented with complete resolution of her manifestations continued free of symptoms for one and half year postoperatively. The accessory soleus muscle is a potential extrinsic cause for tibial nerve compression neuropathy.

LEVEL OF CLINICAL EVIDENCE

5.

Muscular Abnormalities as a Cause of the Tarsal Tunnel Syndrome: An Infrequent Bilateral Clinical Case

A clinical case of a female patient affected by bilateral tarsal tunnel syndrome is described. The peculiarity of this case is the difference in the observed anatomopathological muscular abnormalities between the two feet. On one side, an accessory muscular venter of the toes’ long flexor was identified. On the other side, posterior tibial nerve compression was determined by an accessory venter of the hallux long flexor, associated with an abnormal venter of the toes’ long flexor, with a minor extent if compared to contralateral findings.

Plantar fasciopathy: A current concepts review

Plantar fasciopathy is very prevalent, affecting one in ten people in their lifetime.

Around 90% of cases will resolve within 12 months with conservative treatment.

Gastrocnemius tightness has been associated with dorsiflexion stiffness of the ankle and plantar fascia injury.

The use of eccentric calf stretching with additional stretches for the fascia is possibly the non-operative treatment of choice for chronic plantar fasciopathy.

Medial open release of approximately the medial third of the fascia and release of the first branch of the lateral plantar nerve has been the most accepted surgical treatment for years.

Isolated proximal medial gastrocnemius release has been reported for refractory plantar fasciopathy with excellent results and none of the complications of plantar fasciotomy.

Cite this article: EFORT Open Rev 2018;3:485-493. DOI: 10.1302/2058-5241.3.170080.

Common Entrapment Neuropathies

PURPOSE OF REVIEW

This article addresses relevant peripheral neuroanatomy, clinical presentations, and diagnostic findings in common entrapment neuropathies involving the median, ulnar, radial, and fibular (peroneal) nerves.

RECENT FINDINGS

Entrapment neuropathies are a common issue in general neurology practice. Early diagnosis and effective management of entrapment mononeuropathies are essential in preserving limb function and maintaining patient quality of life. Median neuropathy at the wrist (carpal tunnel syndrome), ulnar neuropathy at the elbow, radial neuropathy at the spiral groove, and fibular neuropathy at the fibular head are among the most frequently encountered entrapment mononeuropathies. Electrodiagnostic studies and peripheral nerve ultrasound are employed to help confirm the clinical diagnosis of nerve compression or entrapment and to provide precise localization for nerve injury. Peripheral nerve ultrasound demonstrates nerve enlargement at or near sites of compression.

SUMMARY

Entrapment neuropathies are commonly encountered in clinical practice. Accurate diagnosis and effective management require knowledge of peripheral neuroanatomy and recognition of key clinical symptoms and findings. Clinical diagnoses may be confirmed by diagnostic testing with electrodiagnostic studies and peripheral nerve ultrasound.

Common peripheral nerve injuries in sport: diagnosis and management

Peripheral nerve injuries are unusual in sport but impact an athlete's safe return to play. Nerve injuries result from either acute trauma (most commonly in contact/collision sports) or from repetitive microtrauma and overuse. Diagnosis of overuse nerve injuries includes nerve localization and surrounding soft-tissue anatomy, and must account for possible causes of repetitive microtrauma, including biomechanics, equipment, training schedule, and recovery. Prognosis is related to the type of nerve injury. Management should not simply be rest and gradual return to sport but should address biomechanical and training predispositions to injury. Understanding the type of injury and the tissues involved will guide appropriate rehabilitation decisions. Recognizing acute care considerations and implementing appropriate strategies can help minimize secondary trauma to an area following acute injury.

Isolated atrophy of the abductor digiti quinti in patients with rheumatoid arthritis

OBJECTIVE

We aim to discuss the association of isolated atrophy of the abductor digiti quinti muscle in patients with rheumatoid arthritis as well as review the anatomy and imaging findings of this condition on MRI.

MATERIALS AND METHODS

A consecutive series of 55 patients diagnosed with rheumatoid arthritis according to the 2010 ACR/EULAR classification criteria were recruited. MRI of the clinically dominant feet was performed using a 1.5-T scanner.

RESULTS

The study population was predominantly female (94.5%), and the age range was 31-79 years (mean 57.5 ± 11). A total of 55 ankles were examined by MRI, and 20 patients (36.3%), all females, showed abductor digiti quinti denervation signs. Seven patients demonstrated severe fatty atrophy of the abductor digiti quinti, corresponding to Goutallier grade 4, 2 patients showed moderate fatty atrophy (Goutallier grade 3), and the remaining 11 patients showed less than 50% fatty atrophy, corresponding to a Goutallier grade 2. Substantial agreement was found for both intra- and interobserver agreement regarding the Goutallier grading system.

CONCLUSION

Prevalence of signs of abductor digiti quinti denervation on MRI was high in the studied population, suggesting that rheumatoid arthritis may be associated with inferior calcaneal nerve compression.