Entrapment neuropathy about the foot and ankle: an update

Postoperative Medial Plantar and Sural Neuropathy With Complex Regional Pain Syndrome

This case illustrates a distinct presentation of coexistent medial plantar and sural neuropathy leading to the development of complex regional pain syndrome (CRPS) in a 49-year-old male patient. CRPS is a broad medical diagnosis describing prolonged and excessive pain that is out of proportion to exam and has historically been diagnosed according to the Budapest criteria. To our knowledge, this is a rare report of a case of medial plantar and sural neuropathy further complicated with CRPS, status-post calcaneal fracture, surgery, and post-surgical boot placement. The case highlights the complexity of diagnosing and managing multiple concurrent neuropathies and underscores the need for interdisciplinary approaches in treating CRPS to improve patient outcomes.

Diagnostic Approach to Lower Limb Entrapment Neuropathies: A Narrative Literature Review

Entrapment neuropathies of the lower limb are a misunderstood and underdiagnosed group of disorders, characterized by pain and dysesthesia, muscular weakness, and specific provoking movements on physical examination. The most frequent of these syndromes encountered in clinical practice are fibular nerve entrapment, proximal tibial neuropathy, sural nerve neuropathy, deep gluteal syndrome or sciatic nerve entrapment, and lateral femoral cutaneous nerve entrapment, also known as meralgia paresthetica. These are commonly mistaken for lumbar plexopathies, radiculopathies, and musculotendinous diseases, which appear even more frequently and have overlapping clinical presentations. A comprehensive anamnesis, physical examination, and electrodiagnostic studies should help clarify the diagnosis. If the diagnosis is still unclear or a secondary cause of entrapment is suspected, magnetic resonance neurography, MRI, or ultrasonography should be conducted to clarify the etiology, rule out other diseases, and confirm the diagnosis. The aim of this narrative review was to help clinicians gain familiarity with this disease, with an increase in diagnostic confidence, leading to early diagnosis of nerve damage and prevention of muscle atrophy. We reviewed the epidemiology, anatomy, pathophysiology, etiology, clinical presentation, and EDX technique and interpretation of the entrapment neuropathies of the lower limb, using articles published from 1970 to 2022 included in the Pubmed, MEDLINE, Cochrane Library, Google Scholar, EMBASE, Web of Science, and Scopus databases.

Ultrasound as a Useful Tool for a Peripheral Nerve Surgeon: Examples in Clinical Practice

BACKGROUND

 Peripheral nerve surgeons often require additional imaging for examination, diagnostic testing, and preoperative planning. Point-of-care ultrasound (US) is a cost-effective, accessible, and well-established technique that can assist the surgeon in diagnosing and treating select peripheral nerve pathologies. With this knowledge, the properly trained surgeon may perform US-guided nerve blocks to help accurately diagnose and treat causes of neuropathic pain. We offer this paper, not as an exhaustive review, but as a selection of various peripheral nerve pathologies, which the senior author treats, and their associated US examination findings. Our goal is to encourage other peripheral nerve surgeons to incorporate US into their practices.

METHODS

 We provide various cases from our outpatient peripheral nerve clinic demonstrating relevant US anatomy. We also review techniques for US guided nerve blocks with relevant anatomic landmarks.

RESULTS

 US imaging successfully assisted in identification and injection techniques for various peripheral nerve pathologies in a surgeon's practice. Examples were presented from the neck, trunk, upper extremity, and lower extremity.

CONCLUSION

 Our review highlights the use of US by a peripheral nerve surgeon in an outpatient private practice clinic to diagnose and treat select peripheral nerve pathologies. We encourage reconstructive surgeons to add US to their arsenal of diagnostic tools.

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.

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.

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.

Functional Popliteal Artery Entrapment Syndrome: An Approach to Diagnosis and Management

Popliteal Artery Entrapment Syndrome (PAES) is an uncommon syndrome that predominantly affects young athletes. Functional PAES is a subtype of PAES without anatomic entrapment of the popliteal artery. Patients with functional PAES tend to be younger and more active than typical PAES patients. A number of differential diagnoses exist, the most common of which is chronic exertional compartment syndrome. There is no consensus regarding choice of investigation for these patients. However, exercise ankle-brachial indices and magnetic resonance imaging are less invasive alternatives to digital subtraction angiography. Patients with typical symptoms that are severe and repetitive should be considered for intervention. Surgical intervention consists of release of the popliteal artery, either via a posterior or medial approach. The Turnipseed procedure involves a medial approach with a concomitant release of the medial gastrocnemius and soleal fascia, the medial tibial attachments of the soleus and excision of the proximal third of the plantaris muscle. Injection of botulinum A toxin under electromyographic guidance has recently shown promise as a diagnostic and/or therapeutic intervention in small case series. This review provides relevant information for the clinician investigating and managing patients with functional PAES.

Acupotomy for patients with tarsal tunnel syndrome: A protocol for systematic review and meta analysis

BACKGROUND

Tarsal tunnel syndrome (TTS) is a painful condition of the ankle that affects patients' quality of life and ability to work. Multiple clinical studies of nerve decompression by acupotomy have been published in China, and the results are encouraging. However, the efficacy and security of this treatment have not been evaluated scientifically and systematically. The purpose of this systematic review protocol is to evaluate the efficacy and security of acupotomy treatment in patients with TTS, which will be helpful to clinical acupotomy doctors.

METHODS

Relevant randomized controlled trials will be identified by searching 9 databases (PubMed, Embase, Cochrane Library, Chinese literature databases, the Chinese Biomedical Literature Database, China National Knowledge Infrastructure, SinoMed, Technology Journal and the Wanfang Database. Randomized controlled trials examining the use of acupotomy for TTS patients will be identified independently by 2 reviewers by searching the databases from inception to March 2020. Clinical effects will be evaluated as the primary outcome. Visual analog scale scores will be assessed as a secondary outcome. Review Manager 5.3 will be used to perform a fixed effects meta-analysis, and the evidence level will be evaluated by using the Grading of Recommendations Assessment, Development, and Evaluation framework. Continuous outcomes will be presented as mean differences or standard mean differences, while dichotomous data will be expressed as relative risks.

RESULTS

This study will evaluate the effectiveness and safety of acupotomy in the treatment of TTS in randomized controlled trials with high-quality visual analog scale and Roles and Maudsley score.

CONCLUSION

This systematic review will provide evidence to determine whether acupotomy is an effective intervention for patients with TTS.

REGISTRATION NUMBER

DOI 10.17605/OSF. IO/9PYC2 (https://osf.io/9pyc2/).

Peripheral Nerve Stimulation for the 21st Century: Sural, Superficial Peroneal, and Tibial Nerves

OBJECTIVE

Peripheral nerve stimulation (PNS) of the lower extremity has progressed significantly over the last decade. From the proof of concept that ultrasound-guided, percutaneous implantation was possible to advances in waveforms, the field has been rapidly evolving. While most nerves in the lower extremity can be PNS targets, consideration must be given to the ergonomics of pulse generator placement, patient comfort, and avoidance of lead migration. For this paper, we examine some of the conditions amenable to lower extremity PNS, review the evidence and history behind PNS for these conditions, and describe approaches for the tibial, sural, and superficial peroneal nerves.

METHODS

A literature search was conducted using PubMed. Search terms used were "peripheral nerve stimulation," "lower extremity entrapment neuropathies," "sural nerve," "superficial peroneal nerve," "tibial nerve," and "tarsal tunnel syndrome." Emphasis was placed on randomized controlled studies, anatomical dissections, and comprehensive review articles. Approaches to nerves and ultrasound images were based on anecdotal PNS cases from an experienced implanter (SP).

CONCLUSIONS

The development of ultrasound as a viable method of image guidance for percutaneous peripheral nerve stimulation has led to an exponential growth in the field. Lower extremity percutaneous lead placement is both feasible and an appropriate treatment modality for certain pain conditions.

[Foot and ankle tumours : Part II: Malignant bone tumours and soft tissue tumours of the foot with differential diagnostic hints]

CLINICAL ISSUE

Both benign and malignant tumours are encountered in the foot and ankle. Due to their rarity, however, diagnosis is often uncertain. Usual criteria such as tumour size, invasiveness or pain fail to differentiate benign from malignant neoplasias.

STANDARD RADIOLOGICAL METHODS

Plain radiography and-due to the complex foot anatomy-CT are important in the diagnostic evaluation of primary bone tumours. In the case of soft tissue tumours, ultrasonography is used to identify ganglion cysts. Tumour evaluation and staging are then performed using MRI. Nuclear imaging comes into play when multifocal, metastatic or systemic spread of the disease is suspected or if a biopsy procedure is planned.

METHODICAL INNOVATIONS

For the role of dual-energy CT, please refer to part I. Whether dual-energy CT is suitable to assess bone marrow oedema patterns is still debated.

SPECIAL FEATURES OF FOOT AND ANKLE TUMOURS

Primary bone tumours generally present in the ankle or the hindfoot. Malignant bone tumours, e. g. chondrosarcoma, are primarily found in the latter. On the other hand, soft tissue tumours generally present in the mid- and forefoot regions.

ACHIEVEMENTS

While the radiologic diagnostic evaluation of pedal bone tumours is quite reliable, caution is urgently needed in the case of soft tissue tumours because there are many confusing differential diagnoses.

PRACTICAL RECOMMENDATIONS

Proper X‑ray examination of the foot (at least in two plains) or with special views according to bony pathology is needed. All soft tissue masses that are not cysts should be evaluated further. MRI remains the diagnostic modality of choice but never stands alone! Caution: Size and well-defined margins of pedal soft tissue tumours are not considered criteria regarding whether a tumour is malignant or not.

Tarsal tunnel syndrome in the mucopolysaccharidoses: A case series and literature review

BACKGROUND

The mucopolysaccharidoses (MPS) are a group of inherited, progressive, multi-system lysosomal storage disorders. Musculoskeletal manifestations include nerve entrapment syndromes, most commonly carpal tunnel syndrome. Tarsal tunnel syndrome (TTS) has also been reported. The purpose of this study was to investigate the clinical course of MPS patients with suspected TTS and to conduct a literature review of TTS in MPS.

METHODS

A review of the Medline and EMBASE databases was conducted in accordance with published guidelines from the Joanna Briggs Institute of Evidence Based Medicine with search strategy developed by a librarian trained in systematic reviews. A medical record review was undertaken for all patients managed in the multi-disciplinary MPS clinic in a tertiary referral paediatric centre, identifying patients with a suspected or established diagnosis of TTS. Data regarding the demographics, investigations, presentation, management, and clinical course were collected.

RESULTS

The literature review failed to identify any published papers regarding TTS in MPS, with conference proceedings only identified. Within a cohort of 19 MPS patients, four patients with a suspected diagnosis of TTS were identified (MPS I: two patients, MPS VI: two patients). Three patients underwent surgical tarsal tunnel decompression, two with good result. One patient had overlapping symptoms with spinal stenosis and improvement in suspected tarsal tunnel symptoms following spinal decompression and fusion.

Guiding Treatment for Foot Pain

In the electrodiagnostic (EDX) approach of the patient who presents with foot pain, numbness, and/or tingling, it is important to consider a broad differential diagnosis of both neuropathic and nonneuropathic conditions, including focal and systemic causes. This article assists the electromyographer in the selection and utilization of the most appropriate EDX studies for evaluation. The EDX findings and impression can then help guide potential treatment options for the patient with foot pain and other symptoms. Moreover, this discussion demonstrates the added value that EDX evaluation of the foot provides to the comprehensive assessment of foot pain.

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.

Ultrasound-guided therapeutic injections for neural pathology about the foot and ankle: a 4 year retrospective review

OBJECTIVE

To describe a 4-year clinical experience with ultrasound-guided therapeutic perineural injections of peripheral nerves about the foot and ankle.

MATERIALS AND METHODS

Retrospective analysis of foot and ankle perineural injections performed between January 2012 and August 2016. Demographics, clinical indications, presence of structural pathology, immediate and interval pain relief, as well as complications were recorded.

RESULTS

Fifty-nine therapeutic injections were performed among 46 patients, accounting for multiple injections in a single visit or multiple visits [mean age = 43 years (range 18-75), 31 female (67%) and 15 male (33%)]. Most commonly, perineural injections involved the hallux branch of the medial plantar nerve (n = 17, 22%). Least commonly, perineural injections involved the saphenous nerve (n = 3, 4%). Other injections in our series include sural (10), superficial (11) and deep (7) peroneal, medial (5) and lateral (3) plantar nerves, and the posterior tibial nerve (3). Ultrasound evaluation revealed structural abnormality associated with the nerve in 30 cases (51%)-most commonly thickening with perineural scarring (n = 14). Of 45 injections with complete documentation, immediate relief of symptoms was reported in 43 (96%) cases. Interval symptom relief was achieved in 23 injections [short term (n = 12), intermediate (n = 6), and long term (n = 5)] out of 38 for which follow-up was available (61%). Complications are rare, occurring in only one case.

CONCLUSION

Ultrasound-guided perineural injections about the foot and ankle are safe and provide lasting symptomatic relief for many indications. Concomitant sonographic evaluation identifies structural abnormalities that may contribute to neuropathic symptoms, allowing targeting of injection or clinical therapy.

Medial-sided Ankle Pain: Deltoid Ligament and Beyond

Abnormalities of the medial ligaments and posterior tibial tendon can occur because of acute injury or chronic instability or malalignment. Medial ankle injuries may occur because of pronation or supination-external rotation injuries. Deltoid ligament injuries have a significant impact on lateral ankle instability but can be overlooked in patients with lateral ligament injuries. Posterior tibial tendon dysfunction is usually associated with spring ligament or flexor retinaculum injury. Tarsal tunnel syndrome, accessory flexor muscles, and subtalar coalition should be considered as well as ligament and tendon tears in differential diagnosis of chronic medial ankle pain.

Ultrasound-Guided Peripheral Nerve Injection Techniques

OBJECTIVE

Peripheral nerves are well seen using ultrasound (US) imaging, making US an ideal modality for image-guided nerve injections. This article provides a technical guide for common upper and lower extremity peripheral nerve injections, including the median, ulnar, and radial nerves in the upper extremity and the lateral femoral cutaneous, sciatic, common peroneal, tibial, and sural nerves in the lower extremity.

CONCLUSION

US is an effective modality for use in common upper and lower extremity peripheral nerve injections. With correct technique, peripheral nerve injections can be performed safely and are useful for both diagnostic evaluation of and therapy for peripheral neuropathy.