Fibular (peroneal) neuropathy.

Fibular neuropathy has variable presenting features depending on the site of the lesion. Anatomical features make it susceptible to injury from extrinsic factors, particularly the superficial location of the nerve at the head of the fibula. There are many mechanisms of compression or other traumatic injury of the fibular nerve, as well as entrapment and intrinsic nerve lesions. Intraneural ganglion cysts are increasingly recognized when the mechanism of neuropathy is not clear from the medical history. Electrodiagnostic testing can contribute to the localization as well as the characterization of the pathologic process affecting the nerve. When the mechanism of injury is unclear from the analysis of the presentation, imaging with MRI and ultrasound may identify nerve lesions that warrant surgical intervention. The differential diagnosis of foot drop includes fibular neuropathy and other neurologic conditions, which can be distinguished through clinical and electrodiagnostic assessment. Rehabilitation measures, including ankle splinting, are important to improve function and safety when foot drop is present. Fibular neuropathy is less frequently painful than many other nerve lesions, but when it is painful, neuropathic medication may be required. Failure to spontaneously recover or the detection of a mass lesion may require surgical management.

Common Peroneal Nerve and Tarsal Tunnel Release Surgery in an Adolescent Male with Hunter Syndrome: Illustrative Case.

BACKGROUND: Children with Hunter syndrome have a high prevalence of nerve compression syndromes given the buildup of glycosaminoglycans in the tendon sheaths and soft tissue structures. These are often comorbid with orthopedic conditions given joint and tendon contractures due to the same pathology. While carpal tunnel syndrome and surgical treatment has been well-reported in this population, the literature on lower extremity nerve compression syndromes and their treatment in Hunter syndrome is sparse. OBSERVATIONS: We report the case of a 13-year-old male with a history of Hunter syndrome who presented with toe-walking and tenderness over the peroneal and tarsal tunnel areas. He underwent bilateral common peroneal nerve and tarsal tunnel releases, with findings of severe nerve compression and hypertrophied soft tissue structures demonstrating fibromuscular scarring on pathology. Post-operatively, the patient's family reported subjective improvement in lower extremity mobility and plantar flexion. LESSONS: In this case, peroneal and tarsal nerve compression were diagnosed clinically and treated effectively with surgical release and postoperative ankle casting. Given the wide differential of common comorbid orthopedic conditions in Hunter syndrome and the lack of validated electrodiagnostic normative values in this population, the history and physical examination and consideration of nerve compression syndromes are tantamount for successful workup and treatment of gait abnormalities in the child with Hunter syndrome.

Pediatric Peroneal Nerve Palsy Secondary to Fibular Osteochondroma.

Peripheral nerve injuries due to mass effect from bony lesions can occur when the nerve exists in an anatomically constrained location, such as the common peroneal nerve at the fibular head which passes into the tight fascia of the lateral leg compartment. We report a case of a pediatric patient who developed a common peroneal nerve palsy secondary to an osteochondroma of the fibular head and describe the clinical evaluation, radiographic findings, and surgical approach. Rapid diagnosis and nerve decompression after the onset of symptoms restored full motor function at the 8-month postoperative mark.

Intraneural ganglion cyst of the peroneal nerve occurring after coronavirus disease-19 vaccination: A case report.

Ganglion cysts are relatively common, but intraneural ganglion cysts (INGCs) within peripheral nerves are rare and poorly understood. We present the case of a 58-year-old woman who presented with acute right-foot drop. She experienced acute knee pain radiating from the lateral leg to the dorsal foot two days after the first coronavirus disease-19 (COVID-19) vaccination (BNT162b2, Pfizer-BioNTech). She had no history of trauma or medication use. Two weeks after the onset of symptoms, she developed a dorsiflexor weakness of the right foot (Medical Research Council grade, poor). The weakness worsened to a "trace" grade despite providing conservative management for one month. Ultrasonography revealed a fusiform echolucent structure within the course of the right common peroneal nerve around the fibular head. Magnetic resonance imaging revealed multiple intraneural cysts within the right common peroneal nerve. Nerve conduction and electromyographic studies revealed multiphasic motor unit action potentials accompanied by abnormal spontaneous activities in the innervated muscles, along with axonal degeneration of the deep peroneal nerves. Surgical removal of the cyst was performed, and the patient's symptoms gradually improved. Pathological examination revealed a cystic structure containing mucinous or gelatinous fluid and lined with flattened or cuboidal cells. The clinical course and sequential electromyographic findings relevant to this symptomatic cyst were temporally related to the vaccination date. The present case suggests that INGC-induced peroneal palsy is a possible complication after COVID-19 vaccination.

Characterizing peroneal nerve injury clinicoradiological patterns with MRI in patients with sciatic neuropathy and foot drop after total hip replacement.

OBJECTIVE: Sciatic nerve injury following total hip arthroplasty (THA) predominantly affects the peroneal division of the sciatic nerve, often causing a foot drop. This can result from a focal etiology (hardware malposition, prominent screw, or postoperative hematoma) or nonfocal/traction injury. The objective of this study was to compare the clinicoradiological features and define the extent of nerve injury resulting from these two distinct mechanisms. METHODS: Patients who developed a postoperative foot drop within 1 year after primary or revision THA with a confirmed proximal sciatic neuropathy based on MRI or electrodiagnostic studies were retrospectively reviewed. Patients were divided into two cohorts: group 1 (focal injury), including patients with an identifiable focal structural etiology, and group 2 (nonfocal injury), including patients with a presumed traction injury. Patient demographics, clinical examinations, subsequent surgeries, electrodiagnostic study results, and MRI abnormalities were noted. The Student t-test was used to compare time to onset of foot drop and time to secondary surgery. RESULTS: Twenty-one patients, treated by one surgeon, met inclusion criteria (8 men and 13 women; 14 primary THAs and 7 revision THAs). Group 1 had a significantly longer time from THA to the onset of foot drop, with a mean of 2 months, compared with an immediate postoperative onset in group 2 (p = 0.02). Group 1 had a consistent pattern of localized focal nerve abnormality on imaging. In contrast, the majority of patients in group 2 (n = 11) had a long, continuous segment of abnormal size and signal intensity of the nerve, while the other 3 patients had a segment of less abnormal nerve in the midthigh on imaging. All patients with a long continuous lesion had Medical Research Council grade 0 dorsiflexion prior to secondary nerve surgeries compared with 1 of 3 patients with a more normal midsegment. CONCLUSIONS: There are distinct clinicoradiological findings in patients with sciatic injuries resulting from a focal structural etiology versus a traction injury. While there are discrete localized changes in patients with a focal etiology, those with traction injuries demonstrate a diffuse zone of abnormality within the sciatic nerve. A proposed mechanism involves anatomical tether points of the nerve acting as points of origin and propagation for traction injuries, resulting in an immediate postoperative foot drop. In contrast, patients with a focal etiology have localized imaging findings but a highly variable time to the onset of foot drop.

Partial tibial nerve transfer for iatrogenic peroneal nerve palsy after endovenous laser ablation for varicose veins of the lower extremity: A case report.

Postprocedural peroneal nerve palsy after endovenous laser ablation (EVLA) for varicose veins is rare and is associated with poor functional recovery. There have been no reports using tibial nerve transfer for iatrogenic peroneal nerve palsy after EVLA. Herein, we present a case with peroneal nerve injury after EVLA, which was successfully treated by partial tibial nerve transfer for the first time. A 75-year-old female presented with a right foot drop immediately after EVLA of the lesser saphenous vein. The ankle and toe dorsiflexion had a muscle grade of M0 on the British Medical Research Council muscle scale, without voluntary motor unit action potentials (MUAP) in the tibialis anterior (TA) muscle on the needle electromyography. Three months after the injury, surgical nerve exploration revealed a damaged common peroneal nerve with discoloration and scarring at the fibular head. Intraoperative deep peroneal nerve stimulation confirmed the absence of compound muscle action potentials in the TA. The best functioning motor fascicles of the tibial nerve were transferred to the deep peroneal main trunk involving motor branches of the TA, extensor digitorum longus, and extensor hallucis longus (EHL) through the interosseous membrane. The postoperative course was uneventful, with no complications. After 3 months of surgery, nascent MUAP appeared in the TA. After 24 months, the patient regained the TA and EHL muscle function and ambulation without an ankle-foot orthosis and tibial nerve deficits. Thus, our procedure may serve as an alternative to nerve grafting, tendon transfer, and orthoses for better management of the major neural complications associated with EVLA.

Common Peroneal Nerve Injury Due to an All-Inside Repair of the Posterior Horn of Lateral Meniscus: A Case Report.

CASE: An 18-year-old man sustained a peroneal nerve (PN) injury during an all-inside repair of the posterior horn of the lateral meniscus from the medial portal. Although he could dorsiflex his ankle actively after emergence from general anesthesia, he had a foot drop on the day after surgery. Exploration of the PN at 5 months postoperatively revealed that the nerve was entrapped by the suture. Fifteen months after a nerve repair using a sural nerve graft, he recovered from the foot drop. CONCLUSION: This case report highlights the risk of PN injury during an all-inside repair of the posterior horn of the lateral meniscus.

Paralysis Immediately after Surgical Decompression for Common Peroneal Nerve Entrapment.

OBJECTIVE: Common peroneal nerve (C-PN) entrapment neuropathy is the most common peripheral nerve neuropathy of the legs. C-PN decompression surgery is less invasive but may result in neurological complications. We report a rare case of nerve paralysis immediately after C-PN decompression surgery. CASE REPORT: An 85-year-old man presented with leg numbness and pain. An electrophysical study revealed C-PN entrapment in the affected area and he underwent surgical decompression. Immediately after the procedure he complained of slight paralysis without pain (manual muscle test: 3/5), which gradually worsened and was complete at 60 min after surgery. We re-opened the skin incision 3 hours after the first operation and found that a subcutaneous suture had been applied to the connective tissue near the C-PN, resulting in marked compression of the nerve. After release of the suture his paralysis improved immediately. We confirmed that there was no other nerve compression and finished the operation. His paralysis disappeared completely. CONCLUSION: Peripheral nerve surgery, including C-PN decompression surgery, is less invasive, and the risk of complications is low. However, because the C-PN is located in the shallow layer under the skin, an excessively deep suture in the subcutaneous layer may compress the nerve and elicit nerve palsy. Therefore, careful postoperative follow-up is necessary because early decompression leads to good surgical results.

Bilateral peroneal nerve palsy due to prolonged squatting in farmers: clinical and electrophysiological outcome.

INTRODUCTION: Peroneal neuropathy is the most common mononeuropathy of the lower extremities. However, bilateral peroneal nerve palsy (BPNP) is extremely rare due to prolonged squatting. We aimed to evaluate the clinical-electrophysiological findings in patients with BPNP caused by long-term squatting for cotton harvesting in our region. METHODS: Eight patients (16 limbs), admitted to our center between February 2018 and March 2021 with bilateral foot drop after prolonged squatting, were included in our study. The clinical and electrophysiological findings were re-evaluated six months later. RESULTS: We observed that 18.75% of the limbs had pure conduction block, 31.25% had mixed involvement, and half had predominantly axonal damage. Good recovery was observed in ankle dorsiflexion in seven patients during follow-ups. None of the patients were referred for surgery. Electrophysiological examinations showed that the conduction block was resolved, and reinnervation was observed in all patients with axonal degeneration. CONCLUSION: Since the etiology is nontraumatic compression, good recovery can be seen with conservative treatment in BPNP. Electrophysiological studies may determine reinnervation along with clinical examination. The patient should be followed-up for six months with conservative treatment before surgical intervention.

Acute-Onset Footdrop Caused by Intraneural Ganglion Cyst of the Common Peroneal Nerve: The Effects of Extraneural Pressure Gradients on Cyst Propagation.

Ganglion cysts are relatively common entities, but intraneural ganglia within peripheral nerves are rare and poorly understood. We present a case of a 51-year-old man who presented with acute left dropfoot. Initial magnetic resonance imaging (MRI) was misinterpreted as common peroneal neuritis consistent with a traction injury corroborated by the patient's history. However, after surgical decompression and external neurolysis were performed, the patient's symptoms worsened. Repeated MRI revealed an intraneural ganglion cyst of the common peroneal nerve with connection to the superior tibiofibular joint by means of its anterior recurrent branch that was evident retrospectively on preoperative MRI. It is crucial to carefully inspect atypical cases to further recognize and appreciate the dynamic aspect of this disease or "roller-coaster" phenomenon. Intraneural ganglion cysts rely heavily on intraneural and extraneural pressure gradients for propagation, which can be drawn from the expanded work of the unifying articular theory. This report emphasizes the importance of understanding the pathoanatomical and hydraulic factors to appropriately identify and treat intraneural ganglion cysts. Increased recognition of this pathologic entity as a differential diagnosis for acute onset dropfoot is also highlighted.

An overview of common peroneal nerve dysfunction and systematic assessment of its relation to falls.

PURPOSE: Compression of the peroneal nerve is recognized as a common cause of falls. The superficial course of the peroneal nerve exposes it to trauma and pressure from common activities such as crossing of legs. The nerve can be exposed also to distress due to metabolic problems such as diabetes. The purpose of our manuscript is to review common peroneal nerve dysfunction symptoms and treatment as well as provide a systematic assessment of its relation to falls. METHODS: We pooled the existing literature from PubMed and included studies (n = 342) assessing peroneal nerve damage that is related in any way to falls. We excluded any studies reporting non-original data, case reports and non-English studies. RESULTS: The final systematic assessment included 4 articles. Each population studied had a non-negligible incidence of peroneal neuropathy. Peroneal pathology was found to be consistently associated with falls. CONCLUSION: The peroneal nerve is an important nerve whose dysfunction can result in falls. This article reviews the anatomy and care of the peroneal nerve. The literature review highlights the strong association of this nerve's pathology with falls.

Superficial peroneal nerve entrapment neuropathy and role of pulsed radiofrequency neuromodulation.

Peripheral neuropathy secondary to entrapment of the nerves is not an uncommon etiology. Nerve entrapment is a common occurrence following trauma or surgery and poses significant diagnostic challenge. Entrapment neuropathy (EN) may not respond to standard neuropathic medication and may need invasive treatment. Pulsed radiofrequency (PRF) application is a recent modality and is gaining popularity for many EN as it does not cause neural ablation unlike conventional radiofrequency ablation. In this report, we present a case of young patient who presented with severe lower lateral leg pain in whom superficial peroneal nerve (SPN) EN was suspected and diagnostic SPN injection under ultrasound guidance confirmed the diagnosis. He subsequently underwent PRF neuromodulation and experienced long-lasting pain relief.

Delayed Onset of Peroneal Nerve Palsy After Total Knee Arthroplasty.

Peroneal nerve palsy (PNP) and peroneal nerve dysfunction (PND) are rare complications after total knee arthroplasty (TKA). Although PND tends to manifest as transient lateral leg paresthesias that are associated with knee motion, PNP has characteristic motor deficits, including loss of ankle dorsiflexion and eversion strength. Although PND can manifest days, weeks, or months after surgery, delayed cases of PNP have not been well documented. We describe a 72-year-old woman with a delayed case of sudden-onset PNP 10 weeks after TKA. She had no neurologic deficits preoperatively and was recovering uneventfully at 2 and 6 weeks postoperatively. At 10 weeks, she reported insidious onset of drop foot and sensory changes to the lateral leg and dorsum of the foot. Motor deficits included significant loss of ankle dorsiflexion and eversion strength. After a diagnosis of PNP was confirmed with electrodiagnostic studies and lumbar pathology was ruled out with lumbar magnetic resonance imaging, surgical decompression of the peroneal nerve was performed. By 7 weeks after surgical decompression, she had no sensory deficits and nearly full strength in ankle dorsiflexion and eversion. This case shows that PNP can occur several weeks to months outside of the currently documented timeline. Although PNP is an uncommon risk of TKA, it is important to recognize and treat it when it occurs among patients with significant motor and sensory deficits along the distribution of the peroneal nerve postoperatively. [Orthopedics. 2022;45(6):e342-e344.].

Common fibular nerve palsy due to fabella compression: An illustrative case report.

BACKGROUND: The fabella is a sesamoid bone situated in the tendon of the lateral head of the gastrocnemius muscle behind the lateral femoral condyle. Common fibular nerve injury may occur anywhere on its course and the most common etiology remains compression at the level of the head of the fibula. Compression by a fabella is a very unusual cause of common fibular nerve palsy and only few case reports are described in the literature. We present here an illustrative case. CASE DESCRIPTION: A 50-year-old female patient presented with a left drop-foot evolving for two weeks without pain or sensory deficit. Clinical examination revealed a paresis of the left foot dorsiflexors muscles (3/5). A compressive neuropathy of the common fibular nerve at the level of the fibula head was demonstrated by nerve conduction studies. Ultrasound of the left knee revealed nerve compression by a fabella. Early decompressive surgery was performed and the fabella was excised. We noticed an almost complete recovery probably due to early treatment (4+/5 two months after surgery). CONCLUSIONS: Common fibular nerve palsy related to fabella compression is very uncommon. Good clinical outcome has been described at 1-2 years with an early work-up and a prompt surgical decompression.

Surgical Treatment of Foot Drop: Patient Evaluation and Peripheral Nerve Treatment Options.

Foot drop is a common clinical condition which may substantially impact physical function and health-related quality of life. The etiologies of foot drop are diverse and a detailed history and physical examination are essential in understanding the underlying pathophysiology and capacity for spontaneous recovery. Patients presenting with acute foot drop or those without significant spontaneous recovery of motor deficits may be candidates for surgical intervention. The timing, mechanism, and severity of neural injury resulting in foot drop influence the selection of the most appropriate peripheral nerve surgery, which may include direct nerve repair, neurolysis, nerve grafting, or nerve transfer.

Arthroscopic Treatment of Lateral Meniscal Cyst Causing Peroneal Nerve Injury.

Compression of the common peroneal nerve by lateral meniscal cysts is rare. We report a 29-year male patient who complained of a gradually enlarging mass in the right popliteal fossa. He was diagnosed with a lateral meniscal cyst and a common peroneal nerve injury. The patient underwent arthroscopic surgery, including lateral partial meniscectomy and cyst drainage. When followed up at 3 months, the dorsal extensor strength of the right foot recovered to grade 5, and sensation of the distal right lower limb returned to normal. No recurrence of the cyst was found at the last follow-up at 18 months. This is a rare case of common peroneal nerve paralysis caused by a lateral meniscal cyst. Key Words: Meniscal cyst, Common peroneal nerve, Nerve injury.

Resection of Hibernoma of the Proximal Shin Followed by Foot Drop and Tendon Transfer: A Case Report.

This is the description of the case of a 42-year-old male who presented with a growing, painless lump on his anterior leg. The diagnosis of a rare tumor called hibernoma was suspected after inspection of the radiologic findings. The unusual location of the tumor resulted in superficial peroneal nerve entrapment. The tumor was excised and the diagnosis of hibernoma was confirmed by histopathology. Surgery resulted in foot drop that was successfully treated with a tibialis posterior tendon transfer. Our case illustrates a rare tumor in an unusual location that can be challenging for clinicians to discern and to properly treat.

Distal posterolateral corner injury in the setting of multiligament knee injury increases risk of common peroneal palsy.

PURPOSE: The purpose of this study was to identify if the location of posterolateral corner (PLC) injury was predictive of clinical common peroneal nerve (CPN) palsy. METHODS: A retrospective chart review was conducted of patients presenting to our institution with operative PLC injuries. Assessment of concomitant injuries and presence of neurologic injury was completed via chart review and magnetic resonance imaging (MRI) review. A fellowship-trained musculoskeletal radiologist reviewed the PLC injury and categorized it into distal, middle and proximal injuries with or without a biceps femoral avulsion. The CPN was evaluated for signs of displacement or neuritis. RESULTS: Forty-seven operatively managed patients between 2014 and 2019 (mean age-at-injury 29.5 ± 10.7 years) were included in this study. Eleven (23.4%) total patients presented with a clinical CPN palsy. Distal PLC injuries were significantly associated with CPN palsy [9 (81.8%) patients, (P = 0.041)]. Nine of 11 (81.8%) patients with CPN palsy had biceps femoral avulsion (P = 0.041). Of the patients presenting with CPN palsy, only four (36.4%) patients experienced complete neurologic recovery. Three of 7 patients (43%) with an intact CPN had full resolution of their clinically complete CPN palsy at the time of follow-up (482 ± 357 days). All patients presenting with a CPN palsy also had a complete anterior cruciate ligament (ACL) rupture in addition to a PLC injury (P = 0.009), with or without a posterior cruciate ligament (PCL) injury. No patient presenting with an isolated pattern of PCL-PLC injury (those without ACL tears) had a clinical CPN palsy. CONCLUSION: Distal PLC injuries have a strong association with clinical CPN palsy, with suboptimal resolution in the initial post-operative period. Specifically, the presence of a biceps femoris avulsion injury was highly associated with a clinical CPN palsy. Additionally, CPN palsy in the context of PLC injury has a strong association with concomitant ACL injury. Furthermore, the relative rates of involvement of the ACL vs. PCL suggest that specific injury mechanism may have an important role in CPN palsy. LEVEL OF EVIDENCE: IV.

Single versus double tendon transfer for foot drop due to post-traumatic common fibular nerve palsy.

PURPOSE: To compare functional outcomes of single versus double tendon transfer for foot drop correction and toe drop prevention in posttraumatic common fibular nerve palsy. METHODS: A retrospective study was conducted on data from patients with posttraumatic common fibular nerve palsy treated by tendon transfer between 2001 and 2018. In cases of single tendon transfer (STT) the tibialis posterior (TP) tendon was transferred anteriorly through the interosseous membrane to a new insertion on the lateral cuneiform. In cases of double tendon transfer (DTT), the same TP tendon transfer was combined with a transfer of the flexor digitorum longus to the extensor digitorum longus and extensor hallucis longus tendons. Functional assessment was based on the Carayon score to evaluate foot drop correction and on the Yeganeh score to evaluate toe drop prevention. RESULTS: A total of 27 patients were included: 13 in the STT group and 14 in the DTT group. Functional results were comparable between groups in terms of reduction of foot drop, active range of ankle motion and Carayon score. Prevention of toe drop, active toe extension and Yeganeh score were significantly greater in the DTT group, however, active toe extension of was only restored in only 8 cases in the DTT group. CONCLUSIONS: Double transfer of TP and FDL tendons is a reliable method to restore balanced ankle dorsiflexion and prevent toe drop. However, recovery of active toe extension was inconsistent and Carayon scores were not superior to those obtained with a single TP tendon transfer.

Complete Foot Drop With Normal Electrodiagnostic Studies: Sunderland "Zero" Ischemic Conduction Block of the Common Peroneal Nerve.

ABSTRACT: Common peroneal neuropathy is a peripheral neuropathy of multifactorial etiology often left undiagnosed until foot drop manifests and electrodiagnostic abnormalities are detected. However, reliance on such striking symptoms and electrodiagnostic findings for diagnosis stands in contrast to other commonly treated neuropathies, such as carpal tunnel and cubital tunnel syndrome. Poor recognition of common peroneal neuropathy without foot drop or the presence of foot drop with normal electrodiagnostic studies thus often results in delayed or no surgical treatment. Our cases document 2 patients presenting with complete foot drop who had immediate resolution after decompression. The first patient presented with normal electrodiagnostic studies representing an isolated Sunderland Zero nerve ischemia. The second patient presented with severe electrodiagnostic studies but also had an immediate improvement in their foot drop representing a Sunderland VI mixed nerve injury with a significant contribution from an ongoing Sunderland Zero ischemic conduction block. In support of recent case series, these patients demonstrate that common peroneal neuropathy can present across a broad diagnostic spectrum of sensory and motor symptoms, including with normal electrodiagnostic studies. Four clinical subtypes of common peroneal neuropathy are presented, and surgical decompression may thus be indicated for these patients that lack the more conventional symptoms of common peroneal neuropathy.