Surgical treatment of hourglass-like radial nerve constrictions

INTRODUCTION

Spontaneous radial nerve palsy with the surgical revelation of an hourglass-like constriction is a complicated condition. In general, the surgical strategy is decided in accordance with the results of surgical exploration. This study aimed to investigate the efficacies of various choices of surgical methods in the treatment of hourglass-like radial nerve constrictions.

MATERIAL AND METHODS

Ten patients with spontaneous radial nerve palsy undergoing surgical exploration with the revelation of hourglass-like constrictions between November 2010 and December 2018 were reviewed in our hospital. Preoperative physical, electrophysiological and ultrasound examinations were performed for all patients. Varying levels, degrees and numbers of radial nerve constrictions were shown by surgical exposure. Epineurectomy and interfascicular neurolysis were performed in 4 cases with incomplete constrictions; resection and primary suture repair in 2 radial nerves with neurotmesis; resection and autologous nerve grafting in 4 patients with nerve defect>2cm. Both motor and sensory evaluations were performed at a follow-up visit.

RESULTS

Ten patients underwent different history before the onset of symptom. Nerve ultrasound demonstrated swelling as well as constrictions of the radial nerve. All patients who were followed up presented with good to excellent recovery of motor function. The effectiveness of suture and autograft repair tended to be better than that of simple neurolysis.

CONCLUSION

The etiology of hourglass-like fascicular constrictive neuropathy of radial nerve involve with torsional factors. Nerve ultrasound is an important and useful measurement in diagnosing the pathology of spontaneous radial nerve palsy and in helping determine surgical approach. The surgical intervention is beneficial for the patients who do not recover in 4 weeks after onset of symptoms and for severe hourglass-like constrictions that are confirmed by preoperative ultrasound imaging. We recommend that nerve grafting be a suitable method in confrontation of nerve defect>2cm.

Outcomes of Microneurolysis of Hourglass Constrictions in Chronic Neuralgic Amyotrophy

PURPOSE

Wide variability in the recovery of patients affected by neuralgic amyotrophy (NA) is recognized, with up to 30% experiencing residual motor deficits. Using magnetic resonance imaging and ultrasound (US), we identified hourglass constrictions (HGCs) in all affected nerves of patients with chronic motor paralysis from NA. We hypothesized that chronic NA patients undergoing microsurgical epineurolysis and perineurolysis of constrictions would experience greater recovery compared with patients managed nonsurgically.

METHODS

We treated 24 patients with chronic motor palsy from NA and HGCs identified on magnetic resonance imaging and US either with microsurgical epineurolysis and perineurolysis of HGCs (11 of 24) or nonsurgically (13 of 24). Muscle strength (both groups) and electrodiagnostic testing (EDX) (operative group) was performed before and after surgery. Preoperative EDX confirmed muscle denervation in the distribution of affected nerve(s). All patients met criteria for microneurolysis: 12 months without improvement since onset or failure of clinical and EDX improvement after 6 months documented by 3 successive examinations, each at least 6 weeks apart.

RESULTS

Mean time from onset to surgery was 12.5 ± 4.0 months. Average time to most recent post-onset follow-up occurred at 27.3 months (range, 18-42 months; 15 nerves). Average time to latest follow-up among nonsurgical patients was 33.6 months (range, 18-108 months; 16 nerves). Constrictions involved individual fascicular groups (FCs) of the median nerve and the suprascapular, axillary and radial nerves proper (HGCs). Nine of 11 operative patients experienced clinical recovery compared with 3 of 13 nonsurgical patients. EMG revealed significant motor unit recovery from axonal regeneration in the operative group.

CONCLUSIONS

Microsurgical epineurolysis and perineurolysis of FCs and HGCs was associated with significantly improved clinical and nerve regeneration at an average follow-up of 14.8 months compared with nonsurgical management. We recommend microneurolysis of HGCs and FCs as a treatment option for patients with chronic NA who have failed to improve with nonsurgical treatment.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Pathological Findings of Hourglass-Like Constriction in Spontaneous Posterior Interosseous Nerve Palsy

We report the pathological findings of hourglass-like fascicular constriction (HLFC) under optical and electron microscopy. A 24-year-old man with spontaneous posterior interosseous nerve palsy was treated by interfascicular neurolysis at 29 weeks after onset. One fascicle in the radial nerve presented severe HLFC with torsion at 5 cm proximal to the elbow. Functional recovery was achieved by resection of the enlarged fascicle including HLFC and sural nerve grafting. Proximal to the HLFC, the endoneurium was filled with clusters of regenerating nerve fibers. At the level of the HLFC, a complete loss of myelinated nerve fibers and vascular occlusion of endo- and perineurial vessels were found. Few regenerating nerve fibers were observed. Distal to the HLFC, severe endoneurial edema, a complete loss of myelinated and unmyelinated nerve fibers, and bands of Büngner were noted. These electron microscopic findings demonstrated a detailed pathology of the nerve around the HLFC.

Post-Contrast 3D Inversion Recovery Magnetic Resonance Neurography for Evaluation of Branch Nerves of the Brachial Plexus

PURPOSE

To compare 3.0 Tesla brachial plexus three-dimensional (3D) T2-weighted short tau inversion recovery fast spin echo (STIR-FSE) MRI sequences before (pre-contrast STIR) and after (post-contrast STIR) administration of gadolinium intravenous contrast.

METHOD

Eighteen patients were included. Each patient was imaged before and after intravenous contrast administration during the same session. 3D STIR-FSE sequences were obtained at 3.0 Tesla using two 16-channel flexible coils positioned over the lower neck and chest wall region. Three musculoskeletal radiologists qualitatively assessed degree of vascular signal suppression, visualization of the axillary, musculocutaneous, and suprascapular nerves, diagnostic confidence in nerve evaluation, and lesion conspicuity. Marginal ordinal logistic regression models were used to compare subjective ratings between sequences. Pre- and post-STIR lesion conspicuity was compared using Wilcoxon signed-rank test. Inter- and intra-observer agreements were assessed using Gwet's agreement coefficient.

RESULTS

Vascular signal suppression significantly improved following contrast administration (odds ratio, OR = 209.9, 95% confidence interval, CI: 21.0-2094.6, p < .001). The post-contrast STIR technique significantly improved nerve visualization (OR = 8.4, 95% CI: 3.6-19.9, p < .001) and diagnostic confidence in evaluation (OR = 13.2, 95% CI: 4.8-36.0, p < .001) across all nerve segments. Post-contrast STIR improved lesion conspicuity by 1 point, but statistical significance was not reached (Reader 1: p = 0.5, Reader 2: p = 0.063). Post-contrast STIR imaging demonstrated substantial to near-perfect inter- and intra-rater agreement coefficients for both nerve visualization (inter-rater: 0.74-1.0, intra-rater: 0.94-1.0) and diagnostic confidence (inter-rater: 0.79-1.0, intra-rater: 0.94-1.0). Quantitatively, post-contrast STIR demonstrated a 24% increase in mean C6 nerve-to-muscle signal intensity ratio (p = 0.017).

CONCLUSIONS

Post-contrast STIR improved nerve-to-muscle contrast ratio, allowing for enhanced visualization and diagnostic confidence in evaluation of branch nerves of the brachial plexus.

Neuralgic amyotrophy: a paradigm shift in diagnosis and treatment

Neuralgic amyotrophy (NA), also known as Parsonage-Turner syndrome, is characterised by sudden pain attacks, followed by patchy muscle paresis in the upper extremity. Recent reports have shown that incidence is much higher than previously assumed and that the majority of patients never achieve full recovery. Traditionally, the diagnosis was mainly based on clinical observations and treatment options were confined to application of corticosteroids and symptomatic management, without proven positive effects on long-term outcomes. These views, however, have been challenged in the last years. Improved imaging methods in MRI and high-resolution ultrasound have led to the identification of structural peripheral nerve pathologies in NA, most notably hourglass-like constrictions. These pathognomonic findings have paved the way for more accurate diagnosis through high-resolution imaging. Furthermore, surgery has shown to improve clinical outcomes in such cases, indicating the viability of peripheral nerve surgery as a valuable treatment option in NA. In this review, we present an update on the current knowledge on this disease, including pathophysiology and clinical presentation, moving on to diagnostic and treatment paradigms with a focus on recent radiological findings and surgical reports. Finally, we present a surgical treatment algorithm to support clinical decision making, with the aim to encourage translation into day-to-day practice.

Selective Fascicular Involvement of the Median Nerve Trunk Causing Pseudo-Anterior Interosseous Nerve Syndrome: Ultrasound and MR Imaging Features

Fascicular involvement of the median nerve trunk in the upper arm is uncommon in cases of peripheral neuropathy, and its symptoms are consistent with those of anterior interosseous nerve (AIN) syndrome. We report three cases of focal anterior interosseous fascicular involvement in the median nerve trunk presenting as AIN palsy. Our report emphasizes the unique ultrasonographic and magnetic resonance imaging (MRI) features of swelling, hourglass-like constriction and torsion, and entwinement of the nerve fascicle of the dorsal region of the median nerve, which were confirmed surgically. On MRI, all patients showed denervation changes in the AIN territory, as well as in the median nerve territory, without compressing structures.

Update on classification, epidemiology, clinical phenotype and imaging of the nonsystemic vasculitic neuropathies

PURPOSE OF REVIEW

Single-organ vasculitis of the peripheral nervous system (PNS) is often designated nonsystemic vasculitic neuropathy (NSVN). Several variants or subtypes have been distinguished, including migratory sensory neuropathy, postsurgical inflammatory neuropathy, diabetic radiculoplexus neuropathies, skin-nerve vasculitides, and, arguably, neuralgic amyotrophy. NSVN often presents as nondiabetic lumbosacral radiculoplexus neuropathy (LRPN). This review updates classification, clinical features, epidemiology, and imaging of these disorders.

RECENT FINDINGS

A recent study showed the annual incidence of LRPN in Olmstead County, Minnesota to be 4.16/100 000:2.79/100 000 diabetic and 1.27/100 000 nondiabetic. This study was the first to determine the incidence or prevalence of any vasculitic neuropathy. In NSVN, ultrasonography shows multifocal enlargement of proximal and distal nerves. In neuralgic amyotrophy, MRI and ultrasound reveal multifocal enlargements and focal constrictions in nerves derived from the brachial plexus. Histopathology of these chronic lesions shows inflammation and rare vasculitis. Diffusion tensor imaging of tibial nerves in NSVN revealed decreased fractional anisotropy in one study.

SUMMARY

Single-organ PNS vasculitides are the most common inflammatory neuropathies. Neuralgic amyotrophy might result from PNS vasculitis, but further study is necessary. The usefulness of focal nerve enlargements or constrictions in understanding pathological mechanisms, directing biopsies, and monitoring disease activity in NSVN should be further investigated.

Treatment of spontaneous anterior interosseous nerve palsy

OBJECTIVE

The purpose of this study was to clarify the clinical outcomes of spontaneous anterior interosseous nerve palsy (AINP) treated nonsurgically or surgically.

METHODS

The authors retrospectively evaluated the clinical course of 27 patients affected with AINP, treated nonsurgically or surgically. Thirteen patients underwent surgical treatment (interfascicular neurolysis), and 14 patients underwent conservative nonsurgical treatment. The mean patient age at the onset of symptoms was 49 years (range 17–77 years). The mean follow-up duration from onset to the latest follow-up examination was 23 months (range 12–38 months).

RESULTS

In 12 of 14 patients receiving conservative treatment, signs of recovery from the palsy were obtained within 6 months. These patients showed a recovery of manual muscle test (MMT) grade ≥ 3. In contrast, 2 patients who took more than 12 months from symptom onset to initial recovery showed poor recovery (MMT grade ≤ 2). Surgical treatment was performed in 13 patients because of no sign of recovery from palsy. The mean period from symptom onset to the operation was 8.4 months (range 6–14 months). Ten of 13 patients who underwent surgical treatment within 8 months after symptom onset showed good recovery, with MMT grade ≥ 4. However, 3 patients who underwent surgical treatment more than 12 months after onset showed recovery with MMT grade ≤ 3.

CONCLUSIONS

Conservative treatment for AINP may be continued when patients show signs of recovery within 6 months after symptom onset. In contrast, surgical treatment may be performed within 8 months from the onset of symptoms when the patients show no recovery signs for 6 months.

"Isolated" Suprascapular Neuropathy: Compression, Traction, or Inflammation?

BACKGROUND

Several hypotheses have been proposed for the pathophysiology of suprascapular nerve (SSN) palsy, including compression, traction, and nerve inflammation.

OBJECTIVE

To provide insight into the pathophysiology of isolated nontraumatic SSN palsy by performing critical reinterpretations of electrodiagnostic (EDX) studies and magnetic resonance (MR) images of patients with such diagnosis.

METHODS

We retrospectively reviewed all patients referred to our institution for the past 20 yr with a diagnosis of nontraumatic isolated suprascapular neuropathy who had an upper extremity EDX study and a shoulder or brachial plexus MR scan. Patient charts were reviewed to analyze their initial clinical examination, and their original EDX study and MR images were reinterpreted by an experienced neurologist and a musculoskeletal radiologist, respectively, both blinded from the authors' hypothesis and from each other's findings.

RESULTS

Fifty-nine patients were included. Fifty of them (85%) presented with at least 1 finding that was inconsistent with an isolated SSN palsy. Forty patients (68%) had signs on physical examination beyond the SSN distribution. Thirty-one patients (53%) had abnormalities on their EDX studies not related to the SSN. Twenty-two patients (37%) had denervation atrophy in other muscles than the spinati, or neural hyperintensity in other nerves than the SSN on their MR scans, without any evidence of SSN extrinsic compression.

CONCLUSION

The great majority of patients with presumed isolated SSN palsy had clinical, electrophysiological, and/or imaging evidence of a more diffuse pattern of neuromuscular involvement. These data strongly support an inflammatory pathophysiology in many cases of "isolated" SSN palsy.

Spontaneous peripheral nerve palsy with hourglass-like fascicular constriction in the upper extremity

OBJECTIVE

Spontaneous paralysis from hourglass-like fascicular constriction of peripheral nerves is rare, its clinical manifestations are not well documented, and its pathogenesis remains unknown. The unclear origin of this disorder and difficulty in diagnosis result in its uncertain management. The authors sought to gain a more thorough understanding of this condition through describing the anatomy, clinical features, etiology, and treatment of hourglass-like constriction.

METHODS

The authors retrospectively reviewed 20 patients (22 nerves) with hourglass-like constriction. The patients' clinical information was reviewed. Preoperative sonographic assessment and electrophysiological examination of involved nerves were performed. Surgical treatments included interfascicular neurolysis and neurorrhaphy. Samples of tissue subjected to resected constriction were sent for pathological analysis. The patients had regular face-to-face follow-up visits.

RESULTS

Acute pain was always the first symptom and was followed by paralysis. Paralysis progression was rapid and serious. Surgical exploration indicated an hourglass-like constricted segment completely unrelated to the compressive structures. Electrophysiological analysis showed severe denervation, and histopathological examination showed inflammatory cell infiltration, demyelination, and reduction of nerve fibers.

CONCLUSIONS

Hourglass-like fascicular constrictive neuropathy has an integrative effect from multiple different mechanisms. Surgical intervention is beneficial for selected patients who do not recover in a timely fashion and have hourglass-like lesions confirmed by preoperative ultrasound imaging. The authors recommend that early surgical intervention of the nerve be offered to patients who do not show any signs of recovery 3 months after onset. Both interfascicular neurolysis and neurorrhaphy are effective treatment methods. Mild to moderate constriction can usually be treated successfully by interfascicular neurolysis alone, whereas more advanced lesions with loss of fascicle continuity (severe constriction) may be best treated with resection and direct neurorrhaphy.

Hourglass-like constriction neuropathy of the suprascapular nerve detected by high-resolution magnetic resonance neurography: report of three patients

Hourglass-like constriction neuropathy is a neurological condition caused by non-traumatic, non-compressive fascicular constrictions of one or more individual peripheral nerves. Based on clinical manifestations, it is very difficult to differentiate hourglass-like constriction neuropathy from idiopathic neuralgic amyotrophy. Focal hourglass-like constriction neuropathy may be erroneously diagnosed as idiopathic neuralgic amyotrophy. Previous studies demonstrated hourglass-like constrictions of peripheral nerves in the surgical exploration of patients diagnosed with idiopathic neuralgic amyotrophy. Recently, high-resolution ultrasound or magnetic resonance neurography (MRN) have been introduced to detect focal hourglass-like constrictions of peripheral nerves in spontaneous nerve palsy. We present a series of three cases in which the suprascapular nerve was affected by hourglass-like constrictions, which were visualized by high-solution MRN, including a nerve-selective morphological MR pulse sequence with strong fat- and water-signal suppression.

Spontaneous Radial Nerve Palsy due to an Unrecognized Myofibroma: A Case Report

CASE

A 33-year-old woman presented with a six-month history of spontaneous radial nerve palsy and no identified lesion on imaging. She underwent operative exploration where an hourglass deformity was seen and resected. Pathology returned as a rare tumor, a myofibroma. The patient regained full radial nerve function.

CONCLUSIONS

A trial of observation is often indicated in the cases of isolated nerve palsy where anatomic lesions have been eliminated. This case highlights that imaging studies can miss a tumor involving nerve and that painless, spontaneous nerve palsy may be a time where early surgical intervention offers a better chance of recovery.

[Sonographic characteristics of non-traumatic focal hourglass-like nerve constriction]

AIM

To describe the sonographic phenomenon of the focal 'hourglass-like constriction' of the peripheral nerves (FCPN).

MATERIAL AND METHODS

The authors described 7 patients meeting the criteria for the diagnosis of neuralgic amyotrophy with unilateral FCPN identified with ultrasound in 4 cases and detected intraoperatively in 3 cases (preliminary ultrasound was not performed). The US scanner Sonoscape Pro mode gray scale in the transverse and longitudinal scanning, linear probe 8-15 MHz and Logiq9 scanner with elastography were used.

RESULTS

FCPN was detected in the single nerve in 4 patients, in two nerves in 2 patients and in 3 nerves in one patient. Among all the nerves involved in the pathological process, the radial nerve and its branches were affected in 73% (8 nerves); the ulnar nerve was involved in 18% (2 nerves) and the musculo-cutaneous nerve in 9%. The length of the constriction of the peripheral nerve did not exceed 1.7 mm. The deformation coefficient (DC) of constriction area was 3.8 to .,9; the change in the elasticity in the form of an increase of DC to 5.9 when compared to the intact portion of the nerve and a decrease in echogenicity were observed in one patient.

CONCLUSION

High-resolution ultrasound of the nerve can be an informative method for the diagnosis of idiopathic non-traumatic FCPN mononeuropathy.

Isolated spontaneous posterior interosseous nerve palsy: a review of aetiology and management

Isolated posterior interosseous nerve palsy is an uncommon condition and its management is controversial. Existing literature is sparse and a treatment algorithm based on existing best evidence is absent. A comprehensive review was undertaken to elucidate the causes of spontaneous posterior interosseous nerve palsy and suggest a management strategy based on the current evidence. Posterior interosseous nerve palsy can be broadly categorized as compressive and non-compressive, and the existing evidence supports surgical intervention for compressive palsy. For posterior interosseous nerve pathology with no compressive lesion on imaging, conservative management should be tried first. Surgery is therefore reserved for compressive lesions and for failure of conservative management. The commonly performed operative procedures include decompression and neurolysis, neurorrhaphy and nerve grafting, and tendon transfers with or without nerve grafting performed as a salvage procedure. The prognosis is poorer in patients aged > 50 years, those with a delay to surgery, and those who have had long-standing compression with severe fascicular thinning.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

The first case of hourglass-like constriction neuropathy of a digital nerve

Neuropathies of digital nerves are an infrequent phenomenon and their causes are most often mechanical. A rare cause of acute neuropathy is hourglass-like fascicular constriction of a nerve due to torsion. Although several cases of hourglass-like constriction have been described in the literature, none to our knowledge involved digital nerves. In this report, we present the first case of hourglass-like constriction of a digital nerve.

Hourglass-like constriction of the suprascapular nerve: a contraindication for minimally invasive surgery

BACKGROUND

Suprascapular nerve (SSN) entrapment is usually ascribed to static or dynamic compression. When no cause of compression is found, SSN entrapment is defined as idiopathic. Focal hourglass-like constriction (H-LC) of the SSN that results in muscle paralysis represents an unusual condition that may be misinterpreted and erroneously diagnosed as SSN entrapment or as neuralgic amyotrophy.

METHODS

With the aim of finding clinical and surgical clues that could differentiate the traditional form of idiopathic SSN entrapment from the rare H-LC, a series of 6 cases of SSN palsy caused by H-LC is presented.

RESULTS

All but 1 supraspinatus muscle recovered M5 muscle strength. The Constant shoulder score was excellent in 3 patients, good in 1, fair in 1, and poor in 1.

DISCUSSION

If a diagnosis is not made in time, H-LC may evolve from mild to severe nerve torsion that may require a shift in surgical procedure from epineurotomy and external neurolysis to focal resection and suture. If an incorrect therapy is chosen, the chance of recovery might be definitively compromised with the persistence of muscle palsy. Conversely, when SSN palsy persists despite notch decompression, especially when it is performed with a limited open approach or arthroscopically, concerns about the real etiology and location of nerve compression responsible for the nerve palsy may arise.

CONCLUSION

When approaching SSN pathology, H-LC should be considered as a potential cause of nerve palsy, as it may represent a contraindication for a limited open approach or arthroscopic decompression.

Ultrasonography in neuralgic amyotrophy: Sensitivity, spectrum of findings, and clinical correlations

INTRODUCTION

The aim of this study was to assess the value of ultrasonography in neuralgic amyotrophy.

METHODS

Fifty-three patients with 70 affected nerves were examined with high-resolution ultrasound.

RESULTS

The most commonly affected nerve was the anterior interosseous (23%). Ultrasonographic abnormalities in the affected nerves, rather than in the brachial plexus, were observed, with an overall sensitivity of 74%. Findings included the swelling of the nerve/fascicle with or without incomplete/complete constriction and rotational phenomena (nerve torsion and fascicular entwinement). A significant difference was found among the categories of ultrasonographic findings with respect to clinical outcome (P = 0.01). In nerves with complete constriction and rotational phenomena, reinnervation was absent or negligible, indicating surgery was warranted.

DISCUSSION

Ultrasonography may be used as a diagnostic aid in neuralgic amyotrophy, which was hitherto a clinical and electrophysiological diagnosis, and may also help in identifying potential surgical candidates. Muscle Nerve 56: 1054-1062, 2017.

Hourglass-Like Constriction of the Brachial Plexus in the Posterior Cord: A Case Report

BACKGROUND AND IMPORTANCE

Hourglass-like constrictions are fascicular conditions confirmed definitively by interfascicular neurolysis. Certain peripheral nerves have vulnerable areas such as around the elbow in the posterior interosseous nerve. We report the first hourglass-like constriction in the brachial plexus supplying the radial innervated forearm musculature. Preoperative magnetic resonance imaging (MRI) findings of the brachial plexus were consistent with neuralgic amyotrophy (NA).

CLINICAL PRESENTATION

A 9-yr-old boy experienced worsening left arm pain and difficulty in elevating the shoulder. Sequentially, severe palsy emerged when extending the wrist, thumb, and fingers. Based on the clinical picture, we diagnosed him with NA. The oblique coronal T2-weighted short-tau inversion recovery images showed mildly diffuse enlargement and hyperintensity of the brachial plexus. He showed few signs of improvement and interfascicular neurolysis was performed 11 mo after the onset. One of the fascicles in the posterior cord had developed an hourglass-like constriction. Electrical stimulation confirmed that the fascicle supplied forearm muscles. His wrist and finger extension had almost recovered at the 12-mo postoperative visit.

CONCLUSION

Hourglass-like constrictions can occur in the brachial plexus. Although surgical approaches for the constrictions are still controversial, several reports demonstrated their effectiveness. Meanwhile, concerning NA treatment, evidence on the surgical intervention is lacking. Brachial plexus MRI might help in discerning the lesion and planning treatment options including surgical interventions. Hourglass-like constrictions are a possible etiology for certain NA patients with residual symptoms or paresis.

Ultrasonographic findings of proximal median neuropathy: A case series of suspected distal neuralgic amyotrophy

Spontaneous anterior interosseous nerve (AIN) palsy develops following the resolution of nerve pain, which may be considered as distal neuralgic amyotrophy. NA is assumed to have a complex etiology, but an autoimmune mechanism is likely involved. However, precise assessment of the lesion is challenging. We examined five consecutive patients with suspected spontaneous AIN palsy using ultrasonography. On electromyography, all patients exhibited denervation potentials in the muscles, not only in the AIN territory, but also in the proximal median nerve territory (e.g., the flexor carpi radialis or pronator teres). Ultrasonography of the median nerve demonstrated neural swelling at the proximal side of the medial epicondyle in four patients and an hourglass-like constriction of the nerve fascicle in three patients. Four patients were diagnosed with distal neuralgic amyotrophy; of these, three received intravenous immunoglobulin administration, but only limited beneficial effect was achieved in one patient with early stage disease. One patient showed significant median nerve hypertrophy on ultrasonography and was diagnosed with neurolymphomatosis following the detection of malignant lymphoma during a systemic survey. Our experience demonstrates that ultrasonography for proximal median neuropathy presenting as AIN palsy may be useful for the accurate lesion assessment.

Neuralgic amyotrophy. An update

A century after the first description of neuralgic amyotrophy (NA), its pathophysiology remains unknown. An inflammatory (auto)immune pathophysiology is presumed, with mechanical or infectious precipitating conditions, which triggers attacks. Clinically, NA is an acute and painful unique or multiple mononeuropathy that causes palsy, amyotrophy and sensory loss in an asymmetric and patchy distribution. It involves the upper brachial plexus rather than the other parts but also may involve the cervical plexus, lumbosacral plexus and cranial nerves. The impairment can be restricted to one fascicule of one nerve, plexus or root; limited to a few ones; or extensive, involving both upper limbs. Its evolution is usually monophasic and auto-limited and never leads to generalized polyneuropathy. Electrodiagnostically, NA is characterized by severe axonal damage. The recovery is usually good after 6 months to 3 years in 80% of cases. Persistent disability is present in 20% of idiopathic NA cases and is more frequent in hereditary NA, with frequent recurrences, more frequent bilateral impairment, and more atypical distribution (cervical plexus, lumbosacral plexus or cranial nerves) than with idiopathic NA. Hereditary NA is mainly linked to a mutation in the gene of the Septin-9 protein. When the patient is seen early after disease onset, treatment with corticosteroids for 2 weeks seems to shorten the pain duration and the delayed recovery. With diagnosis during the palsy period, treatment is based on pharmacologic and non-pharmacologic therapies according to the complaints of the patient.

Neuralgic amyotrophy: An update on diagnosis, pathophysiology, and treatment

In this review we provide a current overview of the clinical features, pathophysiology, epidemiology, and diagnostic and therapeutic strategies in neuralgic amyotrophy (NA). The disorder has several phenotypic variations, with a classic form in 70% of the patients. It is not rare, with an incidence of 1 per 1,000 individuals, but it is still often missed. Recurrences are common, yet the proposed multifactorial etiology, which includes genetic, biomechanical, and immunologic factors, limits our capacity to predict or prevent them. NA is a clinical diagnosis, and ancillary studies serve to exclude infectious or malignant causes or to assess a differential diagnosis. If patients are seen early and are still in pain, a short trial of high-dose oral corticosteroids is advised, and adequate analgesia may require opioids and non-steroidal anti-inflammatory drugs. Persistent complaints are common, and a multidisciplinary rehabilitation approach focusing on scapular coordination, energy distribution strategies, and self-management is indicated.

Ultrasonographic identification of nerve pathology in neuralgic amyotrophy: Enlargement, constriction, fascicular entwinement, and torsion

INTRODUCTION

The aim of this study was to characterize the ultrasonographic findings on nerves in neuralgic amyotrophy.

METHODS

Fourteen patients with neuralgic amyotrophy were examined using high-resolution ultrasound.

RESULTS

Four types of abnormalities were found: (1) focal or diffuse nerve/fascicle enlargement (57%); (2) incomplete nerve constriction (36%); (3) complete nerve constriction with torsion (50%; hourglass-like appearance); and (4) fascicular entwinement (28%). Torsions were confirmed intraoperatively and were seen on the radial nerve in 85% of patients. A significant correlation was found between no spontaneous recovery of nerve function and constriction/torsion/fascicular entwinement (P = 0.007).

CONCLUSION

Ultrasonographic nerve pathology in neuralgic amyotrophy varies in order of severity from nerve enlargement to constriction to nerve torsion, with treatment ranging from conservative to surgical. We postulate that the constriction caused by inflammation is the precursor of torsion and that development of nerve torsion is facilitated by the rotational movements of limbs.

Triple hourglass-like fascicular constriction of the posterior interosseous nerve: a rare cause of PIN syndrome

Supinator syndrome or posterior interosseous nerve (PIN) syndrome is a compression neuropathy of the deep branch of the radial nerve in the region of the Arcade of Frohse. An extremely rare cause of an acute onset supinator syndrome is the hourglass-like fascicular constriction of the posterior interosseous nerve due to torsion. To our knowledge, only a limited number of cases which describe the sonographic appearance of fascicular torsions are known in the literature. We present a rare case of a supinator syndrome associated with hourglass-like constrictions of the PIN diagnosed by means of sonography.

[Traumatic nerve damage: causes, approaches and prognosis]

Whereas minor injuries to peripheral nerves merely lead to a circumscribed damage of the myelin sheath which is completely healed within 3 months, penetrating injuries lead to degeneration of the distal axonal fragment (Waller degeneration) and simultaneously to time-dependent alterations in the effector organs, in the perikarya in the medulla and spinal ganglia as well as in the brain. Animal experimental studies and also findings in humans confirm that the conditions for regeneration of nerve fibers are most favorable in the first days and weeks following injury. Therefore, for optimal therapy it should be clarified as early as possible whether there is a chance for reinnervation using exclusively conservative therapy or whether an operative reconstruction is necessary due to the severity of structural damage. Imaging investigation procedures, such as neurosonography and magnetic resonance (MR) neurography can provide decisive information on this aspect. As a rule, the decision on the indications for a nerve operation should be made within the first 3 months. Even with optimal therapy the healing process of severe neural injuries is often unsatisfactory. For some years novel procedures for improvement of nerve regeneration have been tested in animal experiments which involve totally different points in the healing process. It is hoped that with these approaches procedures for improvement in the treatment of nerve injuries in humans can be developed in the near future.