Homolateral hourglass-like constrictions of the axillary and suprascapular nerves: case report

Focal inflammatory neuropathies

This chapter focuses on neuropathies that present with focal involvement of nerve roots, plexus, and/or peripheral nerves associated with autoimmune and inflammatory mechanisms that present with focal involvement of nerve roots, plexus and/or peripheral nerves. The clinical presentation, diagnosis, and treatment of focal autoimmune demyelinating neuropathies, focal nonsystemic vasculitic disorders (diabetic and nondiabetic radiculoplexus neuropathies, postsurgical inflammatory neuropathy, and neuralgic amyotrophy), and focal neuropathies associated with sarcoidosis and bacterial and viral infections are reviewed.

Hourglass-Like Constriction Neuropathy of the Upper Limb Nerve: Diffusion-Weighted Magnetic Resonance Neurography Imaging Findings

OBJECTIVE

The purposes of this study were to determine reliable diffusion-weighted magnetic resonance neurography (DW-MRN) features of hourglass-like constriction of the upper limb nerve and to evaluate the application value of DW-MRN compared with ultrasonography (US).

METHODS

We retrospectively reviewed MRN studies of 13 patients. Qualitative and quantitative image analyses were carried out. The number of constrictions based on DW-MRN and US findings was compared.

RESULTS

Of the 13 cases, there were 7 cases with radial nerve abnormalities, 4 with median nerve abnormalities, and 2 with radial and median nerve abnormalities. Diffusion-weighted MRN showed a single-segmental constriction in 7 of 13 cases and multisegmental constrictions in 6 of 13 cases; the hourglass-like constriction appeared in all cases (13 of 13). Thirty-three nerve constrictions were found in DW-MRN, and 29 nerve constrictions were found in US.

CONCLUSIONS

Diffusion-weighted MRN is a noninvasive and helpful diagnostic for hourglass-like constriction of the upper limb nerve.

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.

Diagnosis of Hourglass-Like Constriction Neuropathy of the Radial Nerve Using High-Resolution Magnetic Resonance Neurography: A Report of Two Cases

Hourglass-like constriction neuropathy is a neurological condition caused by fascicular constriction of one or more peripheral nerves, unrelated to intrinsic or extrinsic compression. It is often neglected in clinical practice, and its diagnosis is challenging. Here, we report two cases of hourglass-like constriction neuropathy in the radial nerve diagnosed using high-resolution magnetic resonance neurography (MRN). Two men, aged 47 and 19 years, developed sudden weakness in the left wrist and finger extensors. They were diagnosed with radial neuropathy between the left mid-humerus level and the elbow joint, using the electrodiagnostic test. To evaluate the cause of the nerve lesion and the lesion location, high-resolution MRN was performed. Patient 1 showed an hourglass-like constriction of the left posterior interosseous nerve within the epineurium of the left radial nerve, 8.9 cm proximal to the lateral epicondyle. Patient 2 showed two focal constrictions of the left radial nerve, 8.0 and 6.9 cm proximal to the lateral epicondyle, respectively, and distal to the radial groove. Additionally, bull’s eye signs were observed juxta-proximal to constrictions of the left radial nerve. The findings were indicative of hourglass-like constriction neuropathy. Both of the patients underwent surgery. However, at the 6-month follow-up, their motor weakness showed no improvement. MRN can be beneficial for diagnosing hourglass-like constriction neuropathy and locating the lesion.

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.

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.

[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.

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.

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 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.

Spontaneous nerve torsion: unusual cause of radial nerve palsy

Spontaneous nerve torsion is a rare cause of nerve palsy. We describe a case of nerve torsion affecting the radial nerve in order to inform radiologists of the existence of this condition and subtle features on cross-sectional imaging that can suggest the diagnosis preoperatively.

Hourglass-Like Constrictions of Peripheral Nerve in the Upper Extremity

BACKGROUND:

The development of an hourglass-like constriction in the nerve is rare, and its origin is unknown. Its clinical manifestations are not well documented, and the treatment protocol has not been established.

OBJECTIVE:

To identify the cause, presentation, and possible treatment for patients with nerve palsies secondary to an hourglass-like constriction in the affected nerves.

METHODS:

Patients presenting with peripheral nerve palsy caused by an hourglass-like constriction of nerves were retrospectively investigated in 2 hand centers. The patients' presentation and neurological findings were reviewed, and the immunohistochemistry of excised specimens was studied.

RESULTS:

Forty-two patients who presented with 47 nerve palsies were examined. Forty-one patients experienced a sudden onset of pain in the upper limb, followed by flaccid paralysis in the affected muscles. Ten patients had multiple nerve involvement. Surgical exploration found 1 or more hourglass-like constrictions in the nerve. The treatments included internal neurolysis, neurorrhaphy, and nerve grafting. Thirty-one of 42 patients (36 nerves) were followed up for a mean of 48 months (range, 8–157 months). Fifteen of 16 nerves treated by neurolysis, 10 of 13 nerves treated by neurorrhaphy, and 4 of 7 nerves treated by nerve grafting had good recovery. CD8-positive T-lymphocyte infiltration was observed in all the excised specimens.

CONCLUSION:

The clinical presentation of patients with hourglass-like constrictions in their nerves is similar to that of patients with neuralgic amyotrophy. Histochemical analysis suggests that the pathogenesis may be immunological in origin. The role of surgery in this condition is uncertain.

Typical brachial neuritis (Parsonage-Turner syndrome) with hourglass-like constrictions in the affected nerves

PURPOSE

To report on 5 patients who had acute brachial neuritis (Parsonage-Turner syndrome) with hourglass-like constriction in the affected nerves.

METHODS

We retrospectively reviewed 5 patients who were treated in our department from December 2003 to December 2008. Acute, intense pain around the shoulder girdle and upper arm was the first symptom and was followed by muscle weakness and atrophy. Clinical and EMG examinations showed involvement of 2 or more nerves in the affected extremity. Those severely affected nerves that had no response to conservative treatment were explored, and an hourglass-like constriction was identified. Neurolysis was performed at the sites of constrictions in 2 radial nerves and 1 median nerve. The constricted portion was resected, and direct coaptation was performed in 1 radial nerve and 1 musculocutaneous nerve. The constricted portion was resected, and nerve graft was performed in 2 radial nerves and 1 median nerve.

RESULTS

All patients were followed up for 24 to 84 months after surgery. Of 3 nerves treated with external neurolysis, all attained full recovery. Of 2 nerves treated with resection and neurorrhaphy, 1 attained full recovery, and the other had an incomplete recovery. Of 3 nerves treated with resection and nerve graft, 1 (4-cm nerve graft) attained full recovery, and 2 (4-cm and 13-cm nerve graft, respectively) had incomplete recovery.

CONCLUSIONS

The site of nerve lesion of brachial neuritis was not necessarily within the brachial plexus. Our finding of hourglass-like constrictions in individual peripheral nerves suggest that multifocal involvement of terminal branch lesions may underlie the complex patterns of paralysis often encountered clinically.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Peripheral Nerve Palsy by Torsional Nerve Injury

BACKGROUND:

Peripheral nerve palsy caused by torsional nerve injury is rare. Only a few patients have been reported in the literature. The etiology of this type of nerve lesion is poorly understood.

OBJECTIVE:

To report on 5 patients presenting with peripheral nerve palsy caused by a torsional nerve injury.

METHODS:

Five patients presented with 6 upper peripheral nerve palsy involving the axillary nerve (n = 2), musculocutaneous nerve (n = 2), radial nerve (n = 1), and suprascapular nerve (n = 1). There was no history of trauma in 3 patients, but in the other 2 patients, nerve palsy occurred after a traumatic event. Because of a lack of spontaneous recovery, surgical exploration was performed. Torsion of the whole nerve (n = 5) or only 1 fascicle (n = 1) was found. Epifascicular epineurectomy and detorsion, as well as resection of the torsion site with subsequent primary nerve suture, were performed in 3 lesions.

RESULTS:

Good to excellent recovery of motor function was achieved in all 5 patients. In the last patient who presented with 2 nerve torsions, the follow-up period after the last surgery is too short to allow evaluation.

CONCLUSION:

Although not a frequent event, torsional nerve injury should be taken into consideration when dealing with peripheral nerve injuries. Surgical exploration with detorsion or suture results in good recovery.

Surgical treatment of spontaneous posterior interosseous nerve palsy

We have reviewed 38 surgically treated cases of spontaneous posterior interosseous nerve palsy in 38 patients with a mean age of 43 years (13 to 68) in order to identify clinical factors associated with its prognosis. Interfascicular neurolysis was performed at a mean of 13 months (1 to 187) after the onset of symptoms. The mean follow-up was 21 months (5.5 to 221). Medical Research Council muscle power of more than grade 4 was considered to be a good result. A further 12 cases in ten patients were treated conservatively and assessed similarly.

Of the 30 cases treated surgically with available outcome data, the result of interfascicular neurolysis was significantly better in patients < 50 years old (younger group (18 nerves); good: 13 nerves (72%), poor: five nerves (28%)) than in cases > 50 years old (older group (12 nerves); good: one nerve (8%), poor: 11 nerves (92%)) (p < 0.001). A pre-operative period of less than seven months was also associated with a good result in the younger group (p = 0.01). The older group had a poor result regardless of the pre-operative delay.

Our recommended therapeutic approach therefore is to perform interfascicular neurolysis if the patient is < 50 years of age, and the pre-operative delay is < seven months. If the patient is > 50 years of age with no sign of recovery for seven months, or in the younger group with a pre-operative delay of more than a year, we advise interfascicular neurolysis together with tendon transfer as the primary surgical procedure.