High-resolution MR neurography follow-up of SARS-CoV-2 vaccination-associated neuralgic amyotrophy.

Little is known about the value of high-resolution follow-up imaging in patients with neuralgic amyotrophy (NA) and the question of the best treatment algorithm remains unclear. Three patients (one female, two male) with the clinical presentation of SARS-CoV-2-vaccination-associated NA underwent initial magnetic resonance neurography (MRN) imaging and follow-up examinations. All patients showed a marked clinical improvement, independent of treatment, including an almost full recovery of motor function over the course of 8-12 months which was accurately mirrored by imaging findings on MRN. MRN imaging is a valuable tool for monitoring the further clinical course of patients suffering from vaccination-associated NA.

Fascicular torsions of the anterior and posterior interosseous nerve in 4 cases: neuroimaging methods to improve diagnosis.

Diagnosis of spontaneous fascicular nerve torsions is difficult and often delayed until surgical exploration is performed. This case series raises awareness of peripheral nerve torsions and will facilitate an earlier diagnosis by using nerve ultrasound (NUS) and magnetic resonance neurography (MRN). Four patients with previously ambiguous upper-extremity mononeuropathies underwent NUS and 3T MRN. Neuroimaging detected proximal torsions of the anterior and posterior interosseous nerve fascicles within median or radial nerve trunks in all patients. In NUS, most cases presented with a thickening of affected nerve fascicles, followed by an abrupt caliber decrease, leading to the pathognomonic sausage-like configuration. MRN showed T2-weighted hyperintense signal alterations of fascicles at and distal to the torsion site, and directly visualized the distorted nerves. Three patients had favorable outcomes after being transferred to emergency surgical intervention, while 1 patient with existing chronic muscle atrophy was no longer eligible for surgery. NUS and MRN are complementary diagnostic methods, and both can detect nerve torsions on a fascicular level. Neuroimaging is indispensable for diagnosing fascicular nerve torsions, and should be applied in all unclear cases of mononeuropathy to determine the diagnosis and if necessary, to guide surgical therapies, as only timely interventions enable favorable outcomes.

Diffusion tensor imaging in anterior interosseous nerve syndrome - functional MR Neurography on a fascicular level.

PURPOSE: By applying diffusor tensor imaging (DTI) in patients with anterior interosseous nerve syndrome (AINS), this proof of principle study aims to quantify the extent of structural damage of a peripheral nerve at the anatomical level of individual fascicles. METHODS: In this institutional review board approved prospective study 13 patients with spontaneous AINS were examined at 3 Tesla including a transversal T2-weighted turbo-spin-echo and a spin-echo echo-planar-imaging pulse sequence of the upper arm level. Calculations of quantitative DTI parameters including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) for median nerve lesion and non-lesion fascicles as well as ulnar and radial nerve were obtained. DTI values were compared to each other and to a previously published dataset of 58 healthy controls using one-way Analysis of Variance with Bonferroni correction and p-values <.05 were considered significant. Receiver operating characteristic (ROC) curves were performed to assess diagnostic accuracy. RESULTS: FA of median nerve lesion fascicles was decreased compared to median nerve non-lesion fascicles, ulnar nerve and radial nerve while MD, RD, and AD was increased (p < .001 for all parameters). Compared to median nerve values of healthy controls, lesion fascicles showed a significant decrease in FA while MD, RD, and AD was increased (p < .001 for all parameters). FA of median nerve non-lesion fascicles showed a weak significant decrease compared to healthy controls (p < .01) while there was no difference in MD, RD, and AD. ROC analyses revealed an excellent diagnostic accuracy of FA, MD and RD in the discrimination of median nerve lesion and non-lesion fascicles in AINS patients as well as in the discrimination of lesion fascicles and normative median nerve values of healthy controls. CONCLUSION: By applying this functional MR Neurography technique in patients with AINS, this proof of principle study demonstrates that diffusion tensor imaging is feasible to quantify structural nerve injury at the anatomical level of individual fascicles.

Diagnostic Value of Magnetic Resonance Neurography in Cervical Radiculopathy: Plexus Patterns and Peripheral Nerve Lesions.

OBJECTIVE: The aim of this study was to assess the imaging appearance and diagnostic value of plexus and peripheral nerve magnetic resonance neurography (MRN) in cervical radiculopathy. MATERIALS AND METHODS: This prospective study was approved by our institutional ethics committee and written informed consent was obtained from all participants. A total of 24 patients were included with a diagnosis of cervical radiculopathy based on clinical examination, supporting electrophysiological examinations and spinal imaging consistent with the clinical syndrome. All patients then underwent a high-resolution MRN protocol including the brachial plexus from nerve roots to plexus cords using a 3-dimensional turbo spin echo with variable flip angle short tau inversion recovery and sagittal-oblique T2-weighted spectral adiabatic inversion recovery sequence, and ulnar, median, and radial nerves at the upper arm and elbow in T2-weighted fat saturated sequences. Two readers independently rated plexus elements regarding the presence of lesions at neuroforaminal levels, roots, trunks, and cord segments. Median, ulnar, and radial nerves were likewise rated. Findings were then compared to a referenced standard of cervical radiculopathy that was defined as the combined diagnosis of clinical syndrome including supporting electrophysiological exams and matching positive spinal imaging, and diagnostic performance parameters were calculated. Additional quantitative and qualitative analysis assessed peripheral nerve caliber and normalized T2-signal at arm level in cervical radiculopathy and compared them to 25 inflammatory neuropathy controls. RESULTS: Cervical radiculopathy resulted in distinct plexus lesion patterns for each level of neuroforaminal stenosis. Overall, brachial plexus MRN in cervical radiculopathy reached a sensitivity of 81%, a specificity of 96%, a positive predictive value of 87%, and overall diagnostic accuracy of 87%. Initial spinal magnetic resonance imaging showed multiple positive findings for clinically unaffected root levels and resulted in a specificity of 69%, a positive predictive value of 54%, and an overall diagnostic accuracy of 78%.T2-weighted peripheral nerve lesions were detected in 79% of cervical radiculopathy cases and imitated imaging appearance of inflammatory neuropathies both quantitatively and qualitatively. CONCLUSIONS: Complementing spine imaging in cervical radiculopathy with brachial plexus MRN can improve diagnostic accuracy by increasing specificity and positive predictive value. T2-weighted lesions of peripheral nerves can be caused by cervical radiculopathy, which must be considered a relevant diagnostic pitfall in MRN of peripheral neuropathies.

Posterior interosseous neuropathy: Supinator syndrome vs fascicular radial neuropathy.

OBJECTIVE: To investigate the spatial pattern of lesion dispersion in posterior interosseous neuropathy syndrome (PINS) by high-resolution magnetic resonance neurography. METHODS: This prospective study was approved by the local ethics committee and written informed consent was obtained from all patients. In 19 patients with PINS and 20 healthy controls, a standardized magnetic resonance neurography protocol at 3-tesla was performed with coverage of the upper arm and elbow (T2-weighted fat-saturated: echo time/repetition time 52/7,020 milliseconds, in-plane resolution 0.27 × 0.27 mm2). Lesion classification of the radial nerve trunk and its deep branch (which becomes the posterior interosseous nerve) was performed by visual rating and additional quantitative analysis of normalized T2 signal of radial nerve voxels. RESULTS: Of 19 patients with PINS, only 3 (16%) had a focal neuropathy at the entry of the radial nerve deep branch into the supinator muscle at elbow/forearm level. The other 16 (84%) had proximal radial nerve lesions at the upper arm level with a predominant lesion focus 8.3 ± 4.6 cm proximal to the humeroradial joint. Most of these lesions (75%) followed a specific somatotopic pattern, involving only those fascicles that would form the posterior interosseous nerve more distally. CONCLUSIONS: PINS is not necessarily caused by focal compression at the supinator muscle but is instead frequently a consequence of partial fascicular lesions of the radial nerve trunk at the upper arm level. Neuroimaging should be considered as a complementary diagnostic method in PINS.

Anterior interosseous nerve syndrome: fascicular motor lesions of median nerve trunk.

OBJECTIVE: We sought to determine lesion sites and spatial lesion patterns in spontaneous anterior interosseous nerve syndrome (AINS) with high-resolution magnetic resonance neurography (MRN). METHODS: In 20 patients with AINS and 20 age- and sex-matched controls, MRN of median nerve fascicles was performed at 3T with large longitudinal anatomical coverage (upper arm/elbow/forearm): 135 contiguous axial slices (T2-weighted: echo time/repetition time 52/7,020 ms, time of acquisition: 15 minutes 48 seconds, in-plane resolution: 0.25 × 0.25 mm). Lesion classification was performed by visual inspection and by quantitative analysis of normalized T2 signal after segmentation of median nerve voxels. RESULTS: In all patients and no controls, T2 lesions of individual fascicles were observed within upper arm median nerve trunk and strictly followed a somatotopic/internal topography: affected were those motor fascicles that will form the anterior interosseous nerve further distally while other fascicles were spared. Predominant lesion focus was at a mean distance of 14.6 ± 5.4 cm proximal to the humeroradial joint. Discriminative power of quantitative T2 signal analysis and of qualitative lesion rating was high, with 100% sensitivity and 100% specificity (p < 0.0001). Fascicular T2 lesion patterns were rated as multifocal (n = 17), monofocal (n = 2), or indeterminate (n = 1) by 2 independent observers with strong agreement (kappa = 0.83). CONCLUSION: It has been difficult to prove the existence of fascicular/partial nerve lesions in spontaneous neuropathies using clinical and electrophysiologic findings. With MRN, fascicular lesions with strict somatotopic organization were observed in upper arm median nerve trunks of patients with AINS. Our data strongly support that AINS in the majority of cases is not a surgically treatable entrapment neuropathy but a multifocal mononeuropathy selectively involving, within the main trunk of the median nerve, the motor fascicles that continue distally to form the anterior interosseous nerve.

The potential value of ultrasonography in the evaluation of carpal tunnel syndrome.

The authors compared ultrasonography with electrophysiology for the diagnosis of carpal tunnel syndrome (CTS) on 110 clinically affected wrists. An increased cross sectional area in the proximal carpal tunnel larger than 0.11 cm(2) in combination with compression signs on longitudinal scans proved to be highly predictive for CTS (sensitivity, 89.1%; specificity, 98.0%). Ultrasound was comparable to electrophysiology in the diagnosis of CTS, and in 35% of cases changes in morphology suggested a specific therapeutic strategy.

Carpal tunnel syndrome caused by thrombosis of the median artery: the importance of high-resolution ultrasonography for diagnosis. Case report.

The rare case of a patient with carpal tunnel syndrome caused by thrombosis of a persistent median artery is presented. Progressive pain in the wrist and dysesthesias in the third and fourth fingers were the atypical complaints. High-resolution ultrasonography revealed a bifid median nerve that was compressed by an occluded median artery. The intraoperative findings are described, and emphasis is placed on the importance of using high-resolution ultrasonography for presurgical diagnosis.