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

Abstract

PurposeBy 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.MethodsIn 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.ResultsFA 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.ConclusionBy 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.

Denoising of diffusion MRI improves peripheral nerve conspicuity and reproducibility

“…Diffusion MRI (dMRI) is a noninvasive MR technique that can provide objective, quantitative measurements that reflect microstructural nerve integrity . dMRI is based on the naturally occurring Brownian motion of water molecules.…”

“…1 Diffusion MRI (dMRI) is a noninvasive MR technique that can provide objective, quantitative measurements that reflect microstructural nerve integrity. [4][5][6][7] dMRI is based on the naturally occurring Brownian motion of water molecules. The highly organized microstructure of a nerve's axon bundles directionally restricts diffusion (anisotropy), in comparison to an unconstrained space where water molecules freely diffuse in all directions (isotropy).…”

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

“…7,8 Pseudo-AINS has been found to occur in association with supracondylar fractures of the humerus, proximal radius fracture, partial damage to the median nerve in the antecubital fossa during catheterization of the brachial artery or venipuncture, median nerve entrapment by an accessory bicipital aponeurosis, nerve inflammation, or fascicular constriction/torsion of nerve. [1][2][3][4]7 Hourglass-like constrictions of peripheral nerves in the upper arm cause a rare form of neuropathy, often characterized by the sudden onset of pain in the shoulder or arm, followed by muscle weakness and atrophy, with limited sensory involvement. 4,6,[9][10][11][12][13] The symptoms of one of our patients were similar to those described in previous reports 4,5,14 and were also in accordance with the recently reported criteria for neuralgic amyotrophy.…”

“…5,6,14 Imaging modalities, such as US and MRI, may be useful tools for diagnostic examination of selective fascicular involvement of the proximal median nerve before the AIN branch arises. 1,3,5,9,10 Within a peripheral nerve, individual nerve fibers are grouped together as fascicles. It is difficult to prove the existence of selective fascicular nerve lesions in spontaneous neuropathy using only clinical and electromyography findings.…”

“…Recently, with the aid of high-resolution magnetic resonance imaging (MRI) and ultrasonography (US), fascicular involvement of the median nerve trunk in the upper arm has been proposed as a new pathogenic mechanism in clinical cases presenting with symptoms of AINS. [1][2][3][4][5][6] However, with most articles in the literature focusing on the neurological or surgical aspects of AINS, [1][2][3][4] clinicians and radiologists have little information on the imaging features of this disease. Here, we present three cases of selective fascicular involvement of the median nerve in the upper arm, presenting as symptoms of AINS.…”