Role of High-Resolution Magnetic Resonance Neurography in the Evaluation of Peripheral Neuropathy and Plexopathy

Purpose: To evaluate the diagnostic role of high-resolution magnetic resonance neurography (MRN) in plexopathy and peripheral neuropathy. MRN localizes the abnormality with its extent accurately. With MRN imaging findings, the etiology can be categorized as neoplastic, infective, traumatic, inflammatory, or radiation-induced neuropathy.

Methods and Materials: The study included patients (n = 65) with clinical suspicion of neuropathy/plexopathy referred by their physician to our department for MRN. The study included both traumatic and nontraumatic cases. The study was done on a 3-T MRI machine with the standard departmental protocol using T1-weighted (T1W), T2-weighted (T2W), proton-density-weighted spectral attenuated inversion recovery (PDW-SPAIR), short tau inversion recovery (STIR), diffusion-weighted imaging with background body signal suppression (DWIBS), VDWIBS, and three-dimensional nerve view sequences and postcontrast T1W sequence if required. We analyzed the caliber, signal intensity, course, fascicular pattern, and enhancement pattern of the nerve. Then the data were collected, processed, analyzed, and results were tabulated. We correlated the results of clinical examination, nerve conduction study, histopathology (in cases of nerve sheath tumors), and intraoperative findings (in cases of nerve injuries) with the MRN diagnosis.

Results: Of 65 patients, 25 had neurogenic tumors of the peripheral nerve, 1 had fibrolipomatous hamartoma in the median nerve, 3 had acute brachial neuritis, 3 had radiation plexitis, 11 had posttraumatic brachial plexopathy, 15 had posttraumatic neuropathic changes in peripheral nerves, 1 patient had infective neuritis, 2 patients had malignant brachial plexopathy, and 2 patients had chronic inflammatory demyelinating polyneuropathy (CIDP) as evidenced by imaging findings of MRN. Two patients had no abnormality on MRN. Most of the patients with a nerve sheath tumor had histopathologic follow-up correlating well with the preoperative MRN diagnosis. We were able to classify nerve sheath tumors as benign and malignant; benign tumors were classified into neurofibroma and schwannoma based on MRN imaging findings. In cases of nerve injury, we were able to grade the severity of injury based on MRN imaging findings. MRN imaging findings in patients with high-grade nerve injury correlated well with intraoperative findings. Other patients with CIDP, acute brachial neuritis, infective neuritis, radiation plexopathy, and low-grade nerve injury were managed conservatively with a good clinical outcome at 3-month clinical follow-up.

Conclusion: High-resolution MRN is a novel noninvasive imaging technique that is reliable and useful in offering the detailed anatomical information necessary to diagnose plexopathy and peripheral neuropathy. This anatomical information from MRN adds up to the functional information of nerve obtained from the clinical examination and electrodiagnostic study to classify the etiology causing neuropathy, providing a faster diagnosis, planning of appropriate treatment strategies, and preventing unnecessary biopsy and surgery.

Fig. 1 Neurotmesis of right median nerve.

Fig. 2 Moderate diffuse enlargement and altered signal intensity of the roots, trunks, and divisions of the bilateral brachial plexus.

Fig. 3 Neurofibroma of dorsal nerve of the penis. Axial high-resolution T2-weighted image and short tau inversion recovery coronal image (on the left) showing hyperintense lesion in the deep fascia of the dorsal aspect of the midshaft of the penis. The lesion is abutting the ipsilateral corpora cavernosa.

Fig. 4 Diffusion-weighted imaging with background body signal suppression neurography showing neurofibroma along the left dorsal nerve of the penis.

Fig. 5 Diffusion-weighted imaging with background body signal suppression inverted full maximum intensity projection is showing neurofibroma along the C6 nerve root and division of the brachial plexus.

Fig. 6 Diffusion-weighted imaging with background body signal suppression neurography showing neurofibroma along the C6 nerve root and at the level of division of the left brachial plexus.

Publication History

Article published online:
17 December 2020