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.
Correspondence Jennifer Kollmer: Heidelberg University Hospital, Heidelberg, Germany. firstname.lastname@example.org.
INCLUDE WHEN CITING Published online May 24, 2019; DOI: 10.3171/2019.3.JNS183302.
Disclosures Dr. Kollmer received a research grant from Alnylam Pharmaceuticals, the Olympia Morata grant from the Medical Faculty of the University of Heidelberg, personal fees from Pfizer and Alnylam, financial support for conference attendance from Pfizer and the Amyloidosis Foundation, and honoraria for consultancy from Akcea Therapeutics. Prof. Bendszus received grants from the German Research Foundation (SFB 1118), Hopp Foundation, Novartis, European Union, Medtronic, Stryker, Siemens, Guerbet, and Codman; received honoraria for consultancy from BBraun, Roche, Boehringer, Ingelheim, Guerbet, Codman, and Vascular Dynamics; and received payments for lectures from Novartis, Guerbet, Codman, Bayer, Teva, and Roche.
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