Teaching NeuroImages Neurology Resident and Fellow Section A 55-year-old patient with therapy-refractory carpal-tunnel-syndrome Teaching NeuroImages Neurology Resident and Fellow Section © 2016 American Academy of Neurology

Repeated surgical interventions did not provide any relief. Vignette A 55-year-old man with typical findings of carpal-tunnel-syndrome complained progression of his symptoms. Repeated surgical interventions did not provide any relief. Nerve sonography of the median nerve was performed for the first time after four unsuccessful interventions. Krogias et al. © 2016 American Academy of Neurology

Imaging Multimodal imaging and diagnosis of perineurinoma. A: Sonography revealing enlarged nerve (encircled, area=0.58cm²) at wrist. B: T1w-MRI depicting enlarged fascicles (black arrow). White arrow: tendons. C: Resection of epineural sheet reveals tumorous transformation of fasciles with perineural swelling (asterisk). D: (HE) intrafascicular tumor cells surrounded by collagen fibers. E: EMA-stained positive tumor cells. Krogias et al. © 2016 American Academy of Neurology

Sonographic detection of intraneural perineurinoma in therapy-refractory carpal-tunnel-syndrome Nerve sonography revealed massive enlargement of median nerve (cross-sectional-area=0.58cm²) with hyperechoic perineurial tissue. Beyond postoperative perineural fibrosis, immense findings were suspicious to an underlying tumor. MRI confirmed a tumorous nerve swelling. Histology of hypertrophic fascicles confirmed the diagnosis of intraneural perineurinoma. Nerve sonography should be performed in therapy-refractory cases, as it might uncover unusual causes of entrapment syndromes. References:   1. Mauermann M, Amrami K, Kuntz N, et al. Longitudinal study of intraneural perineurioma: a benign, focal hypertrophic neuropathy of youth. Brain 2009; 132:2265–2276. 2. Cartwright MS, Walker FO. Neuromuscular ultrasound in common entrapment neuropathies. Muscle Nerve 2013; 48:696-704 Krogias et al. © 2016 American Academy of Neurology