European Journal of Radiology 82 (2013) 526–529 Contents lists available at SciVerse ScienceDirect European Journal of Radiology journa l h o me pa ge: www.elsevier.com/locate/ejrad Increased reflectivity and loss in bulk of the pronator quadratus muscle does not always indicate anterior interosseous neuropathy on ultrasound Alberto Tagliafico a,∗ , Maribel Miguel Perez f , Luca Padua b,c , Andrea Klauser d , Antonio Zicca a , Carlo Martinoli e,1 a Department of Human Anatomy, DIMES, Università di Genova, Largo Rosanna Benzi 8, 16138 Genoa, Italy b Department of Neuroscience, Institute of Neurology, Catholic University, Largo Francesco Vito 1, Rome, Italy c Department of Neuroscience, Don Gnocchi Foundation, Rome, Italy d Department of Diagnostic Radiology, Medical University Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria e Radiology Department, DISC, Università di Genova, Largo Rosanna Benzi 8, 16138 Genoa, Italy f Unit of Human Anatomy and Embryology, Department of Pathology and Experimental Therapy, Faculty of Medicine (C Bellvitge), University of Barcelona, Barcelona, Spain a r t i c l e i n f o Article history: Received 12 March 2012 Received in revised form 17 May 2012 Accepted 28 September 2012 Keywords: Pronator quadratus Ultrasound Atrophy Anterior interosseous nerve Kiloh–Nevin a b s t r a c t Purpose: To assess if isolated atrophy of the pronator quadratus muscle indicates anterior interosseous neuropathy on ultrasound. Materials and methods: IRB approval and written informed from every patient were obtained. A prospective study including 100 consecutive wrist and hand ultrasound studies in 77 patients (46 females and 31 males; 23 patients had bilateral studies) with a mean age of 45 years (range, 21–86 years) was performed between March 2010 and January 2012. The patients were chosen irrespective of age, sex, and body mass index. The studies were performed for several reasons, the most common being wrist pain (n = 56), followed by ganglion cyst (n = 11) and soft-tissue masses (n = 10). Clinical his- tories, previous imaging studies and US examinations were evaluated to rule out anterior interosseous nerve neuropathy. US examinations were performed with a commercially available equipment. Prona- tor quadratus was checked for atrophy using flexor pollicis longus, flexor digitorum superficialis and profundus for comparison. Descriptive statistic was used. Results: US signs of pronator quadratus atrophy were present in 7/100 (7%) of patients. None of the patients had a bilateral atrophy of the pronator quadratus. In the patients with atrophy of the pronator quadratus, adjacent flexor muscles were normal. There was no significant difference between males and females (3 females vs 4 males) (p = 0.506). Conclusion: Increased reflectivity and loss in bulk of the pronator quadratus muscle does not always indicate anterior interosseous neuropathy on ultrasound. © 2012 Published by Elsevier Ireland Ltd. 1. Introduction The entrapment of the anterior interosseous nerve in the fore- arm, a condition also known as the Kiloh–Nevin syndrome [1], may be present in different conditions, such as fibrous bands, anoma- lous muscles (Gantzer muscle) and accessory tendons from the flexor digitorum superficialis [2,3]. Isolated anterior interosseous neuropathy leads to pain in the volar forearm and difficulty in per- forming pinching movements with the digits (inability to do “ok” ∗ Corresponding author. Tel.: +39 0103537882; fax: +39 0103537885. E-mail address: albertotagliafico@gmail.com (A. Tagliafico). 1 Tel.: +39 0105555248; fax: +39 0105556288. with the fingers) and handwriting. US diagnosis of an overt ante- rior interosseous neuropathy may be suggested by loss in bulk and increased reflectivity of the innervated muscles: the flexor pollicis longus, the flexor digitorum profundus and the pronator quadra- tus [4–6]. However, using magnetic resonance imaging (MRI), increased signal intensity of the pronator quadratus muscle has been described on fluid-sensitive images in patients without ante- rior interosseous nerve syndrome [7–9]. Similarly, we noted that on wrist ultrasonographic examinations it is possible to find loss in bulk and increased reflectivity at the pronator quadratus mus- cle in patients without symptoms related to anterior interosseous neuropathy. Therefore, the purpose of this study was to assess the prevalence of denervation-like signs (loss in bulk and increased reflectivity) in the pronator quadratus in patients without anterior 0720-048X/$ – see front matter © 2012 Published by Elsevier Ireland Ltd. http://dx.doi.org/10.1016/j.ejrad.2012.09.028