Ultrasound diagnosis of peroneal nerve variant in a child with compressive mononeuropathy Marta Lucchetta a , Giovanna A. Liotta b,c , Chiara Briani a , Eduardo M. Fernandez Marquez d , Carlo Martinoli e , Daniele Coraci d , Luca Padua c,d, ⁎ a Dipartimento di Neuroscienze, Università di Padova, Via Giustiniani, 5, 35128, Padova, Italy b Dipartimento di Neuroscienze, Scienze Psichiatriche ed Anestesiologiche, Università di Messina, Messina, Italy c Fondazione Don Carlo Gnocchi Onlus, Italy d Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, Pol. A. Gemelli, Rome, Italy e Cattedra di Radiologia R, DICMI, Università di Genova, Genova, Italy Received 3 August 2010; accepted 16 September 2010 Key words: Ultrasound; Exostosis; Accessorial peroneal nerve branch Abstract We report on a 6-year-old child presenting with subacute foot drop. Neurophysiologic and radiologic studies revealed a peroneal nerve compression secondary to fibular exostosis. Before undergoing surgical removal of the exostosis, the patient underwent further neurophysiologic and ultrasonographic evaluation that showed the presence of an accessory peroneal nerve branch that caused gastrocnemius involvement. Findings at surgery confirmed the supposed anatomical variant. Both nerve components were carefully preserved during the operative procedure. The association of ultrasono- graphic and neurophysiologic studies was crucial in identifying the etiopathologic mechanism and anatomical picture and provided clinicians and surgeons with important information in planning the procedure. © 2011 Elsevier Inc. All rights reserved. Nerve entrapment and compression produce sensory and/ or motor deficit that may cause severe disability. These conditions are common in adults, but very rare in children. Being an uncommon clinical picture, the diagnosis may be difficult. Clinically, a neurophysiologic study is often requested, as it is the most accurate tool to investigate nerve involvement and evaluate the type and site of the nerve lesion. Usually, nerve compression owing to entrapment occurs in well-known sites (eg, wrist, elbow); and neuro- physiologic evaluation is standardized. Nerve compression/ damage out of entrapment sites is uncommon in adults and rare in children. High-resolution ultrasound (US) is an emerging technique for the evaluation of peripheral nerves and represents a useful complement to neurophysiologic studies [1,2]. In some cases, US examination results are crucial for reaching a diagnosis and choosing the correct therapeutic option [3]. 1. Patient presentation A 6-year-old girl was referred for the subacute develop- ment of right foot drop over the last 5 months. Two months ⁎ Corresponding author. Institute of Neurology, Università Cattolica del Sacro Cuore, 00168, Rome, Italy. Tel.: +39 06 3015 6623; fax: +39 06 3550 1909. E-mail address: lpadua@rm.unicatt.it (L. Padua). www.elsevier.com/locate/jpedsurg 0022-3468/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2010.09.055 Journal of Pediatric Surgery (2011) 46, 405–407