Spine Cervicothoracic postarachnoiditic hydrosyringomyelia secondary to pedicular hook dislocation: case report Pasqualino Ciappetta, MD a, ⁎ , Pietro Ivo D'Urso, MD a , Carlo Delvecchio, MD a , Antonio Colamaria, MD a , Giuseppe De Giorgi, MD b a Section of Neurosurgery, Department of Neurosciences, University of Bari Medical School, Bari, Italy b Department of Orthopedics and Traumatology, University of Bari Medical School, Bari, Italy Received 7 August 2007; accepted 28 August 2007 Abstract Background: Pedicular hook dislocation is a rare complication of spinal instrumentation. We report on the first case of hydrosyringomyelia secondary to intracanalar hook displacement after scoliosis surgery. Case Description: A 15-year-old girl presented to our institution with a 7-month history of persistent neck and occipital pain as well as numbness of the lower extremities and previous dorsolumbar instrumentation with dorsal pedicular hooks and lumbar screws. Magnetic resonance imaging showed intramedullary cystic cavity from C5 to T7, isointense to cerebrospinal fluid (CSF) on T1- and T2-weighted images. Computed tomographic scan showed intracanalar displacement of the left hook. On admission, the patient presented with mild weakness of the lower extremities, hypalgesia below the level of T4, and urinary disturbance. The patient underwent surgical hook removal, T4 laminectomy, and midline dural opening: the arachnoid membrane was found to be thick and adhered to the dura and dorsolateral spinal cord. The arachnoid scarring was dissected, and the cord was untethered. A small posterior-median myelotomy was performed, and a syringosubarachnoid catheter was placed into the subarachnoid space to restore CSF flow. Conclusions: Late intracanalar displacement of spinal devices is an event that may complicate spinal instrumentation for scoliosis. This case highlights the importance of correct spinal device positioning and that of careful follow-up after instrumentation to detect complications early. We also discuss the pathogenetic pathway of the postarachnoiditic syringomyelia in this case. © 2009 Elsevier Inc. All rights reserved. Keywords: Hydrosyringomyelia; Pedicular hook; Scoliosis; Spinal arachnoiditis 1. Introduction Surgical treatment in idiopathic scoliosis generally yields good results with a low complication rate. In reviewing the literature, we did not find cases of hydrosyringomyelia secondary to intracanalar hook disloca- tion after instrumentation for adolescent idiopathic scoliosis. We describe the case of a 15-year-old girl with cervicothor- acic hydrosyringomyelia secondary to arachnoiditis 2 years after she underwent a surgical procedure for scoliosis. 2. Case report A 15-year-old girl presented to our institution with a 7-month history of persistent neck and occipital pain as well as numbness of the lower extremities. At the age of 13 years, after being diagnosed with adolescent idiopathic scoliosis combined with a thoracolum- bar curve, the patient underwent Cotrel-Dubousset instru- mentation from the T4 vertebra to the L4 vertebra. Preoperative magnetic resonance imaging (MRI) of the cervicothoracolumbar region confirmed scoliosis, but there was no cord alteration, syringomyelia, or Chiari's malforma- tion. Postoperative radiography showed correct hook posi- tioning (Fig. 1A). The patient also remained asymptomatic Available online at www.sciencedirect.com Surgical Neurology 71 (2009) 500 – 503 www.surgicalneurology-online.com Abbreviations: CSF, cerebrospinal fluid; MRI, magnetic resonance imaging. ⁎ Corresponding author. Tel.: + 39 080 5592900; fax: +39 080 5592001. E-mail address: durso.pietroivo@libero.it (P. Ciappetta). 0090-3019/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2007.08.052