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.