Reversible tonsillar prolapse and syringomyelia after embolization of a tectal arteriovenous malformation. Case report and review of the literature.

The authors report the case of a 21-year-old woman who presented with headaches, frequent sensations of loss of equilibrium, and intermittent strabismus. A tectal arteriovenous malformation (AVM) was diagnosed based on magnetic resonance (MR) imaging findings. The AVM drained toward the straight sinus and was associated with a tonsillar prolapse (Chiari malformation Type I [CM-I]) and cervical syringomyelia. The tectal AVM was embolized with N-butyl cyanoacrylate, and disconnection of about 80% of the lesion was obtained. All clinical symptoms resolved after embolization, and radiosurgery was proposed to treat the malformation remnant. A control MR image confirmed the regression of the tonsillar prolapse and the disappearance of the syrinx. This report emphasizes that CM-I and syringomyelia may be acquired and related to hydrovenous disorders.