Presyrinx in children with Chiari malformations S. Goh, MD C.L. Bottrell, BA A.H. Aiken, MD W.P. Dillon, MD Y.W. Wu, MD, MPH ABSTRACT Background: Presyrinx is a reversible state of spinal cord edema caused by alterations in CSF flow dynamics. Only three pediatric cases have been reported previously. We describe the clinical and radiologic features of presyrinx in six pediatric patients. Methods: We electronically searched pediatric spine MRI reports generated at our institution from January 1995 to April 2007 for the keyword “presyrinx” and identified six patients with this radiologic diagnosis. We reviewed the neuroimaging studies and medical records for information regarding symptoms, treatment, and outcome. Results: Of six patients identified with presyrinx, four had a Chiari I malformation and two had a Chiari II malformation. The MRI characteristics of the presyrinx included T2 prolongation, mild indistinct T1 prolongation, and cord enlargement without frank cavitation. Cine phase-contrast MRI studies were performed in three patients and showed severely diminished or absent CSF flow at the foramen magnum. Five patients underwent surgical decompression. All three patients with postoperative spine imaging showed restoration of CSF flow and resolution of the presyrinx. Symptoms of chronic or acute myelopathy attributable to the presyrinx were present in two pa- tients. These symptoms resolved postoperatively. Conclusions: Chiari I and II malformations obstructing CSF flow at the craniocervical junction may cause presyrinx in children. Presyrinx should be considered in the differential diagnosis of chronic or acute myelopathy in patients at risk for abnormal CSF flow dynamics. Neurology ® 2008;71:351–356 The presyrinx state, first described in 1999, is a potentially reversible state of spinal cord edema caused by obstruction to normal CSF flow pathways, typically in the cervical region. 1 This entity has since been described in at least 15 cases in the neurosurgical and neuroradiologic literature 1-10 and has been reported in three pediatric patients. 1,3,7 Several cases of parenchymal cord signal abnormality accompanying syringomyelia that were described prior to 1999 may also represent presyrinx. 11,12 The pathophysiology of syrinx and presyrinx remains a topic of debate. One potential mechanism involves increased pulse pressure in the subarachnoid space causing CSF to move through the perivascular and interstitial spaces of the spinal cord toward the central canal, resulting in edema of the spinal cord. 1,13-22 The development of a noncommunicating syrinx remote from the site of CSF obstruction has been explained by variations in the competence of the central canal and the degree and location of canal stenosis. 17 Some have postulated that presyrinx occurs if the central canal is not patent. 1 In this situation, CSF entering the perivas- cular and interstitial spaces of the spinal cord parenchyma is unable to enter the central canal to form a cyst. More recently, other mechanisms of syringomyelia have also been proposed. 23,24 The progression from presyrinx to syrinx has been documented by serial imaging, thus giving rise to its name. 1,2 A presyrinx may be seen at the cranial end of an advancing syrinx. On MRI it is characterized by T2 prolongation and, in most cases, indistinct T1 prolongation and e-Pub ahead of print on June 18, 2008, at www.neurology.org. From the School of Medicine (S.G., C.L.B., Y.W.W.) and Department of Radiology (A.H.A., W.P.D.), University of California San Francisco. C.L.B. is an MD candidate. Disclosure: The authors report no disclosures. Address correspondence and reprint requests to Dr. Suzanne Goh, Resident in Child Neurology, University of California San Francisco, 350 Parnassus Ave., Suite 609, San Francisco, CA 94143 Suzanne.goh@ucsf.edu Copyright © 2008 by AAN Enterprises, Inc. 351