Interstitial spinal cord edema in syringomyelia associated with Chiari type I malformation

¹ Sapporo Medical University, Japan

^* To whom correspondence should be addressed. E-mail: akiyuki{at}sapmed.ac.jp.

Accepted 7 March 2008

	Abstract

Objective: The pathophysiology of syringomyelia in Chiari type 1 malformation has not been clarified. Edema-like spinal cord swelling was recently reported in several pathological conditions including Chiari type 1 malformation as a pre-syrinx state. However, the role of the pre-syrinx state in development of syringomyelia is unknown. The purpose of this study is to investigate the parenchymal changes of the spinal cord in syringomyelia associated with Chiari type 1 malformation.

Methods: Pre- and postoperative magnetic resonance imaging findings in fourteen patients who underwent foramen magnum decompression in our institute were reviewed. The analysis was focused on differences in visualization of the syrinx between T1- and T2-weighted images and abnormal parenchymal signal changes. There were 6 men and 8 women, aged from 6 to 79 years. No patients showed hydrocephalus.

Results: Twelve patients had large and expansive syrinx, while 2 patients showed small syrinx confined to the center of the spinal cord. T2-weighted images displayed significantly larger intramedullary abnormal signal areas. Nine patients showed parenchymal hyperintensity areas around the enlarged central canal or base of the posterior white columns adjacent to the syringomyelic cavity. Such parenchymal hyperintensity areas markedly diminished with reduction of the syrinx after surgery and were considered to be interstitial edema.

Conclusions: From this study, the interstitial edema of the spinal cord commonly accompanies syringomyelia with Chiari type 1 malformation. Accumulation of the extracellular fluid due to disturbed absorption mechanisms may play an important role in the pathophysiology of syringomyelia associated with Chiari type 1 malformation.