Review Article: A New Classification for Pathologies of Spinal Meninges—Part 2: Primary and Secondary Intradural Arachnoid Cysts

In a previous paper, pathologies of the spinal dura were analyzed, classified, and discussed.1 This paper concentrates on cystic intradural pathologies of spinal meninges, ie, spinal arachnoid cysts. Intradural arachnoid cysts are rare causes of radicular symptoms or spinal cord compression. A considerable proportion is accompanied by syringomyelia due to obstruction of cerebrospinal fluid (CSF) flow.2,3Arachnoid cysts are underdiagnosed as they may easily be missed by standard magnetic resonance images (MRI) due to their thin walls and pulsatile movements with CSF. The differential diagnosis includes cystic extramedullary pathologies of dysraphic origin, such as neurenteric cysts, neuroepithelial cysts, or dermoid cysts, as well as cysts of parasitic origin or cystic schwannomas.2,47

This paper gives an overview on clinical presentations and surgical results for intradural spinal arachnoid cysts. According to patient history, 2 types of cysts should be distinguished: arachnoid cysts secondary to inflammatory reactions related to trauma, subarachnoid hemorrhages, meningitis, intradural surgery, or instillation of substances into the subarachnoid space such as pantopaque are considered as secondary arachnoid cysts, while those without a prior history of an inflammatory incident are defined as idiopathic, ie, primary arachnoid cysts.

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