Spinal Subdural Space and Collections: A Pictorial Review

Spinal fluid collections can involve the epidural, subdural, subarachnoid, or intramedullary spaces. Among these, subdural fluid collections are uncommon and may be diagnostically challenging due to their potential for heterogeneity and their proximity to the epidural and subarachnoid compartments. A variety of etiologies can contribute to the formation of subdural fluid collections, broadly including iatrogenic, traumatic, infectious, inflammatory, neoplastic, and vascular categories. MRI with and without contrast is the imaging technique of choice, and the MRI appearance may point toward a specific etiology. Early recognition of the spinal subdural collection and its underlying etiology is essential for guiding proper management. This article reviews the anatomy of the spinal compartments and the appearance of spinal subdural fluid collections and their mimics.Learning Objective: To describe the imaging appearance of spinal subdural collections, including features that distinguish spinal subdural collections from epidural or subarachnoid collections, and recognize common etiologies of these collections.