Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a clear body fluid that surrounds the central nervous system and resides in cavities within the brain and spinal cord, primarily the ventricular system. This chapter focuses on abnormal accumulations of CSF – or fluids that appear like CSF – during the imaging examination. The normal grayscale display of CSF is unique to the imaging technique: CSF may be seen during ultrasonography, computed tomographic, and magnetic resonance images. Production and absorption of CSF occur in multiple areas throughout the brain and spinal cord. Abnormal intra-axial fluid accumulation refers to congenital or acquired fluid accumulation in the brain parenchyma or ventricular system. Communicating hydrocephalus is characterized by CSF that can exit the ventricular system and enter the subarachnoid space. Solitary and multiple extra-axial CSF accumulations may involve the cranial subarachnoid space, cisterns, subdural space, and epidural space. Abnormal CSF-like fluid accumulations tend to occur in the epidural space.