Comparison of the radioisotope cisternography findings of spontaneous intracranial hypotension and iatrogenic cerebrospinal fluid leakage focusing on chronological changes

Background: Radioisotope cisternography (RICG) is useful for detecting cerebrospinal fluid (CSF) leakage in spontaneous intracranial hypotension (SIH) patients. However, RICG can cause iatrogenic CSF leakage (ICSFL) due to a lumbar puncture. Objectives: To compare the RICG findings of SIH and ICSFL. Methods: The presence of direct findings suggesting CSF leakage and indirect findings including early visualization of the bladder and absence of radioactivity over the brain convexities were evaluated in seven SIH and six ICSFL patients. Radioisotope clearance was assessed semi-quantitatively. Results: In contrast to the variety of anatomical levels at which direct findings were detected in the SIH patients, the ICSFL patients only displayed direct findings at the lumbosacral level. None of the ICSFL patients displayed direct findings at 1 hour after the tracer injection. Although early visualization of the bladder was depicted in all patients, no activity was visualized over the brain convexities in the SIH patients. In the semi-quantitative analysis, the tracer retention index at 24 hours was lower in the SIH patients than the ICSFL patients. Conclusions: The early appearance of direct findings above the lumbosacral level, the absence of radioactivity over the brain convexities and a low tracer retention index are suggestive of SIH.