Cisternographic imaging patterns: effects of partial extra-arachnoid radiopharmaceutical injection and postinjection CSF leakage.

A cisternographic pattern of subarachnoid block with transient or no ventricular radiopharmaceutical reflux was observed in 52% of 105 patients with partial extra-arachnoid injections or postinjection leakage of CSF or both at the lumbar puncture site. In several patients, adequate repeat studies demonstrated considerably different CSF flow patterns. This block pattern was seen in only 11% of 217 patients with adequate intrathecal injections. Lumbar CSF leakage may alter the pattern seen on a cisternographic study and, if present, the study should be interpreted with caution.