Conus medullaris syndrome as a complication of radioisotope cisternography.

OBJECTIVE Conus medullaris syndrome (CMS) is a clinical neurologic syndrome caused by a conus medullaris lesion. CMS is a heterogeneous entity with various etiologies such as trauma or a space-occupying lesion. Multiple cases of CMS following spinal anesthesia have been reported, but CMS after radioisotope (RI) cisternography has not yet been reported. METHODS We present four patients who developed CMS after RI cisternography. RESULTS All experienced neurological deficits such as paraparesis, sensory loss, and urinary incontinence three to four days after RI cisternography. Two showed abnormalities on lumbar magnetic resonance imaging, and three had complete symptom resolution within ten weeks. CONCLUSIONS The pathomechanism of the CMS is unclear, but we hypothesize that RI neurotoxicity might be responsible. It is possible that the use of low-dose 99mTc-DTPA or an alternative diagnostic tool such as magnetic resonance cisternography could help to prevent this complication.