Cerebral cavernous malformations (CCMs) are heterogeneous vascular malformations that may cause headaches, seizures, focal neurologic deficits, stroke, and death. With an incidence of 0.1 to 0.5%, they constitute 10 to 20% of all CNS vascular malformations.1 Heterozygous loss-of-function mutations have been identified in KRIT1 ( CCM1 ),2 MGC4607 ( CCM2 ),3 and PDCD10 ( CCM3 ).4 We describe a patient with multiple CCMs presenting with a hemorrhagic thoracic cord cavernous malformation and an unreported CCM1 mutation. #### Proband. A man age 29 with a history of multiple CCMs, including an acutely hemorrhagic left cerebellar CCM resected in 1999, reported a 7-day history of progressive bilateral lower extremity weakness and numbness. He was unable to ambulate on the day of admission, with paresis of his right leg, severe left leg motor impairment, and numbness in his thighs and groin. He reported a painful, distended bladder without urination in over 36 hours. Physical exam demonstrated nearly complete plegia in the right lower extremity. The left lower extremity was 3/5 proximally and 2/5 distally. Sensory exam revealed a dense, multimodality level …