Prophylactic central nervous system therapy using intraventricular injection via Ommaya reservoir for acute lymphoblastic leukemia in a child with low conus medullaris

Abstract

We report a case of a 6-year-old girl who was newly diagnosed with acute lymphoblastic leukemia and received prophylactic central nervous system therapy via intraventricular injection using an Ommaya reservoir. Intrathecal injection via lumbar puncture was deemed too risky because of the presence of a residual tumor and a low-lying conus medullaris following spinal lipoma surgery. On day 15 of treatment, after the peripheral blasts had disappeared, cerebrospinal fluid analysis was performed without intrathecal injection, confirming the absence of central nervous system infiltration. Following early consolidation therapy, an Ommaya reservoir was inserted. The administered intraventricular drug doses were half those of the standard intrathecal injections (6 mg methotrexate, 15 mg cytarabine, and 5 mg prednisolone). The intrathecal injections, which could not be performed before Ommaya reservoir insertion, were administered during maintenance therapy. A total of 15 intraventricular injections were administered during the study period. Chemotherapy was completed without any neurotoxic side effects, and brain magnetic resonance imaging (MRI) at the end of the treatment showed no abnormalities. The patient has remained in remission for 72 months since diagnosis.