Abstract 314: Intracisterna Magna (ICM) Injection

Introduction/Purpose Intracisterna magna (ICM) injection is used as a route to deliver intrathecal gene therapy to treat neuropathies and lysosomal storage disorders. This allows requiring smaller doses than if therapy was delivered through other routes of vector delivery in the brain and spinal cord. This procedure had never been performed in humans before, only animals, at the time of procedure. Case description and technique The procedure was performed under general anesthesia. It was vital that the patient did not move during the entirety of the procedure. This is generally a high risk procedure due to the surrounding vasculature and risk of stroke. Contraindications include anatomic variability where the posterior inferior cerebellar artery (PICA) or vertebral artery would be obstructing the area for access. Other contraindications include the presence of an occipital sinus, Chiari I malformation or low lying tonsils. Potential complications include soft tissue injury, vascular injury, bleeding, and CSF leak. The pediatric patient's head was flexed to open the pathway to the cisterna magna. Cross sectional imaging with CT with contrast was used to identify the vertebral artery, PICA, and veins. The patient was positioned lateral decubitus with the right side down. The posterior craniocervical junction was sterilely prepped and draped. Xylocaine was used for local anesthesia. 25G 3 inch spinal needle was advanced into posterior neck, progressing into the cisterna magna using 2mm cuts until CSF was seen draining through needle. 0.5cc Isovue‐180 contrast was injected showing uptake in the cisterna magna. 5cc CSF removed was removed followed by introduction of 5cc of the experimental drug per protocol followed by a saline chaser. There was no immediate complication and the patient was admitted to the pediatric intensive care unit (PICU) for ongoing cardiorespiratory and neurologic monitoring. Outcome This was the first patient with GM1 gangliosidosis to be treated via ICM injection of a viral vector at the time of procedure.