Concentric Tube Robot for Intrathecal Drug Administration

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurological disorder characterized by motor neuron degeneration. Although there is no known cure, FDA approved treatment options exist. However, these medications are administered orally, which limits dosing due to hepatic toxicity and asthenia. In addition, the expression of multidrug transporters on the blood-brain barrier (BBB) is increased in ALS patients, significantly reducing the influx of drug into the central nervous system from the blood stream. Recent work has explored intrathecal administration to obtain higher spinal cord concentrations, bypassing the BBB and avoiding the risk for adverse events associated with systemic drug exposure. However, current intrathecal catheter designs distribute the drug heterogeneously. In this paper we present a fluidic model for the first ever concentric tube robot (CTR) for intrathecal drug delivery and its corresponding envisioned system implementation for homogeneous intrathecal delivery of riluzole throughout the cerebral spinal fluid for patients suffering from ALS. The fluidic model is derived using the energy equation, and orifice diameters along the CTR are optimized to minimize fluidic head loss while maintaining a desired flow rate at each orifice. Simulation results show that the proposed design is able to provide homogeneous drug delivery via optimal design of the orifices along the whole CTR body.