"Intrathecal" refers to a medical procedure or treatment that involves delivering medication directly into the intrathecal space, which is the area surrounding the spinal cord. This method allows for higher concentrations of medication to reach the central nervous system, often resulting in more effective pain relief or treatment for conditions like multiple sclerosis or cancer. The intrathecal route is commonly used for administering opioids, anesthetics, or chemotherapy drugs. It is typically performed using a thin needle and can be done as a one-time injection or through an implanted pump for continuous delivery. This approach minimizes systemic side effects compared to oral or intravenous methods.