Intrathecal Chemotherapy

• Intrathecal chemotherapy delivers anti-cancer drugs directly into the cerebrospinal fluid.
• It is vital for treating cancers that have spread to or originated in the central nervous system.
• The procedure typically involves a lumbar puncture or a surgically implanted reservoir.
• Common uses include leukemia, lymphoma, and certain brain tumors.
• Potential side effects range from mild, temporary issues to more serious neurological complications.

What is Intrathecal Chemotherapy?

Intrathecal chemotherapy refers to a method of administering anti-cancer drugs directly into the intrathecal space, which is the fluid-filled area between the thin membranes (meninges) that surround the brain and spinal cord. This direct delivery bypasses the blood-brain barrier, a protective mechanism that prevents many drugs from reaching the central nervous system (CNS) when administered intravenously or orally. By delivering chemotherapy agents directly into the cerebrospinal fluid (CSF), higher concentrations of the drug can reach cancer cells in the CNS, making it an effective strategy for treating or preventing CNS involvement of various cancers.

This specialized approach is essential because many systemic chemotherapy drugs cannot effectively cross the blood-brain barrier in sufficient concentrations to treat CNS malignancies. Conditions such as leukemia, lymphoma, and certain solid tumors can spread to the brain and spinal cord, necessitating this targeted delivery method. The goal is to eradicate cancer cells within the CNS, prevent their spread, or manage symptoms associated with CNS involvement.

Intrathecal Chemotherapy Procedure and Uses

The intrathecal chemotherapy procedure involves carefully introducing chemotherapy drugs into the cerebrospinal fluid. There are primarily two methods for this administration. The most common method is a lumbar puncture, also known as a spinal tap, where a thin needle is inserted into the lower back to access the intrathecal space. The drug is then injected directly into the CSF. This procedure is typically performed in an outpatient setting and may require local anesthesia.

Another method involves a surgically implanted device called an Ommaya reservoir. This small dome-shaped device is placed under the scalp, connected to a catheter that extends into a ventricle of the brain. The Ommaya reservoir allows for repeated, less invasive drug administration by injecting through the skin into the reservoir, which then delivers the medication into the CSF. This is often preferred for patients requiring frequent or long-term intrathecal treatments.

Intrathecal chemotherapy uses primarily target cancers that affect or have a high risk of spreading to the central nervous system. These include:

• Leukemias: Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) often require intrathecal chemotherapy to prevent or treat CNS relapse.
• Lymphomas: Non-Hodgkin lymphoma and Hodgkin lymphoma, especially aggressive types, can involve the CNS.
• Brain Tumors: Certain primary brain tumors or metastatic tumors that have spread to the meninges (leptomeningeal carcinomatosis).
• Germ Cell Tumors: Some germ cell tumors can also metastasize to the CNS.

This targeted approach ensures that the chemotherapy reaches the affected area directly, maximizing its efficacy against CNS cancer cells while potentially minimizing systemic side effects.

Potential Side Effects of Intrathecal Chemotherapy

While highly effective, intrathecal chemotherapy side effects can occur due to the direct administration of potent drugs into the central nervous system. These side effects can vary in severity and may include both immediate and delayed reactions.

Common immediate side effects often resemble those of a lumbar puncture itself, such as headache, nausea, vomiting, and back pain at the injection site. These are usually temporary and can be managed with supportive care. More specific to the chemotherapy agents, patients might experience neurological symptoms like temporary confusion, dizziness, seizures, or vision changes. Myelosuppression, a decrease in blood cell counts, is less common than with systemic chemotherapy but can still occur with some drugs.

Another potential side effect is chemical meningitis, an inflammatory reaction of the meninges, which can cause fever, headache, stiff neck, and sensitivity to light. This is usually sterile (not caused by infection) and resolves with symptomatic treatment. In some cases, particularly with certain drugs or high doses, more severe and potentially long-lasting neurological complications, known as neurotoxicity, can arise, including nerve damage, paralysis, or cognitive impairment. The medical team closely monitors patients receiving intrathecal chemotherapy to manage and mitigate these potential side effects. The choice of chemotherapy agent, dosage, and frequency of administration are carefully tailored to balance efficacy against the risk of adverse reactions.