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Treatment and the treatment process

Intrathecal chemotherapy

Intrathecal chemotherapy means giving a drug by lumbar puncture directly into the fluid around the spinal cord and brain. This topic explains why it is needed and how it is done.

Last updated: ~2 min read
A bed with a flat pillow in soft light and a glass of water on the side table.
Figure 1.Resting and drinking after the procedure can help.

01Short answer

Leukemia cells can spread to the brain and spinal cord — the central nervous system (CNS). Most drugs given into a vein do not cross the blood–brain barrier well, so the CNS can become a "hiding place" for leukemia. Intrathecal treatment solves this: the drug (usually methotrexate, sometimes with cytarabine and hydrocortisone — "triple" intrathecal) is injected into the spinal fluid by lumbar puncture. In ALL this is essential prevention throughout treatment; it is also used in some AML and other conditions. The procedure usually takes 15–30 minutes, under local anaesthetic in adults and often brief general anaesthetic in children. A fluid sample is taken at the same time and checked for leukemia cells.

02Simple explanation

The problem. The brain is protected by the blood–brain barrier, so drugs reach it poorly.

The solution. The drug is put straight into the spinal fluid.

How? With a thin needle in the lower back.

A bonus. The fluid is checked for leukemia cells.

03Scientific explanation

Blood–brain barrier: tightly joined cells in brain capillaries limit the entry of many drugs. High-dose systemic methotrexate and cytarabine partly cross it, but intrathecal delivery creates a much higher concentration in the CNS (NCI).

CNS status: at diagnosis, spinal fluid results are classed as CNS1, CNS2 or CNS3; with CNS involvement, intrathecal doses are given more often. Cranial radiotherapy is now used only in selected cases.

Side effects: post-puncture headache, back pain, rarely chemical arachnoiditis (fever, neck stiffness), and neurological effects of methotrexate (seizures, stroke-like episodes), usually temporary. If platelets are low, a transfusion may be given before the procedure.

04What happens in the body?

How is it done?

You lie on your side with your knees drawn up to your chest, or sit leaning forward. The skin is cleaned and numbed, then a thin needle is placed between the vertebrae, a little fluid is removed and the drug is injected. A small dressing is put on at the end.

A teal stream of light around a translucent spine and brain on a dark navy background.
Figure 3.Via the spinal fluid, the drug reaches the brain and spinal cord.

Why protect the brain?

Without prevention, a large share of ALL relapses used to occur in the CNS. Intrathecal treatment has greatly reduced this risk.

A glowing wall of cells separates a reddish vessel from blue brain tissue; drug particles stop at the wall.
Figure 2.The blood–brain barrier holds back most drugs.

After the procedure

Some centres advise lying down for a while and drinking plenty of fluids. A headache usually passes within a few days. If the pain is severe or does not go away, tell your team.

05Steps of intrathecal treatment

A simplified outline.

Preparation — Platelets, clotting.1PreparationPlatelets, clotting.
Numbing — Local or general anaesthetic.2NumbingLocal or general anaesthetic.
Injection — Fluid taken, drug given.3InjectionFluid taken, drug given.
Rest — Lie down, drink.4RestLie down, drink.
CNS protectedLower relapse risk.
Fluid testChecked for leukemia cells.
TeamA safe procedure.

06Key facts about intrathecal treatment

QuestionAnswerNote
DrugsMethotrexate; sometimes cytarabine + hydrocortisone"Triple" intrathecal
For whom?Everyone with ALL; some AML and othersBy protocol
How often?Weekly in induction, then less oftenDepends on CNS status
Duration15–30 minutesLonger with preparation
NumbingLocal; general anaesthetic in childrenDepends on centre
Common side effectHeadache and back painUsually passes

* Your doctor sets the exact schedule.

07Key terms

Intrathecal
Given into the spinal fluid.
Lumbar puncture
Taking fluid from the lower back.
Spinal fluid
The fluid around the brain and spinal cord.
Blood–brain barrier
A boundary protecting the brain from substances in the blood.
CNS
Central nervous system.
Post-puncture headache
A headache after the procedure that worsens when sitting.

08Key points

  • Drugs reach the brain poorly.
  • The intrathecal route protects the CNS.
  • It is essential in ALL.
  • The procedure is short.
  • The fluid is checked at the same time.
  • Report a severe headache.

09Frequently asked questions

Does it hurt?

With numbing, people often feel only pressure; sometimes there is brief pain.

How many times will it be done?

In ALL, from several to more than 20 times over the whole treatment, by protocol.

Can I drive afterwards?

Not that day if you had an anaesthetic or sedation.

Is there a risk of paralysis?

The needle goes in below where the spinal cord ends; serious complications are very rare.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Does it hurt?

  2. How many times will it be done?

  3. Can I drive afterwards?

  4. Is there a risk of paralysis?

My questions

12Sources

  1. National Cancer Institute (NCI). Adult Acute Lymphoblastic Leukemia Treatment (PDQ) – Patient Version
  2. National Cancer Institute (NCI). Childhood Acute Lymphoblastic Leukemia Treatment (PDQ) – Patient Version
  3. Cancer Research UK. Chemotherapy
  4. National Cancer Institute (NCI). Chemotherapy to Treat Cancer
  5. Cancer Research UK. Other ways of having chemotherapy
  6. Macmillan Cancer Support. Intrathecal chemotherapy
  7. NHS. Post-traumatic stress disorder (PTSD)
  8. MedlinePlus. Epilepsy
  9. MedlinePlus. Autoimmune Diseases
  10. MedlinePlus. Mouth Disorders
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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