One of the rarer complications of acute myeloid leukemia (AML) is central nervous system (CNS) involvement. This complication can occur in both children and adults. Children will be regularly tested for CNS involvement from diagnosis. Adults can undergo testing after a relapse.
AML is a type of blood cancer that starts in bone marrow cells, where blood cells are formed. The cells, also called leukemic blasts, develop abnormally and do not function properly. The cells can survive and grow better than healthy cells and can block the production of healthy cells.
Leukemia is the most common cancer in children. Studies have shown that 6-29% of children with AML have CNS involvement at the time of diagnosis.
Most adults newly diagnosed with AML are over age 65. However, it is more common for children with AML to have CNS involvement than in adults. Adults do not undergo routine testing for this condition when diagnosed unless a doctor suspects the CNS to be involved.
This article explains what the CNS is and how AML can affect its function. It also lists the symptoms, outlook, and treatment options for AML involving CNS involvement.
The human CNS performs many functions simultaneously. For example, it controls intentional or voluntary movements, including walking and speech.
The CNS also controls involuntary movements, such as breathing and blinking. In addition, it can shape a person’s perceptions, emotions and thoughts.
The brain is the central processing unit that receives information and gives it meaning. The spinal cord is the communication system through the nerves that reach to other parts of the body.
The vertebrae of the spine form different sections, and each section communicates with a different body part.
Read more about the CNS here.
AML can affect the CNS in both adults and children. However, CNS involvement is more common in people with acute lymphoblastic leukemia, which is another type of leukemia.
Doctors will confirm CNS involvement if they discover leukemic cells in the cerebrospinal fluid. This can also occur with tumors in the cerebrum in the brain, or in the meninges, the membrane layers that protect the brain and spinal cord.
Researchers suggest that several specific factors may lead to a higher risk of AML involving CNS involvement:
Children instead of adults
A 2021 review states that children are at greater risk of developing CNS involvement in AML than adults. This is because the AML is more likely to spread to the CNS and grow tumors there.
However, children are more likely than adults to undergo routine tests for the condition after receiving an AML diagnosis. Therefore, many more adults may also have CNS involvement, but it cannot be diagnosed.
The review also suggests that CNS involvement in adults with AML may be asymptomatic. However, the researchers acknowledge that this was a small review and that more research is needed.
Read more about AML in children here.
A relapse is when a person experiences AML again after a period of remission.
The authors of a 2017 study found that CNS involvement occurred in 0.6% of AML cases, or less than 1 in 100 people. Those who experienced relapse had a higher prevalence of CMS involvementement, which occurred in 2.6% of relapses, or in less than 1 in 300 people.
number of cells
A 2015 study of 395 participants over the age of 18 found that 20 of the participants had CNS involvement. Seven subjects had an initial CNS disorder and four had an isolated CNS relapse.
The people with CNS involvement were probably younger than 45 years of age, had higher leukocytes, platelets and immature cell blasts, and had a specific chromosomal abnormality.
The review authors note that more research is needed to determine whether these are specific risk factors for AML involving the CNS.
Symptoms depend on the area of the nervous system that is affected.
CNS involvement in AML usually causes no symptoms. However, nervous system symptoms may include:
Other, rarer symptoms may indicate cranial nerve involvement. These symptoms include:
Spinal cord involvement can cause symptoms such as:
Survival rates for adults living with AML with CNS involvement are low compared to other blood cancers or with AML without CNS involvement. However, studies emphasize that treatment options improve with medical advances.
The survival rates of people with leukemia have more than quadrupled since the 1960s. For AML, the 5-year survival is a total of 29.8% and 70.6% for children under 15 years of age.
People with AML with CNS involvement receive treatment for the condition when it occurs. This can be:
Chemotherapy: This treatment can be intensive and may contain the drug cytarabine. Maintenance chemotherapy afterward may involve taking a drug called tioguanine.Intrathecal Therapy: This type of treatment can help with severe chronic pain or spasticity. It also helps to reduce cancer cells. Doctors use a pump to deliver this treatment directly into the spinal cord. These are chemotherapy drugs.Cranial Radiation: This is a type of radiation therapy that can help prevent further spread of cancer cells in the brain.Stem cell transplants: Some people with AML and CNS involvement may be eligible for a stem cell transplant. This may involve taking stem cells from the same person who will receive them, or taking the cells from a donor.
Treatment may depend on a number of factors, such as:
age overall health, including other health conditions, previous cancer treatment, type of AMLCNS, involvement in diagnosis
Read more about the treatment of AML here.
AML with CNS involvement is rare, but it is more common in children with AML, who are routinely screened for this condition. Intrathecal chemotherapy treats the nervous system and protects it from leukemia cells. Treatment may include stem cell transplants.
CNS involvement in adults with AML also requires more complex treatment. Adults are not routinely tested for CNS involvement unless they have symptoms.
Scientists continue to test new therapies to improve the survival rates of individuals with AML involving CNS involvement.