Fact Sheet Number 513
Leucoencephalopathy)
- WHAT IS PML?
- HOW CAN PML BE DETECTED?
- HOW IS PML TREATED?
- WHERE CAN I GET MORE INFORMATION?
- THE BOTTOM LINE
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PrintProgressive multifocal leucoencepha- lopathy is a serious viral
infection of the brain.
“Encephalo” means brain, and “pathy” means
disease. Encephalopathy is a disease of the brain. “Leuco-”
means white. Leucoencephalopathy is a disease of the white matter
of the brain.
“Progressive” means that this disease gets worse
in a short time. “Multifocal” means that it shows up
in several places at the same time.
Researchers estimate that about 4% of people with AIDS develop
PML, especially if their T-cell
counts are below 100. The exact rate is hard to know because
PML is difficult to diagnose.
PML is fatal in about 90% of cases. People diagnosed with PML
live an average of 6 months. Most die within 2 years.
The “JC” virus causes PML. Most adults have been
exposed to JC virus and have no disease. In people with weakened
immune systems, JC virus can become active.
DETECTED?
The symptoms of PML start with weakness or coordination problems
in an arm or leg. There may be difficulty thinking or speaking.
Vision and memory problems, seizures and headaches can occur.
These symptoms can also occur with other opportunistic infections,
including toxoplasmosis, lymphoma,
inner ear infections, or cryptococcal
meningitis. It is important to rule out these other diseases.
PML can be diagnosed using a magnetic resonance imaging (MRI)
scan of the brain. Another way to test for PML is by checking
spinal fluid. The sample is taken by inserting a needle into the
spinal canal, a procedure called a spinal tap.
A major problem with treating any brain infection is the “blood-brain
barrier”. The blood vessels around the brain are different
from the rest of the body. They are “tightly woven”
to protect the brain from toxic substances. Chemicals that dissolve
in fat can get through. Those that dissolve in water can’t. Unfortunately,
this includes most antibiotics and many other medications.
There is currently no proven treatment for PML. Research studies
have had conflicting results, and other possible treatments have
not been carefully studied. However, PML has slowed down in some
patients taking combination antiviral therapy including a protease
inhibitor.
Ara-C (Cytosine arabinoside or cytarabine) has been tried against
PML. It was given intravenously, and also pumped directly into
the brain. It seemed to work in one small study, but not in later
ones. Ara-C is very toxic, and damages bone marrow.
High-dose AZT has been tried against
PML, because AZT can cross the blood-brain barrier. Other substances
that have been tried with different degrees of success include
acyclovir, heparin, peptide-T, beta interferon, dexamethasone,
and n-acetylcysteine, topotecan and cidofovir.
Because PML can progress rapidly, it is important to begin
treatments quickly.
MORE INFORMATION?
An excellent source of information is the book, Progressive Multifocal
Leucoencephalopathy (PML): Case Studies and Potential Treatments.
Peter and Lisa Brosnan wrote the book in 1993. They are not medical
specialists, but Lisa’s brother was diagnosed with PML and the
Brosnans began searching for possible treatments. Lisa’s brother
died, but they continued and published their work.
You can get a copy of their book by writing to Peter Brosnan,
1709 N. Fuller Avenue #25, Los Angeles, CA 90046. To cover his
costs, he asks physicians and institutions to send $30, people
with AIDS $20, and in cases of hardship he will send it free.
PML is a viral infection of the brain. It is usually fatal. It
can be confused with other medical conditions.
There is no approved treatment for PML, although several treatments
may be helpful. Any treatment must be started as early as possible.
Combination antiviral therapy may slow the progress of PML.
Revised January 31, 2002
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