Progressive multifocal
leukoencephalopathy (PML)
June 2007 View PDF En
español
Commentary
Currently, some doctors assert that PML is not treatable. However,
many people have responded to various treatments. Although anti-HIV
therapy does not directly affect the JC virus, the wise use of it
appears to greatly impact survival after a PML diagnosis, most likely
because the immune system recovers and starts to control the JC
virus once HIV replication is arrested.
It is important to realize that successful PML treatment at best
usually means only stabilizing or partly resolving symptoms, even
when brain lesions shrink. This is different from a complete resolution
of symptoms. Despite an arrest or decrease of lesions in the brain,
someone with PML may face lifelong symptoms. These may include weakness
on one side of the body or limbs, loss of vision and/or permanent
impairment of certain functions (slurred speech, memory loss, disorientation,
loss of balance, etc.), even if survival is extended and PML lesions
stabilize or improve.
In one reported case of complete resolution of PML lesions in the
brain after starting HAART—despite their loss—partial
vision loss caused by the JC virus in the part of the brain that
controls sight remained permanent. This suggests that treating PML
early and aggressively is wise as the damage that is allowed to
continue, unchecked, may be permanent. It is not uncommon, however,
after a brain injury or disease for the brain to repair somewhat,
or for other parts of the brain to compensate and for symptoms from
the condition to improve.
PML is difficult to study. Factors that add to this difficulty
include the rapid onset of symptoms, similarities to other conditions
like toxo, and the fact that some people spontaneously recover or
stabilize for unknown reasons. Most information on PML treatments
now comes from small studies and anecdotal reports.
PML diagnosis remains a problem. A brain biopsy is quite invasive
and therefore less invasive techniques need to be developed. A spinal
tap (lumbar puncture) is hardly non-invasive, but compared to a
brain biopsy it’s a far better choice to many people.
Among people with HIV, about 30% without and 70% with PML have
detectable JC virus floating in their blood. Given the large percentage
of people with measurable levels of JC virus without PML, using
blood as a way to diagnose PML is not practical. Far too many people
without PML could be misdiagnosed as having PML. Using cerebral
spinal fluid (CSF) to diagnose PML may provide a medium ground,
but it’s not perfect.
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