(Ivanhoe Newswire) -- A drug called natalizumab is used to effectively treat multiple sclerosis (MS), but it also increases the risk of a rare potentially fatal brain infection called progressive multifocal leukoencephalopathy (PML).  New research out of Biogen Idec in Weston, MA, suggests that early detection of PML may improve survival rates and disability levels.

  

Researchers examined 319 people with MS who were treated with natalizumab and diagnosed with PML.  Due to the risk of PML, people taking the drug are monitored by their doctors for symptoms.  The study compared people who had symptoms of PML at the time of diagnosis to people who did not have symptoms, but who were diagnosed with the disease by tests in the spinal fluid and brain scans for the virus that causes PML.  The disability levels of participants in the study were assessed before the PML diagnosis, at the time of diagnosis, and at six months and one year after the diagnosis.

  

Twenty-one people had no PML symptoms at the time of their diagnosis, while 298 people had symptoms.  Study author and medical director, Tuan Dong-Si, MD, suggests that the study results suggest that people who do not have any symptoms at diagnosis may have improved survival and less disability.  

 

At the time of PML diagnosis, people who did not have any symptoms had an average score of 67 on the Karnofsky Performance Scale, which measures disability.  People with symptoms had a score of 54. 

 

A Karnofsky score of 70 indicates that the patient may be able to take care of themselves.  However, they may be unable to do normal activities or do active work.  A score of 50 indicates that a person may require a considerable amount of assistance and frequent medical care.  One year after PML diagnosis, the average score of those patients without symptoms at diagnosis was 70, compared to 47 for those with symptoms.

 

As of January 1, 2013, 100 percent of participants without symptoms at time of diagnosis were living, compared to 77 percent of people with symptoms at the time of diagnosis. 

 

“These results suggest that the consequences of PML infection can be mitigated by early detection of the disease," Dr. Dong-Si was quoted as saying. 

 

SOURCE:  Presentation at the American Academy of Neurology, March 2013

 

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