Ann Clin Transl Neurol. 2014;1(10):755-764. Outcome and survival of asymptomatic PML in natalizumab-treated MS patients.
OBJECTIVE:As of 3 September 2013, 399 cases of natalizumab-associated progressive multifocal leukoencephalopathy (PML) were confirmed inmultiple sclerosis (MS) patients. We evaluated outcomes of natalizumab-treated MS patients who were asymptomatic at PML diagnosis.
METHODS:Asymptomatic patients diagnosed with PML by magnetic resonance imaging (MRI) findings and JC virus DNA detection in the central nervous system were compared with patients presenting with symptoms at diagnosis. Demographics, MRI, and survival over 12 months were analyzed. Expanded Disability Status Scale (EDSS) and Karnofsky Performance Scale (KPS) scores were recorded pre-PML, at diagnosis, and at 6 and 12 months post-diagnosis.
RESULTS: A total of 372 PML cases were analyzed; 30 patients were asymptomatic and 342 were symptomatic at PML diagnosis. Classifications of PML lesions on MRI in asymptomatic versus symptomatic patients were unilobar (one lobe) in 68% versus 37%, multilobar in 21% versus 24%, and widespread in 11% versus 40%. In both groups with unilobar lesions, frontal lobe lesions predominated. Prior to PML, mean EDSS and KPS scores were similar for asymptomatic and symptomatic patients. At diagnosis, mean EDSS score was significantly lower for asymptomatic patients (4.1; n= 11) than for symptomatic patients (5.4; n = 193; P = 0.038). Six months after PML diagnosis, asymptomatic patients had less functional disability than symptomatic patients. 96.7% of asymptomatic patients and 75.4% of symptomatic patients were alive.
INTERPRETATION: PML patients asymptomatic at diagnosis had better survival and less functional disability than those who were symptomatic at diagnosis.
The Karnofsky score runs from 100 to 0, where 100 is "perfect" health and 0 is death. Although practitioners occasionally assign performance scores in between standard intervals of 10. This scoring system is named after Dr. David A. Karnofsky, who described the scale with Dr. Joseph H. Burchenal in 1949. The primary purpose of its development was to allow physicians to evaluate a patient's ability to survive chemotherapy for cancer.
100 - Normal; no complaints; no evidence of disease.
90 - Able to carry on normal activity; minor signs or symptoms of disease.
80 - Normal activity with effort; some signs or symptoms of disease.
70 - Cares for self; unable to carry on normal activity or to do active work.
60 - Requires occasional assistance, but is able to care for most of his personal needs.
50 - Requires considerable assistance and frequent medical care.
40 - Disabled; requires special care and assistance.
30 - Severely disabled; hospital admission is indicated although death not imminent.
20 - Very sick; hospital admission necessary; active supportive treatment necessary.
10 - Moribund; fatal processes progressing rapidly.
0 - Dead