Progressive multifocal leukoencephalopathy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: Progressive multifocal leucoencephalopathy, Multifocal leucoencephalopathy, Multifocal leukoencephalopathy, PML, PMLE
Overview
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Progressive multifocal leukoencephalopathy (PML), also known as progressive multifocal leukoencephalitis, is a rare and usually fatal viral disease that is characterized by progressive damage (-pathy) or inflammation (-itis) of the white matter (leuko-) of the brain (-encephalo-) at multiple locations (multifocal). It occurs almost exclusively in people with severe immune deficiency, e.g. transplant patients on immunosuppressive medications, or AIDS patients.
References
Historical Perspective
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References
Pathophysiology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Pathophysiology
PML is a demyelinating disease, in which the myelin sheath covering the axons of nerve cells is gradually destroyed, impairing the transmission of nerve impulses. It affects the white matter, which is mostly composed of axons from the outermost parts of the brain (cortex). Symptoms include weakness or paralysis, vision loss, impaired speech, and cognitive deterioration. PML is similar to another demyelinating disease, multiple sclerosis, but since it destroys the cells that produce myelin (unlike MS, in which myelin itself is attacked but can be replaced), it progresses much more quickly. Most patients die within four months of onset. PML destroys oligodendrocytes and produces intranuclear inclusions.
References
Causes
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The JC virus (JCV) is a type of human polyomavirus (formerly known as papovavirus) and is genetically similar to BK virus and SV40. It was discovered in 1971 and named after the two initials of a patient with progressive multifocal leukoencephalopathy (PML). The virus is widespread, with 86% of the general population presenting antibodies, but it usually remains latent, causing disease only when the immune system has been severely weakened. The virus causes PML and other diseases only in cases of immunodeficiency, as in AIDS, or immunosuppression, as in organ transplant patients.
Epidemiology
The virus is very common in the general population, infecting 70 to 90 percent of humans; most people acquire JCV in childhood or adolescence [1]. It is found in high concentrations in urban sewage worldwide, leading some researchers to suspect contaminated water as a typical route of infection [2].
Minor genetic variations are found consistently in different geographic areas; thus, genetic analysis of JC virus samples has been useful in tracing the history of human migration [3].
Infection and pathogenesis
The initial site of infection may be the tonsils [4], or possibly the gastrointestinal tract [2]. The virus then remains latent in the gastrointestinal tract [5] and can also infect epithelial cells in the kidneys, where it continues to reproduce, shedding virus particles in the urine.
JCV can cross the blood-brain barrier into the central nervous system, where it infects oligodendrocytes and astrocytes, possibly through the 5-HT2A serotonin receptor [6]. It is found within the brain even in people with no symptoms [7].
When immunodeficiency or immunosuppression allows JCV to reactivate, it attacks the previously infected tissues. In the kidneys, this results in hemorrhagic cystitis and ureteral stenosis; in the brain, it causes the usually fatal progressive multifocal leukoencephalopathy or PML by destroying oligodendrocytes. Several studies since 2000 have suggested that the virus is also linked to colorectal cancer, as JCV has been found in malignant colon tumors, but these findings are still controversial [8].
References
- ↑ Padgett, B.L. and Walker, D.L. (1973). “Prevalence of antibodies in human sera against JC virus, an isolate from a case of progressive multifocal leukoencephalopathy”. J. Infect. Dis. 127 (4): 467–470. PMID 4571704.
- ↑ 2.0 2.1 Bofill-Mas, S., Formiga-Cruz, M., Clemente-Casares, P., Calafell, F. and Girones, R. (2001). “Potential transmission of human polyomaviruses through the gastrointestinal tract after exposure to virions or viral DNA”. J. Virol. 75 (21): 10290–10299. PMID 11581397.
- ↑ Pavesi, A. (2005). “Utility of JC polyomavirus in tracing the pattern of human migrations dating to prehistoric times”. J. Gen. Virol. 86 (Pt 5): 1315–1326. PMID 15831942.
- ↑ Monaco, M.C., Jensen, P.N., Hou, J., Durham, L.C. and Major, E.O. (1998). “Detection of JC virus DNA in human tonsil tissue: evidence for site of initial viral infection”. J. Virol. 72 (12): 9918–9923. PMID 9811728.
- ↑ Ricciardiello, L., Laghi, L., Ramamirtham, P., Chang, C.L., Chang, D.K., Randolph, A.E. and Boland, C.R. (2000). “JC virus DNA sequences are frequently present in the human upper and lower gastrointestinal tract”. Gastroenterology. 119 (5): 1228–1235. PMID 11054380.
- ↑ Elphick, G.F., Querbes, W., Jordan, J.A., Gee, G.V., Eash, S., Manley, K., Dugan, A., Stanifer, M., Bhatnagar, A., Kroeze, W.K., Roth, B.L. and Atwood, W.J. (2004). “The human polyomavirus, JCV, uses serotonin receptors to infect cells”. Science. 306 (5700): 1380–1383. PMID 15550673.
- ↑ White, F.A., 3rd., Ishaq, M., Stoner, G.L. and Frisque, R.J. (1992). “JC virus DNA is present in many human brain samples from patients without progressive multifocal leukoencephalopathy”. J. Virol. 66 (10): 5726–5734. PMID 1326640.
- ↑ Theodoropoulos, G., Panoussopoulos, D., Papaconstantinou, I., Gazouli, M., Perdiki, M., Bramis, J. and Lazaris, ACh. (2005). “Assessment of JC polyoma virus in colon neoplasms”. Dis. Colon. Rectum. 48 (1): 86–91. PMID 15690663.
External links
References
Differentiating Progressive multifocal leukoencephalopathy from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Differentiating Progressive multifocal leukoencephalopathy from other Diseases
Progressive multifocal leukoencephelopathy (PML) is more common among immunocompromised patients who are at high risk for other fungal, bacterial, and viral infections. It should be differentiated from the following diseases:
| Disease | Differentiating signs and symptoms | Differentiating tests |
|---|---|---|
| CNS lymphoma[1] |
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| Disseminated tuberculosis[2] |
|
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| Aspergillosis[3] |
|
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| Cryptococcosis |
|
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| Chagas disease[4] |
|
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| CMV infection[5] |
|
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| HSV infection[6] |
|
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| Varicella Zoster infection[7] |
|
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| Brain abscess[8][9] |
|
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| Progressive multifocal leukoencephalopathy[10] |
|
References
- ↑ Gerstner ER, Batchelor TT (2010). “Primary central nervous system lymphoma”. Arch. Neurol. 67 (3): 291–7. doi:10.1001/archneurol.2010.3. PMID 20212226.
- ↑ von Reyn CF, Kimambo S, Mtei L, Arbeit RD, Maro I, Bakari M, Matee M, Lahey T, Adams LV, Black W, Mackenzie T, Lyimo J, Tvaroha S, Waddell R, Kreiswirth B, Horsburgh CR, Pallangyo K (2011). “Disseminated tuberculosis in human immunodeficiency virus infection: ineffective immunity, polyclonal disease and high mortality”. Int. J. Tuberc. Lung Dis. 15 (8): 1087–92. doi:10.5588/ijtld.10.0517. PMID 21740673.
- ↑ Latgé JP (1999). “Aspergillus fumigatus and aspergillosis”. Clin. Microbiol. Rev. 12 (2): 310–50. PMC 88920. PMID 10194462.
- ↑ Rassi A, Rassi A, Marin-Neto JA (2010). “Chagas disease”. Lancet. 375 (9723): 1388–402. doi:10.1016/S0140-6736(10)60061-X. PMID 20399979.
- ↑ Emery VC (2001). “Investigation of CMV disease in immunocompromised patients”. J. Clin. Pathol. 54 (2): 84–8. PMC 1731357. PMID 11215290.
- ↑ Bustamante CI, Wade JC (1991). “Herpes simplex virus infection in the immunocompromised cancer patient”. J. Clin. Oncol. 9 (10): 1903–15. doi:10.1200/JCO.1991.9.10.1903. PMID 1919640.
- ↑ Hambleton S (2005). “Chickenpox”. Curr. Opin. Infect. Dis. 18 (3): 235–40. PMID 15864101.
- ↑ Alvis Miranda H, Castellar-Leones SM, Elzain MA, Moscote-Salazar LR (2013). “Brain abscess: Current management”. J Neurosci Rural Pract. 4 (Suppl 1): S67–81. doi:10.4103/0976-3147.116472. PMC 3808066. PMID 24174804.
- ↑ Patel K, Clifford DB (2014). “Bacterial brain abscess”. Neurohospitalist. 4 (4): 196–204. doi:10.1177/1941874414540684. PMC 4212419. PMID 25360205.
- ↑ Tan CS, Koralnik IJ (2010). “Progressive multifocal leukoencephalopathy and other disorders caused by JC virus: clinical features and pathogenesis”. Lancet Neurol. 9 (4): 425–37. doi:10.1016/S1474-4422(10)70040-5. PMC 2880524. PMID 20298966.
Epidemiology and Demographics
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Epidemiology and Demographics
About 2-5% of AIDS patients develop PML. It is unclear why PML occurs more frequently in AIDS than in other immunosuppressive conditions; some research suggests that the effects of HIV on brain tissue, or on JCV itself, make JCV more likely to become active in the brain and increase its damaging inflammatory effects (Berger, 2003).
There are case reports of PML being caused by pharmacological agents, although there is some speculation this could be due in part to the existing impaired immune response or ‘pharm combos’ rather than individual drugs. Rituxan and Natalizumab (branded Tysabri).
References
Risk Factors
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Risk Factors
Anyone with a weakened immune system, however, are at greater risk of developing PML. Causes of a weakened immune system include:
- AIDS (less common now because of better AIDS treatments).
- Certain medications used to treat multiple sclerosis, rheumatoid arthritis, and related conditions.
- Leukemia and lymphoma.
References
Natural History, Complications and Prognosis
Patients with Progressive Multifocal leukoencephalopathy(PML) have a long-term neurological sequelae and is often fatal. The mortality rate is 30%-50% [1] in early months of diagnosis. Those who are immunocompromised are at significant risk of reactivation.
COMPLICATIONS
PML may complicate into the following :
- Neurologic Dysfunction
- Dementia
- Blindness
- Seizures
PROGNOSIS
- The prognosis is variable and depends on the underlying severity of PML.
- Impairment of immune system (eg. HIV) or use of immunosuppressants may worsen prognosis and leads to rapid progression of the disease.[1]
- Patients who survive have substantial morbidity and severe neurological disabilities.[2]
Reference
Reference
- Progressive Multifocal Leukoencephalopathy Information Page. NIH-National Institute of Neurological Disorders and Stroke. 29 July 2019. Retrieved 12 June 2021.
- Castle, D., & Robertson, N. P. (2019). Treatment of progressive multifocal leukoencephalopathy. Journal of Neurology, 266(10), 2587–2589. https://doi.org/10.1007/s00415-019-09501-y
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | X Ray | CT | MRI | Echocardiography or Ultrasound | Other Imaging Findings | Other Diagnostic Studies
Treatment
Treatment
Medical Therapy | Surgery | Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies
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