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Progressive Multifocal Leukoencephalopathy (PML)

Demyelinating brain infection caused by JC virus reactivation

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Nöroloji department. Book Appointment →

What is Progressive Multifocal Leukoencephalopathy (PML)?

PML is caused by reactivation of John Cunningham (JC) polyomavirus, a ubiquitous virus that infects 50–70 percent of adults asymptomatically.

In immunocompromised hosts, JC virus reactivates and infects oligodendrocytes, causing progressive demyelination of the cerebral white matter, brainstem and cerebellum.

Most common in patients with HIV/AIDS (CD4 count typically less than 200), hematologic malignancies, organ transplant recipients and those on immunosuppressive biologics (especially natalizumab).

Multifocal asymmetric white matter lesions on MRI are characteristic, often without contrast enhancement and without mass effect (in contrast to other CNS lesions).

Diagnosis confirmed by JC virus DNA in cerebrospinal fluid (CSF PCR) or brain biopsy showing demyelination with bizarre astrocytes, enlarged oligodendrocyte nuclei and JC virus antigens.

Symptoms

Progressive cognitive decline, personality changes, dementia
Focal neurologic deficits depending on lesion location: hemiparesis, hemisensory loss, ataxia, visual field defects
Aphasia and other language disturbances
Visual disturbances including hemianopia, cortical blindness
Cerebellar signs: dysarthria, ataxia, dysmetria
Seizures (uncommon at presentation, more common later)
Symptoms develop over weeks to months and progress steadily without treatment
Headache and fever are uncommon (helping distinguish from other infections)

Risk Factors

HIV infection with low CD4 count (typically less than 200 cells/microL)
Natalizumab therapy for multiple sclerosis or Crohn disease (risk increases with duration over 2 years and JCV antibody positivity)
Other immunosuppressive biologics: rituximab, efalizumab, fingolimod, dimethyl fumarate (rare)
Hematologic malignancies: chronic lymphocytic leukemia, lymphoma, especially after rituximab
Solid organ transplantation with chronic immunosuppression
Idiopathic CD4 lymphopenia
Sarcoidosis with corticosteroid-induced immunosuppression

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Subacute progressive cognitive decline in immunocompromised patient
  • New focal neurologic deficits without clear alternative explanation
  • Visual disturbances, ataxia or weakness in patients on immunosuppressive therapy
  • Personality changes or behavioral changes in HIV-positive patient with low CD4
  • Patients on natalizumab with new neurologic symptoms
  • Any neurologic decline in transplant or hematologic malignancy patient on immunosuppression

Treatment Methods

01
Diagnosis: brain MRI showing characteristic multifocal white matter lesions, JC virus PCR in CSF (specificity high but sensitivity 70–90 percent), brain biopsy if PCR negative and high suspicion
02
Restore immune function — the cornerstone of PML treatment
03
HIV-associated PML: initiate or optimize antiretroviral therapy (ART) immediately to reconstitute immunity
04
Natalizumab-associated PML: stop natalizumab immediately and perform plasma exchange or immunoadsorption to remove drug
05
Other immunosuppressive-associated PML: stop or reduce immunosuppression as feasible
06
Watch for immune reconstitution inflammatory syndrome (IRIS) which can paradoxically worsen symptoms — manage with corticosteroids
07
No specific antiviral therapy is consistently effective; experimental approaches include pembrolizumab, nivolumab (PD-1 inhibitors), allogeneic JCV-specific T cells
08
Supportive care: anticonvulsants for seizures, physical and occupational therapy, speech therapy
09
Monitor with serial MRI and CSF JC virus DNA to assess response
10
Prognosis varies: HIV PML 1-year mortality has fallen to 30–50 percent with ART; natalizumab PML mortality 20–25 percent; outcomes depend on degree and speed of immune restoration

Which Department to Visit?

You can visit our Nöroloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.