Progressive Multifocal Leukoencephalopathy
Originally described in patients with lymphoproliferative disorders and impaired cell-mediated immunity, PML occurs in 1%–4% of HIV-infected patients. PML has also been reported in patients with MS who have been treated with immunomodulating medications such as natalizumab. The disease is caused by the JC virus, a polyomavirus that infects oligodendrocytes. Gray matter is relatively spared. The central visual pathways and ocular motor fibers can be affected. Neuro-ophthalmic manifestations include homonymous hemianopia, blurred vision, cerebral blindness, prosopagnosia, and diplopia. Other neurologic findings are altered mental status, ataxia, dementia, hemiparesis, and focal deficits. Behavioral and cognitive abnormalities are very common.
MRI scan shows areas of demyelination, most frequently in the parieto-occipital region. PML typically involves the subcortical white matter, with focal or confluent nonenhancing lesions (Fig 14-21). Therapy is aimed at correcting the underlying immune deficiency state, and prognosis is poor. In some cases, plasma exchange may be helpful.
Figure 14-21 Progressive multifocal leukoencephalopathy (PML) in a patient with AIDS. A, Axial FLAIR image demonstrates increased signal in the left occipital lobe white matter that extends anteriorly. B, Axial gadolinium-enhanced T1-weighted spin-echo image (same location as part A) demonstrates a nonenhancing hypointense lesion in the left occipital white matter. T1 hypointensity is typical of PML lesions. Note the absence of mass effect and negligible enhancement.
(Courtesy of Joel Curé, MD.)
Sørensen PS, Bertolotto A, Edan G, et al. Risk stratification for progressive multifocal leukoencephalopathy in patients treated with natalizumab. Mult Scler. 2012;18(2): 143–152.
Sudhakar P, Bachman DM, Mark AS, Berger JR, Kedar S. Progressive multifocal leukoencephalopathy: recent advances and a neuro-ophthalmological review. J Neuroophthalmol. 2015;35(3):296–305.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.