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| Year : 2013 | Volume
: 59
| Issue : 3 | Page : 248 |
Acute reversible toxic leukoencephalopathy - A different entity
S Srinivasan, SZ Ali
Department of Diagnostic Radiology, Khoo Teck Puat Hospital, 90 Yishun Central, Singapore 768228, Singapore
| Date of Web Publication | 12-Sep-2013 |
Correspondence Address:
S Srinivasan
Department of Diagnostic Radiology, Khoo Teck Puat Hospital, 90 Yishun Central, Singapore 768228
Singapore
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0022-3859.118063
How to cite this article:
Srinivasan S, Ali S Z. Acute reversible toxic leukoencephalopathy - A different entity. J Postgrad Med 2013;59:248 |
Sir,
We read with great interest the report of a case of leukoencephalopathy induced by chemotherapeutic agents. [1] It should be noted that such leukoencephalopathies are different from reversible posterior leukoencephalopathy syndrome (RPLS), which is otherwise known as posterior reversible encephalopathy syndrome (PRES). RPLS classically occurs in conditions associated with sudden elevation of blood pressure, and magnetic resonance (MR) imaging usually shows vasogenic edema in the parieto-occipital white matter. [2] Typical RPLS does not show restricted diffusion on diffusion-weighted MR (DW-MR) imaging sequence. [2] The white matter changes associated with chemotherapeutic agents are not confined to parieto-occipital region and, hence, the condition is classified under acute reversible toxic leukoencephalopathy [3],[4] which is a different entity. Previously, they were mistakenly called as atypical forms of PRES or RPLS. [5]
Because of increasing use of chemotherapeutic agents such as 5-fluorouracil (5-FU), such leukoencephalopathies are being increasingly reported recently [3],[4] and are not so rare as stated by the authors. One reason could be the lack of search of recent radiological literature by the authors.
Diffusion restriction in the white matter is not due to vasogenic edema (as mentioned by the authors). In simple vasogenic edema, there would be unrestricted movement of the hydrogen molecules (also known as protons) and, hence, would not cause restriction of diffusion in DW-MR imaging. In toxic leukoencephalopathy, the etiology of restricted diffusion is presumed to be intramyelinic edema, endothelial damage, and cytotoxicity or direct demyelination. [3]
Another teaching point which we would like to emphasize is that the restricted diffusion disappears after stopping the chemotherapeutic agent, as noted by Sivasubramanian et al. [3] and Mckinney et al. , [4] although authors have acknowledged that they could not repeat the MR imaging due to patient's refusal.
| :: References | |  |
| 1. | Paul BS, Singh G, Bansal R, Paul G. Diffusion weighted MR imaging of 5-fluorouracil and oxaliplatin-induced leukoencephalopathy. J Postgrad Med 2013;59:135-7. 
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| 2. | Lamy C, Oppenheim C, Méder JF, Mas JL. Neuroimaging in posterior reversible encephalopathy syndrome. J Neuroimaging 2004;14:89-96.
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| 3. | Sivasubramanian S, Moorthy S, Sreekumar KP, Kannan RR. Diffusion-weighted magnetic resonance imaging in acute reversible toxic leukoencephalopathy: A report of two cases. Indian J Radiol Imaging 2010;20:192-4.
[PUBMED] |
| 4. | McKinney AM, Kieffer SA, Paylor RT, SantaCruz KS, Kendi A, Lucato L. Acute toxic leukoencephalopathy: Potential for reversibility clinically and on MRI with diffusion-weighted and FLAIR imaging. AJR Am J Roentgenol 2009;193:192-206.
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| 5. | McKinney AM, Short J, Truwit CL, McKinney ZJ, Kozak OS, SantaCruz KS, et al. Posterior reversible encephalopathy syndrome: Incidence of atypical regions of involvement and imaging findings. AJR Am J Roentgenol 2007;189:904-12.
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Author reply |
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| Paul, B.S. and Singh, G. and Bansal, R.K. and Paul, G. | | Journal of Postgraduate Medicine. 2013; 59(3): 248-249 | | [Pubmed] | |
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