Acute Toxic Leukoencephalopathy: Potential for Reversibility Clinically and on MRI With Diffusion-Weighted and FLAIR Imaging

Abstract

Acute toxic leukoencephalopathy with reduced diffusion may be clinically reversible and radiologically reversible on DWI, and may also be reversible, but to a lesser degree, on FLAIR MRI. None of the imaging markers measured in this study appears to correlate with clinical outcome, which underscores the necessity for prompt recognition of this entity. Alerting the clinician to this potentially reversible syndrome can facilitate treatment and removal of the offending agent in the early stages.

Case Files of the New York City Poison Control Center: Paradichlorobenzene-Induced Leukoencephalopathy

“…Clinical features included abulia, ataxia, speech abnormalities, spastic paraparesis, and hypotonia with prominent cerebellar and cerebral white matter destruction on MRI [70,71]. Although initially thought to be related to the inhalation of aluminum fumes, it is likely attributed to some unidentified impurity in the drug supply since reports of leukoencephalopathy have also occurred with intravenous heroin, inhaled oxycodone, and crack cocaine [72,73].…”

Detection of Microhemorrhage in Posterior Reversible Encephalopathy Syndrome Using Susceptibility-Weighted Imaging

“…[2][3][4] Notably, this distribution of edema distinguishes PRES from reversible "toxic" leukoencephalopathies, which may be caused by similar factors (such as immunosuppressive and antineoplastic medications), but the pattern of edema in such toxic leukoencephalopathies usually occurs in the reverse fashion beginning with the deep white matter. [2][3][4][5] The combination of the clinical and imaging findings composing PRES has also been recognized and reported under various other names, such as "hypertensive encephalopathy," "cyclosporine neurotoxicity," or "CNS manifestations of toxemia of pregnancy." [6][7][8][9][10] A number of atypical imaging features of PRES have been described, such as the presence of hemorrhage, cytotoxic edema (on DWI), and contrast enhancement; of these, hemorrhage has been reported in larger series to occur in approximately 15%-17% of patients, based on T2*GRE imaging, FLAIR, and CT. 2,11 Although PRES-related hemorrhage usually does not affect clinical outcome, larger IPHs may occasionally develop, and these could potentially affect outcome.…”

Reduced Diffusion in a Subset of Acute MS Lesions: A Serial Multiparametric MRI Study

“…In these patients, ADC reductions of 11%-37% have been demon- strated, while signs of increased brain perfusion (due to the high energy demand) were noted in affected tissue. 20 A reduction of the ADC has been detected in different acute neurologic diseases (eg, stroke, 21,22 focal epilepsy, 23 toxic demyelination 24 ). We would favor an inflammatory mechanism that could lead to disturbances of energy metabolism, namely mitochondrial dysfunction, and, in turn, lead to reduced diffusion.…”