Acute toxic leukoencephalopathy: potential for reversibility clinically and on MRI with diffusion-weighted and FLAIR imaging. AJR Am J Roentgenol. 2009;193:192-206. [PMID: 19542414 DOI: 10.2214/ajr.08.1176]

Diffusion-weighted magnetic resonance imaging in acute reversible toxic leukoencephalopathy: A report of two cases

Acute toxic leukoencephalopathy may be caused by endogenous or exogenous toxins. It may reverse clinically if the offending agent is withdrawn or the underlying condition is treated. However, demonstration of reversibility on imaging, especially with diffusion-weighted MRI, has been reported only very recently. We report two such cases.

Leukoencephalopathy and Akinetic Mutism in a Married Couple: A Probable Association with Oriental Medicine

Background

Case Report

Conclusions

Methadone-induced toxic leukoencephalopathy: diagnosis and follow-up by magnetic resonance imaging including diffusion-weighted imaging and apparent diffusion coefficient maps

BACKGROUND AND PURPOSE

Effects of methadone misuse have been rarely described. The purpose of this case report is to increase the knowledge of methadone-related leukoencephalopathy.

METHODS

We report the long-term follow-up by brain magnetic resonance imaging including isotropic diffusion-weighted imaging and mean apparent diffusion coefficient values of a 49-year-old patient who attempted suicide by intravenous methadone.

RESULTS AND CONCLUSIONS

Lesion pattern included subtle cerebellar involvement, mainly reversible extensive bilateral and symmetric brain involvement, cystic degeneration in the periventricular regions, sparing of corpus callosum and subcortical U-fibers, development of diffuse brain atrophy, and clear-cut clinical improvement.

Clinical and imaging features of fludarabine neurotoxicity

Neurotoxicity from intravenous fludarabine is a rare but recognized clinical entity. Its brain imaging features have not been extensively described. Three patients received 38.5 mg or 40 mg/m per day fludarabine in a 5-day intravenous infusion before bone marrow transplantation in treatment of hematopoietic malignancies. Several weeks later, each patient developed progressive neurologic decline, including retrogeniculate blindness, leading to coma and death. Brain MRI showed progressively enlarging but mild T2/FLAIR hyperintensities in the periventricular white matter. The lesions demonstrated restricted diffusion but did not enhance. Because the neurotoxicity of fludarabine appears long after exposure, neurologic decline in this setting is likely to be attributed to opportunistic disease. However, the imaging features are distinctive in their latency and in being mild relative to the profound clinical features. The safe dose of fludarabine in this context remains controversial.

Acute hepatic encephalopathy: diffusion-weighted and fluid-attenuated inversion recovery findings, and correlation with plasma ammonia level and clinical outcome

BACKGROUND AND PURPOSE

In acute hepatic encephalopathy, MR imaging abnormalities have been described in the PVWM, thalami, and corticospinal tracts. We sought to determine characteristic regions of involvement on FLAIR and DWI, to evaluate their reversibility, and to correlate MR imaging extent with clinical severity.

MATERIALS AND METHODS

Twenty patients who presented clinically with acute hepatic encephalopathy and MR imaging <21 days after symptom onset were reviewed retrospectively. Two neuroradiologists recorded involved regions on FLAIR and DWI in each, measured ADC values in affected regions and NAWM, and scored the MR imaging severity/extent. The initial severity (West Haven grade), follow-up clinical severity (degree of improvement), and maximal PAL within ±8 days of MR imaging were recorded and correlated with the MR imaging severity.

RESULTS

On FLAIR and DWI respectively, there were abnormalities in the thalami (85%, 70%), PLIC (75%, 80%), PVWM (80%, 85%), and DBS (70%, 35%) and diffuse cortical involvement (30%, 25%). There were relatively strong significant (P < .005) correlations of FLAIR (r = 0.680, P = .001) and DWI severity (r = 0.690, P = .001) with PAL, and of PAL with the clinical outcome (r = 0.691, P = .001). Both FLAIR (r = 0.592, P = .006) and DWI (r = 0.487, P = .029) severity correlated moderately with the clinical outcome but were not significant at the P < .005 level after Bonferroni correction.

CONCLUSIONS

Patients with acute hepatic encephalopathy may exhibit characteristic regions of involvement on FLAIR with DWI findings that can be reversible. The MR imaging extent on FLAIR and DWI strongly correlates with the maximal PAL, and PAL correlates well with the clinical outcome. Diffuse cortical involvement has a higher potential for neurologic sequelae but can be reversible.

Gliomatosis cerebri mimicking chemotherapy-induced leukoencephalopathy in a patient with non-Hodgkin's lymphoma

Patients with hematological malignancies may develop white matter lesions, which are usually associated with chemotherapy. Magnetic resonance imaging (MRI) is the imaging modality of choice for identifying chemotherapy-induced, or "toxic", leukoencephalopathy. Brain biopsy in patients with hematological malignancies suspected of sustaining toxic leukoencephalopathy has rarely been performed, because its characteristic MRI findings are considered pathognomotic. Biopsy may be indicated in atypical cases, however, and it may yield unexpected results. We describe a case with white matter lesions that developed in an elderly man treated for non-Hodgkin's lymphoma. The lesions, initially diagnosed with toxic leukoencephalopathy based on MRI findings, turned out to be gliomatosis cerebri.

Reversible posterior leukoencephalopathy syndrome

Reversible posterior leukoencephalopathy syndrome (RPLS) is characterized by subacute onset of headache, decreased alertness, vomiting, seizures, visuoperceptual disturbances, together with bilateral white matter lesions in posterior brain regions on brain imaging. The most frequently associated conditions related to RPLS are arterial hypertension and the use of immunosuppressive or cytotoxic treatment. T2-, Fluid Attenuation Inversion Recovery (FLAIR), and Apparent Diffusion Coefficient (ADC)-weighted magnetic resonance imaging (MRI) reveal hyperintensities in parietooccipital white matter but grey matter and other regions including frontal and temporal lobes, brainstem, cerebellum, basal ganglia, or even spinal cord may also be involved. According to ADC findings, the underlying pathophysiologic mechanism is probably one of vasogenic (rather than cytotoxic) oedema. These MRI findings help in differentiating RPLS from ischaemic events and other diseases resembling RPLS. Failure of cerebral autoregulation, endothelial dysfunction, disrupted blood-brain barrier, vasospasm, and direct toxic drug effects may all play a role in the pathophysiology of RPLS. Treatment consists of discontinuation of the causal drug, treatment of high blood pressure, and antiepileptic therapy. Clinical recovery and regression of radiological abnormalities are typically seen after early treatment. However, delay in diagnosis and treatment can result in irreversible brain damage, often in association with complicating cerebral infarction or haemorrhage.