Cyclosporine, tacrolimus (FK506) and interferon-a are effective immunosuppressive agents for the treatment of organ transplant rejection. Previous theories regarding the mechanism of neurotoxicity include neuropeptide-mediated ischemia and high-pressure failure of cerebral autoregulation . Neurotoxicity usually coexists with hypertensive crisis; however, it also occurs in normotensive individuals. These drugs have profound effects directly on the endothelium and cause release of potent vasoconstrictors such as en-dothelin. Disruption of the blood-brain barrier with possible focal loss of vascular autoregulation causes extravasation of fluid,which leads to vasogenic edema.
Figure 7.16 a,b
Eclampsia in a 30-year-old woman with seizures. a T2-weighted image shows high signal intensity lesions in the right corona radiata, posterior corpus callosum and left parieto-occipital region (arrows).The lesion in the left parieto-occipital region has a central very low signal intensity, representing hemorrhage. b On DW image,a small infarct in the right corona radiata (arrow) and a hemorrhagic infarct in the left parieto-occipital region (arrowheads) are shown as hyperintense associated with decreased ADC (not shown).The lesion in the posterior corpus callosum represents vasogenic edema
Tacrolimus neurotoxicity in a 42-year old woman with confusion after liver transplantation. a T2-weighted image shows high signal intensity lesions in the bilateral fronto-parieto-occipital subcortical white matter (arrows). b On DW image, these lesions show slightly hyperintense or isointense signal intensity (arrows). c ADC map shows increased ADC, which with hyperintense lesions (arrows) on DW image indicates T2 shine-through effect.These lesions were resolved on follow-up MRI (not shown)
Uremic encephalopathy in a 10-year-old girl with seizure. She improved after dialysis. a T2-weight-ed image shows hyperintense lesions in bilateral parietal and right frontal subcortical white matter and cortex (arrows). b DW image reveals punctate foci of high signal within T2 high signal area (arrow) in the right frontal lobe and an additional bright lesion in the left occipital lobe.c Follow-up T2-weighted image obtained 5 days later shows incomplete resolution of left parietal high signal area (arrow). d T1-weighted image reveals punctate foci of high signal corresponding to high signal area on the initial DW image (arrow). (From )
Magnetic resonance imaging shows signal changes within the cortex and subcortical white matter in the occipital, posterior temporal, parietal and frontal lobes (Fig. 7.17). Non-transplant patients or those with total body irradiation develop white matter lesions, whereas those conditioned with chemotherapy develop mixed cortical and white matter lesions .
Was this article helpful?