Unilateral Posterior Reversible Encephalopathy Syndrome

An 80-year-old male with a history of type 2 diabetes mellitus, systemic hypertension, and chronic kidney disease – Stage 5 presented to the emergency department with complaints of difficulty in viewing objects on the left side for the past 2 days. He had no other symptoms at that time. At admission, he was noted to have a blood pressure of 210/110 mmHg. Neurological examination revealed left hemianopia and no other deficits were noted. Magnetic resonance imaging (MRI) of the brain was taken; however, it was normal [Figure 1]. On the next day, he developed recurrent episodes of the left focal seizures. Electroencephalogram showed a burst of epileptiform discharges from the right cerebral leads. He was initiated on antiepileptics and the dosage of antihypertensive drugs was optimized. On the next day, he developed disorientation and weakness in his left upper and lower limbs. On examination, he was conscious, confused, obeying commands, and had grade 0/5 power of left upper and lower limbs. MRI brain showed hyperintensity involving the right subcortical region of the occipital lobe on diffusion-weighted imaging, with normal apparent diffusion coefficient values [Figure 2]. Magnetic resonance angiography was normal. On the same day evening, he developed another episode of left focal seizure and antiepileptics were optimized. Over the next 48 h, his sensorium improved, he had no further seizures, left hemianopia improved, and the power of left upper and lower limbs improved to 5/5. The possibility of a unilateral posterior reversible encephalopathy syndrome (PRES) was considered. He was followed up at the end of 4 weeks of the onset of initial symptoms, he had recovered completely and his MRI brain was completely normal [Figure 3].Figure 1: Normal magnetic resonance imaging brain, (a) diffusion-weighted imaging and (b) apparent diffusion coefficient.Figure 2: Magnetic resonance imaging brain showing hyperintensity involving the right subcortical region of occipital lobe on diffusion weighted imaging (blue arrow) (a), with normal apparent diffusion coefficient (b).Figure 3: Normalization of magnetic resonance imaging brain repeated after 4 weeks; (a) diffusion-weighted imaging and (b) apparent diffusion coefficient.PRES is a clinicoradiological syndrome characterized by varied clinical symptoms including altered sensorium, visual disturbance, headache, and seizures.[1] It is a disorder of reversible subcortical vasogenic edema. The most common trigger is hypertension; other triggers include renal failure, eclampsia, sepsis, autoimmune disorders, and cytotoxic drugs.[2] Endothelial dysfunction is implicated to be the underlying mechanism. MRI of the brain typically shows symmetric vasogenic edema involving subcortical white matter of bilateral parietal and occipital lobes which usually does not show restricted diffusion or contrast enhancement.[3] Atypical radiological findings include involvement of the anterior cortex, unilateral involvement, restricted diffusion, contrast enhancement, and hemorrhage. Unilateral PRES is rare and constitutes only 2.6% of all cases.[4] In most of the previously published reports, unilateral PRES was observed in cases with preexisting vascular abnormalities affecting cerebrovascular hemodynamics; however, it was not seen in our patient.[5] Informed written consent was obtained from the patient for reporting this case. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.