A 32-year-old lady presented with convulsive status epilepticus, altered sensorium, andacute-onset visual loss of counting fingers at one-meter distance. Optic fundi were normal, pupillary reactions brisk, and plantar responses were bilaterally extensor. She had a history of Crohn's disease diagnosed 11 years prior to presentation and was on mesalamine (5-amino salicylic acid) 400 mg twice daily. She had sputum-positive pulmonary tuberculosis (TB) detected four years prior, which was multidrug resistant, andshe was on ethionamide, high-dose ethambutol, cycloserine, and levofloxacin daily. Two months prior to current admission, she had an exacerbation of diarrhea, and colonoscopy showed extensive linear ulceration with cobble stoning in the rectumand transverse and ascending colon. Biopsy showed mixed inflammatory infiltrate and noncaseatinggranulomaof colonic mucosa, consistent with Crohn's disease exacerbation. Her mesalamine dose was doubled to 800 mg twice daily since then.
On current admission, her cerebrospinal fluid study and vasculitic profile were normal, and viral markers including hepatitis B antigen, retro, and hepatitis C virus were negative. Computed tomography (CT) of the brain showed hypodensity in bilateral parieto-occipital subcorticalregions. Magnetic resonance imaging (MRI) of the brain [Figure 1] showed T1 hypointense, T2, and FLAIR (FLAIR: Fluid-attenuated inversion recovery) hyperintense lesions in bilateral parieto-occipital (left > right) and frontal regions without contrast enhancement. Lesions showed no diffusion restriction and were suggestive of PRES. Electroencephalogram (EEG) [Figure 2] showed medium amplitude 3-4 Hz delta and slow theta activity which was generalizedalong with periodic short-interval (0.75 Hz) sharp waves of 100-150 muV amplitude over the right occipital region. There were small-amplitude sharp wave discharges of ~50 muV amplitude superimposed over the after-coming slow waves, giving a PLEDs-plus morphology. On admission, the patient was loaded with valproate for status epilepticus, and it was continued parenterally with follow-up EEG monitoring till the PLEDS-plus subsided. The second EEG of the patient showed disappearance of the PLEDs-plus morphology. But intermittent photic stimulation at low frequency showed grade III photoparoxysmal response (PPR) from bilateral occipital regions (right > left), although the background activity remained the same [Figure 3]. The third EEG of the patient showed disappearance of the PLEDs-plus morphology and PPR. The patient improved clinically with no further seizures, and visual acuity improved to 6/12. The clinical improvement in vision correlated with the electrical resolution of posterior head region PLEDs-plus, which evolved rapidly over three days with parenteral valproate therapy. Mesalamine, given for Crohn's disease, was thought to be the offending drug causing PRES; this was therefore stopped and replaced by steroids.