A 13-year-old female patient with a history of acute lymphoblastic leukemia was admitted to the PICU due to septic shock. She developed two episodes of seizures during her recovery at the age of 12. The first episode started with a 5-second view of a colorful rainbow spot in the midline and lasted for 1 minute. She was noted to have limb and facial twitching, with higher intensity in the right face, that spontaneously resolved. This was followed by a similar episode about 30 minutes later, lasting for 45 seconds, which also stopped spontaneously. One dose of lorazepam was given after the second seizure. She required noninvasive ventilation due to encephalopathic state with decreased consciousness. She was also noted to be hypertensive (BP ∼160/101).

After the patient’s consciousness improved, she reported that she had no memory of the event except seeing the above-mentioned rainbow spot. She was noted to be lethargic with slow responses; there was no headache, vomiting, or numbness. Pupils were equal and reactive to accommodation and light. Neurological examination showed that no facial weakness or asymmetry; cranial nerves also appeared intact. She had normal tone, and her upper limbs were rated 4/5 with antigravity movement, but she had mild proximal muscle weakness in her lower limbs in the power assessment. On the past-­pointing test slight underperformance was observed in the left upper limb. Deep tendon reflexes appeared normal in the upper limbs but were depressed in both knees; these presented after reinforcement but were still absent in ankles. Downgoing plantar reflexes were observed. Sensation was normal.

The patient was initially treated with levetiracetam as an anticonvulsant. Her hypertension was brought down by hydralazine, and labetalol was also administered via IV bolus injection and later changed to oral enalapril and amlodipine. During her recovery, she reported multiple episodes of visual and auditory hallucinations. The former included seeing a rainbow curtain form in both eyes and seeing animals such as a white dinosaur and an orange tiger; the latter included hearing voices from different men talking about buying groceries in a supermarket and having once received a command hallucination asking her to pull away her nasal cannula. Repeated EEG showed no epileptiform discharges.

LP was performed. The opening pressure was normal, no abnormal cells were seen, bacterial and fungal cultures were negative, and viral encephalitis panel was negative. CT venogram showed no evidence of dural venous sinus thrombosis. EEG was abnormal with a mildly suppressed background, which suggested a generalized cerebral dysfunction of nonspecific etiology.

Brain MRI revealed bilateral and relatively symmetric cortico-subcortical edema. Right parieto-occipital hemorrhage was noted ( Fig. 76.1 ).

Posterior reversible leukoencephalopathy syndrome. Brain MRI, (A) axial T2 and (B) FLAIR show bilateral and relatively symmetric cortical/subcortical edema, greatest posteriorly ( arrows ). There is hemorrhage in the right parieto-occipital region ( asterisk ). Additional foci of signal change are noted in the vascular borderzones ( arrowhead ). FLAIR , Fluid-attenuated inversion recovery. (Case courtesy Mai-Lan Ho, MD.)