Case 341: Infratentorial Posterior Reversible Encephalopathy Syndrome Associated with Interferon-β in Relapsing Multiple Sclerosis

A 36-year-old man with known history of relapsing multiple sclerosis (RMS) of 13-year duration who was undergoing continuous treatment with subcutaneous interferon-β (INF-β) (44 µg three times per week) presented to the emergency department of our hospital with blurry vision of 1-week duration. Routine MRI performed 1 month earlier had revealed five new fluid-attenuated inversion recovery (FLAIR) T2-hyperintense cerebellar lesions without contrast enhancement, suggesting active RMS, albeit without corresponding neurologic deficits. The patient denied any other symptoms, apart from known yet intensified intermittent tension-type headaches. His history was unremarkable for drug use, recent infections, or travel. There was no routine use of other medication. Apart from a markedly elevated blood pressure (214/122 mm Hg), vital signs were within normal ranges (heart rate, 72 beats per minute; temperature, 97.9 °F [36.6 °C]; respiratory rate, 19 breaths per minute; oxygen saturation, 100%). Physical examination findings were unremarkable. Findings of a neurologic examination were normal, except for known saccadic gaze, with an Expanded Disability Status Scale (or EDSS) of 1. Acute ophthalmologic evaluation with fundoscopy showed bilateral hypertensive retinopathy, without signs of optic neuritis. Laboratory analysis revealed known increased liver enzyme levels due to INF-β treatment (aspartate aminotransferase level, 123 U/L [2.05 µkat/L]; normal range, 11-34 U/L [0.18-0.57 µkat/L]; alanine aminotransferase level, 179 U/L [2.99 µkat/L]; normal range, 9-59 U/L [0.15-0.99 µkat/L]; γ-glutamyl transferase level, 154 U/L [2.57 µkat/L]; normal range, 12-68 U/L [0.20-1.14 µkat/L]). The patient was admitted for further diagnostic evaluation, including new brain and spinal (not shown) MRI studies. Antihypertensive treatment with perindopril and amlodipine was initiated. Further laboratory examinations revealed microalbuminuria (albumin-to-creatinine ratio in urine, 59.21 mg/mmol; reference range, <3.00 mg/mmol) and hyperlipidemia (low-density lipoprotein cholesterol level, 3.84 mmol/L; reference range, 1.60-3.40 mmol/L). Blood serologic examination and cerebrospinal fluid (CSF) laboratory analysis were unremarkable, except for positive oligoclonal bands, with a polymerase chain reaction panel that was negative for common meningitis and/or encephalitis pathogens and a polymerase chain reaction test that was negative for human polyomavirus 2 (or JC virus) DNA in the CSF. The clinical course supported a wait-and-see approach without the use of steroids or antimicrobial therapy. Follow-up contrast-enhanced brain MRI was performed 1 week after presentation.