Posterior Reversible Encephalopathy Syndrome, Multiple Sclerosis and interferon therapy: Association, co-incidence or convoluted interplay?

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) has only rarely been reported in patients with multiple sclerosis (MS).

METHODS: Case report of a patient with relapsing remitting (RR) MS patient on interferon (INF) treatment, who developed posterior fossa PRES.

RESULTS: A 46-year-old male diagnosed with RR MS in 2010 was placed on INF beta-1a therapy. He remained in clinical remission for seven years. He then presented with headache of one month duration and worsening upper extremity ataxia. Cranial MRI revealed two new enhancing cerebellar lesions (one with tumefactive features). Within the next 10 days the patient developed severe holocephalic headache, vomiting, altered consciousness and gait instability. Urgent brain MRI revealed diffuse hyperintense lesions in T2WI and FLAIR sequences in bilateral cerebellar hemispheres and the right thalamus, with marked swelling, increased diffusivity indicative of vasogenic edema and patchy-nodular enhancement, while smaller lesions were also found in posterior temporal, parietal and occipital lobes. Severely elevated blood pressure was noted. Treatment with hypertonic agents, esmolol drip and IV steroids was instituted, resulting in remarkable improvement within the next several days. Repeat MRI showed almost complete resolution of the cerebellar lesions. Interferon beta was discontinued and blood pressure remained well controlled.

CONCLUSIONS: Patients with RR MS on IFN beta therapy can develop PRES via the combination of hypertension and endothelial dysfunction by IFN, even when stable on this treatment. Neurologists should be keen to differentiate the appearance of PRES lesions from those of fulminant MS relapse, opportunistic infections or malignancy.