Authors' Reply.

Dear Editor,

Hemodynamic dysregulation due to autonomic nerves involvement is common in Guillain-Barre syndrome (GBS). About 61% of patients suffering from GBS have transient hypertension and 43% have postural hypertension.[1] Persistent hypertension is not a prerequisite for posterior reversible encephalopathy syndrome (PRES) and 15 to 20% of subjects with PRES are normotensive or hypotensive.[2] Transient hypertension is sufficient to disrupt the autoregulation and lead to PRES. Moreover, the upper limit for autoregulation varies between different individuals. Our patient did not have persistent hypertension, but could have had transient hypertension.

In the literature, there are 5 case reports of PRES following IVIG. Mathy et al reported PRES on the first day of IVIG, and Voltz et al described PRES after 3 days of IVIG. Doss-Esper et al reported PRES and reversible cerebral vasoconstriction syndrome leading to stroke after one day administration of IVIG, Koichihara et al described PRES in a 14-year-old girl 3 days after IVIG, and Faruk Incecik et al reported PRES after 5 days of IVIG. Actually, all patients developed PRES within 5 days of IVIG treatment. Although these patients were diagnosed to develop PRES related to IVIG, transient autonomic disturbance secondary to GBS could also have contributed to PRES.[34567] In the study conducted by Doss-Esper et al, the patient developed acute hypertension after IVIG. Our patient developed PRES following 10 days of IVIG treatment which makes it an improbable cause for PRES. PRES has been reported to be associated with other autoimmune diseases, such as neuromyelitis optica spectrum disorders, autoimmune thyroid disease and systemic lupus erythematosus.[8910] Further research is required to explain the occurrence of PRES with GBS and other autoimmune disorders.

Based on just few case reports, we would not conclude that PRES precedes GBS. We believe PRES can either precede or occur during the course of GBS. GBS with dysautonomia can be considered as an independent risk factor for PRES.

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