To objectively analyze the electroencephalogram (EEG) results in patients with posterior reversible encephalopathy syndrome (PRES) through systematic review and meta-analysis. 

To our knowledge, this is the first meta-analysis performed on this subject matter.

MEDLINE, EMBASE, and ClinicalTrials.gov databases were systematically searched for studies with EEG findings in patients with PRES. Following search strategy was used, “PRES” OR “posterior reversible encephalopathy syndrome” OR “reversible posterior encephalopathy syndrome” OR “Reversible posterior leukoencephalopathy syndrome” AND “EEG” OR “electroencephalography” OR “electroencephalogram”. A random effects model was used to estimate pooled proportions of EEG data with 95 percent confidence intervals (CIs), and the study heterogeneity was analyzed.

In total, 20 studies with 503 patients were included in this single-arm meta-analysis. EEG findings were stratified into four groups, 1) generalized or focal slowing, 2) electrographic seizures, 3) status epilepticus, 4) lateralized periodic discharges (LPDs). Generalized slowing in the pooled proportions was the most common finding among the patients with PRES (0.70, [95% CI: 0.61-0.80]; I² = 90%; p < 0.01), and focal slowing was observed in 19% (0.19 [95% CI: 0.10-0.34]; I² = 77%; p < 0.01). Electrographic seizures were captured on routine or continuous EEG in 23% of the cases (0.23 [95% CI: 0.11-0.49]; I² = 90%; p < 0.01). Status epilepticus were observed in 24% of the cases (0.24 [95% CI: 0.12-0.51]; I² = 93%; p < 0.01). Proportions of LPDs were the least common finding present in only 8% of the population (0.08 [95% CI: 0.03-0.21]; I² = 77%; p < 0.01).

Our study showed that the slowing of the EEG was most common finding in PRES. Generalized slowing was seen in 71% and focal in 19%. Status epilepticus was observed in 24% of patient population. Electrographic seizures were recorded in 23% of patients and LPDs were seen in 8% of patients.