Clinical application and evaluation of the Bien diagnostic criteria for Rasmussen encephalitis

Abstract

Purpose: The 2005 diagnostic criteria for Rasmussen encephalitis (RE) are based on seizures, clinical deficits, electroencephalography (EEG), neuroimaging, and pathology (Brain, 128, 2005, 451). We applied these criteria to patients evaluated for RE and epilepsy surgery controls to determine the sensitivity, specificity, and positive and negative predictive values (PPVs, NPVs) using pathology as the gold standard.

Methods: We identified patients evaluated for RE based on medical records from 1993 to 2011. Fifty-two control patients with refractory epilepsy, unilateral magnetic resonance imaging (MRI) changes, and biopsies were selected from an epilepsy surgery database from matching years. Patients meeting all three of group A and/or two of three group B criteria were classified as meeting full criteria (positive). Patients not meeting full criteria were classified as negative. When available, pathology findings were re-reviewed with neuropathologists, and MRI imaging was re-reviewed with a neuroradiologist.

Key findings: RE was considered in the differential diagnosis for 82 patients, of whom 35 had biopsies. Twenty patients met full criteria (positive) without another explanation, including seven for whom biopsy was required to meet criteria and one in whom another etiology was identified. Two patients met full criteria but had another explanation. Thirty-five met partial criteria (negative), of whom 14 had another etiology identified. Twenty-five met no criteria (negative). The diagnostic criteria had a sensitivity of 81% with four false negatives (criteria-negative, biopsy-positive) when compared to pathology as a gold standard. Five false positives (criteria positive, biopsy negative) had identifiable alternate diagnoses.

Significance: The 2005 Bien clinical diagnostic criteria for RE have reasonably high sensitivity and specificity and good clinical-pathologic correlation in most cases. We suggest modification of the criteria to allow inclusion of cases with well-described but less common features. Specifically we suggest making the diagnosis in the absence of epilepsia partialis continua (EPC) or clear progression of focal cortical deficits or MRI findings if biopsy is positive and two of the A criteria are met (B3 plus two of three A criteria). This would improve the sensitivity of the criteria.

Keywords: Encephalitis; Epilepsia partialis continua; Epilepsy; Focal seizures; Inflammation; Rasmussen encephalitis.