Anti-contactin-associated protein-2 encephalitis: relevance of antibody titres, presentation and outcome.

BACKGROUND AND PURPOSE: To clarify the relevance of titres of IgG antibodies against contactin-associated protein-2 (CASPR2) in diagnosing anti-CASPR2 encephalitis and to describe features and outcomes. METHODS: This was a retrospective analysis of 64 patients with CASPR2 antibodies, categorized independently as 'autoimmune encephalitis' or 'other disease'. Logistic regression methods were performed to identify potential predictors of 'autoimmune encephalitis' in addition to CASPR2 antibodies. RESULTS: An upfront CASPR2 antibody serum titre cut-off at ≥1:200 had a diagnostic sensitivity of 85% and a specificity of 81%. Logistic regression analyses indicated that, in addition to titre, encephalitic magnetic resonance imaging (MRI) was a significant predictor of 'autoimmune encephalitis' (Nagelkerke's R2 = 0.81, P < 0.001) with high sensitivity (84%) and very high specificity (100%). Patients with CASPR2 antibodies and an estimated probability of >70% of having anti-CASPR2 encephalitis (n = 22) had limbic encephalitis (n = 18, one patient plus ataxia), Morvan syndrome (n = 2) or a hyperkinetic movement disorder (n = 2). Median modified Rankin score (mRS) at diagnosis was 3 (range 1-4). Twenty patients were male; median age was 64 (range 54-75) years; 5/15 patients with cerebrospinal fluid data had intrathecal CASPR2 antibody synthesis, and 12/19 with follow-ups >3 months (median 12 months, range 4-43 months) improved by ≥1 mRS point resulting in a median mRS of 2 (range 0-6; one death; all but one having received immunotherapy); and 2/15 patients with follow-up MRI developed hippocampal atrophy. CONCLUSIONS: Only higher CASPR2 serum antibody titres indicate anti-CASPR2 encephalitis, and diagnostic accuracy increases if MRI findings are considered. Anti-CASPR2 encephalitis has characteristic features and a favourable outcome with immunotherapy.

14 & 6Hz positive spikes coinciding with PLEDs.

OBJECTIVE: We describe the coincidence of 14 & 6Hz positive spikes with PLEDs in a patient with clonic status epilepticus of the left upper extremity and the persistence of 14 & 6Hz positive spikes after cessation of status. METHODS: Digital video-EEG recordings were performed using 32-channel EEG equipment (XLTEK, Canada) with all electrodes of the international 10-20 system and additional anterior temporal electrodes in a patient during clonic status epilepticus and 2 months later after cessation of status. RESULTS: The initial EEG during clonic status epilepticus showed right hemispheric PLEDs and right lateral temporal 14 & 6Hz positive spikes in between the PLEDs. Follow up EEG recording 2 months later after cessation of status revealed an absence of PLEDs, a continuous slowing over the right hemisphere and the occipital background of 7Hz. Right lateral temporal 14 & 6Hz positive spikes were recorded in the same frequency and the same localization as in the previous status EEG. CONCLUSIONS: This case demonstrates that a hemisphere which is in a status epilepticus as clinically reflected by clonic status of the left hand and PLEDs in the EEG is still capable to produce a benign variant pattern like 14 & 6Hz positive spikes. SIGNIFICANCE: The generator of 14 & 6Hz positive spikes may still persist despite the presence of severe structural and epileptogenic lesions in the same hemisphere.