A diagnostic pearl in new-onset confusion: Answer

Abstract

D The EEG reveals diffuse slowing and a characteristic pattern of fast (beta) activity overriding slow (delta) waves, giving a distinctive “brush” appearance termed extreme delta brush (EDB). This finding is considered highly specific for NMDAR antibody encephalitis and its electrographic recognition should prompt appropriate serological testing [[1]Wang J. Wang K. Wu D. Liang H. Zheng X. Luo B. Extreme delta brush guides to the diagnosis of anti-NMDAR encephalitis.J Neurol Sci. 2015; 353: 81-83Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar]. In our patient, NMDAR antibodies were strongly positive in both CSF and serum thus confirming the diagnosis. EDBs were first described in 2012 as a finding unique to NMDAR encephalitis [[2]Schmitt S.E. Pargeon K. Frechette E.S. Hirsch L.J. Dalmau J. Friedman D. Extreme delta brush: a unique EEG pattern in adults with anti-NMDA receptor encephalitis.Neurology. 2012; 79: 1094-1100Crossref PubMed Scopus (495) Google Scholar]. Various EEG alterations, commonly slowing but also epileptic activity, are identified in the vast majority of NMDAR encephalitis cases but these are non-specific; however up to 30% of cases will also have EDBs on EEG [2Schmitt S.E. Pargeon K. Frechette E.S. Hirsch L.J. Dalmau J. Friedman D. Extreme delta brush: a unique EEG pattern in adults with anti-NMDA receptor encephalitis.Neurology. 2012; 79: 1094-1100Crossref PubMed Scopus (495) Google Scholar, 3Veciana M. Becerra J.L. Fossas P. Muriana D. Sansa G. Santamarina E. et al.EEG extreme delta brush: an ictal pattern in patients with anti-NMDA receptor encephalitis.Epilepsy Behav. 2015; 49: 280-285Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar]. In addition to raising diagnostic suspicion, their presence suggests a more prolonged disease course and an association with seizures and status epilepticus [2Schmitt S.E. Pargeon K. Frechette E.S. Hirsch L.J. Dalmau J. Friedman D. Extreme delta brush: a unique EEG pattern in adults with anti-NMDA receptor encephalitis.Neurology. 2012; 79: 1094-1100Crossref PubMed Scopus (495) Google Scholar, 3Veciana M. Becerra J.L. Fossas P. Muriana D. Sansa G. Santamarina E. et al.EEG extreme delta brush: an ictal pattern in patients with anti-NMDA receptor encephalitis.Epilepsy Behav. 2015; 49: 280-285Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar]. NMDAR encephalitis is an autoimmune disorder mainly affecting younger patients with a female preponderance and varying reported rates of underlying malignancy; in particular ovarian teratoma [[4]Graus F. Titulaer M.J. Balu R. Benseler S. Bien C.G. Cellucci T. et al.A clinical approach to diagnosis of autoimmune encephalitis.Lancet Neurol. 2016; 15: 391-404Abstract Full Text Full Text PDF PubMed Scopus (1949) Google Scholar]. Insomnia, disturbed cognition, abnormal behaviour, psychosis, seizures and dsykinesias have all been described. Definite diagnosis requires positive identification of the pathogenic IgG antibodies against GluN1 subunit of the NMDA receptor [[4]Graus F. Titulaer M.J. Balu R. Benseler S. Bien C.G. Cellucci T. et al.A clinical approach to diagnosis of autoimmune encephalitis.Lancet Neurol. 2016; 15: 391-404Abstract Full Text Full Text PDF PubMed Scopus (1949) Google Scholar]. Our patients’ investigations for malignancy including whole-body PET/CT were all negative. Her CSF had otherwise shown a predominantly lymphocytic pleocytosis, marginally raised protein, normal glucose and negative viral PCR. During her prolonged hospital stay she developed frequent seizures and deteriorating consciousness refractory to immunomodulatory therapy in the form of high-dose corticosteroids, plasma exchange and cyclophosphamide. However she is responding well to rituximab and her serum NMDAR antibodies are now undetectable on this latest treatment. None (all authors). No funding was provided in relation to this manuscript. A diagnostic pearl in new-onset confusionJournal of Clinical NeuroscienceVol. 53PreviewA previously healthy 75-year-old lady presented with 2 weeks of subacute onset confusion and behavioural disturbance. On initial assessment she was afebrile with a Glasgow Coma Scale of 13/15 (E4M5V4), and apart from confusion her neurological examination was normal. Serum full blood count, inflammatory markers, electrolytes, renal and liver function tests were all within normal limits. Urinalysis, chest X-ray and computed tomography of the brain were unremarkable. An EEG was requested (Fig. 1A and B). Full-Text PDF