ABSTRACT
Introduction
Autoimmune encephalitis (AIE) is a group of immune-mediated inflammatory processes of the brain with marked psychiatric features. Although relatively rare, they might offer difficult differential diagnosis with psychiatric conditions, especially catatonia and psychotic syndromes. Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is the most common AIE, presenting with psychiatric syndromes in 90% of cases. The associated psychopathology is complex, pleomorphic, and best characterized when there is involvement of a psychiatrist in the assessment.
Areas covered
This text will review the main aspects of AIE to psychiatrists and/or neuropsychiatrists.
Expert opinion
Immune system dysfunction has been implicated in the pathophysiology of psychiatric symptoms and disorders. The use of diagnostic criteria for possible AIE, especially when specific antibodies of AIE are not available, allows early diagnosis and prompt treatment which are associated with better clinical outcomes. The study of the psychiatric aspects of AIE can broaden our knowledge of the underlying mechanisms of various psychiatric manifestations.
Article highlights
The estimated annual incidence of autoimmune encephalitis (AIE) is between 8 and 15 cases per 1.000.000 people per year.
Firstly described in 2005, anti-NMDAR encephalitis is the most common AIE, with female to male ratio of 4:1 and an average age at onset of 21 years. Psychiatric symptoms are present in approximately 90% of cases. The psychopathology is often polymorphic, with psychosis (45–67%) and catatonia (~30%) being relatively frequent.
Psychiatric syndromes have been described in other AIE. For instance, they have been reported in 67% of patients with anti-GABA-B encephalitis and 63% of patients with anti-LGI1 encephalitis. Discerning between AIE and primary psychiatric disorders can be a challenging task.
There are warning signs, or ‘red flags,’ which point to the diagnosis of AIE: presence of a psychotic syndrome with rapid progression (less than 3 months), absence of previously known psychiatric disorder, occurrence of neurological (e.g. seizures) and/or systemic symptoms (e.g. fever), and poor response to standard psychopharmacological strategies.
There are different immune-based therapies for AIE. First-line strategies consist of steroids, intravenous immunoglobulin, or plasmapheresis. Second-line consists of cyclophosphamide and rituximab. Patients with paraneoplastic AIE need to have the primary tumor removed.
List of abbreviations
ADEMAcute disseminated encephalomyelitis
AIE Autoimmune encephalitis
CSFCerebrospinal fluid
CNS Central nervous system
EEGElectroencephalography
FBDS Faciobrachial dystonic seizures
GABA Gama-aminobutyric acid
HE Hashimoto<apos;>s encephalopathy
HU Neuronal nuclear antibody type I
HSV Herpes simplex virus
LGI1Anti-leucine-rich glioma inactivated 1
MOG Myelin-oligodendrocyte-glycoprotein
MRI Magnetic resonance imaging
NMDAR N-methyl-d-aspartate receptor
PNS Paraneoplastic neurologic syndrome
SARS-CoV-2Severe acute respiratory syndrome coronavirus 2
Declaration of interests
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
Reviewer disclosures
Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.