Page 239 - Read Online

tomography can show cortical hypermetabolism in other autoantigens (LGI1 and CASPR2) are associated
acute stages and hypometabolism in more subacute with this LE.
stages of the illness. [5,41] In over three‑quarters of patients,
EEG shows generalized or frontotemporal slow or Antibody‑mediated mutation and disrupted function
disorganized activity without epileptic discharges. [28] of LGI1 (a secreted neuronal protein that interacts
These findings may overlap with electrographic seizures. with presynaptic and postsynaptic receptors) have
been associated with the syndrome of autosomal
Other autoimmune encephalitis dominant lateral temporal lobe epilepsy, [5,47] and have
This group of autoimmune diseases can be defined as been shown to cause increased excitability, which
LE. LE was first described in the 1960s in patients with may result in memory disturbances, confusion and
severe short‑term memory impairment or dementia seizures, with MRI findings that are usually typical of
in association with bronchial carcinoma. [42] Cardinal LE. LGI1 antibodies have been most recently associated
symptoms of LE are severe short‑term memory with adult‑onset brief, but frequent motor events
impairment with psychiatric symptoms such as which comprise unilateral upper limb jerking and
personality change, depression, anxiety, hallucinations, ipsilateral facial grimacing, termed “faciobrachial
confusion, and complex partial‑often temporal or dystonic seizures”. [43] Some patients develop
classically in LGI1 encephalitis facio‑brachial tonic hyponatremia (60%) or REM sleep‑behavior disorders.
seizures [43] and generalized seizures. [44] Another Only 11% of cases are associated with a neoplasm, most
prominent symptom found in 40% of patients and commonly thymoma or SCLC. [16] In those who do have
also exhibited in mice lacking LGI1, [16] is myoclonus. a tumor, the encephalitis can precede the identification
of the neoplasm in up to three‑quarters of patients. [48,49]
Anti-AMPAR encephalitis
AMPAR antibodies (Glutamate receptors ‑ GluR1/2) Anti-CASPR2 encephalitis
can be one of the autoimmune causes of LE. Glutamate Contactin associated protein 2 is an axonal protein of
is one of the main excitatory neurotransmitters with the neurexin IV superfamily. Mutations in the human
GluR1/2 being the predominant AMPA subtype in the gene encoding CASPR2 have been associated with
hippocampus (GluR3 is associated with the distinct autism, epilepsy, obsessive‑compulsive disorders,
disorder, Rasmussen’s syndrome). About 70% of and Tourette syndrome. [10] These patients usually
patients have an underlying tumor in the lung, breast develop symptoms of encephalitis, drug‑refractory
or thymus. [13,45] These patients develop acute limbic epilepsy, peripheral nerve hyperexcitability, or
dysfunction that can be associated with prominent both (Morvan’s syndrome or neuromyotonia). [17,50]
psychiatric symptoms. Most patients, commonly CNS symptoms include cognitive impairment, memory
middle‑aged women, present with the subacute loss, hallucinations, and seizures.
onset of disorientation, confusion, memory loss, and
aggressive behavior. CSF findings and brain MRI are MOOD AND PSYCHOTIC SYMPTOMS IN
similar to those of anti‑NMDAR encephalitis. The AUTOIMMUNE ENCEPHALITIS
long‑term prognosis depends on the controlling of the
tumor and presence of coexisting symptoms related to Depending on the clinical presentation and the
onconeuronal antibodies. timing of evaluation, the psychiatric manifestations
of autoimmune encephalitis can be diagnosed following
Anti-γ-amino-butyric acid beta encephalitis DSM 5 criteria as mood disorder with psychotic
This encephalitis is caused by disruption of the and or catatonic features due to a general medical
metabotropic GABAbR, and equally affects both sexes. condition (GMC), but also as psychotic disorder or
These patients present with LE, prominent seizures, delirium due to GMC, where the GMC is autoimmune
and memory dysfunction. [46] About half of the patients encephalitis. In many patients, there is no previous
had an associated tumor, either a small cell lung personal or family history of psychiatric disorders. The
cancer (SCLC) or a neuroendocrine tumor of the lung. psychiatric presentation looks like a delirious mania
[15]
The MRI and CSF findings are similar to those in other or acute confusional state that develops over a short
types of LE, with unilateral or bilateral increases in period of time, fluctuates over the course of the day and
medial temporal lobe FLAIR or T2 signal consistent manifests with changes in cognition, affect, behavior,
with LE and CSF lymphocytic pleocytosis. and perception. Initially, the features may be subtle, but
over days to weeks, there may be dramatic worsening,
Anti-LGI1 encephalitis culminating in an unresponsive and catatonic state. [51]
Although previously termed anti‑voltage‑gated
potassium channel encephalitis (anti‑VGKC Patients may present labile mood, with a wide range
encephalitis), recent evidence suggests that actually of emotions including anxiety, low or euphoric mood,

Neuroimmunol Neuroinflammation | Volume 2 | Issue 4 | October 15, 2015 231