Anti-leucine-rich glioma inactivated protein 1 encephalitis with sleep disturbance as the first symptom: A case report and review of literature

BACKGROUND Anti-leucine-rich glioma inactivated protein 1(anti-LGI1) encephalitis is an infrequent type of autoimmune encephalitis(AE) characterized by acute or subacute cognitive and psychiatric disturbance, facio-brachial dystonic seizures(FBDSs), and hyponatremia. Anti-LGI1 AE has increasingly been considered a primary form of AE. Early identification and treatment of this disease are clearly very important.CASE SUMMARY Here, we report that a male patient developed severe anti-LGI1 encephalitis, which was initially misdiagnosed as a sleep disturbance. He was hospitalized for epileptic seizures and typical FBDSs half a month after he developed sleep disturbances. LGI1 antibodies were detected in his cerebrospinal fluid and serum(1:100 and 1:3.2, respectively), which led to the diagnosis of classic anti-LGI1 AE. No obvious abnormality was observed on brain computed tomography images. T2-weighted fluid-attenuated inversion recovery and T2-weighted scans of brain magnetic resonance imaging(MRI) showed slightly elevated signals within the left basal ganglia area. No tumor was detected within the brain of this patient using MRI. After hormone and antiepileptic drug treatment, the patient’s symptoms improved significantly.CONCLUSION Anti-LGI1 antibody-associated encephalitis has characteristic clinical manifestations, such as cognitive impairment, psychiatric symptoms, seizures, sleep disorders, hyponatremia, and FBDSs. LGI1 antibodies are present in the serum and/or cerebrospinal fluid, but their production is sensitive to immunosuppressants, and this disease has a relatively good prognosis. In particular, we should be aware of the possibility of anti-LGI1 antibody-associated encephalitis in adolescents with sleep disorders to avoid missed diagnoses and misdiagnoses.

Neurological diseases associated with autoantibodies targeting the voltage-gated potassium channel complex:immunobiology and clinical characteristics

Voltage-gated potassium channels(VGKCs)represent a group of tetrameric signaling proteins with several functions,including modulation of neuronal excitability and neurotransmitter release.Moreover,VGKCs give a key contribution to the generation of the action potential.VGKCs are complexed with other neuronal proteins,and it is now widely known that serum autoantibodies directed against VGKCs are actually directed against the potassium channel subunits only in a minority of patients.By contrast,these autoantibodies more commonly target three proteins that are complexed with alpha-dendrotoxin-labeled potassium channels in brain extracts.These three proteins are contactin-associated protein-2(Caspr-2),leucine-rich,glioma inactivated 1(LGI-1)protein and the protein Tag-1/contactin-2.Neoplasms are detected only in a minority of seropositive patients for VGKC complex-IgG and do not significantly associate with Caspr-2 or LGI-1.Among all the cancers described in association with VGKC complex-IgG,lung carcinoma,thymoma,and hematologic malignancies are the most commonly detected.We will review all the major neurological conditions associated with VGKC complex-IgG.These include Isaacs’syndrome,Morvan syndrome,limbic encephalitis,facio-brachial dystonic seizures,chorea and other movement disorders,epilepsy,psychosis,gastrointestinal neuromuscular diseases,a subacute encephalopathy that mimics Creutzfeldt-Jakob prion disease both clinically and radiologically and autoimmune chronic pain.The vast majority of these conditions are reversible by immunotherapy,and it is becoming increasingly recognized that early diagnosis and detection of VGKC complex-IgG is critical in order to rapidly start the treatment.As a result,VGKC complex-IgG are now part of the investigation of patients with unexplained subacute onset of epilepsy,memory or cognitive problems,or peripheral nerve hyperexcitability syndromes.