VGKC Encephalitis

Clinic

• It seems that VGKC encephalitis would be a COD. Limbic encephalitis, Neuromyotonia, Morvan 's syndrome, Anti-LGI-1 encephalitis and Anti-CASPR2 encephalitis would be the best candidates.
• VGKC-complex = Voltage gated potassium channel-complex
• Antibodies against VGKC-complex play central role in this autoimmune encephalitis
• It is including
  • Limbic encephalitis
  • Seizure
  • Neuromyotonia (i.e. Isaacs' Syndrome)
• Further studies led to VGKC antibodies being recognized in Morvan’s syndrome and limbic encephalitis as well.

Types

• Anti-LGI-1 encephalitis

• Anti-CASPR2 encephalitis
• Morvan’s syndrome

• Neuromyotonia (i.e. peripheral hyperexcitability)
• Limbic encephalitis
• Anti-DPPX Encephalitis

Summation of Sign / Symptoms

	Cognitive Dysfunction Memory deficits	Myoclonus Myokymia Fasciculations Cramp Peripheral nerve hyperexcitability Dyskinesia	Tremor	Seizures	Brainstem Cerebellar Dysfunction Ataxia	Sleep disturbance Agrypnia RBD	Delusions, Hallucinations, Agitation, Psychosis	General symptoms	Sympathetic over activation) Hyperhidrosis Tachycardia Increased body temperature Hypertension	Fatigue, Exercise intolerance
Anti-LGI-1 encephalitis	+++	+++		+++ Faciobrachial dystonic seizures	+++	+++		Hyponatremia
Anti-CASPR2 encephalitis	+++			+++	+++	+++		weight Loss / Neuropathic pain	+++
Morvan’s syndrome		+++				+++	+++	Pruritus	+++
Neuromyotonia		+++							+++	+++
Limbic encephalitis	+++			+++		+++	+++	Headache
Anti-DPPX Encephalitis	+++	++	+++	+++	+++

Case 1

• Encephalitis due to antibodies to voltage gated potassium channel (VGKC) typically presents with limbic encephalitis and medial temporal lobe involvement on neuroimaging.
• Here is a case of 13 year girl female with VGKC encephalitis with signal changes in the cerebellar dentate nuclei bilaterally and clinical features that suggested predominant cerebellar involvement.
• A 13 year old previously healthy and developmentally normal female presented with 3 days of fatigue and muscle aches.
• One day prior to admission to our institution, she developed unsteadiness and inability to walk.
• This was followed by alteration of sensorium that progressed to stupor and bilateral 6^th nerve palsies.
• Brain MRI showed hyperintensities involving the dentate nuclei bilaterally
• She had no clinical seizures and EEG on multiple occasions failed to reveal epileptiform discharges or electrographic seizures.
• Extensive infectious and rheumatological work-up was negative.
• Antibodies to VGKC were positive and elevated
• She had significant dysarthria, truncal and gait ataxia, dysmetria, and nystagmus.
• Although these cerebellar signs improved, she was left with residual deficits. Repeat MRI showed resolution of the previously seen signal changes in the dentate nuclei.

Case 2

• An 80-year-old gentleman who presented with memory impairment, seizure and hyponatraemia.
• He was found to have high titre of VGKC antibodies in his serum
• He was commenced recently on carbamazepine for generalised tonic clonic seizures.
• His blood tests showed sodium of 121. After extensive investigations, low sodium was thought to be due to antiepileptic.
• The neurology team diagnosed him as immune-mediated encephalitis based on increasing falls, short-term memory loss (reported by his wife and evening ward staff), seizures and low sodium.
• Serum VGKC antibodieswere strongly positive
• Herpes simplex, varicella zoster, enterovirus PCR and treponema pallidum were all negative.

Sign/ Symptoms

	Case 1	Case 2	Miasm
	Altered level of consciousness Dysarthria Ataxia Nystagmus	Seizure Memory weakness Hyponatraemia	CJD