Limbic encephalitis associated with potassium channel antibodies: demonstration of clinical and paraclinical responses to immunotherapy

Abstract

Materials and methods We describe the case of a 79-year old patient with symptoms of LE who presented with high fever, affective changes in personality, auditory hallucinations, memory loss, irrelevant talking and confusion. The brain MRI at admission showed a left hippocampal T2-weighted lesion with meningeal gadolinium-enhancement and the EEG showed periodic lateralized epileptiform discharges (PLEDS) on the left temporal area. Routine blood tests were normal. CSF examination at admission revealed 50 cells/mm3, predominantly polynuclear (87%) and 0.74 g/l proteins. Polymerase chain reaction for herpes virus 1 to 3, 6 and enterovirus were negative. The patient was treated with acyclovir but three weeks later he developed myoclonia with secondary generalized epileptic seizures. The serum was negative for paraneoplastic antibodies including Hu, Yo, Ri, CV2/CRMP5, Amphiphysin, Ma2/ Ta. Results Despite the anti-epileptic treatment, the patient's symptoms deteriorated. MRI showed new lesions. The EEG showed a new focus of right parietal PLEDS. Serum voltage-gated potassium channel antibodies (VGKC-Ab) were detected at high levels (3.495 pM). Steroids and plasma exchange were initiated with marked and sustained improvement of neuropsychological function. This clinical improvement correlated with both EEG and radiological amelioration.