No abstract

BackgroundUrea cycle disorders are secondary to defects in the system converting ammonia into urea, causing accumulation of ammonia and other byproducts which are neurotoxic. Ornithine transcarbamylase deficiency is the most common of the urea cycle disorders and frequently presents with coma or seizures during hyperammonemia. However, seizures can also occur without metabolic decompensation.Case presentationWe describe a 23-year-old Chinese woman with urea cycle disorder who presented with confusion due to focal seizures arising from the left frontotemporal region. Interestingly, her ammonia levels remained normal during the seizures. Neuroimaging showed bilateral mesial temporal sclerosis. Her seizures were successfully controlled with two anti-epileptic medications.ConclusionsThis case adds evidence of the predisposition of the temporal lobe to injury in urea cycle disorder. Urea cycle disorder can lead to mesial temporal sclerosis which leads to increased susceptibility of patients to seizures regardless of their metabolic state.

A 15-year-old boy developed progressive cerebellar dysfunction over three weeks.Examination showed ataxic gait, unsteady tandem gait, horizontal nystagmus, intention tremor, and ataxia on heel-toe-shin testing (Video 1). Dysdiadochokinesia and dysarthria were found but not illustrated in the video. Neuroimaging and cerebrospinal fluid (CSF) biochemistry was normal. Serum and CSF metabotropic glutamate receptor type 1 (anti-mGluR1) auto-antibodies were found. His cerebellar function improved markedly within three months of initiating immunotherapy (Video 1). The median age of onset of anti-mGluR1 encephalitis is 55 years old. 1,2 Paraneoplastic syndromes should be considered, but anti-mGluR1 encephalitis is often autoimmune in younger patients. 1,2 WNL-2022-201173_slides ---http://links.lww.com/WNL/C322 WNL-2022-201173_vid1 ---http://links.lww.com/WNL/C323