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Nitrous oxide (N 2 O) is widely used as an anesthetic or an analgesic. N 2 O prolonged and recurrent administration is known to affect vitamin B12 metabolism with subsequent clinical consequences. We report herein the case of a 13-year-old girl with sickle cell disease exhibiting severe neurological and biochemical signs of functional vitamin B12 deficiency due to prolonged and repeated exposure to N 2 O. This was an incentive to prospectively investigate functional vitamin B12 deficiency in patients affected by sickle cell disease regularly exposed to N 2 O. We measured plasma concentrations of vitamin B12, total homocysteine, methionine and methylmalonic acid in 39 patients with sickle cell disease between 2015 and 2016. No patients developed neurological symptoms related to N 2 O administration but 19 patients (49%) had biochemical abnormalities suggesting mildly disturbed vitamin B12 metabolism e.g. decreased B12 vitamin, hypomethioninemia, or slightly increased methylmalonic acid or homocysteine. The clinical case highlight the potential severe deleterious effects of N 2 O over exposure on B12 vitamin metabolism in particular in patients affected with sickle cell disease. Conversely, when used without excess even repeatedly, there seem to be no overt clinically relevant abnormalities in vitamin B12 metabolism as observed on the cohort of 39 sickle cell disease affected patients., Competing Interests: The authors declare no competing interests., (© 2020 Published by Elsevier Inc.)

Biallelic mutations in the PLCB1 gene, encoding for a phospholipase C beta isoform strongly expressed in the brain, have been reported to cause infantile epileptic encephalopathy in only four children to date. We report here three additional patients to delineate the phenotypic and genotypic characteristics of the disease. Our three patients were one sporadic case with an intragenic homozygous deletion and two cousins with the homozygous p.(Arg222*) nonsense variant in PLCB1. These patients had severe to profound intellectual disability, epileptic spasms at age 3-5 months concomitant with developmental arrest or regression, other seizure types and drug-resistant epilepsy. With this report, we expand the clinical, radiologic and electroencephalographic knowledge about the extremely rare PLCB1-related encephalopathy. Since the first report in 2010, the overall number of reported patients with our additional patients is currently limited to seven. All seven patients had epileptic encephalopathy, mainly infantile spasms and 6/7 had profound intellectual disability, with one only being able to walk. Truncal hypotonia was the most frequent neurological sign, sometimes associated with pyramidal and/or extrapyramidal hypertonia of limbs. Microcephaly was inconstant. In conclusion, the phenotypical spectrum of PLCB1-related encephalopathy is relatively narrow, comprises infantile spasms and severe to profound intellectual disability, and does not seem to define a recognizable clinical entity., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Epileptic encephalopathy with continuous spikes-and-waves during sleep (EE-CSWS) is a rare childhood epilepsy syndrome characterized by a regression in cognitive, behavioral and psychiatric functioning, seizures and a specific electroencephalographic pattern. An early recognition and an appropriate treatment might play a key role in the outcome of this epileptic encephalopathy. We conducted a case-control study to evaluate if there is any clinical or electroencephalographic sign suggestive of EE-CSWS after the first seizure. We retrospectively identified 10 EE-CSWS patients with available EEG recordings at time of the first seizure. We matched them with 10 controls from our first seizure clinics. All EEG recording were analyzed for the study. We did not find any clinical or EEG features that would suggest later development of EE-CSWS. As reported by others, the occurrence of multiple seizures types and a seizure worsening during the follow-up is more frequent in the cases than in the controls. These clinical criteria might be used as a red flag in clinical practice to identify the very few patients with EE-CSWS among the frequent patients with BECTS., (Copyright © 2018 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)