Nitrous Oxide Abuse: Clinical Outcomes, Pharmacology, Pharmacokinetics, Toxicity and Impact on Metabolism.

The recreational use of nitrous oxide (N2O), also called laughing gas, has increased significantly in recent years. In 2022, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) recognized it as one of the most prevalent psychoactive substances used in Europe. Chronic nitrous oxide (N2O) exposure can lead to various clinical manifestations. The most frequent symptoms are neurological (sensitive or motor disorders), but there are also other manifestations like psychiatric manifestations or cardiovascular disorders (thrombosis events). N2O also affects various neurotransmitter systems, leading to its anesthetic, analgesic, anxiolytic and antidepressant properties. N2O is very challenging to measure in biological matrices. Thus, in cases of N2O intoxication, indirect biomarkers such as vitamin B12, plasma homocysteine and plasma MMA should be explored for diagnosis and assessment. Others markers, like oxidative stress markers, could be promising but need to be further investigated.

Comparison of biomarker for diagnosis of nitrous oxide abuse: challenge of cobalamin metabolic parameters, a retrospective study.

BACKGROUND: Recreational use of nitrous oxide (N2O) leads to neurological disorders including combined subacute degeneration of spinal cord, psychological disorders, and thrombosis. Serum or urine N2O assays could not be routinely performed. Hence, it is necessary to investigate other biological markers such as metabolic markers. We aimed here to challenge the three main biological markers used for the diagnosis of nitrous oxide abuse as total vitamin B12, homocysteine, and methylmalonic acid. METHODS: We retrospectively collected clinical and biological data from 52 patients with known, documented chronic N2O abuse and associated clinical signs (peripheral neuropathy disability score or thrombosis event). Sera and plasma total vitamin B12, methylmalonic acid (MMA), and homocysteine were performed to identify the most specific marker of chronic N2O intoxication and related clinical outcomes. RESULTS: Plasma homocysteine was almost consistently increased in case of N2O chronic consumption, whereas MMA increase and total vitamin B12 decrease are not systematically found. Our results showed that none of the markers are correlated with levels of N2O consumptions. However, homocysteine and MMA are correlated with clinical severity, but MMA seems to be a better marker of clinical severity. CONCLUSION: There is no specific marker of nitrous oxide abuse according to levels of consumption, total vitamin B12 decrease could not be used either as consumption or as severity marker. However, we showed that homocysteine is consistently increased and could be used as marker of recent N2O consumption. On the other hand, we showed that MMA could be used as a marker of clinical gravity.

Epidural cavernous haemangioma during pregnancy: a case report and a literature review.

Cavernous haemangiomas are benign vascular malformations that can locate in the central nervous system. The epidural spinal location remains unusual. Pregnancy is known to be a precipitating factor. The aim of this study is to review general aspects of these lesions and specific facts about their relationship to pregnancy. A 32-year-old full-term pregnant woman is managed during early labor for a progressive spinal cord compression syndrome. After delivery, exploration by a lumbar MRI found an epidural vascular dorsal mass. Surgical exploration and histopathological examination confirmed the diagnosis of epidural cavernous haemangioma. The patient achieved complete recovery after 1 month. Spinal cavernous haemangiomas are rare malformations. Specific mechanisms seems to be involved in their growth during pregnancy. Although clinical and radiological presentation are spectacular and misleading, the prognosis is generally good, and urgent surgical treatment during pregnancy is usually not indicated.

Clinical course of neuromyelitis optica spectrum disorder in a moroccan cohort.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) was suggested to be more frequent and have specific features among populations from Africa or North Africa. However, we could not find any large study about NMOSD in an African population in the medical literature. OBJECTIVES: To describe the characteristics of NMOSD in a Moroccan monocenter population. PATIENTS AND METHODS: A retrospective study was conducted. Patients fromJanuary 1999 to December 2015 fulfilling the 2015 International Consensus Criteria for NMOSD were included. RESULTS: Sixty four patients fulfilled the criteria. Mean age at onset was 35.7 ±â€¯10.7 years, and the sex ratio was 1/3.57. First clinical event was represented by optic neuritis (38.1%), followed by myelitis (27.0%) and a Devic's syndrome (17.2%). Mean annualized relapse rate was 1.07 ± 1.23 and mean EDSS at last visit was 5.1 ±â€¯2.8. Aquaporine 4 antibodies were positive in 47.1%. Brain lesions were found in 71.2%. Most patients (76.6%) received disease-modifying therapy, mainly cyclophosphamide (86.0%) and 49% remained relapse-free after treatment initiation CONCLUSION: Data from our study suggest more similarities between North African NMOSD patients and non-Caucasian populations. More studies are needed to assess other pathological patterns and compare disease course to other populations.