Background and purpose Although several case series have described nitrous‐oxide‐associated neurological disorders, a comprehensive assessment of exposure characteristics (e.g., time to onset, level of exposure) in substance abusers has not been performed. The aim of this study was to describe the onset patterns of recreational use of nitrous‐oxide‐induced neurological disorders. Methods All cases of neurological disorders related to nitrous oxide recreational use reported to the Hauts‐de‐France addictovigilance center between January 2019 and August 2020 were selected. Only cases requiring hospitalization with informative data to perform the nitrous oxide causality assessment were included. Results A total of 20 cases from five hospitals were included. The male‐to‐female ratio was 6:1 and the median age was 19 years (range 16–34). The neurological presentation (myeloneuropathy 64%, 7/11; sensorimotor neuropathy 36%, 4/11) included for all patients gait disorders due to proprioceptive ataxia and limb hypoesthesia. The median dose used per occasion was 100 cartridges (range 5–960; n = 19). The median time from the start of nitrous oxide use to the onset of neurological symptoms was 6 months (range 0.7–54; n = 16). The cumulative dose was significantly higher in patients with damage to all four limbs than in patients with lower limb symptoms only (p = 0.042). Conclusions A low intermittent exposure may be sufficient to cause neurological damage in some subjects, suggesting that, at the population level, there is no safe exposure to nitrous oxide in recreational settings. The severity of neurological impairment could increase once used at high doses and for prolonged durations of nitrous oxide.

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by acute and usually severe headache related to multifocal vasoconstriction of cerebral arteries, reversible within 3 months. About 10% of RCVS are pregnancy-related, but only three cases of antepartum RCVS have been described. We report the case of a 26-year-old pregnant woman who presented at 36 weeks gestation with antepartum RCVS. Delivery was managed by cesarean section under general anesthesia. Though she developed focal neurologic deficits on the first postoperative day, these resolved at hospital discharge. This case highlights pre-and post-partum multidisciplinary management including cesarean section under general anesthesia.

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