Neurological Manifestations Induced by Nitrous Oxide Abuse: A Case Series and Review of Literature.

INTRODUCTION: Nitrous oxide (NO) abuse is increasing among young people. This can result in severe neurological disorders such as myelopathy and/or peripheral neuropathy. We report the clinical presentations, biological, radiologic and electrophysiological findings of 5 patients hospitalized with neurological symptoms consecutive to NO abuse. In addition, a literature review was conducted to describe the neurological characteristics and to identify factors associated with a poor recovery. CASE REPORT: Among the 5 patients included, 2 had a myeloneuropathy, 2 had a sensorimotor neuropathy, and 1 had a normal spinal cord magnetic resonance imaging and electromyography despite neurological manifestations consistent with myeloneuropathy. After vitamin B 12 supplementation, recovery was reported in 4 patients, and 1 was lost to follow-up.From the literature review, 154 patients were included [94 males; median age 22 (19 to 26) y; NO exposure 9 (3 to 18) mo]. A myelopathy was identified in 116 patients (75%) and a peripheral neuropathy was documented in 89 patients (58%). Compared with patients who recovered, those with sequelae were more likely to have a motor deficit at presentation ( P <0.001), to use NO regularly ( P <0.001), to have a lower vitamin B 12 level ( P =0.04), and a higher concentration of homocysteine ( P =0.04). A less extensive myelopathy was more frequently found in the group with favorable outcomes ( P =0.002). CONCLUSION: Neurological disorders caused by NO may be challenging with severe clinical patterns. We identified several factors associated with a poor recovery, to make clinicians aware of NO-induced neurotoxicity.