Reversible Neuropsychiatric Disturbances Caused By Nitrous Oxide Toxicity: Clinical, Imaging And Electrophysiological Profiles Of 21 Patients With 6-12 Months Follow-Up

Purpose: Nitrous oxide (N2O) abuse has become an increasingly severe problem in China. The aim of the study was to summarize the features of N2O-induced neurology and enhance the awareness of this disease among physicians.Patients and Methods: We retrospectively reviewed the clinical, imaging, electrophysiological characteristics and the prognosis of patients with N2O neurotoxicity in our hospital from January 2016 to August 2019.Results: Twenty-one patients (average age: 22.6 +/- 4.6 years) were collected. Eighty-six percent (18/21) patients presented with acute or subacute neurological disorders as their initial symptoms. The remaining fourteen percent (3/21) had psychiatric symptoms as the earliest symptoms. With progression, movement dysfunction appeared in ninety percent (19/ 21) of the patients with fifty-three percent (10/19) presented with weakness limited to both lower extremities. Sixty-two percent (13/21) of the patients presented with subjective sensory deficit. Seventy-one percent (15/21) had vibration sense impairment and positive Romberg's sign. Sixty-seven percent of the patients had hyporeflexia or areflexia. Fourteen percent (3/ 21) showed positive Babinski's sign. Seventy-eight percent (14/18) showed significantly increased homocysteine (HCY) level and only seventeen percent (3/18) showed decreased serum vitamin B-12 level. T-2 hyperintensity involving the posterior columns and lateral columns with inverted V sign in cervical spinal MRI had been observed in forty-seven percent (8/17) of the patients. Axonal peripheral neuropathy occurred in eighty-five percent (17/20) of the patients. The level of serum vitamin B-12 and HCY, as well as imaging findings, were rapidly recovered after supplementation of Vitamin B-12.Conclusion: The N2O-induced neuropsychiatric disturbances mainly occurred in the young groups and should be recognized by clinicians. The prognosis of N2O intoxication is relatively good.