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 (N(2)O) abuse has become an increasingly severe problem in China. The aim of the study was to summarize the features of N(2)O-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 N(2)O 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 N(2)O-induced neuropsychiatric disturbances mainly occurred in the young groups and should be recognized by clinicians. The prognosis of N(2)O intoxication is relatively good.