Introduction: As the recreational use of nitrous oxide in the public has increased, there have been increasing case reports of nitrous oxide related myeloneuropathies. Although myelopathy is a common finding in severe cervical spinal stenosis, it should raise flags in younger patients. We report the clinical and radiological manifestations in 7 cases with nitrous oxide related subacute combined degeneration of the spinal cord from a single large tertiary medical center and offer a review of the literature.
Methods: Our case series included 7 patients seen from 2014 to 2018 and followed over 3-60 months that were identified as having nitrous oxide related myelopathy. Chart review was conducted to describe the history and physical findings of each patient. A thorough literature search was performed using MEDLINE and EMBASE using the search terms “nitrous oxide”, “subacute combined degeneration”, “case report”, and “myelopathy.” In total, 34 publications met the inclusion criteria, with 58 patients included in our analysis.
Results: The mean age of patients was 40. 78% of cases were related to recreational use of NO, and the mean age of recreationally using patients was 31. Most patients are treated with intramuscular (IM) vitamin B12 injections. Two patients treated with oral vitamin B12 worsened neurologically. We also found an inverse relationship between serum vitamin B12 levels and severity of symptoms.
Conclusions: Although myelopathy is a common finding in patients with severe cervical spinal stenosis, further consideration should be given to younger patients. Patients with nitrous oxide related myelopathy tend to have worse symptoms when vitamin B12 levels are less than 100 ng/L and have improved recovery rates when treated with IM B12.
Patient Care: Identification of this disease process with increasing incidence and optimal treatment as well as diagnostic implications of serum levels
Learning Objectives: 1) Suspect other pathology when younger patients present with signs of myelopathy
2) Measuring B12 levels may correlate with severity of disease
3) Treat B12 deficiency with IM injections