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Neurological Rehabilitation

Subacute Combined Degeneration as a Result of Nitrous Oxide Overuse

Friday, October 24, 2025
8:00 AM - 9:15 AM MT
Location: Kiosk 6

    Poster Presenter(s)

  • Hannah Park, DO

    Resident
    New York University Grossman School of Medicine PM&R Program
    New York, New York

    • Co-Author(s)

  • Andres Gronda, MD

    Resident
    New York University Grossman School of Medicine PM&R Program
    New York, New York

  • CC

    Cherie Chen, DO (she/her/hers)

    Resident Physician
    New York University Grossman School of Medicine PM&R Program
    New York, New York

  • DG

    Daniel Good, DO

    PM&R Resident
    New York University Grossman School of Medicine PM&R Program
    New York, New York

  • Mark Ragucci, DO

    Attending physician
    Institute of Rehabilitation Med NYU Med Center
    Brooklyn, New York

Disclosure(s):
Hannah Park, DO: No financial relationships to disclose
Andres Gronda, MD: No financial relationships to disclose
Mark Ragucci, DO: No financial relationships to disclose
Case Diagnosis: 24-year-old female presented with altered mental status and subacute combined degeneration secondary to prolonged nitrous oxide use and underwent rehabilitation course for improved gait and mobility.

Case Description or Program Description: Patient presented with encephalopathy and progressive gait instability. She reported multiple falls and lower extremity weakness and paresthesia in the setting of recreational nitrous oxide use for a few weeks. She was found with severe vitamin B12 deficiency, which was repleted. Therapy was initiated in acute care before being admitted to acute inpatient rehabilitation.

Setting: Acute inpatient rehabilitation

Assessment/Results: In inpatient rehabilitation, patient worked on her truncal ataxia and gait imbalances due to foot drop and impaired proprioception. She was fit with ankle-foot orthoses and continued weekly vitamin B12 injections. By discharge, she regained minimal ankle mobility and noted only mild improvements in her proprioception but was able to ambulate 200 feet and negotiate 8 stairs with a single point cane.

Discussion (relevance): Nitrous oxide is used in the medical setting as an anesthetic agent, but its use recreationally has been increasing over the last decade. Nitrous oxide is an NMDA receptor antagonist and partial opioid agonist that can cause decreased consciousness, dizziness, psychedelic effects, and euphoric feelings. Acute toxicity involves dizziness, nausea, headache, and fainting. Chronic toxicity causes subacute combined degeneration associated with vitamin B12 deficiency and results in neurologic deficits including decreased strength and sensation, anemia, and even panic attacks and delusions. These deficits can be permanent and significantly affect patients’ independence and quality of life, especially if there is a delay in seeking care.

Conclusions: Recreational nitrous oxide use has been rising over the last decade, and the associated risks of irreversible neurologic damage are not well-known by many users. Delayed intervention can increase the risk for permanent effects, and rehabilitation is critical for patients who have developed subacute combined degeneration.