Nitrous oxide is an odorless gaseous agent used primarily in the administration of anesthesia, as a cooking agent, and often abused as a recreational drug. Recreational abuse of nitrous oxide is done through the inhalation of whip-cream chargers better known as "whippets". Here we outline a case of nitrous oxide abuse through whippets which lead to both thoracic spinal cord myelopathy presenting with profound upper and lower extremity spasticity, and cognitive decline.  

A 46-year-old male presented with subacute onset of bilateral upper and lower extremity rigidity and cognitive decline. Symptoms had started approximately 1 month ago, and vital signs were within normal limits. A comprehensive neurologic exam was completed revealing symmetrical 3+ hyperreflexia, bilateral upward Babinski, non-sustained clonus of the lower extremities, and clasp-knife spasticity of all four extremities. A mini-mental status exam (MMSE) was completed revealing mild dementia (21 points scored). Laboratory testing revealed elevated methylmalonic acid 2920 nmol/L, and homocysteine of 97.5 umol/L. Of note, serum vitamin B12 levels were 714 pg/mL, no anemia or macrocytosis was noted. An MRI of the thoracic spine revealed increased T2 signal within the central portion of the lower and upper thoracic cord. Upon further questioning, the patient endorsed inhaling 30-40 nitrous oxide whipped cream canisters daily for the past 14 months.

He was diagnosed with nitrous oxide-induced B12 deficiency. The patient was started on intramuscular cyanocobalamin 1000 ug daily for 7 days and discharged with oral B12 to an inpatient rehab facility. At the three-month follow-up, symptoms had not improved.