"Whippets"-induced cobalamin deficiency manifesting as cervical myelopathy.
BACKGROUND
Nitrous oxide (N2O) is inhaled in anesthesia and as a recreational drug from whipped cream dispensers. Its abuse reaches approximately 10% in some age groups. By inactivating cobalamin (Cbl) (vitamin B12), N2O can cause neurologic and hematologic manifestations. We present a case of N2O-induced Cbl deficiency presenting as cervical myelopathy.


METHODS
After regularly inhaling N2O for many months, a 31-year-old man developed limb paresthesiae and ataxia over 3 months. Examination revealed finger pseudoathetosis, hyporeflexia, decreased sensation, and gait ataxia. Brain magnetic resonance imaging (MRI) was normal, but the posterior columns of the cervical and upper thoracic cord revealed patchy nonenhancing hyperintense lesions. Serum Cbl was 98 pg/mL (normal = 170-900 pg/mL). Cbl replacement led to recovery within 3 months.


CONCLUSIONS
This patient presented with the symptoms and signs of Cbl deficiency. The MRI lesions in the posterior columns aided the diagnosis. Physicians need to have a high level of suspicion in cases of unexplained Cbl deficiency and myelopathy.
Diamond
Alan L
AL
Department of Neurology, St. Louis University School of Medicine, Missouri 63110, USA.
Diamond
René
R
Freedman
S Mitchell
SM
Thomas
Florian P
FP
D000328:Adult; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009609:Nitrous Oxide / Q000008:administration & dosage; D013116:Spinal Cord / Q000473:pathology; D013118:Spinal Cord Diseases / Q000209:etiology* / Q000473:pathology; D019966:Substance-Related Disorders; D014806:Vitamin B 12 Deficiency / Q000139:chemically induced* / Q000150:complications
D009609:Nitrous Oxide