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Critical Care |

"Whippet" Into Your Differential FREE TO VIEW

Matthew Anderson, MD; Trina Hollatz, MD
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University of Wisconsin, Madison, WI


Chest. 2015;148(4_MeetingAbstracts):198A. doi:10.1378/chest.2262474
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Abstract

SESSION TITLE: Critical Care Case Report Posters

SESSION TYPE: Affiliate Case Report Poster

PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM

INTRODUCTION: The differential diagnosis of a patient presenting with confusion and neurologic abnormalities is broad. Recreational drug use is a common etiology while vitamin deficiency is more rare. Here we present a case of recreational drug abuse precipitating severe vitamin deficiency resulting in neurologic abnormalities.

CASE PRESENTATION: A 60-year-old male presented with altered mental status and ataxia. He had a history of deteriorating mental status and progressive ataxia for several months. Notably he had been a chronically abusing nitrous oxide (N2O), known recreationally as “whippits”. In the ED the patient’s mental status worsened, requiring intubation for airway protection. Physical exam was limited due to sedation. Diagnostic investigations revealed negative toxicology, pancytopenia, severely low vitamin B12 level with elevated methylmalonic acid and homocysteine levels. MRI of the spine revealed increased T2 signal intensity at the C3-C4 and C4-C5 levels. The patient was diagnosed with N2O induced severe vitamin B12 deficiency and neurotoxicity. He was treated with vitamin B12, leucovorin and thiamine, which yielded rapid improvement in hematologic abnormalities. He was discharged to inpatient rehabilitation with mild improvement in his neurologic abnormalities.

DISCUSSION: N2O is used as an inhalational dissociative anesthetic and is available as a propellant in pressurized containers. N2O is a commonly abused inhalant. Abuse resulting in severe vitamin B12 deficiency and injury to the dorsal column of the spinal cord and peripheral nervous system has been described; however, it is uncommon likely due to a dose-response correlation. Mechanistically nitrous oxide irreversibly inactivates vitamin B12 leading to a functional deficiency ultimately inhibiting myelin formation in the spinal cord and peripheral nerves. Diagnostic imaging may reveal lesions on T2 weighted MRI. Treatment consists of vitamin B12 replacement and discontinuation of N2O use. Hematologic abnormalities normalize with vitamin supplementation; however, the neurologic prognosis varies.

CONCLUSIONS: The clinician should consider N2O induced vitamin B12 deficiency when a patient presents with neurologic deficits, altered mental status and/or pancytopenia with a history of N2O abuse.

Reference #1: Hsu C et al.Myelopathy and polyneuropathy caused by nitrous oxide toxicity:a case report.Am Jour of Emer Med.2012;30:1016.e3-e6

Reference #2: Baum VC.When Nitrous Oxide is No Laughing Matter.Pediatr Anessthesia.2007;17(9):824-830

DISCLOSURE: The following authors have nothing to disclose: Matthew Anderson, Trina Hollatz

No Product/Research Disclosure Information


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