# Subacute Combined Degeneration Secondary to Nitrous Oxide Toxicity

## TL;DR

A man developed spinal cord damage due to vitamin B12 deficiency caused by long-term recreational use of nitrous oxide.

## Contribution

This case highlights nitrous oxide abuse as a cause of subacute combined degeneration of the spinal cord.

## Key findings

- Chronic nitrous oxide abuse led to vitamin B12 deficiency and SCD in a 35-year-old man.
- MRI showed signal abnormalities in the cervical and thoracic spinal cord, especially in the dorsal columns.
- Symptoms included bilateral paraesthesia, weakness, and urinary incontinence.

## Abstract

Subacute combined degeneration (SCD) of the spinal cord is a neurological condition caused by vitamin B12 deficiency and is most associated with cases of malabsorption, nitrous oxide exposure, or pernicious anemia. The lateral corticospinal tracts and dorsal columns are classically affected, leading to neurologic symptoms including gait disturbance, sensory deficits, and weakness. We report the case of a 35‐year‐old man who presented with paraesthesia and weakness of the upper and lower extremities bilaterally, along with urinary incontinence. Examination revealed a long segment of signal abnormality and enhancement involving the cervical and thoracic spinal cord, predominantly along the bilateral dorsal column. Upon further investigation, the patient reported a chronic history of recreational nitrous oxide abuse resulting in vitamin B12 deficiency inevitably leading to the development of SCD of the spinal cord.