A 20-year-old man with progressive distal paresthesia
The following case has been published in the journal Neurology.

A 20-year-old man presented with a 3-week history of progressive distal paresthesia in his lower limbs. His gait became clumsy and he became unable to mobilize. The patient was vegetarian and after questioning admitted to regular recreational nitrous oxide use.

Examination revealed a clear dorsal column syndrome with pseudoathetosis of the upper limbs and reduced proprioception of upper and lower limbs with reduced vibration sensation to the xiphisternum. Knee jerk reflexes were brisk bilaterally with absent ankle jerk reflexes and extensor plantars.

MRI revealed high signal in the dorsal column throughout the spinal cord. Vitamin B12 levels were low (84 ng/L). This presentation represents subacute combined degeneration of the cord secondary to nitrous oxide abuse by inactivating B12 levels. The patient was treated with vitamin B12 replacement and intensive neurorehabilitation.

Major takeaway:-
- Nitrous oxide abuse should always be considered in a young patient with dorsal column syndrome.

Source: https://pxmd.co/5GpU6