A Case of Subacute Degeneration of the Spinal Cord Due to Vitamin B12 Deficiency Triggered by Nitrous Oxide Use

Abstract

In this case report, we discuss a young female who presented to the emergency department with a recent onset of weakness, paraesthesia, and gait disturbance suggestive of peripheral neuropathy and gait ataxia. This was attributed to the occasional use of recreational nitrous oxide (N2O) over the past 10 months. Subacute combined degeneration of the spinal cord is a condition affecting the lateral and posterior columns of the spinal cord, mainly caused by demyelination. The use of recreational N2O depletes the levels of vitamin B12 thus leading to this demyelination of the nervous system. Physical examination revealed T6 and T7 and L3 and L4 sensory deficits bilaterally with hyporeflexia in bilateral knee and ankle reflexes with reduced power in the left lower limb as well as a spastic gait. Her vitamin B12 levels were low (98 g/dL). MRI spine showed a high signal in the posterior cord/ dorsal column. The patient made good recovery post-intramuscular B12 administration and physiotherapy with planned outpatient neurology rehabilitation.

Keywords: nitrous oxide inhalation; nitrous oxide myelopathy; nitrous oxide toxicity; peripheral neuropathy; rare cause of vitamin b12 deficiency; subacute combined degeneration of the spinal cord.

Figure 1. MRI spine demonstrating symmetrical high signalling in the dorsal column/posterior spinal cord from C2-C6