J Clin Neurol.  2023 Jan;19(1):44-51. 10.3988/jcn.2023.19.1.44.

Electrophysiologic Characteristics of Nitrous-Oxide-Associated Peripheral Neuropathy: A Retrospective Study of 76 Patients

• Fang X
• Yu M
• Zheng D
• Gao H
• Li W
• Ma Y

• KMID: 2537183
• DOI: http://doi.org/10.3988/jcn.2023.19.1.44

Abstract

Background and Purpose
The electrophysiologic characteristics of peripheral neuropathy secondary to nitrous oxide (N₂O) abuse remain unclear. The paper therefore aimed to summarize the electrophysiologic characteristics of N₂O-associated peripheral neuropathy and identify the risk factors of severe nerve injury.
Methods
The electrophysiologic results and clinical data of patients with peripheral neuropathy secondary to N₂O abuse at our hospital between 2018 and 2020 were analyzed retrospectively, and their electrophysiologic changes were summarized.
Results
Most patients exhibited decreased sensory and motor nerve conduction velocities (75% and 76%), decreased sensory nerve and compound motor action potentials (57% and 59%), and prolonged distal motor latency (59%), while a response was absent in 36%. These findings indicate that N₂O abuse can result in generalized injury to sensory and motor nerves. Electrophysiologic results indicated axonal neuropathy in 37 cases (49%), demyelinating peripheral neuropathy in 4 (5%), and mixed neuropathy in 12 (16%). Peripheral nerve injury was more common in the lower limbs (72%) than in the upper limbs (42%, p<0.0001). The upper and lower limbs were primarily affected by sensory nerve demyelination (35%) and motor axonal injury (67%), respectively. Subgroup analysis indicated that longer N₂O exposure and longer disease course were associated with more-severe motor axonal injury in the lower limbs.
Conclusions
N₂O-associated peripheral neuropathy can lead to sensory and motor nerve injury, with axonal injury being the most common. Injuries were more severe in the lower limbs. Prolonged N₂O exposure and disease course increased the severity of motor axonal injury in the lower limbs.

Keyword

nitrous oxide abuse; peripheral neuropathy; electrophysiologic study; severity; vitamin B12