Electrophysiological characteristics of subacute combined degeneration of spinal cord in patients with nitrous oxide poisoning / 中国医师进修杂志

ABSTRACT

Objective:To analyze the electrophysiological characteristics of subacute combined degeneration of spinal cord in 10 patients with nitrous oxide poisoning.Methods:Ten patients with nitrous oxide poisoning (case group) and 20 controls (control group)treated in Dalian Municipal Central Hospital Affiliated of Dalian Medical University from January 2016 to January 2020 were included in this study. MRI and electrophysiological examinations were performed on the head, cervical spine and thoracic spine, including distal motor latency (DML), motor nerve amplitude (CMAP), motor conduction velocity (MNCV), sensory conduction velocity (SNCV), sensory nerve amplitude (SNAP), N20 latency of upper limb cortical somatosensory evoked potential and P40 latency of lower limb cortical somatosensory evoked potential. The above indexes were compared between the two groups.Results:In the case group, DML of motor nerve was prolonged, MNCV was slowed down, CMAP was decreased, SNCV was slowed down and SNAP was decreased compared with the control group, the differences were statistically significant ( P<0.05). The incubation periods of N20 and P40 in the case group were longer than those in the control group (32.70 ± 3.34) ms vs. (18.85 ± 1.37) ms, (57.00 ± 4.08) ms vs. (38.40 ± 1.54) ms, the differences were statistically significant ( t = 16.20, 18.20, P<0.01). The inverted "V" type T 2 long signal of cervical spinal cord and thoracic spinal cord could be seen on MRI of cervical or cervical and thoracic vertebrae in 5 patients. Conclusions:Nitrous oxide poisoning can cause obvious subacute combined degeneration of spinal cord, involving peripheral nerve and spinal cord damage. Peripheral nerve damage can involve motor fibers and sensory fibers, mainly axonal damage, accompanied by demyelination damage, especially in both lower limbs.