<p>Clinical, Electrophysiological and Radiological Features of Nitrous Oxide-Induced Neurological Disorders</p>

Abstract

These authors contributed equally to this workPurpose: We summarized the clinical manifestations, laboratory and electrodiagnostic characteristics and magnetic resonance imaging (MRI) findings of nitrous oxide (N 2 O) abuse-induced neurological disorders. Patients and Methods: We retrospectively reviewed 33 patients with N 2 O abuse-induced neurological disorders and reported their demographic data, clinical manifestations, laboratory examinations, nerve conduction studies, together with spinal and brain MRI. Results: The most frequent clinical manifestations included numbness and weakness in the extremities and unspecified gait disturbance. Low serum vitamin B 12 levels were found in 9 patients, and high homocysteine levels were noted in 27 patients. Nerve conduction studies showed a sensory-motor neuropathy. Sixteen patients showed bilateral high-intensity T2 signal within the posterior column on spinal MRI, and four patients showed cerebral white matter lesions on brain MRI. Conclusion: N 2 O abuse has become a significant public health problem because of the severe neurological disorders related to chronic abuse. Clinical physicians should be aware of the toxic effects of N 2 O.

Key Characteristics of Nitrous Oxide-Induced Neurological Disorders and Differences Between Populations

“…This means that the lesions in the spinal cord secondary to N 2 O abuse are longitudinally extensive myelitis. The extended vertebral levels in our study were a little longer than those in the study by Bao et al ( 16 ) and similar to those in the study by Zheng et al ( 3 ). An interesting observation is that, despite lesions in the cervical segment of the spinal cord, many patients had no sensory change at the corresponding spinal level.…”

“…An interesting observation is that, despite lesions in the cervical segment of the spinal cord, many patients had no sensory change at the corresponding spinal level. A low proportion of patients with sensory change at the spinal level was also seen by Bao et al ( 16 ). Vasconcelos et al considered that an absence of sensory change at the spinal level might be associated with better clinical resolution since the absence of sensory change at the spinal level indicated that transmission of sensory impulses to higher centers is preserved ( 18 ).…”

“…However, attention must be given to the cause of differences between neurological disorders caused by N 2 O compared to those caused by vitamin B12 deficiency. In both our case series and previous cases, the cervical segment is much more vulnerable in patients who abuse N 2 O ( 3 , 16 ). Zheng et al found that 32 patients had lesions in the cervical spinal cord and one patient had lesions in both cervical and thoracic spinal cord in 33 patients with N 2 O abuse who performed MRI ( 3 ).…”

“…Zheng et al found that 32 patients had lesions in the cervical spinal cord and one patient had lesions in both cervical and thoracic spinal cord in 33 patients with N 2 O abuse who performed MRI ( 3 ). Bao et al found that, in 16 patients who abused N 2 O, the most commonly impaired vertebral levels were C3–C5 (50.6%), followed by C2 (41.6%) and C6 (37.2%) ( 16 ). Lan et al suggested that the vulnerability of the cervical segment to N 2 O neurotoxicity is attributable to the higher density of myelinated fibers of fasciculus gracilis in the cervical segment compared with the thoracic segment ( 17 , 18 ).…”

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“…Zheng et al found that 32 patients had lesions in the cervical spinal cord and one patient had lesions in both cervical and thoracic spinal cord in 33 patients with N 2 O abuse who performed MRI (3). Bao et al found that, in 16 patients who abused N 2 O, the most commonly impaired vertebral levels were C3-C5 (50.6%), followed by C2 (41.6%) and C6 (37.2%) (16). Lan et al suggested that the vulnerability of the cervical segment to N 2 O neurotoxicity is attributable to the higher density of myelinated fibers of fasciculus gracilis in the cervical segment compared with the thoracic segment (17,18).…”