An unusual case of subacute combined degeneration due to nitrous oxide abuse, which relapsed after bariatric surgery: A case report.

RATIONALE: Several studies have reported subacute combined degeneration (SCD) induced by nitrous oxide (N2O) abuse. However, few studies have reported that N2O-induced SCD recurred because of sleeve gastrectomy after neurological symptoms improved.

PATIENT CONCERNS: We report the case of an 18-year-old woman who developed paresthesia, weakness in 4 limbs, and an unstable gait after frequent, excessive N2O inhalation.

DIAGNOSIS: The patient was diagnosed as having SCD.

INTERVENTIONS AND OUTCOMES: Nineteen days after intravenous mecobalamin and supplementation with other kinds of vitamin B, her weakness and paresthesia resolved. However, 7 months after discharge, the patient experienced recurrence following sleeve gastrectomy. Blood biochemistry revealed low vitamin B12 levels. After a 22-day treatment, similar to the first hospitalization, her residual numbness and unsteady gait improved.

LESSONS: This case highlights that patients, especially those at high risk of vitamin B12 deficiency, undergoing sleeve gastrectomy require careful nutritional follow-up and routine monitoring of micronutrients such as vitamin B12 and homocysteine. Continuous vigilance is essential for patients with common and rare neurological complications.