Israel Medical Association Journal

Myositis is described as any disease-causing inflammation in muscles. Muscle weakness is the most common symptom. Etiology includes infection, injury, medication side effects, and autoimmune conditions. The treatment varies according to the cause [1]. Statin induced necrotizing autoimmune myopathy (SINAM) is an exceptionally rare yet devastating complication of statin therapy that can occur at any time after initiation. The condition is also known as anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody (anti-HMGCR antibody) myopathy. SINAM should be considered in patients who develop proximal muscle weakness and marked elevated creatine phosphokinase (CPK) while taking statin therapy [2]. We report on a patient who presented with excessive fatigue, generalized muscle pain, and weakness without dysphagia.

Background: The recreational use of nitrous oxide (N₂O) has increased in recent years with a noticeable surge in the incidence of nitrous oxide-related myeloneuropathy.

Objectives: To raise awareness of increasing myeloneuropathy due to recreational nitrous oxide misuse in Israel.

Methods: We conducted a case series documenting the clinical and investigative features of eight patients presenting with nitrous oxide-induced myeloneuropathy who were admitted to our departments.

Results: Paresthesia was the chief complaint in all patients, with sensory gait ataxia being a common feature, which was often accompanied by Romberg's sign and mild lower limb weakness. Vitamin B12 levels were below the normal range in seven patients, accompanied by elevated homocysteine and methylmalonic acid levels. Magnetic resonance imaging scans revealed hyperintense signals in the dorsal columns of the cervical spine. All patients improved following vitamin B12 injections.

Conclusions: Enhancing awareness, prompting the use of appropriate investigations, and advocating for timely treatment are needed to overcome the risks associated with nitrous oxide misuse.