Painful tonic spasm (PTS) is a common yet debilitating symptom in patients with neuromyelitis optica spectrum disorder (NMOSD), especially those with longitudinally extensive transverse myelitis. Although carbamazepine is an effective treatment, it poses the risk of severe adverse reactions, such as Steven-Johnson syndrome (SJS). In this case report, we describe an NMOSD patient with severe PTS suffering from carbamazepine-induced SJS who responded well to cannabis extract. Since cannabinoids can ameliorate spasticity in an experimental autoimmune encephalomyelitis model through cannabinoid 1 (CB1) receptor activation, cannabis extract which includes delta-9-tetrahydrocannabinol (THC) is a potential treatment option for PTS in NMOSD patients.

Keywords: Cannabis; Carbamazepine; Longitudinally extensive transverse myelitis; Neuromyelitis optica (NMO); Painful tonic spasm; THC.