2020 Volume 66 Issue 12 Pages 605-609
Carbamazepine is widely used as an anticonvulsant or antipsychotic agent. As a sodium channel blocker, it provides therapeutic benefit in patients with trigeminal neuralgia and may be used for the differential diagnosis of pain. We report a case of marked thrombocytopenia during carbamazepine administration in a patient with idiopathic trigeminal neuralgia. A 37-year-old woman presented with acute intermittent electric shock-like pain when pressure was applied to the left mental foramen, or when cold air was applied to the left lower lip. We observed no sign of dental infection. No obvious vascular contact in intracranial lesions or the trigeminal nerve root entry area was observed in MR imaging. We initiated carbamazepine (200 mg/day) therapy for a clinical diagnosis of idiopathic left trigeminal neuralgia (tertiary branch). The patient developed petechial hemorrhages on the face, neck, and extremities 16 days after carbamazepine administration, and blood test results revealed significant thrombocytopenia (her platelet count was remarkably low, at 1.5×104 /μ L). We suspected carbamazepine-induced thrombocytopenia. The medication was discontinued, resulting in a gradual disappearance of the petechial hemorrhages and recovery of the platelet count to 23.7×104 /μ L six days after carbamazepine cessation. Subsequently the left-sided mental foramen pain was controlled with pregabalin administration (150 mg/day), without any adverse effects.
