Lacosamide: a new therapeutic option for refractory trigeminal neuralgia

Case Presentation: A 60-year-old previously healthy female patient presented, approximately 6 months earlier, with sudden, intermittent, shock-like pain of very high intensity in the right V2 and V3 trigeminal territories. The pain progressively worsened with touch, chewing, and speech at trigger zones. Brain MRI was requested for investigation and demonstrated compression of the right trigeminal cisternal segment by a vascular loop in the prepontine cistern. Given the diagnosis of classical trigeminal neuralgia, standard first-line treatment with carbamazepine 200 mg every 8 hours was initiated. After 21 days without apparent improvement, the dose was increased to 400 mg every 8 hours, with the addition of second-line medications, including baclofen 10 mg every 8 hours, amitriptyline 25 mg at night, and opioids due to pain crises. The patient showed minimal improvement and remained highly symptomatic. Therefore, carbamazepine was further adjusted to 1600 mg/day, which led to disabling adverse effects. After discussion with the patient, neurosurgical treatment with right trigeminal microvascular decompression was offered. Following the patient’s refusal, an alternative pharmacological approach was chosen with lacosamide 50 mg every 12 hours, titrated to 100 mg every 12 hours. The patient experienced substantial pain relief, allowing reduction of the other medications, and currently remains only on carbamazepine 200 mg every 8 hours and lacosamide 100 mg every 12 hours, with complete pain control. Discussion: Trigeminal neuralgia is a neuropathy characterized by recurrent, short-lasting episodes of intense unilateral facial pain, typically described as electric shock-like or stabbing, occurring along one or more branches of the trigeminal nerve. First-line treatment for this neuropathic syndrome consists of carbamazepine or oxcarbazepine. In cases without adequate response, combination therapy with second-line agents such as baclofen, pregabalin, phenytoin, and gabapentin may be considered. Although trigeminal neuralgia is the most common cranial neuralgia, refractory and difficult-to-control cases still occur, making the search for effective alternative treatments necessary, such as lacosamide. Final Comments: While carbamazepine acts on fast sodium channels, reducing repetitive high-frequency neuronal firing, lacosamide, when used as an adjunct therapy, enhances slow inactivation of these channels, thereby reducing prolonged neuronal excitability. Thus, when used in combination, they act on complementary mechanisms of trigeminal nerve excitability, representing an effective alternative for the management of difficult-to-control trigeminal neuralgia.