What is the diagnosis and treatment for trigeminal neuralgia?

From the Guidelines

Trigeminal neuralgia should be treated with Carbamazepine (CBZ) as the first-line agent for pain control, as it has been shown to provide partial or complete pain relief in 70% of patients. This recommendation is based on a systematic review of four placebo-controlled studies, including a total of 147 patients, which demonstrated the superiority of CBZ over placebo 1. The typical starting dose of CBZ is 200 mg at night, gradually increased by 200 mg every 7 days to a final dose of 400–1200 mg, divided into 2–3 doses per day. Some key points to consider when treating trigeminal neuralgia with CBZ include:

• The most common side effects of CBZ are drowsiness, headache, and dizziness 1
• CBZ is a sodium channel-blocker that is commonly used for trigeminal neuralgia (TGN) and has been shown to be effective in managing neuropathic corneal pain 1
• The dose of CBZ can be tapered to a minimal effective dose once response has been achieved and patients maintain pain relief 1
• CBZ has been recommended as a first-line agent for pain control in TGN, with a level A recommendation based on the pooled results of four placebo-controlled studies 1

From the FDA Drug Label

Trigeminal Neuralgia(see INDICATIONS AND USAGE) Initial:On the first day, 100 mg twice a day for tablets for a total daily dose of 200 mg This daily dose may be increased by up to 200 mg/day using increments of 100 mg every 12 hours for tablets, only as needed to achieve freedom from pain. Do not exceed 1200 mg daily. Maintenance:Control of pain can be maintained in most patients with 400 to 800 mg daily. However, some patients may be maintained on as little as 200 mg daily, while others may require as much as 1200 mg daily Carbamazepine tablets are indicated in the treatment of the pain associated with true trigeminal neuralgia. The initial dose of carbamazepine for trigeminal neuralgia is 100 mg twice a day, with a total daily dose of 200 mg. The dose can be increased by up to 200 mg/day in increments of 100 mg every 12 hours as needed to achieve freedom from pain, not exceeding 1200 mg daily. The maintenance dose to control pain is typically between 400 to 800 mg daily, but can range from 200 mg daily to 1200 mg daily 2. Carbamazepine is indicated for the treatment of pain associated with true trigeminal neuralgia 2. Key points:

• Initial dose: 100 mg twice a day
• Maximum daily dose: 1200 mg
• Maintenance dose: 400 to 800 mg daily
• Indication: treatment of pain associated with true trigeminal neuralgia

From the Research

Definition and Characteristics of Trigeminal Neuralgia

• Trigeminal neuralgia (TN) is a highly disabling disorder characterized by very severe, brief, and electric shock-like recurrent episodes of facial pain 3.
• The trigeminal nerve (V) is responsible for detecting sensory stimuli that arise from the craniofacial area, and it is divided into three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3) 4.
• TN can be classified into idiopathic, classic, and secondary, with classic trigeminal neuralgia associated with neurovascular compression in the trigeminal root entry zone 4.

Diagnosis and Diagnostic Criteria

• New diagnostic criteria subclassify TN based on the presence of trigeminal neurovascular conflict or an underlying neurological disorder, allowing for better characterization of patients and decision-making regarding medical and surgical treatments 3.
• MR imaging, including high-resolution trigeminal sequences, should be performed as part of the diagnostic work-up 3.

Treatment Options

• Carbamazepine and oxcarbazepine are the first-line pharmacological treatments for TN, with a mechanism of action that modulates voltage-gated sodium channels, leading to a decrease in neuronal activity 3, 4.
• Other drugs that can be used alone or as add-on therapy include lamotrigine, gabapentin, pregabalin, botulinum toxin type A, and baclofen 3, 4.
• Surgery should be considered if the pain is poorly controlled or medical treatments are poorly tolerated, with trigeminal microvascular decompression being the first-line surgery in patients with trigeminal neurovascular conflict 3.
• Combination therapy may be the optimal approach, allowing for lower doses of carbamazepine or oxcarbazepine and reducing the number and severity of potential adverse events 5.

Efficacy and Tolerability of Treatment Options

• Oxcarbazepine has been shown to be effective and well-tolerated in patients with TN unresponsive to carbamazepine 6.
• Carbamazepine and oxcarbazepine are effective in most patients, but their undesired effects can cause withdrawal from treatment or a dosage reduction to an insufficient level in many patients 7.
• New pharmacological alternatives, such as sodium channel blockers selective for the sodium channel 1.7 (Nav1.7) receptor, are being explored and may provide a better-tolerated option in the future 5, 7.