To Evaluate Efficacy of Monotherapy of Oxcarbazepine Versus Combination of Gabapentin With Oxcarbazepine in the Management of Trigeminal Neuralgia

INTRODUCTION:

Orofacial pain is defined as pain in and around the oral cavity. The orofacial region is complex, and any pain of orofacial origin could be related to the hard or soft tissue in that region or a dysfunction of the nervous system. Amongst all the orofacial pains, trigeminal neuralgia is one of the most debilitating, which badly affects the quality of life of the patient1. Trigeminal neuralgia is defined by the International Classification of Headache Disorders as abrupt, sharp, spontaneous pain that is caused by activation of one or more trigeminal nerve branches and lasts for a few seconds to two minutes. Classic trigeminal neuralgia (idiopathic) typically manifests at 40-60 years of age, whereas symptomatic trigeminal neuralgia (due to compression of the trigeminal ganglion) typically manifests around 30-40 years of age. There are two categories of treatment for trigeminal neuralgia: surgical and medicinal. But no single surgical or medicinal procedure has had a 100% success rate. Neuroleptic medications, muscle relaxants, and anticonvulsants are the recommended medical treatments for TN. However, the most popular invasive therapy choices for individuals not responding to conservative measures include gamma knife surgery, microvascular decompression, and gasserian ganglion percutaneous procedures3. Carbamazepine is generally regarded as the first-line medication for the treatment of trigeminal neuralgia among the recommended medical interventions. But not every patient can take carbamazepine, which might make compliance difficult. Moreover, liver failure, aplastic anemia, and hyponatremia are significant side effects of carbamazepine. The structural analogue of carbamazepine is oxcarbazepine. Oxcarbazepine is more well-tolerated in patients than carbamazepine because it selectively induces P450 enzymes, has fewer pharmacologic interactions with other drugs, and has fewer adverse effects. Gabapentin is an analogue of GABA and is useful for the treatment of neuropathic pain. Second-line drugs like gabapentin are added if the patient is unable to tolerate the adverse effects or drug interactions4. Trigeminal neuralgia is a severely incapacitating illness that affects fundamental human activities, including eating, drinking, talking, and touching one's face. As a result, it interferes with day-to-day activities. According to epidemiological research, there is a higher risk of anxiety, depression, and suicide5. For accurate diagnosis and treatment, a thorough history and identification of the affected nerve are crucial. In Pakistan, many trigeminal neuralgia patients have incorrect diagnoses, lead to pointless operations, and receive inefficient therapies. The purpose of this study is to evaluate the efficacy of gabapentin combination regimens versus monotherapy (oxcarbazepine). The extant literature indicates that there has not yet been a single national or international trial that compares the efficacy of oxcarbazepinemonotherapy with combined therapy using gabapentin, though studies comparing other treatment options or medicines have been conducted 6,7.

METHODS:

Prospective observational study was conducted at Rehman College of Dentistry for the duration of one year, i.e., from 1st May 2023 till May 2024. Universal sampling was used, and 44 patients who reported to our dental OPD and fulfilled the inclusion criteria were included in the study. Patients of either gender, with ages ranging from 20 to 80 years, presenting in the Outpatient Department, who fulfilled the diagnostic criteria of idiopathic trigeminal neuralgia according to the International Headache Society, were included in the study. All patients with orofacial and odontogenic pain other than TN, TMJ disorders having a centralized cause of TN as evidenced by MRI, patients unwilling to participate or who failed to show up for follow-up, pregnant and lactating females, patients who had previous surgical procedures for neuralgia or are allergic to neuralgia medications, and patients with comorbid conditions were excluded from the study. After seeking ethical approval from the Institutional Research Board (via reference number RCD-04-23-167), written consent was taken, and patients were randomly assigned to one of the two groups through block randomization using the lottery method. Patients randomly distributed into two groups were given monotherapy with oxcarbazepine or combination therapy with gabapentin in addition to oxcarbazepine. Pain was calculated on a Visual Analogue Scale (0-10). Pain variable would again be calculated at 2 weeks and 2 months. Data analysis was conducted using the SPSS program 26. Qualitative data were displayed as frequency and percentage, whereas quantitative variables were displayed as mean ± SD. The independent sample t-test was used to compare the mean pain score between the groups; a p-value of less than 0.05 was deemed significant.

Inclusion criteria

• Patients of either gender aged 20-80 years
• Patients presenting to the Outpatient Department (OPD)
• Patients fulfilling the diagnostic criteria for idiopathic trigeminal neuralgia according to the International Headache Society (IHS)

Exclusion criteria

• Patients with orofacial or odontogenic pain conditions other than trigeminal neuralgia (TN)
• Patients with temporomandibular joint (TMJ) disorders
• Patients with a centralized cause of TN evident on MRI
• Patients unwilling to participate in the study
• Patients who failed to attend follow-up visits
• Pregnant or lactating females
• Patients with a history of previous surgical procedures for neuralgia
• Patients with known allergy to medications used for neuralgia
• Patients with significant comorbid medical conditions