Frequency of Dimethyl Fumarate Induced Lymphopaenia Among Omani Patients with Multiple Sclerosis

Objectives: Dimethyl fumarate (DMF) is known to cause lymphopenia in treated multiple sclerosis (MS) patients. There is a dearth of research on DMF therapy in the Arab world, especially in Oman. This study aimed to analyse the prevalence of lymphopenia among Omani MS patients and the reasons for discontinuing DMF. Methods: In this retrospective study, we reviewed the medical records of Omani MS patients who were treated using DMF at two tertiary hospitals in Muscat from the period 2017 February to 2023 February. Their demographic, clinical, and laboratory data were retrieved and analysed. Absolute lymphocyte count (ALC) values at baseline and at the last follow up, as well as the reasons for discontinuing DMF were collected. Descriptive and inferential statistical techniques were used for data analysis. Binary-logistic regression analysis was used to identify the risk factors for DMF-induced lymphopenia. Results: The study included a total of 64 MS patients and the majority (40; 63%) were female. The DMF therapy was started at mean age of 33 7.7 years. After administration of DMF, 14 (21.9%) patients developed 1–3 grades lymphopenia with the following breakup: grade-1: 5/64 (7.81%) patients; grade-2: 8/64 (12.5%) patients; grade-3: 1/64 (1.6%) patient. DMF was discontinued in 23 (36.0%) patients, mainly in response to adverse events or confirmed pregnancy. Female sex was the only significant predictor of DMF-induced lymphopenia (p = 0.037). Conclusion: Most Omani MS patients had mild lymphopenia (grades 1–2), like other regional and international reports. Early adverse events and pregnancy were the main reasons provided for discontinuing DMF therapy. Keywords: Multiple Sclerosis; Dimethyl Fumarate; Absolute Lymphocyte Count; Lymphopenia; Oma

Absence of Meckel's Cave with Trigeminal Neuralgia: A Case Report

Trigeminal neuralgia (TN) is a disabling painful condition along the course of the sensory distribution of the trigeminal nerve that most commonly occurs due to vascular compression or conflict at the root entry zone of the trigeminal nerve. We report a 27-year-old female patient who presented with pain and an electric shock-like sensation on the right side of her face that started three years ago. Magnetic resonance imaging of the brain was done and revealed no neurovascular conflict along the course of the trigeminal nerve. The absence of Meckel's cave with atrophy of the cisternal segment of the trigeminal nerve on the affected side was reported. The absence of Meckel's cave is an exceedingly rare cause of TN, and only a handful of reported cases in the literature suggest the association between them