Clinical Evaluation of OnabotulinumtoxinA for the Management of Chronic Migraine in Tripoli, Libya (A Prospective Observational Study)

Abstract

Background: Chronic migraine (CM) is a disabling neurological disorder characterized by frequent headache days and substantial impairment in daily functioning and quality of life. OnabotulinumtoxinA is an established preventive therapy for chronic migraine and is commonly administered according to the standardized Phase III Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) protocol. The PREEMPT regimen uses fixed-site injections with a base dose of 155 Units administered across 31 injection sites, with treatment generally repeated at 12-week intervals, Objective: This study aimed to evaluate the clinical effectiveness, functional impact, and short-term tolerability of OnabotulinumtoxinA administered according to the PREEMPT protocol among patients with chronic migraine in Tripoli, Libya, Methods: A prospective observational study was conducted among 20 adult patients diagnosed with chronic migraine. Participants received 155 Units of OnabotulinumtoxinA distributed across 31 injection sites according to the PREEMPT protocol and were followed for 12 weeks. Clinical outcomes included Monthly Headache Days (MHD), acute medication-use days, Headache Impact Test-6 (HIT-6) scores, treatment response, Medication-Overuse Headache (MOH), and adverse effects. Statistical analysis was performed using SPSS, with paired-samples t-tests used to compare baseline and Week-12 measurements, Results: The mean number of MHD decreased from 21.1 ± 3.2 days at baseline to 9.95 ± 2.8 days at Week 12, representing a mean reduction of 11.15 days (t(19)=14.32, p<0.0001). Acute medication-use days decreased from 15.4 ± 3.7 to 4.85 ± 2.1 days/month, with a mean reduction of 10.55 days (t(19)=11.84, p<0.0001). Mean HIT-6 scores decreased from 66.5 ± 4.1 to 50.3 ± 5.2 points, representing a mean reduction of 16.2 points (t(19)=13.51, p<0.0001). Overall, 16 participants (80%) achieved at least a 50% reduction in MHD. Among the 13 participants who met the study's baseline criteria for MOH, all no longer met those operational criteria at Week 12. Treatment was generally well tolerated; 11 participants (55%) reported no adverse effects, while reported adverse events were mild, localized, and transient, Conclusion: In this small real-world cohort, OnabotulinumtoxinA administered according to the PREEMPT protocol was associated with substantial reductions in headache frequency, acute medication use, and headache-related disability over 12 weeks. The treatment demonstrated a generally favorable short-term tolerability profile. However, the small sample size, absence of a control group, and short follow-up period limit causal inference and generalizability. Larger controlled multicenter studies are warranted in the Libyan healthcare setting.