Explosive synchronization and high-dimensional connectivity in fibromyalgia: A brain network mechanism of chronic pain

Fibromyalgia (FM) is a chronic pain disorder characterized by widespread pain and hypersensitivity, yet its brain network mechanisms remain poorly understood. We investigated the network conditions of explosive synchronization (ES)—a phenomenon of abrupt state transition to hypersensitivity—and its structural underpinnings using topological data analysis (TDA). In this pilot study, we recorded electroencephalography (EEG) in 19 FM patients and 15 healthy controls. We computed ES indices and quantified high-dimensional topological structures using integrated Betti numbers (IBs). FM patients exhibited a significantly stronger ES index at rest ( p < 0.05). In the FM group, ES indexes significantly correlated with clinical outcomes, including symptom severity (e.g., FIQR total score; ρ = 0.602, p < 0.05). The abundance of high-dimensional topological cycles significantly correlated with pain severity (e.g., FIQR score; ρ = 0.590, p < 0.05) and ES strength during evoked pain. Moreover, pain-induced topological changes (|ΔIB|) were positively associated with clinical severity. Our findings suggest that chronic pain in FM is linked to specific alterations in brain network structure, highlighting a strong interplay between high-dimensional topology and ES-prone states. We propose that these features create a topological landscape hindering flexible network integration, thereby facilitating abrupt hypersensitive transitions. These network features may serve as mechanistic indicators for pain severity and represent novel targets for neuromodulation therapies.