The identification of white matter fibers in the hematoma of intracerebral hemorrhage patients.

Background: Intracerebral hemorrhage (ICH) carries high mortality, and survivors often have severe neurological deficits. Although surgical clot evacuation is widely used, clinical trials have not demonstrated a clear benefit. White matter is essential for neural network function and may be vulnerable during hematoma evacuation, but whether white matter fibers exist within human ICH hematomas remains unknown. This study aimed to determine the presence and characteristics of intra-hematomal white matter fibers and their relationship with immune cell infiltration. Methods: We collected hematoma specimens from patients with spontaneous supratentorial ICH undergoing surgical evacuation within 24 h of onset. Histological and immunohistochemical staining, including hematoxylin-eosin and myelin basic protein (MBP), was performed to identify white matter fibers. Lymphatic vessel hyaluronan receptor-1 (LYVE-1) staining was used to evaluate macrophage infiltration around identified fibers. Results: Myelin-containing structures were consistently observed within the hematoma core on both hematoxylin-eosin and MBP staining. These structures appeared fragmented and structurally fragile. LYVE-1-positive cells were found clustered around intra-hematomal myelin-containing structures, potentially indicating active immune cell infiltration in these regions. Conclusion: This study provides the first direct histological evidence that white matter fibers persist within human ICH hematomas. This finding provides an anatomical basis for future studies exploring the biological and potential clinical significance of intra-hematomal white matter-associated structures.