A Histopathological Study of Hemostatic Agents Retrieved During Neurosurgical Procedures

Current knowledge on tissue reactions and resorption of hemostatic agents in neurosurgery is mostly derived from animal and non-neurosurgical studies. The limited available data in humans consist of small case series including only a few types of hemostatic agents. This study outlines the histological findings, including inflammatory response, and the degree of resorption observed in hemostatic agents retrieved during cranial and spinal reoperations.

Histological slides of hemostatic agents and surgical materials retrieved during secondary cranial and spinal procedures performed over a 12-year period were retrospectively evaluated. In a retrospective observational cohort design, the samples were semiquantitatively scored for the microscopic degree of resorption and inflammatory response. Results are summarized using descriptive statistics. Given the sample of convenience, the relationship between the type of agent and the degree of inflammatory response seen on histological examination is assessed in exploratory analysis.

Histopathological findings of 160 samples are described, encompassing 14 hemostatic agents and 2 types of surgical materials retrieved during neurosurgical reoperations. Samples were from different types of hemostatic agents (eg, oxidized regenerated cellulose, bone wax, gelatin sponge, fibrin sealant) and materials (eg, neurosurgical patties, polyvinyl alcohol sponge) from cranial (76.3%) and spinal (23.7%) reoperations.Hemostatic agents were found to remain in situ for extended periods, with one case of recognizable remnants at 14.7 years postoperatively, exceeding most manufacturers' reported time frames. Even in the absence of adverse events directly attributable to the hemostatic agent or material, inflammatory reactions and fibrosis were frequently observed across all types of hemostatic agents and materials analyzed.

This study describes a broad spectrum of inflammatory reactions associated with hemostatic agents and materials used in neurosurgery, even in the absence of clinically attributable symptoms. Several hemostatic agents remain in situ for extended periods, challenging claims made by manufacturers.