Raj Reddy

Introduction. Subdural hematomas (SDH) are accumulations of blood in the subdural space induced by head trauma. SDH can be further classified as chronic subdural hematoma (CSDH) in instances where this slow bleed persists for weeks or months¹. A mechanical shearing force tears the bridging veins traversing the subdural space. Bridging veins under extra tension due to preexisting brain atrophy (i.e. dementia, alcoholism, dehydration, or normal aging) are at increased risk of rupture². Asymptomatic CSDH, diagnosed by imaging indicated by a history of recent trauma, is treatable without surgical intervention. Symptomatic CSDH, diagnosed by presence of psychological or neurologic deficits, is treated by craniotomy and associated with good outcomes³. Surgery is considered the best treatment for symptomatic CSDH⁴. Middle meningeal artery embolization is an emerging treatment that involves strategically inducing cessation of arterial flow to allow CSDH to resolve^{5, 6}. However, superior outcomes with this treatment depend on earlier detection of CSDH⁵, a current challenge in the field. A biomarker for chronic subdural hematoma may provide an objective, scalable, and sensitive diagnostic tool that enables earlier, superior treatment and better outcomes subsequently.  Methods. Takei investigates the reliability of serum VEGF levels on progression and recurrence of chronic subdural hematoma, characterizing four types of CSDH CT findings with intraoperatively-taken serum and hematoma VEGF levels. Another study creates CSDH mimicking conditions via injection of Matrigel and bEnd.3 cells, which constitutively emit VEGF, into murine subdural space⁷. Results. Takei found that chronic subdural hematomas categorized as trabecular-type on CT had the highest VEGF levels. Furthermore, Takei also found that as the interval between minor head injury to surgery increased, the VEGF decreased in the trabecular group. Takei speculates that this decrease is because trabecular CSDHs are in fact a resolution stage of the disease. Xu observed successful formation of a structure resembling natural formation of internal and external neomembranes in their murine model, a key phenomenon of human SDH. Conclusions. Intraoperatively measured hematoma VEGF concentrations are more reliable indicators of CSDH disease state and time-course than VEGF concentrations taken from peripheral serum⁸. However, this diagnostic tool does not provide practical advantage over imaging after considering its invasiveness. A novel murine model of CSDH allows researchers to control for timing of the disease state, and thus for further investigation of biomolecular markers⁷.

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