Embolization of the Middel Meningeal Artery (MMA) with NVS-1 System for treatment of chronic Subdural Hematomas (cSDHs)

A chronic subdural hematoma (cSDH) occurs when delicate blood vessels between the brain’s surface and its outer protective layer (the dura) tear and leak. Embolization is a treatment designed to seal off these vessels by delivering an embolic material into them, creating a plug that prevents further bleeding. The endovascular embolization of the middle meningeal artery (MMA) will be performed in an operating room using the NVS-1 System (comprising of NVS-Gel1, NVS-Catheter1 and NVS-Laser1). Typically the MMA embolization lasts about two hours, and may be carried out under either conscious sedation or general anesthesia. All patients with cSDH are admitted under the Neurosurgery service and receive multidisciplinary input from Neuroradiology and Neurology, ensuring coordinated surgical and non-surgical management throughout admission. If the Neuro team determines that MMA embolization is clinically indicated, the study will be discussed with prospective participants and a PICF will be shared by the Principal Investigator prior to admission. The procedure will be performed by a board certified interventional neuroradiologist, supported by a trained neurointerventional team in a single academic hospital setting. Operators must be experienced, AHPRA registered and board-certified neuro-interventionalists or interventional neuroradiologists who routinely perform complex endovascular procedures, including MMA embolization with liquid agents. All operators are expected to have prior experience in the safe use of laser and radiation equipment, with relevant training obtained. All operators must be trained in using the NVS-1 System. Before the procedure, baseline computed tomography (CT) scans will be performed to visualize the vessels contributing to the hematoma. The operator will navigate the NVS-Catheter1 (a thin, flexible device) with a guidewire through the vascular system to reach the MMA in the brain. Contrast dye will be administered through a guide catheter to allow real-time imaging of the target and surrounding vessels with X-rays (digital subtraction angiography). Once the NVS-Catheter1 is in position, NVS-Gel1 will be injected into the MMA until it fills the cross sectional area of the target vessel. The NVS-Laser1 is then activated to trigger the solidification mechanism of the NVS-Gel1. Injecting NVS-Gel1 and curing it with NVS-Laser1 activation is repeated at the discretion of the operator until MMA embolization has occurred. Angiographic images will be taken to confirm that the vessels have been successfully embolized. At the end of the procedure, CT imaging will be repeated to document placement of the NVS-Gel1 material. A Sponsor representative with technical expertise in the NVS-1 system will be present during the first embolization to ensure that the procedure is conducted according to the study protocol and that all required information is accurately collected. Subsequent embolizations will rely on the operator as they have been previously trained by the Sponsor personel. The CT and angiography images will later be reviewed by an independent Imaging Core Lab to verify that NVS-Gel1 was placed appropriately, effectively blocking the targeted vessels and not extending into non-target areas. If the post-procedure CT indicates that embolization was unsuccessful, the procedure will not be repeated. In addition, some participants may undergo surgical evacuation of the hematoma either before or after embolization. This separate surgery would be performed by a neurosurgeon in line with standard hospital practice. Participants will be monitored neurologically in step-down or intensive care for 24 hours at the hospital with non-contrasted head CT obtained 24 +/- 2 hours post procedure to evaluate for hemorrhage or early changes in hematoma volume. Their medical care will be managed by their treating physician as required. Participants will return for follow-up for CT imaging at Day 30 (+/- 7 days) and for MRI at Day 90 (+/- 14 days). These imaging studies will be used to track changes from baseline in hematoma thickness, volume, and any midline shift of brain structures.