Acute Subdural Hematoma Evacuation

Subdural hematoma (SDH) is a type of intracranial bleeding that occurs between the dura and the arachnoid membrane surrounding the brain. Acute SDH is primarily caused by head trauma, with the majority of cases being attributed to falls, motor vehicle accidents, or violence.¹ The pathophysiology behind the formation of chronic SDH (CSDH) is still not fully understood, with inflammatory response hypothesized to play an important role. Furthermore, subclinical brain injury caused by minor trauma to the bridging veins can also contribute to the long-term buildup of blood within the hematoma encapsulated by neomembranes. Additionally, it is possible for an initially acute SDH to undergo transformation into a chronic state. Following the formation of the hematoma, the process of blood resorption begins as erythrocytes and other cellular components undergo decomposition. Moreover, the initiation of collagen synthesis occurs, resulting in the migration of fibroblasts throughout the inner dural surface, forming a compact outer membrane.² Sufficient potential subdural space is a prerequisite for CSDH, as seen in elderly patients with brain atrophy or intracranial hypotension. The risk of CSDH appears to increase over time, likely due to the aging of the population and the rising prevalence of treatment with antiplatelet and anticoagulant medications.

CSDH is a common neurosurgical condition. The incidence of CSDH varies between 1.72 and 20.6 cases per 100,000 individuals annually, with a notably higher occurrence among the elderly patients.³ Presenting symptoms of CSDH include headaches, weakness, numbness of extremities, dysarthria, gait disturbances, and altered level of consciousness. The occurrence of acute-on-chronic SDH is not uncommon, accounting for 8% of all CSDH cases.⁴ This term refers to a second episode of acute hemorrhage into a pre-existing CSDH.⁵ 

The presented video is a step-by-step demonstration of the surgical procedure performed on an elderly female patient with an acute-on-chronic SDH, presumably resulting from recurrent head injuries sustained from falls. The patient presented with altered mental status with a GCS score of 8.

Head computed tomography (CT) is the preferred imaging method for the diagnostic workup of acute head trauma due to its rapidity, relative simplicity, and widespread accessibility. Upon examination, hyperintense hyperdensity indicative of acute SDH was detected on CT scans. Further analysis suggested the presence of a pre-existing CSDH, manifested by hypodense areas, juxtaposed with areas of hyperdensity, indicating the acuity of the encounter. Radiographic evidence revealed a midline shift of the brain and compression of the left ventricle, underscoring the urgent need for intervention to alleviate intracranial pressure.

The differential diagnosis in primary head injury may include the following: concussion (symptoms without intracranial injury detected on CT), skull fracture, contusion (localized punctate hemorrhages), hematoma (subdural, epidural, intracerebral), subarachnoid hemorrhage, and axonal shear or laceration. 

Secondary injury refers to the progressive pathophysiological consequences that arise following the primary injury. These consequences involve complex neurobiological cascades, which are altered or initiated at the cellular level. The secondary injury may encompass various processes, including but not limited to: cerebral edema, increased intracranial pressure, hemorrhage progression, seizures, ischemia, infection, traumatic venous sinus thrombosis.⁶

In this case, a decision was made to evacuate the hematoma by craniotomy. The latter is the most invasive yet highly effective surgical technique for removing intracranial hematomas. It offers superior access and more efficient drainage of acute SDH compared to the less extensive burr hole craniostomy.⁷

The patient was placed in a supine position, with the head rotated 90 degrees away from the side of the hematoma to create a flat surface for the surgical procedure. A pillow needs to be placed under the ipsilateral shoulder for support, allowing most of the body to be rotated to the desired side where you want the head to be, thus decreasing the angle of rotation of the head relative to the body from 90 to 45–60 degrees, while still having the procedure side of the head facing upwards. It is important to be cautious and avoid excessive rotation, as this can lead to compression of the jugular veins, causing increased intracranial pressure and hindering venous return. These hemodynamic changes may impair hemostasis during surgery and may lead to or worsen hemorrhagic complications postoperatively. Therefore, ensuring the correct placement of the patient is crucial to improve the surgical outcomes.

First, a skin incision was performed to access the underlying tissue layers. Attention was then directed towards the control of superficial bleeding from the skin. The insertion of retractors aids in the management of bleeding through its compressive properties. The scalp was carefully dissected to expose the underlying cranial structures. Bipolar tissue hemostasis was used to achieve successful hemostasis. After thorough preparation, the stage was set for the creation of the burr hole. During this step, a specialized drill with a safety mechanism was used to prevent inadvertent penetration into the cranial cavity. This mechanism ceases the drilling process when encountering absence of resistance, thereby reducing the likelihood of intracranial injury. Bone fragments were removed in the process to prevent potential complications, such as infection. A craniotome cutter was used for cutting the bone flap outward from the burr hole. The bone flap was carefully elevated to reveal an intact dural layer. A tiny needle is inserted superficially through the dura, allowing enough space to be left to the rim for subsequent suturing. Subsequently, the dura was opened in a cruciate fashion to gain access to subdural space. The hematoma was removed using gentle irrigation and suction, resulting in alleviation of brain compression. Once the hematoma was completely evacuated, the surgical field was inspected to ensure successful hemostasis, and the dural flap was sutured in place using a running technique with 4-0 coated polyester suture material, ensuring secure closure without compromising dural integrity. This meticulous closure technique minimizes the risk of cerebrospinal fluid leakage and postoperative complications. Upon completion of dural closure, the bone flap was carefully repositioned and secured in place with plates and screws. Pin fixation ensures optimal alignment and stability of the bone flap. Once the flap is securely reimplanted, the screws can be removed, completing the reintegration of the cranial architecture. Lastly, the edges of the scalp and the skin were reapproximated using sutures.

Chronic SDH is a common neurosurgical pathology affecting more than 160,000 individuals annually in the United States and Europe combined. The rising incidence of SDH, predicted to become the most common cranial neurosurgical condition among adults by the year 2030,⁸ already has a socioeconomic impact on current healthcare systems. Optimizing surgical treatment can effectively reduce the occurrence of complications and the likelihood of the recurrence, while minimizing the socioeconomic burden. The current standard of care involves surgically evacuating the hematoma through a cranial opening, and this video provides a detailed overview of the modern craniotomy technique.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.