Double burr hole trepanation combined with a subperiostal passive closed-drainage system is a technically easy, highly effective, safe, and cost-efficient treatment strategy for symptomatic chronic subdural hematomas. The absence of a drain in direct contact with the hematoma capsule may moderate the risk of postoperative seizure and limit the secondary spread of infection to intracranial compartments 1).
The main aim of surgery should be a complete removal of the aggressive liquid. In case of many membranes that separate the hematoma into chambers like honeycomb an open procedure cannot be avoided. Nevertheless, the preferred operative therapy for most of CSDH is a burr hole craniostomy with a closed drainage system 2) 3).
see Skin Preparation.
Preferably under general anesthesia the surgical approach should be over the thickest part of the hematoma and the patients positioned in a way that the burr hole comes to the highest point to avoid pneumocephalus.
Therefore, the head is rotated and the ipsilateral shoulder is usually padded.
The supine position is used with the patient‘s head rotated for temporal access. Extremes of head rotation can obstruct the jugular venous drainage, and a shoulder roll can combat this problem or lateral positioning (park bench position).
Sites of predilection are frontal about 1 cm anterior to the coronal suture or parietal posterior to the parietal eminence. The area around Kocher’s point offers a safe entry without injury of branches of the middle meningeal artery or the motor strip. Additionally, the skin incision should be brought, if possible, into alignment with an eventual future skin flap for craniotomy. A curved flap avoids a burr hole position directly under the skin cut and a possible impaired wound-healing as a consequence. Further, the base of the C-shaped incision should be opposite of the planned direction of the drain tip. Obviously, a kinking of the drain is obviated 4).
The dura mater is coagulated and cut in a stellate fashion.
Under direct vision, the external membrane is perforated by the tips of the bipolar forceps. In general, there are the open or the closed ways of evacuation of the hematoma after the drain is inserted 5)
The open variant should be chosen only if irrigation is desired: the dura and external membrane are opened widely so that the fluid of the hematoma and irrigation can drip out beside the drain during rinsing. Removal of the fluid enriched with inflammatory mediators is considered obviously as an advantage, although a remaining pneumocephalus is seen as an approved factor of recurrence 6) 7).
In the closed way the aim is that no air enters the subdural space. Before the dural opening the drain is tunneled beneath the galea in the direction towards the middle of the base of the skin flap. A distance from the burr hole to the drain’s exit point of at least 5 cm prevents infection 8).
Then the dura and external membrane are incised. This opening should have the same diameter as the drain to allow for a watertight and airtight drain introduction. The hematoma can therefore be evacuated only through the drain: the more fluid that is going to be collected, the more negative pressure that will be built up, which helps the brain to unfold again.
The dura is covered with a small piece of a gelatin sponge and the burr hole is filled and with bone chips collected at the beginning.
The last steps are to connect the drain to a closed collecting system and secure the connection and the exit point from the skin with sutures.
Drain insertion after CSDH drainage is important, but position (subgaleal or subdural) and duration did not appear to influence recurrence rate or clinical outcomes. Similarly, drain location did not influence recurrence rate nor outcomes where both parietal and frontal burr holes were made. Further prospective cohort studies or randomized controlled trials could provide further clarification 9).