A practical scalp incision design is directly related to ease of procedure and surgical effect, and is a prerequisite for the successful surgery of CSDHs. The ideal scalp incision design for CSDH surgery should satisfy the following 4 criteria: The incision should be positioned to facilitate drainage of the hematoma and provide the most flexible option for intraoperative incision extension. Moreover, the scalp incision should heal well, and satisfy the patient’s desire for an aesthetic incision [8, 9].
Selection of the site of the incision has no standard rules or criteria, either for burr hole craniotomy or mini-craniotomy; selection is mainly based on the location and volume of the CSDHs. Clinically, the volume of a CSDH that requires surgical intervention is usually large, and most of the hematoma accumulates in the frontotemporal and parietal regions. Hematoma can be drained in any position of the projected scalp of the hematoma cavity. However, if the incision is below the superior temporal line, part of the temporal muscle is bound to be dissected, which causes different degrees of postoperative temporal muscle injury and edema, and even atrophy in severe cases. These may cause pain, weakness, or other annoyances during chewing.
If the incision is too far below the superior temporal line, the middle meningeal artery or its thick branches may be encountered during the procedure. The procedure with improperly handled will result in postoperative complications such as acute subdural or epidural hematoma. In serious cases, a second operation is required. With our long-term clinical experience, we found that the scalp projection of the main anterior part of the hematoma cavity is in the coronal suture or slightly anterior to it, and that of the posterior part of the hematoma cavity is approximately at the parietal tubercle, or about 0.5- to 1-centimeter anteroinferior to the parietal tubercle. These two areas are at the same computed tomography level, roughly. Setting the incision at the above two locations can direct hematoma drainage and effectively avoid potential complications. In addition, for a single burr-hole craniotomy, we recommend that the incision should be located at 0.5- to 1-centimeter anteroinferior to the parietal tubercle. This low location facilitates drainage and thus reduces the recurrence rate of hematoma.
After the site is selected, the incision shape should be strategized. There are no standard guidelines, and shape can depend on the preference of the operator. All factors should be considered, including extensibility, blood supply, and aesthetic appearance. Each of these is discussed below.
Extensibility of the scalp incision shape
Clinically, most CSDHs can be successfully drained during surgery. However, difficulties may be encountered in some cases such as sediment hematoma, multi-fibrous compartmented hematoma, and calcified hematoma. For these types of hematomas, the scalp incision should be extended, and a large craniotomy should be performed to remove the hematoma.
A procedure is also needed when there is severe active bleeding, but the site of bleeding cannot be explored. Additionally, the possibility that the incision may have to be reused should be considered in the design of its shape; the patient may need reoperation for hematoma recurrence or other craniocerebral diseases later in life. Consequently, if the designed incision shape cannot be flexibly extended, subsequent procedures will not go smoothly or even fail.
Scalp incision shape and blood supply
After the position is selected, the incision shape is related to the blood supply of the scalp incision, and directly affects the postoperative wound healing. Some authors have reported that the “T” or “n” incision shapes, especially in patients with diabetes or drug abuse, are more prone to ischemia and necrosis, leading to wound healing complications [10, 11]. In our clinical experience, when the angle formed by the incision lines, or lines tangent to the incision are less than or equal to 90 degrees, then the incision, especially the corner of the incision, is prone to ischemia and necrosis. Therefore, a scalp incision that is smooth and wider than 90 degrees is a powerful guarantee for good wound healing.
Aesthetic appearance of the scalp incision shape
Patients are concerned about the cosmetic results of surgeries, and an aesthetically displeasing scalp incision can result in a psychological burden, especially for those with thin hair or baldness [7]. The aesthetic satisfaction of patients has become an important index to evaluate surgical outcomes [8, 9, 12]. With the present investigation, we observed that a regular and streamlined incision shape, consistent with the skull contour line, was more acceptable to the public’s aesthetic standards.
Summary
Motivated by the need for scalp incision in decompressive hemicraniectomy, and based on our clinical experience, we applied the adjustable question mark-shaped incision design to satisfy the concerns for extensibility, blood supply, and aesthetic appearance discussed above. The scalp design is suitable for all chronic subdural procedures such as burr-hole craniotomy, mini-craniotomy, and large craniotomy. In the present case series, all the patients experienced good scalp incision healing, including the 2 patients who underwent an extension of the incision extending. Overall, 36 (97%) patients were satisfied with the incision design itself, and only one patient was dissatisfied due to widening of the scar. Notably, most of the patients who were cosmetically self-consciousness were women, and the mean age was younger than that of the patients overall. As it happens, the majority of the patients with scalp dysfunction were also women. These results may be because women, especially younger women, are more concerned with their physical appearance than the general population. This suggests that psychological counseling before surgery is particularly important to prepare patients for the possible postoperative outcomes, especially young women, which will be our focus of the future research.