The basic principles for using a craniotomy drill are as follows:

1. The basic principle of crossing the midline for craniotomy. A small bone flap that crosses the midline for craniotomy. Crossing the sinus opening can be done in different ways. To ensure sufficient exposure and avoid damage to the venous sinus, it is recommended to adhere to the following principle: in small (sagittal sinus, sagittal position less than 5cm) bone flap craniotomy, 2 bone holes and 1 paranasal bone hole can be perforated in the sinus. The skull starts from the lateral foramen and stops about 1.5cm beside the sinus. Then cut the bone outward from the sinus foramen and merge it with the outer bone seam.

According to the need for exposure on the other side of the midline (such as superficial tumors), the bone flap can last for more than 1.5 centimeters on the other side of the sinus, or only two holes can be drilled in the cavity. Cross the midline craniotomy for medium and large bone flaps. For larger bone flaps, a bone hole should be opened every 3-4 centimeters along the sinus. Use arrows to indicate the method of bone cutting. We will not use a craniotomy drill in the anterior part of the forehead above the base of the forehead, as this is for cosmetic purposes and to reduce the risk of frontal sinus injury. Whether to cross the sinus foramen depends on the surgical purpose.

2. The basic principles of midline frontal craniotomy. The pathway across the midline of the forehead is used to approach, enter, or pass through lesions in the interhemispheric fissure, skull base, or orbital apex. Possible single or double frontal bone flaps. Usually, the head is raised slightly without the need for rotation. In the unilateral approach, the head and body can tilt slightly towards opposite sides as if entering the interhemispheric fissure. The degree of head curvature depends on the surgical purpose.

Important anatomical landmarks include coronal suture, sagittal suture, anterior fontanelle, superior sagittal sinus, and frontal sinus. Another important anatomical landmark is the ventricular puncture point, which is 1cm before coronal suture and 2.5cm outside the midline. Forehead craniotomy with skin incision, located on the opposite side of one ear, palpate and locate the STA frontal branch. To avoid damaging the STA frontal branch, start from 1cm in front of the ear. The incision must usually be located 1 centimeter in front of the front end when crossing the centerline.

The above is an introduction to the basic principles of using a craniotomy drill. Thank you for reading.