posterior cranial fossa decompression

Decompression of the posterior cranial fossa is a common technical operation. The surgical procedure is similar to the craniotomy of the posterior cranial fossa, but the dura mater should be more extensively star-shaped, the posterior margin of the foramen magnum and the posterior arch of the atlas should be as far as possible. To be wider, the dura mater should also be cut open to achieve adequate decompression so that the cerebellar tonsils of the lower jaw no longer oppress the medulla and upper cervical cord. Treating diseases: brain edema Indication 1. The intracranial pressure is still high after the operation of the posterior cranial fossa, the space-occupying lesions are not completely removed, or the tumor is highly malignant. 2. Increased intracranial pressure caused by diffuse lesions, or occipital foramen magnum crisis before surgery. 3. Critically ill patients with heart, vasomotor center, or respiratory integrated central function impairment. Contraindications 1. An elderly or already dying patient. 2. Endangered patients, family members or units refused surgery. 3. Intracranial lesions with increased intracranial pressure, after decompression of the posterior cranial fossa, there is a risk of causing cerebellar hernia. Preoperative preparation The volume of the posterior cranial fossa is small, and the important structures such as the brain stem, the posterior cranial nerve and the vertebral-basal artery cannot be damaged or excessively pulled. Therefore, the design of the incision is very important when the skull is opened. It must be accurately positioned before surgery. Road to meet the needs of surgical operations. Under the occipital cranium, the neck should be reached. The skin preparation must include the entire head, the neck and the shoulders. Posterior cranial fossa lesions are often associated with increased intracranial pressure and obstructive hydrocephalus. In order to facilitate the exposure and operation of the operation, it is often necessary to puncture the posterior horn of the lateral ventricle to release the fluid. In the case of a large hole of the occipital fossa, the lateral ventricle puncture drainage can be performed first. Surgical procedure Incision Posterior cranial fossa decompression is generally the most widely used straight incision. After selecting the position, the incision line is drawn with gentian violet or methylene blue. For routine disinfection, the disinfection range should be up to the top of the forehead, and the shoulders should be placed on both sides before the ear and the neck side. Cover a single towel and attach it to the skin with a slit film or suture to prevent slippage during surgery. Infiltrate the layers along the incision line with 0.25% to 0.5% procaine (adrenalin), and puncture the occipital or proximal 1 and 2 cervical vertebrae with a long needle on both sides of the incision line. ~ 10ml procaine to reduce intraoperative bleeding, easy to separate muscles. Cut the skin and subcutaneous tissue in the median, coagulate or ligature the bleeding point. The periosteum is cut from the medial aspect of the occipital trochanter, and is bypassed at both sides of the occipital trochanter, leaving a small diamond-shaped fascia at the trochanter for suturing at the end of the operation. The occipital trochanter is strictly incision along the midline ligament, reaching the occipital and posterior tibial tuberosity and the spinous process. The muscles and tendons attached to the occipital bone were peeled off from both sides by a periosteal stripper. After the tissue was cut and separated on the posterior tibial tuberosity, the periosteum was cut transversely on both sides along the posterior arch surface, and the stripper was peeled off. The spinal spinous processes and the muscles on both sides of the lamina are stripped outward. During the stripping process, the electrocoagulated muscles stop bleeding, and there are blood vessels on both sides of the middle line of the trochanter, and stop bleeding with bone wax. Use an automatic retractor to open the slit. 2. Skull opening window Mostly for the bone window craniotomy. First drill a hole in the occipital scale of one side. Due to the tilt of the position, the drill bit cannot be perpendicular to the surface of the skull, so the lower part should be blocked with the bones to avoid slipping off. After drilling through the skull, use a rongeur to gradually bite the occipital bone. The occipital fenestration area should be determined according to the surgical exposure requirements. Upward can bite to the occipital trochanter and the lower edge of the transverse sinus. Both sides can bite to the posterior margin of the mastoid, and bite the posterior margin of the foramen magnum. If necessary, the posterior arch of the atlas can be bitten. However, the posterior margin of the foramen magnum and the posterior arch bite width of the atlas should be limited to 1 to 1.5 cm from the midline of each side to prevent damage to the vertebral artery, resulting in adverse consequences. 3. Dural incision The dura mater is made into a petal-shaped incision, which is turned in the direction of the transverse sinus, and a median incision is attached below. There is a cerebellar palsy in the midline of the dura mater of the posterior cranial fossa, which contains the occipital sinus. The developmental degree of the occipital sinus and the sinus sinus varies from person to person. Those who develop well may have more bleeding when they are cut. They need to be electrocoagulated or sutured to stop bleeding, or clipped with silver clips. The dura mater and the upper cervical vertebrae should be fully incision to facilitate decompression. 4. suture wound After the end of the decompression surgery, the dura mater is not sutured for the purpose of decompression. The muscles under the occipital muscle are tightly sutured with a thick thread. The sutures must be sutured across the entire layer of the muscle or layered. There should be no gaps to avoid cerebrospinal fluid leakage or pseudocysts. The trochanteric trochanter is the junction of muscle and fascia, which is the most prone to leakage and must be tightly sutured. The fascia, subcutaneous tissue and stratified suture of the skin. Drain can be placed outside the dura mater or another small mouth can be taken out, and removed 24 to 48 hours after surgery. complication 1, the posterior cranial fossa is small, postoperative bleeding, edema, the consequences are more serious, so the hemostasis should be particularly careful during surgery. The vertebral artery, the posterior inferior cerebellar artery and the basilar artery injury, brain stem ischemia, the consequences are serious. 2, the posterior cranial nerve injury can cause hoarseness, cough and difficulty swallowing. Severe muscle suture, the area is not tightly wrapped, can cause cerebrospinal fluid leakage or pseudocyst, causing aseptic meningitis, handling is very difficult.