posterior fossa craniotomy

Craniotomy is used in the treatment of various brain diseases and injuries. Since the circumcision in BC, after a long period of unremitting research and improvement, it has now reached a fairly perfect level. At present, almost no intracranial structure is impossible for neurosurgeons. This is not only due to the improvement of surgical techniques, but also the continuous improvement of surgical instruments and new technical equipment in recent years, the improvement of hemostasis methods, the promotion and application of microsurgical techniques, the anesthesia methods and the monitoring of vital signs during surgery. The prevention and treatment of cerebral edema and the reduction of intracranial pressure and other comprehensive measures. Craniotomy is basically divided into two categories, namely bone window craniotomy and bone flap craniotomy. Bone opening in the bone window is to bite part of the skull into the skull, leaving bone defects after surgery. Posterior cranial fossa surgery, diaphragmatic decompression, and open injury debridement belong to this category. The craniotomy is a bone flap or a free bone flap with a muscle periosteum pedicle. The bone flap is turned into the cranium. At the end of the operation, the bone flap is sutured and fixed, and no bone defect remains after surgery. Most intracranial surgery belongs to this category. Treatment of diseases: hydrocephalus in children with brain tumors Indication 1. Posterior fossa tumors include excision of tumors in the cerebellum, cerebellar cerebral horn, fourth ventricle, and large occipital region. 2. Traumatic or spontaneous hematoma in the posterior fossa. 3. Vascular diseases requiring surgery, such as aneurysms, arteriovenous malformations, etc. 4. Inflammation of the posterior fossa or parasitic lesions, such as cerebellar abscess, fourth intraventricular cysticercosis, arachnoid adhesions or cysts. 5. Some congenital diseases, such as craniocerebral junction malformations. 6. Some obstructive hydrocephalus, such as obstruction of the aqueduct, median hole adhesion, feasible adhesion separation or ventricular-occipital large pool shunt. 7. Some analgesic procedures, such as trigeminal nerve root resection, neurovascular decompression and medullary trigeminal spinal cord severance. Contraindications 1. The patient's general condition cannot tolerate surgery, such as severe heart, lung, liver, and kidney dysfunction. Severe shock, water and electrolyte balance disorders, severe anemia or malnutrition should be suspended. 2. Have bleeding quality, bleeding is not easy to control. 3. Severe hypertension, especially those with brain-type hypertension and severe cerebral arteriosclerosis. 4. Systemic or severe local infection in the acute phase. 5. Brain function, especially brain stem failure, to treat those who are hopeless. 6. Head soft tissue or adjacent tissue infection. Preoperative preparation 1. The volume of the posterior cranial fossa is small. 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. Surgical approach to meet the needs of surgical operations. 2. Under the occipital cranium, the neck should be reached. The skin preparation must include the full head, neck and shoulders. 3. Posterior fossa lesions are often accompanied by 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. Puncture can be performed at the time of craniotomy, or before the craniotomy. The drainage tube is placed first, and the external drainage is performed for 1 to 3 days before craniotomy. Surgical procedure Incision The cranial incision of the posterior cranial fossa has a straight midline straight incision, a midline straight incision, a posterior mastoid incision, a hooked incision, and a barbed incision. The midline straight incision is the most widely used, and it is suitable for the midline of the posterior cranial fossa and cerebellar hemisphere lesions. The paramedian midline incision is suitable for one side of the cerebellar hemisphere or the cerebellopontine angle lesion. Because of the need to cut a thicker item muscle, the bleeding is more, so the application is not wide. The hook and barb incision and the incision after the mastoid are suitable for one side of the posterior cranial fossa. The arcuate incisions on both sides are large and have been rarely used. 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 The craniotomy of the posterior cranial fossa is mostly a 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 dural incision depends on the need for surgery. Generally, the valve is incision, and the sinus is turned in the direction of the transverse sinus, and the 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. 4. Reveal the structure of the posterior fossa The dura mater is turned in the direction of the transverse sinus, showing structures such as the cerebellum below, the lower jaw, the tonsils, the fourth ventricle, the medulla and the cervical spinal cord junction. 5. Intracranial operation See each specific operation. 6. suture wound After the end of intracranial surgery, in addition to suturing the dura mater for decompression purposes, try to suture the dura mater, the dura mater is large, and the fascia can be repaired when the suture is difficult. 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 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. Dura mater and muscle suture are not strict, the bandage is not tight, can cause cerebrospinal fluid leakage or pseudocyst, causing aseptic meningitis, handling is very difficult.