Cortical resection

Cerebral cortex resection is currently the most basic method for the treatment of focal epilepsy. It was initiated by Horsley in 1886 and later refined and finalized by Penfield et al. The efficacy of surgery is related to the complete removal of epileptogenic foci. The total effective rate was 71%, of which 43.2% were completely lost in seizures and 27.8% were significantly improved. Treating diseases: epilepsy Indication 1. Drug-refractory focal epilepsy. 2. The clinical manifestations are consistent with the results of EEG and imaging studies. 3. Surgical removal of the lesion does not cause serious neurological dysfunction. Contraindications 1. The epileptic foci is unstable, and the lesions have not yet developed mature, and the surgery is temporarily contraindicated. For example, in children, the course of epilepsy is still short. Another example is post-traumatic epilepsy, which is less than 2 to 3 years. Seizures in both cases have a chance of spontaneous relief or cure with appropriate medication. 2. The epileptogenic focus is located in an important functional area, and there are severe neurological dysfunction after resection. Preoperative preparation 1. Reduce or completely stop anti-epileptic drugs 1 to 2 days before surgery. 2. Disable morphine and diazepam sedatives before surgery to avoid affecting the observation of intraoperative EEG. Surgical procedure 1. The incision should be determined according to the location of the epileptogenic focus, but it is larger than the general craniotomy, exposing important functional areas, such as the central anterior and posterior, lateral fissure and so on. Usually the bone flap is craniotomy. 2. According to the DSA and MRI images, the anterior and posterior anterior and posterior central sulcus locations are identified by the corpus callosum structure. The horizontal line from the pillow to the frontal pole is drawn through the lower edge of the knee and the pressure part of the body, representing the length of the brain, that is, the horizontal line HP. Then draw three lines perpendicular to the HP line: the AC line is drawn through the front edge of the knee; the PC line is drawn through the trailing edge of the press; the MC line is drawn at equal distance between the AC and the PC. PCG stands for the central front, PO stands for the central back, and FRol stands for the central ditch. 3. Visual observation of cerebral cortex with or without morphological abnormalities, scars, cysts, cerebellar gyrus and other deformities help identify the epileptogenic zone. 4. Electrical stimulation of the cerebral cortex to confirm the functional area, looking for epileptogenic focus. First, start the stimulation center with 0.5V voltage, and then increase 0.5V each time, and gradually increase it to 5V. The stimulation wave width is 2ms, the frequency is 60 times/s, and most of the reactions can be obtained at 2 to 3V. It is better to stimulate the center and return to the center before returning. It can avoid the occurrence of convulsions, and use the central part to return to the lower part of the tongue as the sensory reaction point. Place digital small pieces of paper on each stimulus point and record on the drawing. After the stimulation, the cerebral cortex electrogram was performed, and the post-discharge phenomenon was observed to find the epileptogenic focus. 5. Cortical electroencephalography (ECoG). A horseshoe-shaped (made of plexiglass and stainless steel) scaffold-type cortical electrodes or a modified hand-held silicone rubber with a strip of electrodes embedded in different numbers of electrodes were used to perform electrocortical tracing, to find the epileptogenic focus and to determine its extent. First fix the electrode holder on the edge of the skull window and discharge the electrode on the cortex or put the strip electrode directly on the cortex, and trace it on the drawing. It is generally believed that the most frequent spike area in the interictal period is the epileptogenic focus. Often manifested as a single spike, a cluster of spikes that erupt briefly, multiple spikes and a combination of spine waves in some patients. It should be noted that the spikes and sharp waves traced on the surface of the cerebral cortex do not always represent the origin of the epilepsy, but may be transmitted from the distant site. Such as conduction from the frontal lobe to the temporal lobe, and from the tip of the temporal lobe to the frontal lobe or from the tip of the palate to the posterior part of the palate. At this time, the primary epileptogenic focus should be determined in combination with abnormal phenomena seen by the naked eye, imaging findings, abnormal background electrical activity (normal cortical electrical activity rhythm disorder), and preoperative EEG localization. If no spikes are recorded during the procedure, an induction test should be performed, usually with intravenous injection of 50-100 mg of brepiftal sodium bromide, and the injection is completed in a few seconds. Within 90 s after the injection, epileptic spikes appear or increase, which is the epileptogenic focus. The positive rate of up to 85% has become a routine means. In the case of ECoG tracing, the effects of anesthetic drugs, such as thiopental, diazepam (diazepam), and nitrous oxide, may be produced to produce fast or slow waves, which may affect the observation of cerebral cortex. 6. Subdural cortex resection, using Penfield method to remove gray matter of epileptogenic foci. The pia mater is first cut at the edge of the sulcus, and the gray matter under the pia mater is removed with a sharp cut or a thin aspirator. It can also be cut with an ultrasonic aspirator (CUSA). However, only the gray matter is removed to the depth of the sulcus, the white matter under the gray matter is intact, the damage to the edge tissue of the sulcus is reduced, and the pial membrane on the nearby cerebral palpebral is intact, and the blood vessels in the sulcus cannot be damaged. For larger forehead, apical and occipital lobe lesions, partial lobectomy should be performed: 1 frontal lobe resection: in non-dominant hemispheres, the extent of large frontal lobe resection should be limited to the previous part of the central anterior sulcus, and resection can be divided into two steps. On the lateral convex surface of the brain, the upper, middle and lower gyrus were removed, and then the anterior cingulate was removed. The posterior cortex should be preserved. In the dominant hemisphere, the 2.5 cm brain tissue should be kept back to the back to avoid language barriers. 2 parietal resection: the scope of resection is limited to the top inter-ditch, retaining the central and posterior. The vein draining from the central or central posterior sulcus to the superior sagittal sinus must be preserved. In the dominant hemisphere, the veins in the inferior parietal region should also be preserved. In the non-dominant hemisphere, as long as the central back is intact, the parietal lobe after the removal of the central posterior groove will not have loss of sensory motion, but may have partial visual field defects. The indications for parietal resection are rare, and usually require clinical manifestations, imaging studies, and EEG data to be removed. 3 occipital lobe resection: occipital lobe can be removed when there is a positive epileptogenic focus, but even subtotal resection can produce complete ametropia. 7. Review the cerebral cortex. The electrical activity of the marginal cortex should be examined repeatedly after resection. If there is still epileptic activity, the scope of resection should be expanded. 8. Close the incision. The dura mater should be tightly sutured after surgery. Reset the bone flap. The scalp is sutured in two layers. Drainage tube or rubber hollow drainage under the epidural and scalp. complication Complications were rare. A group of 432 patients with cerebral cortex except for the temporal lobe had a operative mortality rate of 0 and a disability rate of 6%. Mainly for infection, brain dysfunction, such as hemiplegia, aphasia, hemianopia and so on.