Stereotactic intracerebral metal foreign body extraction

In the Second World War, magnets were used to absorb foreign metal in the brain during brain debridement. Riechert (1955) began to remove intracranial metal foreign bodies by stereotactic method using a special foreign body forceps. In 1977, Xu Jianping of this country succeeded in removing intracranial shrapnel by this method, and experimented with a samarium-cobalt magnetic bar with a magnetic energy of 200mT (2000Gs and a suction force of 75g, and an experiment on the removal of shrapnel). Wu Shengyu et al. (1979) developed a high-performance magnetic guide needle with a magnetic energy of 3 700 Gs and a suction force of 530 g, which was applied in clinical practice and achieved satisfactory results. Stereotactic method and magnetic needle removal of intracranial foreign body have the advantages of simple operation, accurate positioning, small damage to brain tissue, etc., and are suitable for the removal of foreign bodies in the deep brain. Even if the foreign body is located in the basal ganglia and the thalamus, such surgery can be considered. . Treatment of diseases: foreign body injury Indication In recent years, the treatment of intracranial metal foreign bodies tends to adopt a more aggressive attitude, but surgical indications should still be strictly controlled. 1. In the early stage of brain debridement, metal foreign objects that are easily accessible in the injured or adjacent to the magnetic guide needle can be removed in one stage. 2. The shrapnel with a size of 1 cm or more has a high incidence of infection. If the brain dysfunction is not increased, the appropriate approach is selected and the directional surgical removal is applied. 3. Oriented enucleation should be used instead of large metal foreign bodies above 1 cm that are generally more damaging to the craniotomy or failed to be removed. 4. Small shrapnel of size less than 1 cm, the incidence of infection is very low, and surgical removal depends on the situation. For the application of magnetic guide needles that are easy to aspirate, it is also considered to be removed without increasing brain damage; the shrapnel or CT examination shrapnel that causes local brain irritation (epilepsy) should be removed when accompanied by localized suppuration. Contraindications 1. Metal foreign bodies are located in the brain's large blood vessels or brainstem, or adjacent to sports, speech areas, no local irritation, or no local infections detected by CT examination, such as directional surgery has caused severe brain dysfunction and life-threatening. 2. Small shrapnel and shrapnel for many years after injury, generally do not advocate surgical removal. Preoperative preparation 1. Learn more about the injury, do the skull X-ray including CT examination, and if necessary, perform cerebral angiography to determine the location of the foreign body and its relationship with peripheral nerve structures and large blood vessels. 2. Conventional injection of tetanus anti-toxic serum. 3. The head and side slices of the skull must be re-photographed before surgery to observe whether the foreign body is displaced. 4. On the day before surgery, draw the position of the shrapnel directly on the scalp in the direction of the front and the side, and select the best surgical approach, that is, the incision in the important functional area of the brain that is closest to the foreign body. And skull drilling. The scalp incision line was marked with gentian violet. 5. Others with general craniotomy. Surgical procedure 1. Scalp incision, skull drilling and orientation instrument installation and fixation are the same as general directional surgery. 2. Because the intracranial metal foreign body is the visible target of the X-ray examination, the head and the lateral slice can be directly photographed, and the target can be found from the slice. 3. Calculate the target coordinates: that is, measure the front and back (Y), upper and lower (Z) distances from the center point of the foreign object to the origin of the instrument coordinate, and the distance (X) from the center of the foreign object to the median sagittal plane of the head. 4. Adjust the three coordinate axes of the orienter according to the target coordinate value, or directly adjust the direction of the two sides of the positive direction of the orientation instrument under the monitoring of X-ray TV (X-TV), and operate the operator (magnetic guide) Needle and foreign body pliers are delivered to the shrapnel. 5. For the ferromagnetic shrapnel, a special high-performance magnetic needle is used to accurately guide the foreign body in the brain through the orientation instrument. At this time, the front end of the needle is in contact with the elastic piece, and a metal slamming sound is generated, and the operator also has a magnetic attraction. The magnetized shrapnel always attracts the magnetic guide pin with one end of its long axis, and the magnetic guide pin is withdrawn, and the metal foreign matter comes out. For non-ferromagnetic intracranial foreign bodies (such as lead, copper, etc.), special foreign body pliers are used to clamp foreign objects under stereotactic or TV guidance. This method does not have a fixed effect on the shrapnel like the magnetic guide pin. When clamping, the shrapnel may be displaced, causing damage to the brain tissue and blood vessels. It can also be sucked out by a negative pressure pipette. 6. After suturing the scalp incision and removing the foreign body, the wound was washed with physiological saline, a rubber sheet was built in, and the scalp was sutured with a silk thread. complication 1. Aggravation of neurological symptoms and signs caused by additional damage to brain tissue. 2. Intracranial hemorrhage foreign body forceps open the jaws when the foreign body is clipped, or the sharp foreign body passes through the brain tissue channel, which may damage the blood vessels and cause bleeding. The surface of the foreign body is formed by a fibrous envelope with blood vessels on it, and bleeding may occur when it is removed. Postoperative observation should be closely observed changes in the condition, such as intracranial hemorrhage, early detection, timely craniotomy to remove the hematoma. 3. Foreign body removal surgery has the danger of causing the outbreak and spread of infection. Therefore, antibiotics should be routinely applied before and after surgery to prevent infection.

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