I. What problems can occur with skull defects.
1, aggravate brain injury
The cranial defect area causes the patient’s skull deformity, collapsing when upright, expanding when lying down, concave during the day and convex at night, due to the lack of cranial protection, the external atmospheric pressure directly compressing the brain tissue through the defect area, and the repeated back and forth movement causes progressive damage to the local brain tissue of the defect. The damage mainly includes mechanical, cerebrospinal fluid dynamics and cerebral hemodynamics. Under normal circumstances, the subarachnoid space exists between the skull and the brain surface, and the cerebrospinal fluid flows with the rhythmic pulsation of the brain tissue. When the skull is defective, the scalp lacks the support of the skull and collapses directly onto the brain surface, and the subarachnoid space in the defect area disappears, affecting the cerebrospinal fluid reflux, which is a factor causing chronic hydrocephalus and aggravating hydrocephalus. It also seriously affects the reflux of the superficial veins on the surface of the brain, making the blood flow to the brain tissue impaired. In addition, the reciprocal movement of the brain tissue in the area, the mechanical friction between the brain tissue and the edge of the defective skull, over time, leads to local brain atrophy and aggravation of the brain scar. The cumulative effect of the above three aspects of damage eventually results in new symptoms of neurological dysfunction, or aggravation of the original symptoms, seizures, hydrocephalus, etc.
2.Impact on brain function recovery
Patients are afraid of the pulsation, bulge and collapse of the defect area, afraid of sunlight, vibration and even noisy sound, and often have poor self-control, concentration or memory loss, or depression, fatigue, reticence and low self-esteem, dizziness, headache, local tenderness, irritability and restlessness, etc. The above symptoms are called skull defect syndrome. The above symptoms are called cranial defect syndrome. It leads to the decrease of quality of life and affects the rehabilitation effect.
3.Aesthetics and safety
Cranial defects are aesthetically displeasing, especially those located in the frontal area; the chance of brain tissue damage due to accidental injury is greatly increased after large area of cranial defects.
Second, which patients should undergo cranial repair.
1, cranial defect diameter more than 3 cm, regardless of the presence of symptoms should be cranial repair.
2. If the diameter of cranial defect is less than 3 cm, the following conditions should be repaired.
Timing of cranial repair surgery.
Repair as soon as possible after the original craniotomy incision is healed and the increased intracranial pressure is relieved.
Cranial repair.
Cranial repair is usually performed by using the original surgical incision, placing the cranial repair material between the scalp and the dura mater (or the membrane scar formed outside the brain tissue) to protect the brain tissue, firmly fixing the repair material with the surrounding normal skull by inlaying or covering, and finally suturing the scalp incision.
V. Materials available for cranial repair.
1.Titanium memory alloy is a high-tech material widely used in human repair and fixation, which has the advantages of hardness, good shaping effect, firm fixation and rare rejection reaction with the body, but the price is relatively expensive.
2, silicone cranial bone is prefabricated by the manufacturer according to the shape of most people’s skull, and sheared on the corresponding prefabricated material according to the defect site during surgery, which may not fully conform to the shape of the specific patient, but its price is low.
3.Artificial bone cement is close to cranial bone in composition, with good histocompatibility and easy shaping, but weak impact resistance.
4.Plexiglass has the advantages of hardness and light quality, but poor shaping, weak impact resistance and rejection reaction with the body are common.
VI. Digital three-dimensional cranial reconstruction technology.
The specific process is as follows.
1.Take a thin layer CT scan of the patient’s skull, and then reconstruct the patient’s skull in three dimensions by using CT workstation.
2.Produce a cranial simulation model using numerical control technology.
3. calculate and produce a three-dimensional restoration of the defective part using numerical control technology with reference to the healthy part and simulation technology.
4. in vitro verification of the restoration with the cranial simulation model.
5.Surgical placement of the restoration.