Removal Of Brain In Fetuses And Infants

When the sutures are not closed and the cranial bones are still soft, Beneke's technique is used to open the cranium. The scalp is reflected as in adults. Starting at the lateral edge of the frontal fontanelle, the cranium and dura on both sides are cut with a pair of blunt scissors along the line indicated in Fig. 6-4A. (In this age group, the skull is often difficult to separate from the underlying dura in the manner described for adults.) This cut leaves a midline strip approx 1 cm wide, containing the superior sagittal sinus and the falx, and an intact area in the temporal squama on either side, which serves as a hinge when the bone flap is reflected. The older the infant, the narrower the sagittal strip will be because ossification advances toward the midline.

An alternate method of cutting, which follows the cranial suture lines, is illustrated in Fig. 6-4B and B'. With this method, fracture lines will be created along these bone flaps on their reflection; an optional cut along the posterior base of the frontal bone on either side will facilitate the procedure. The falx is then sectioned in a manner similar to that described for adults.

To minimize brain distortion during removal, several methods have been proposed (4-9). In an early stage of the autopsy, fixatives such as 10% formalin in 70% alcohol can be infused through the neck arteries; this increases the consistency of the brain and facilitates its removal (7). The fixative also can be injected percutaneously into the lateral ventricles, through the lateral margin of the anterior fontanelle, while the CSF fluid is allowed to exit via an intrathecal spinal needle (5,7). Zamboni's fixative, which is yellow, shows whether the injection is sufficient. All these methods interfere with microbiologic examination.

In a modification of Beneke's method the skull is incised lightly along the cranial sutures and at the fontanelles (7). By reversing the scalpel and passing it under the bones, the bones are separated from the underlying dura. The bone flaps are reflected after a small nick is made at the base in each of the bones. This procedure is similar to the method illustrated in Fig. 6-4 and B'. The dura is then cut as close to the base of the skull as possible. This method has the advantage of protecting the usually friable surface of the infant brain from damage during its removal. Damage to the brain can be minimized further if the scalp and calvarium are opened and the falx sectioned with the body in a sitting position and the infant's head being supported by an assistant. The tentorium and vein of Galen are transected in this position by gently separating the parietooccipital lobes. After the tentorium is sectioned, the body is suspended upside down by the assistant, the brain being supported during the movement by the hand of the prosector.

The brain is cut away from the base of the skull in this upside-down position, which minimizes movement of the brain and damage to the brain substance and its surfaces. The bone flaps can be repositioned in their normal position on one side; supporting the head with the hand on this side, the brain can be freed on the other side. This is repeated on the opposite side. The brain is not touched directly during these procedures and,

Fig. 6-2. Protective device. Prosector's hand holds saw inside bag. Dashed line indicates tape-seal of bag to, from left, prosector's gown, opposite side of the bag and neck of deceased. Adapted from ref. (1).

Fig. 6-3. Lines of saw cuts for skull cap removal. Frontal point (A) is approx two fingerbreadths above supraorbital ridges. Temporal point (B) is at the top of ear in its natural position before scalp reflection. Point (C) is approx 2 cm above (B). Occipital point (D) is approx two fingerbreadths above exter-

Fig. 6-3. Lines of saw cuts for skull cap removal. Frontal point (A) is approx two fingerbreadths above supraorbital ridges. Temporal point (B) is at the top of ear in its natural position before scalp reflection. Point (C) is approx 2 cm above (B). Occipital point (D) is approx two fingerbreadths above exter-

when all attachments are severed, it is allowed to fall free, preferably into a body of water and not on to a hard surface.

Beneke's method of leaving the tentorium and removing the cerebral hemispheres from the brain stem and cerebellum is controversial (9). We keep the brain as intact as possible at this stage but inspect the tentorium and neighboring structures during the removal procedure.

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