Removal Of Brain In Adults

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INCISION OF SCALP The head is elevated slightly with a wooden block or a metal headrest attached to the autopsy table. The hair is parted with a comb along an imaginary coronal plane connecting one mastoid with the other over the convexity (Fig. 6-1). A sharp scalpel blade can then be used to cut through the whole thickness of the scalp from the outside. The incision should start on the right side of the head (the "viewing-side" in most American funeral parlors) just behind the ear-lobe, as low as possible without extending below the earlobe, and extend to the comparable level on the other side. This will make reflection of the scalp considerably easier. Sufficient tissue should be left behind the ear to permit easy sewing of the incision by the mortician.

The anterior and posterior halves of the scalp are then reflected forward and backward, respectively, after short undercutting of the scalp with a sharp knife, which permits grasping of the edges with the hands. The use of a dry towel draped over the scalp edges facilitates further reflection, usually without the aid of cutting instruments. If the reflection is difficult, a scalpel blade can be used to cut the loose connective tissue that lags behind the reflecting edge as the other hand continues to peel the scalp. The knife edge should be directed toward the skull and not toward the scalp. The anterior flap is reflected to a level 1 or 2 cm above the supraorbital ridge. The posterior flap is reflected down to a level just above the occipital protuberance.

SAWING OF CRANIUM The cranium is best opened with an oscillating saw. Because aerolization of bone dust poses a risk of infection (see Chapter 16), the procedure should be done within a protective device such as inside a plastic bag (1,2). (Fig. 6-2) Alternatively, a handsaw can be used, especially for cases of suspected Creutzfeldt-Jakob disease (3,4). Various saw cuts are in use but we recommend the method illustrated in Fig. 6-3; the configuration of the saw cut minimizes slippage of the skull cap during restoration of the head by the embalmer. Naturally, the saw cut may have to be modified after some neurosurgical procedure(s) or in the presence of skull fracture(s). The temporalis muscle should be cut with a sharp knife and cleared from the intended path of the saw blade.

Ideally, sawing should be stopped just short of cutting through the inner table of the cranium, which will easily give way with the use of a chisel and a light blow with a mallet. Leaving the dura and underlying leptomeninges intact allows to view the brain with the overlying cerebrospinal fluid (CSF) still in the subarachnoid space. To obtain this view, after removal of the skull cap, the dura must be cut with a pair of scissors along the line of sawing and reflected.

To protect the brain, the extended index finger of the hand that holds the neck of the oscillating saw should gauge the distance of the blade penetration. The oscillating blade should be moved from side to side during cutting to avoid deep penetration in a given area. Our saw (Lipshaw Co.) is equipped with a guard (see Chapter 8) and can be used with little training, without fear of deep penetration.

The frontal point of sawing should start approx two finger-breadths above the supraorbital ridge. While the lateral aspects of the skull are being cut, turning the head to the opposite side permits the brain to sink away from the cranial vault and thereby diminishes the chance of injury to the brain.

When the dura is left intact, as in the method described earlier, the skull cap can be peeled away easily. A twist of a chisel placed in the frontal saw line will admit the fingers inside the skull cap. A blunt hook may be used to pull the skull cap away from the underlying dura. A hand inserted between the skull and the dura (periosteum) helps the blunt separation of these while the other hand is pulling the skull cap. If the dura adheres too firmly to the skull, it can be incised along the line of sawing and the anterior attachment of the falx to the skull can be cut between the frontal lobes. The posterior portion of the falx can be cut from inside after the skull cap is fully reflected. The dura is then peeled off the skull cap. The superior sagittal sinus may be opened with a pair of scissors at this time. Routinely, the dorsal dural flaps on both sides can be removed easily from the brain by severing the bridging veins. In the presence of epi- or subdural hemorrhage and neoplasia, it is best to leave the dural flaps attached to the dorsal brain and section them together.

DETACHMENT OF BRAIN The frontal lobes are gently raised and the olfactory bulbs and tracts are peeled away from the cribriform plates. The optic nerves are cut as they enter the optic foramina. Under its own weight, the brain is allowed to

Coronal Mastoid Incision

Fig. 6-1. Scalp incision. Dotted line indicates coronal plane of the primary incision. It starts on right side over the mastoid just behind earlobe and passes over palpable posterolateral ridges of parietal bones to reach opposite mastoid. This line is slightly tilted backward from plane parallel with face.

Fig. 6-1. Scalp incision. Dotted line indicates coronal plane of the primary incision. It starts on right side over the mastoid just behind earlobe and passes over palpable posterolateral ridges of parietal bones to reach opposite mastoid. This line is slightly tilted backward from plane parallel with face.

fall away from the floor of the anterior fossa, while it is being supported with the palm of one hand. The pituitary stalk is cut, followed by the internal carotid arteries as they enter the cranial cavity. Cranial nerves III, IV, V, and VI are severed as close to the base of the skull as possible. Subdural communicating veins are also severed. Next, the attachment of the tentorium along the petrous ridge is cut on either side with curved scissors. At this time, the brain must not drop backward excessively because this will cause stretch tears in the cerebral peduncles. This also can be prevented by raising the head very high from the beginning, with pronounced flexion of the neck, using a wooden pillow or a metal support attached to the table.

Cranial nerves VII, VIII, IX, X, XI, and XII are then cut identifying each one in sequence. The vertebral arteries are severed with scissors as they emerge into the cranial cavity. Then, the cervical part of the spinal cord is cut across as caudally as possible, but too oblique a plane of sectioning should be avoided. Curved scissors will be best for this purpose. If a critical lesion exists in the region, a cross-section perpendicular to the neuroaxis at the pontomedullary junction or higher may be elected in order to preserve the integrity of the abnormality.

The brain can then be reflected further back by using the support hand to deliver the brain stem and cerebellum from the posterior fossa without causing excessive stretching at the rostral brain stem level. The brain is pulled away from the base of the skull after cutting the lateral attachment of the tentorium to the petrous bones. The pineal body must not be left behind during this maneuver.

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