35. Percussion and Palpation. The external examination may be closed by the percussion of the heart, lung, spleen, liver and stomach boundaries, and by the palpation of the abdomen. The fine opportunity for control of technique, judgment as to sound, size, consistence, shape, etc., should not be lost. Rigor mortis of the abdominal muscles can be removed by kneading the muscles or by the application of hot cloths.
CHAPTER V.
THE EXAMINATION OF THE SPINAL CORD.
1. METHODS OF EXAMINATION. The spinal cord may be opened anteriorly or posteriorly. The choice of method is largely a matter of convenience or of individual skill in using certain instruments, such as the Brunetti chisels. The method of opening posteriorly is more commonly used in this country, as it requires less skill. It necessitates, however, an additional long skin incision that must be tightly stitched together to prevent leakage of blood and fluids after the restoration of the body. For this reason it is not as clean a method as the anterior opening, which requires only the one main skin-incision. In private practice the latter method is often advisable, as by it an examination of the cord can often be secured when the relatives would not consent to its removal posteriorly, on the ground of undue mutilation of the body. The anterior examination also permits a better inspection and an easier removal of the spinal ganglia and nerves.
Examination of Cord Posteriorly. For the opening of the spinal cord posteriorly the cartilage-knife, bone-forceps, bone-nippers and rhachiotome are necessary; in place of the latter the single saw, double chisel, Brunetti chisels or single chisel may be employed. The posterior examination of the cord should take place at the beginning of the autopsy, after the external inspection of the cadaver, before the thorax and abdomen are examined. The removal of the sternum gives a loss of resistance to the manipulations upon the back of the cadaver, and the turning-over of the body after it has been opened anteriorly is usually an unpleasant procedure because of the dripping of blood and other fluids. When it is found necessary to examine the cord posteriorly after the opening of thorax and abdomen it is better to fill these cavities with tow or excelsior, replace the sternum and sew up the anterior skin-incision before turning the body over.
The cadaver is placed face downwards, with medium-sized blocks beneath the cervical and lumbar regions, the arms being folded underneath the body. With the cartilage-knife an incision is then made through the skin and subcutaneous tissues in the median line, over the spinous processes, beginning above at the occipital prominence and ending at the lower border of the sacrum. The skin and subcutaneous tissues are then dissected back by bold slashing strokes for a distance of a hand’s breadth on both sides of the spine, thus laying bare the muscles of the neck and back. The muscles may be stripped back with the skin, but the heavy flaps thus formed are very likely to fall back and cover the seat of operation. Chain retractors may be used to hold the skin flaps back, particularly in the case of a very fat individual, but usually the separate stripping of the skin and muscles is sufficient. To remove the muscles the cartilage knife is set close against the spinous processes of the uppermost vertebræ and a deep cut made on each side of the spine throughout its entire length, severing the vertebral attachments of all muscles and tendons. About four finger-breadths outside of these cuts there should now be made from above downwards on both sides another deep cut through the muscles parallel with the first two incisions. The bundles of tendons and muscles between these parallel cuts on both sides of the spine are then separated from the bones as cleanly as possible, beginning either above or at the sacral end, severing the muscle-mass at the end at which the separation begins, but leaving it attached at the other end, where it is laid over the side of the body out of the way, and replaced after the examination of the cord is completed; or the two bundles of muscle may be cut off at both ends and disposed of without further trouble. Portions of tissue clinging to the vertebræ should then be scraped or cut away with the chisel or knife.
When the vertebræ are bared the next step is the removal by saw, bone-forceps or chisel of the posterior bony wall of the spinal canal in such a manner as to expose the cord and permit of its removal without causing any damage to it, either from the instruments or from fragments of broken bone. A single-bladed saw with curved ends may be used to saw through the laminæ on both sides of the spinous processes; or even the small bone-saw (Fig. [9]) may be used for this purpose. The blade of the saw should be held obliquely against the spinous processes with the sawing edge directed outward so as to cut the laminæ close to the medial borders of the ascending and descending transverse processes. The sawing is complete when the spinous processes become movable. The straight-edged chisel may be used to cut any adhesions left after sawing, and the bone-forceps may be used to cut the atlas and axis. When the laminæ have been cut through on both sides of the spinal column for its entire length, including the sacrum, the posterior ligament between the atlas and occiput is cut with the cartilage knife; and the strip of bone and ligaments loosened by sawing is torn off from above downward by grasping it in the upper cervical region with a pair of bone-nippers and jerking it off forcibly downward toward the sacrum, thus exposing the spinal canal. It may be taken off in the opposite direction by cutting the ligament between the last lumbar vertebra and the sacrum and stripping upward.
The use of the single saw is not advised, however, as it is too time-consuming. The laminæ on both sides of the spinous processes may be cut at the same time by the use of Luer’s rhachiotome (Fig. [11]). The blades are separated according to the size of the vertebral arches and are set so as to include the spinous processes and cut the outer border of the laminæ close to the transverse processes in such a manner as not to injure the cord. Since the spinal canal is broader in the cervical and lumbar regions than in the dorsal, the distance between the saw-blades must be regulated accordingly. The dorsal portion is first sawed. The sawing should be in long cuts without too great pressure, the instrument being steadied by placing the left hand on the upright bar. As soon as the spinous processes become movable on slight pressure the sawing should be stopped. Should the blades become caught in the saw-cuts great care should be taken to avoid injuring the cord while releasing them. The straight-edged chisel may be inserted into the cuts and any parts still adherent may be carefully sprung apart. This is necessary particularly in the upper cervical region. The entire posterior wall of the canal may be loosened in this way, the sacrum being also sawed, when it is desired to open this part of the canal. When all the spinous processes are movable the attachments either above or below are cut with the cartilage-knife, and the spinous processes and laminæ torn off by the bone-nippers in one piece, either toward the head or sacrum as is the more convenient.
The laminæ may be cut by a chisel instead of a saw. The straight-edged or curved single chisel, the “tomahawk” chisel, or the double-bladed chisel of Esquirol may be employed. The latter instrument has adjustable chisel-blades that can be set to include the spinous processes. These blades are very strong and short, and have convex cutting edges. The use of a wooden mallet (Fig. [17]) is to be preferred to that of the steel hammer in driving chisels of any type. The straight, curved and tomahawk chisels are held with their cutting edges directed slightly outwards. The Amussat rhachiotome is a chisel-knife with a curved metallic handle, the cutting edge running along the length of the chisel. When set at an angle of 45° to the laminæ it is driven through them by means of blows from a wooden mallet delivered upon the chisel-back over the cutting edge. The Brunetti chisels are shown in Fig. [15]. In using these to open the spinal cord posteriorly, a block should be placed beneath the abdomen so as to raise the lumbar vertebræ above the level of the dorsal. The intervertebral ligaments of the last lumbar vertebræ are then cut through with the belly of the cartilage-knife held at right angles to the spine. The laminæ and spinous process of the last lumbar vertebra are then cut out with the straight-edged chisel or bone-forceps, exposing the canal. The right and left Brunetti chisels are then alternately used, beginning usually with the “left” chisel, the blunt probe-point being introduced into the canal, while firm pressure downward is made upon the handle, while at the same time the cutting edge is driven through the outer borders of the vertebral arches by blows from a wooden mallet delivered upon the head of the handle. Great care must be taken to keep the cut at the same level throughout. It is better, however, to cut too high rather than too low. In the latter case the cord may be injured, while in the former the bone may later be easily trimmed off sufficiently without causing any damage. The arches of three to four or even more vertebrae may be cut without removing the chisel. The same thing is then done on the other side, using the “right” chisel. The loosened portion of bone and ligaments is then cut or torn off with the bone-forceps or nippers. The cut bone should not be touched with the hands because of the danger of injury and subsequent infection from the sharp spicules and splinters of bone. As the canal is opened the block under the body is pushed towards the head, the object being always to cut down hill and not upward. When the cervical region is reached the head of the cadaver should be firmly held by an assistant so as to give sufficient resistance to the blows of the mallet. The skilful use of the Brunetti chisels is difficult to acquire and a great deal of practice is necessary, but when once the knack is obtained the spinal canal can be opened in this way more quickly than by any other method. In private practice the noise made by the hammer upon the head of the handles of the chisels is unpleasant, and should be avoided by the use of felt or something else on the head of the chisel or mallet to deaden the sound.
Another easy and convenient way of opening the spinal canal posteriorly is the cutting of the laminæ by means of special bone-forceps designed for this purpose. The cutting-edges may engage the laminæ from without or the lower blade may be introduced into the canal as a blunt probe, while the upper blade cuts down upon it through the side of the arch. Such bone-forceps should be very strong and have long handles to give sufficient purchase, as a good deal of force is necessary to cut through the laminæ. With a good instrument the canal can be opened in this way in about 10-15 minutes. It requires much less skill than is needed for good and quick work with the Brunetti chisels, and for that reason is recommended, as is also the use of Luer’s rhachiotome, for the general practitioner.
In the case of marked curvatures of the spine it may be impossible to use either rhachiotome or Brunetti chisels. The straight single chisel and small saw can be used on the concave and convex sides of the curvature respectively. In children and young adults the canal can be easily opened with the bone-forceps.