Scalp division
One or two slices with the knife along the same incision line is usually sufficient to deepen the incision down the cranial surface.
Scalp clips are placed along the incision edge compressing cut arteries between the skin and galea.
FIGURE: division of the layers of the scalp with the knife (dividescalpknife)
Once the layers of the scalp down through the galea have been cut and the Raney clips applied, any persistent spots of oozing can usually be managed with bipolar coagulation.
Alternative to the knife, the "hot knife" (also called "monopolar" or "Bovie") can be used to go through these superficial scalp layers. Because the Bovie burns tissue which interferes with wound healing, so it is probably best to use the knife when possible.
FIGURE: division of the layers of the scalp with the monopolar "hot knife" (dividescalphotknife)
Over temporalis and occipital muscles that insert onto the base of the skull, the galea lies over the muscular fascia. The same loose areolar tissue that separates the galea from the underlying periosteum separates galea from underlying muscle fascia when present
A technique to make retrieval and re-approximation of muscle easier at the time of closure is to avoid coagulating it during the opening. To preserve the muscle, incise it at one spot and then place a Metzenbaum scissors into this incision and cut the fascia along the same line as the incision.
Division of the temporalis muscle is potentially bloody, particularly if it is divided against the direction of its fibers. It can be divided and hemostasis obtained at the same time by using the cutting setting of the Bovie coagulator (this muscle dividing technique is appropriate for craniotomies where the muscle will be dissected off of the underlying bone). The periosteum can be cut either with a 10 blade or using the Bovie monopolar. The Bovie should be set so that it coagulates and cuts but without unduly burning tissue.
FIGURE: cutting the periosteum (cutperiosteum)
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Scalp retraction
A periosteal dissector is used to scrape the periosteum off the bone at the same time it pushes the muscle away, leaving a space of exposed cranial bone. The assistant should also have a retracting and sweeping type instrument to try to maintain the muscle fibers on stretch. The tip of the Bovie is touched to the skull surface at the point of insertion of the muscle fibers. With a gentle forwards and backwards movement, the fibers layer by layer are dissected off the skull. As the bulk of free muscle increases, the assistant may want to pick it up and hold it away from the skull surface with a heavy forceps.
Reflecting muscle becomes more difficult as one proceeds forward due to the bulk muscle and the fact that the skin incision limits how much it can be reflected back. In order to reflect the muscle adequately it may be necessary to extend the skin incision and enlarge the scalp flap.
FIGURE: Periosteal elevator elevating temporalis fibers from skull surface (periostealaction.gif)
The goal in scalp elevation is to create a flap of tissue that is enough out of the way of the surgical field that required burr holes can be placed and the bone flap cut with relative ease. The scalp flap should not be so unwieldy that it cannot be retracted out of the surgical field with a few rubber bands, fish hooks, or heavy silk sutures. Its inner aspect must not bleed during the remainder of the procedure.
With the monopolar blade oriented parallel to the surface of the skull its tip is applied to the line of insertion of the temporalis muscle fibers. The scalp will not bleed if the periosteum is undermined and included when the overlying scalp is reflected forward. The scalp flap is held by hooks in its base pulling it up and away from the craniotomy over the projected bone flap. For scalp reflection, rubber bands can be alternatively attached to towels claps into the base of the flap.
Good hemostasis should be obtainable just by proceeding deliberately layer by layer and attempting not to leave any muscle fibers on the bone. Orient the monopolar blade with the plane of the blade parallel to the line of the segment of incision. Slowly draw then monopolar closer with it only gently pushing down on the upper layers of muscle that will retract as their water content is vaporized.
By the time the monopolar is at the end of the first muscle incision there is a trough at the bottom of that is deeper muscle still red and waiting to be divided. There must be only one trough through the muscle. Each successive sweep of the monopolar only deepens it orthogonal to the bone surface.
The muscle can be divided and hemostasis obtained at the same time by using the cutting setting of the Bovie coagulator (this muscle dividing technique is appropriate for craniotomies where the muscle will be dissected off of the underlying bone. Alternative to the knife, the Bovie can be used to go through these superficial scalp layers, but the Bovie burns tissue and impairs wound healing, so it is probably best to use the knife when possible.
The muscle is divided by applying the tip of the monopolar to the surface of the muscle with a broad to and fro movement maintaining the distance between the tip and the muscle at the depth being cut. The upper layers of muscle separate and retract as their water content is vaporized. By the time the monopolar is at the end of the first muscle incision there is a trough at the bottom of that is deeper muscle still red to be divided with the next crosswise sweep of the monopolar tip.
Unless division through the muscle is at each successive level along the same trajectory plane the divided sides will not separate neatly, will bleed unnecessarily, and probably atrophy more as well. The ends of the trough through muscle are squared off as were those of the scalp incision and opening. Each successive sweep of the monopolar only deepens it orthogonal to the bone surface.
For posterior fossa craniectomies, muscle division is easiest in the avascular plane between the symmetric suboccipital and cervical paraspinous muscles. A vertical incision between the paraspinous muscles can be deepened ½ to 1 cm per pass of the knife down to the foramen magnum (or, more easily identified, the spinous process of C1). The key to this dissection if to stay in white fibrous tissue. If muscle is encountered to the right or left, the knife should be brought back to the last cut through avascular fascial tissue and its trajectory downwards reoriented away from that into muscle.
The temporalis muscle can be elevated with the flap without unsatisfactory cosmetic results in the vast majority of cases although there will usually be some atrophy due to loss of vascularization by detaching from the underlying bone.
This muscle dividing technique is appropriate for craniotomies where the muscle will be dissected off of the underlying bone. A periosteal dissector is used to scrape the periosteum off the bone at the same time it pushes the muscle away, leaving a space of exposed cranial bone. The assistant should also have a retracting and sweeping type instrument to try to maintain the muscle fibers on stretch.
In dividing the attachment between the temporalis muscle and the skull the monopolar electrocautery is moved back and forth the entire length of the muscle with each pass of the Bovie going layer through the muscle. The tip of the Bovie is touched to the skull surface at the point of insertion of the muscle fibers. With a gentle forward and back movement, the fibers layer by layer are dissected off the skull. The Cobb periosteal elevator is used to separate as close to the interface between the muscle fibers and the bone as possible, and will repeatedly advance the Cobb on the advancing muscle flap as necessary.
As the bulk of free muscle increases, the assistant should pick it up and hold it away from the skull surface with a heavy forceps.
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Perforation
When the bone flap requires more than one burr hole they should be placed first at sites of least likelihood of injury to important underlying vascular or neural structures. Holes near the midline (sagittal sinus) are placed last.
The perforator should always be held with two hands. The non-dominant close to the perforator bit with the ulnar hand (wrist and hypothernar eminence) set comfortably on the skull.
FIGURE: Perforating skull with power perforator (perforatingskull.gif)
As the drill bit turns its blades cut into the skull through its successively deeper layers from the outer table, through the marrow-filled diploic space, and finally through the inner table.
Upon withdrawal of the perforator from each burr hole, a piece of bone wax large enough to fill the entire hole is pressed into place. The back end of a small curette is used to push the wax into the interstices along the edge of the bur hole. The excess bone wax is then removed from the bur hole with the cutting side of the curette.
FIGURE: Bone wax being pushed into bone interstices (bonewaxintointerstices.gif)
Irrigation accomplishes two purposes in the setting of drilling bone: First, it cools down the bone. This is important in terms of the mechanics of bone cutting; the bits cut more effectively through cooler bone. Second, washing away bone dust that, wet or dry, obstructs the surgeon’s view.
Bone cutting (craniotome)
The dura around the base of the bur hole is separated from the overlying inner table with a specially designed dural separator. The disadvantage of too widely separating dura from bone is that there are numerous small blood vessels that will be disrupted and will bleed if too much separating is done. It is thus important to plan the direction of each craniotome cut prior to beginning these cuts. The #3 Penfield is an ideal instrument for separating the dura from the overlying bone relatively atraumatically.
Once the dura has been separated from under the edge of the burr hole, the craniotome foot plate is placed into the hole such that the toe of the foot plate is in the space between the dura and the inner table.
FIGURE: Dural separator and placement of foot plate of craniotome (duralseparation.gif)
The craniotome cuts originate far from dangerous structures and are directed towards these. If the sagittal suture must be transected by the craniotome path (as is necessary for a bicoronal bone flap) two burr holes should be placed within 1cm on either side of the midline. Following careful separation of the underlying dura, the craniotome can be used to cut across the midline with minimal risk.
FIGURE: Direction of bone cuts with respect to sagittal sinus (bonecutssagsinus.gif)
If the craniotome segments cut connecting the burr holes are continuous around its perimeter, the a free bone flap results whose only attachment to the head is to the underlying (hopefully mostly intact) dura. The bone is carefully and gradually pried free from its dural attachment with a Cobb and joker. As the bone is lifted up the surgeon should look underneath the bone while the assistant keeps at least one hand (or instrument) physically in contact with the flap at all times to insure that it does not (especially just as it is freed from the dura) suddenly pop up and off the field onto the non-sterile floor.
Once the bone flap has been elevated off of the dura, it may be necessary to shape the bone edge to achieve adequate exposure. For a temporal craniotomy requiring access to the floor of the middle fossa, a fairly large additional craniectomy may be required for adequate exposure.
Ronguers used in head trauma operations cut parallel or at an angle to the force being applied by squeezing the hand. Selection of a rongeur depends on the distance across which the force to cut the bone must be applied and the angle of accessibility to the bone to be cut. Rongeur selection also depends on how much bone is to be cut with each applied force. In tight spaces where control of the amount of potential trauma is desirable or where a cosmetic deformity should be avoided a Kerrison rongeur may be required.
Following removal of a window of bone and larger than 5 by 5 centimeters or so there is enough dura exposed that bleeding from it or into the post-craniotomy epidural space now between the dura and galea. The risk of post operative epidural is greater the area of it exposed following bone elevation. Dural tenting should be done whenever the volune of a bone flap is 25 square centimeters or more.
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Dural tenting
Tenting sutures should be placed near corners and turns of the bone flap. The goal is to place just enough tenting sutures to achieve hemostasis, but not so many that undue time is consumed in this stage of the operation. For a small craniotomy flap, the number of tenting sutures may be dictated by the size of the flap. If the flap is large the distance between tenting sutures should be approximately 2-1/2 to 3 cm.
FIGURE Location of dural tenting holes along bone margin (locationtentingholes.gif)
Small diameter (___ mm) holes are drilled along the margin of the bone edge using a power drill. The assistant holds a ribbon retractor just under the edge of the bone to protect the dura. Holes are drilled ½ to ¾ cm back from the bone edge at 45 degrees to the plane of the skull surface. The holes go through the outer table of the bone and to come out about half way through the skull on the inner aspect of the craniotomy perimeter.
Sometimes it is not possible to achieve a 45 degree angle with the drill because of soft tissues which are in the way or because of the positioning of the patient, in which case the ribbon retractor can be placed directly over the dura but slid further in and the drill can be advanced from the surface at ½ to ¾ cm from the edge orthogonally down, stopping once the tip has perforated the inner table. It is best to see the tip slowly emerge and not make contact with the protective brain ribbon retractor.
The purpose of tenting sutures is to prevent collection of blood in the epidural space after replacement of the bone flap and scalp closure. These sutures achieve hemostasis in two ways: First, they put the dura under tension collapsing some of the blood vessels within the dura. Second, they eliminate the space between the dura and the bone around the perimeter of the bone flap.
The dural tenting stitch is normally of a non-absorbable material such as 4-0 neurilon, which comes on a “pop-off” needle. The pointed tip of the needle is placed ¼ cm from the edge of the bone on the surface of the dura. at 90 degree orthogonal to the dura. Then, using a brisk but decidedly smooth twist of the wrist, following the curve of the needle, the needle is swept through both layers of the dura without hooking into the pial surface.
Placing a 4-0 neurilon suture in the dura is somewhat difficult. One is reluctant to place the needle too deep and go through the dura, subarachnoid space, and inadvertently damage the surface of the brain. On the other hand, if the suture does not grab both layers of the dura, once tension is placed on the suture to tie it up to the bone edge, the stitch will pull out through the inadequately bitten dura. Or, at a subsequent point, such as when the bone flap is laid in place, there may be enough pressure exerted on the dura to pull out a tenting suture that only traverses one layer of the dura.
FIGURE Needle through dura avoiding pia (needlethroughduraavoidpia.gif)
Because the pointed end of the needle can damage the brain and tear the dura, it is best to pass the needle from the inner edge of the bone upward through the bone hole. The pointed edge of the needle is grasped with the needle holder and the blunt end of the needle, with the attached suture, is placed up through the hole. When the blunt end of the needle is visualized sufficiently that it can be grasped from above, release the needle holder and grab the needle from above, pulling it and the attached suture through the hole..
Tenting sutures must remain undisturbed by replacement and re-fixation of the bone flap. The same hole that is used for the tenting suture will be used for wires or sutures if these are used to secure the bone flap in place. A hole corresponding to the one along the bone edge of the cranial opening will be placed on the bone flap which was removed during surgery and will then be replaced on closure. Once the dura has been pulled up and the tenting suture knotted, it is very difficult to place a wire through the hole without puncturing the dura, potentially tearing the tenting suture and/or going through the hold and dura into the brain. Place any wires or sutures that are to be used to secure the bone flap before tying up the tenting sutures or even placing them within the tenting suture hole.
While tying sufficient tension should be applied to the sutures such that the dura is tightly apposed to the overlying bone at the edge of the craniotomy flap. Tenting sutures are tied with four throws. The knot should be tight enough that it feels almost like the suture will break but it does not. The dura should be tightly approximated to the bone by the suture material. The knots should come down just over or at the edge of the bony holes and their position can be adjusted slightly with a Geralds with teeth so that they do not protrude upward into the overlying scalp at closure.
When to place the tenting sutures is another issue. If there is not active, troublesome bleeding from the space between the bone, the craniotomy inner surface of the bone and the dura, and the intracranial pathology is resulting in increased intracranial pressure with the desirability of rapid removal, go ahead and open the dura before tenting sutures are placed. However, if there is any bleeding that is extradural, the few minutes that it takes to place a few tenting sutures may be well spent in providing good hemostasis at this point in the operation.
Evacuation of epidural hematoma
A brain spoon or other device that scoops up blood is not appropriate for use if the blood is lying on the pial surface. Such devices can be used safely when the dura lies between the hematoma and brain tissue. A kitchen spoon may be used in lifting an epidural clot off of the dura without significant risk of injury to the subarachnoid vessels or the pial surface of the brain.
FIGURE: evacuation of epidural hematoma with brain spoon (edhspoonevac.gif)
Irrigation applied as a stream under pressure can be used to lift an epidural hematoma off of the dura sufficiently that it can be sucked away or grabbed and handed off. Once the dura has been cleared of overlying clot its surface can be visualized allowing for identification of the sites of any active hermorrhage.
The reason why acute blood cannot be removed from a small craniotomy or burr hole is that the blood is thick and almost solid and the aspirating device applies suction force only at the orifice at its end which has a diameter of only 3 to 4 mm. The problem is somewhat analogous to trying to remove Jell-O from a plastic container by placing a hole 3 cm large and trying to aspirate the contents with a straw. The extent of removal of acute coagulated blood possible is dependent on achieving suction or grasping access to the full extent of the clot along its perimeter.
Dural opening
Dural opening, like that of the scalp and cranium, is a procedure complicated only slightly by the multilevel nature of the tissue. The surgeon must open both dural layers in order to be able to grab and retract it to expose the underlying subarachnoid space and pial surface.
FIGURE Opening dura both layers held with Geralds (openingdurageralds.gif)
A small round-ended 15 blade is used to do a layer-by-layer opening of the dura. To the edges of dura on either side of the incision through it is applied retraction by grabbing with teethed Geralds both sides and applying countertraction to them. The dural opening is extended until Geralds forceps with teeth can be comfortably placed between to grab both dural layers. At this point scissors can be easily inserted and cutting be done without risk to the pia. just a few millimeters below.
FIGURE Geralds pickups with teeth and scissors (liftcutdurageraldsscissors.gif)
Subdural hematoma evacuation
A suction device moved to and fro over the clot can injure the brain surface because the depth of the interface between the bottom of the clot and the pial surface cannot be ascertained until it is inadvertently encountered, at which point damage to the pial surface may already have been done. For this reason it is advisable to combine suction moved to and fro with gentle irrigation to try to develop a plane between the clot and the pial surface and lift the clot away from the pial surface. Once a patch of pial surface has been identified, irrigate this off and place a cottonoid patty on the surface of the brain to protect it from further suction trauma. Now the depth of the clot can be gauged and suction can be applied more vigorously and rapidly. Irrigation can be used to lift the clot from the surface of the brain.
FIGURE: Suction through cottonoid (suckcottonoid.gif)
Solid portions of the clot can be lifted with round broad grasping cup forceps.
FIGURE Subdural hematoma being lifted off pial surface (liftsubduraloffpia.gif)
Irrigation fluid applied as a focus jet forced from the aperture at the tip of the bulb syringe can force an advancing plane between the pial surface and a sudural hematoma sitting on it.
FIGURE Irrigate subdural clot off pial surface (irrigatesubduraloffpia.gif)
The site of bleeding that produced a subdural clot should be identified during the surgical evacuation of same in order to assure that another clot does not form postoperatively in the same place. Bridging veins torn and bleeding into the subdural space can be identified close to the midline (landmarks: sagittal sinus, falx cerebri). This bleeding can sometimes can be stopped by electrocautery of what remains of the cut ends of the torn vein. Focal tamponade with surgicel is an alternative but should be avoided unless it is acceptable to leave a mass of surgicel intracranially in a patient who has just undergone surgical mass decompression to relieve or prevent increased intracranial pressure.
Bleeding from small rents in the walls of the small veins on the surface of the brain also will result in a subdural hematoma with blood tending to collect more intimate to the pial surface. The technique for stopping bleeding from cortical veins is to lay a small square of surgicel over the hole in the vein such that the hole is entirely occluded. Bleeding into the surgical square causes it to stick to the outer surface of the bleeding vein thereby occluding the hemorrhagic opening. Heat applied to the blood coagulum-surgicel patch will cause it to stick even more tightly to the underlying vein reinforcing the patch mechanism, but heat should be used cautiously, and especially so in proximity to surface arteries and veins.
Pial opening
Openings in the cortical surface (corticectomies) range according to the size of the lesion over which they are placed as well as its depth and consistency. A corticectomy is necessary to reach intracerebral hematomas that do not come to the surface. While it is a general principal of neurosurgery that one tries to preserve as much brain tissue whenever possible, it is easier and faster to start with a larger opening than to enlarge a small opening gradually during the course of evacuating the clot.
In planning the corticectomy, keep in mind that the opening, which results in the cortex must be, large enough to admit at least a narrow brain retractor ribbon, the smallest of which may be less than 1 cm across. A good shape for the corticectomy is a square. Four neat cuts of the knife through the cortex will be sufficient to create the hole. Manipulation of the knife to fashion a circular corticectomy is more difficult.
The corticectomy should be first outlined by using the bipolar coagulator touched gently to the pial surface. The coagulator tips should be approximated to approximately ½ mm apart just so that an arc of electricity passes between them sufficient to coagulate the tissue. Using an 11 blade (the sharply pointed #11 blade because the pial layer acts like an elastic membrane such that a flat or rounded blade placed on it and pushed down will indent in for a certain distance before the blade can puncture through. This causes trauma to the underlying brain that can be avoided by using a sharp-tipped blade that will immediately incise the pia and enlarge the hole as the blade is pushed downwards), puncture the coagulated pial surface. Complete a single straight edge of the square and then do the three other sides. If there is bleeding from the cortical edges of brain that will not be removed, bipolar these now.
Pial bleeding is notoriously difficult to stop: the monopolar generates a relative explosion of heat at the pial surface that probably disrupts as many small vessels as it occludes. The bipolar is better but still too big for point coagulation of tiny pial arterioles. Tamponade is virtually impossible: even a slight degree of compression to the pial surface results in an impressive downward depression in the brain that can persist for hours after the compressive force stops. Coagulation-promoting agents applied as large surface area hemostatic patches mildly but sufficiently compresses the pial surface by their own weight and that of the blood products they absorb. Intravascular coagulation is promoted by the breakdown of blood products within the Surgicel coagulum.
Avoid cutting or bipolaring the pial surface. Be patient and take the time to stop pial bleeding on the way in. The blood has an uncanny affinity for the depths of the intraparenchymal dissection field, making visualization sometimes impossible.
FIGURE cutting with 15 blade for corticectomy (cutcorticectomy.gif)
The corticectomy flap is now like a trap door that will elevate itself slightly above the rst of the pial surface. A sucker can then be applied to this and the superficial layers of cortex aspirated. Using gently aspiration the white creamy semisolid brain can be aspirated along the projected trajectory toward the hematoma.
The walls of the shaft into the brain should be kept approximately the same as those of the original corticectomy. If a much broader area is aspirated deep within the brain and there is bleeding, it may be difficult to visualize this from the limited opening at the surface.
A brain ribbon retractor can be advanced along the opening into the brain into the brain along this “tunnel” through the gray and white matter and the clot visualized. A sucker can be advanced safely as long as there is visualization of what the sucker tip is coming into contact with.
Take the patty strips and advance them to the depth of the opening in the brain. Then take some long surgicel strips, lay them over your surgical strip, and then bring the surgical strip across to the other side of the opening so that you have effectively laid a strip on the other side. In the depths of a hole in the brain for evacuation of an intracerebral hematoma, different methods of hemostasis include bipolaring any visible bleeding (but this is problematic because most of the vessels at this depth are very small and not bipolar-able). Surgi-Cel can be used as can Gelfoam.
Collagen strips also provide good hemostasis. In the event that none of these techniques work, several pieces of cotton can be soaked in hydrogen peroxide which is then placed into the hole and after waiting five minutes the cotton balls are removed. The hydrogen peroxide will denature the proteins in the tissue and form a local coagulum thereby effecting hemostasis.
Another technique for hemostasis is to place Surgi-Cel over the exposed bleeding brain tissue and to allow the blood to ooze through the Surgi-Cel. Once the Surgi-Cel is wet with blood it can be bipolar coagulated forming a coating of Surgi-Cel with coagulated blood, which is better hemostatic than simply the Surgi-Cel.
FIGURE Coagulating vessels from above and sides (coagulatingvesselsabovesides.gif)
Intracerebral hematoma evacuation
The removal of intracerebral clots is far more traumatic to brain tissue than that of blood on the surface of the brain or epidural. Two types of blood clot are encountered intracerebrally in the setting of trauma: 1. Collections of blood that have displaced the brain tissue as they expand and thus are within them pure clotted blood. 2. Blood in areas of contusion will track through planes within the brain tissue. Intermingling with it. Removing the latter is done always at the cost of the infiltrated brain, which because of the blood within it, is no longer viable anyway.
The collection of blood without brain in it can be aspirated and sometimes because it is displacing brain, it almost is as if it has a capsule and by aspirating one pole of the clot it is sometimes possible to “tease” the clot away from the brain which it has displaced. Such a clot will come out as one single unit or as several chunks. The cavity left behind of brain tissue will often fall in on itself and has a smooth wall that usually will not bleed. If the clot is at all deep it is a good idea to have a headlight on to visualize the completeness of removal.
Visualization is even more essential where the blood clot is mixed in with brain tissue. While removal of contused nonviable brain is desirable in terms of removing a potential culture medium for infection or tissue that contributes to pressure, such removal should not be done at the expense of contiguous normal brain. As the contused tissue is aspirated, white glistening brain without any blood in it appears. When an area of this consistency and color has been defined all around the contused material being removed, the removal is complete.
Again, bleeding within the brain should not be profuse unless the contusion or hematoma is dissecting into a space contiguous with one where major vessels lie on the surface of the brain. The small penetrating arteries seldom present a problem with bleeding and bleeding from the can be controlled with application of a single layer of Surgi-Cell. Multiple layers of this hemostatic agent can, however, contribute to mass effect and therefore restraint should be used in placing them.
A sucker can then be applied to this and the superficial layers of cortex aspirated. Using gentle aspiration the white creamy semi-solid brain can be aspirated along the projected trajectory toward the hematoma. The walls of the shaft into the brain should be kept approximately the same as those of the original corticectomy. If a much broader area is aspirated deep within the brain and there is bleeding, it may be difficult to visualize this from the limited opening at the surface.
A brain ribbon retractor can be advanced along the opening into the brain into the brain along this “tunnel” through the gray and white matter and the clot visualized. The walls of the shaft into the brain should be kept approximately the same as those of the original corticectomy. If a much broader area is aspirated deep within the brain and there is bleeding, it may be difficult to visualize this from the limited opening at the surface.
FIGURE: Ribbon retractor holding back sides of tract through brain (ribbonretractichevac.gif)
A brain ribbon retractor can be advanced along the opening of the brain into the brain along this “tunnel” through the gray and white matter and the clot visualized. A sucker can be advanced safely as long as there is visualization of what the sucker tip is coming into contact with.
Drains
The disadvantages of drainage systems for blood collections post-op are: 1) infection; 2) perpetuation and maintenance of a space within which blood can collect that is created by the drainage tube separating the two layers between which it is placed; 3) masking inordinate amounts of bleeding or active bleeding which should be controlled; 4) drainage of collection may collapse down a potential space and tamponade bleeding bwhich recurs when the drain is taken out and there is no way to access the accumulation.
A drain is no substitute for a good hemostasis prior to closure. A drain provides a pathway of low resistance for accumulating blood so that it will preferentially enter the drain system and be collected external to the patient rather than accumulating within the confines of the space under the scalp or bone flap or subdural.
Of all the risks of post-head trauma craniotomy drains, infection is probably least problematic. Sometimes, however, a site of slow oozing or venous bleeding that should spontaneously stop will be inaccessible from the bony opening or a reasonable extension thereof or will not be visualized despite thorough inspection. A chronic subdural is notorious in this respect. In these cases it may be preferable to place a drain and hope that the bleeding will stop spontaneously without the continued loss of inordinate amounts of blood and that pulling the drain will not precipitate further bleeding. To minimize the risk of causing more bleeding by pulling out the drain, it is advisable to insure that the proximal end of the drain is nowhere near the pial surface where it could traumatize small vessels.
There are two kinds of drainage: active and passive. Passive drainage systems allow blood to flow down a pressure gradient from the intracranial compartment to the external environment that is at the atmospheric pressure. Such a drain is the Penrose plastic tube type. Active systems apply suction to the draining tube. The most commonly used system in intracranial procedures is the Jackson-Pratt system, where the aspiration pressure is that generated by creating negative pressure within a bulb by pushing out air and closing the top. This negative pressure will then put aspiration pressure distally at the end of the tube.
The Penrose drain is placed simply by laying the proximal end in the site where blood will accumulate. The drain is brought through a separate stab wound which is large enough not co completely crimp down the drain but also not so large that there will be undue bleeding through it. The Jackson-Pratt drain is placed by making a separate stab wound through the skin of the scalp with a 15 blade to the depth of the subcutaneous fat. A Kelly or hemostat is then pushed through the skin hole, through the soft tissues and the galea until the tips of the instrument are visible for 1 to 2 cm. It is then possible to open the instrument slightly and grab the distal end of the tube, pull it through the scalp tunnel and attach this end to the suction bulb.
The proximal portion of the J-P system is a flat, rectangular segment with numerous small holes through which the blood or other fluids can be aspirated. This portion of the drain should be cut to an appropriate length to cover the area over which blood may be expected to accumulate but should not be so long that it is folded and redundant, potentially causing mass or compressing tissues unduly, or kinked such that it becomes ineffective.
FIGURE: Jackson-Pratt drain (jpgdrain.gif)
Dural closure
The dura should be realigned with a single suture at corners along the flap. If the opening was cruciate, a single suture can be used to bring together three or four leaves.
Once the leaves are grossly approximated their edges can be sewn together using a running 4-0 Neurilon suture.
FIGURE: Close of dura, cruciate or flap opening (closureduralflap.gif)
Bone fixation
Under most circumstances the bone flap removed in the course of a craniotomy for trauma can be replaced and fixed in its preoperative location. Sometimes the brain is under such pressure from within (whether due to hematoma or diffuse edema and swelling), that the tissue herniates through the craniotomy opening. Pushing the brain back into the cranial cavity is not possible because the amount of pressure required would certainly exceed the already malignant levels that are causing the outward herniation in the first place. The anatomic relationships of structures within the fungating cerebrum are distorted as the tissue protrudes from the skull defect. Pressure on the brain risks compounding the deleterious effects of the brain distortion.
In the face of cerebral fungoides (brain mushrooms out of the skull) the surgeon may have no alternative but to attempt to close skin over the mass of tissue too large for a dural or bony covering. Some have made a case for leaving out the bone flap in cases without intraoperative fungation but where such could be anticipated based on the CT scan. This is not an unreasonable approach provided that the dura is also left open. Although more elastic than bone, dura is tough and unyielding and forces into play all of the problems of intracranial pressure elevation associated with changes in intracranial compartments as enunciated in the Monro-Kellie Hypothesis.
FIGURE: fixation of bone flap with sutures (bonefixsutures.gif)
Galeal closure
The galeal closure is done with “OO” or “OOO” Vicryl (absorbable suture). This is a strong thick suture that will dissolve sometime around two weeks post op. “Burying the knot” of sutures placed for galeal closure reduces the likelihood of a palpable (occult) suture knot or exposed suture end.
FIGURE Closure of the galea (galealclosure.gif)
Skin approximation
Modalities available for skin approximation include: taping, suturing, stapling, and gluing. If sutures are used they should be non-absorbable and placed in either a running locked or inverted mattress configuration. Better approximation of skin edges probably results if an assistant with an Adson forceps in each hand holds up and slightly everts the scalp edges just ahead of the intermittently but continuously advancing skin stapler.
FIGURE: Skin approximation with staples (skinapproxstaples.gif)
FIGURE: Skin approximation with sutures (skinapproxsutures.gif)
Dressing
A partial head dressing can be used for wound less than 5 cm in length in relatively flat cranial surfaces. A 4x4 gauze pad held in place by one or more pieces of tape can be an adequate partial head dressing for a short anatomically uncomplicated surface lesion.
For a full head dressing the operating surgeon needs to hold the patient’s head at the same height and position it was during the procedure while an assistant removes or drops the headpiece of the operating room table could efficiently and safely do this. The surgeon places his or her abdomen against the patient’s vertex and holds the head with pressure against the patient’s head with a second hand manipulating the dressing materials. Then, he unravels a roll of surgical gauaze, bringing it back and forth repeatedly from ear to ear until the entire head is wrapped. This process should be repeated with two or three more roles to make a wrap that is as many layers thick. After the gauze the surgeon lays tape across to secure and fix the dressing in place.
FIGURE: Application of head wrap (headwrap.gif)
Drains and other intra-/extra-cranial tubes should be fixed to the head dressing with tape.
Termination of anesthesia
Once the lesion has been removed and final hemostasis is being obtained, an estimate of the operative time remaining should be conveyed to anesthesia with a request that unless physiologically contraindicated, long acting paralytics be discontinued enough in advance that extubation in the operating room is possible (for patients with preoperative GCS greater than 12), and a neurologic exam can be obtained.
Procedure
Special techniques
At operation, addressing pathology in addition to an intracranial hematoma may require procedures in addition to those of the generic head trauma craniotomy:
· Repair of scalp injuries – may require undermining of scalp tissue and development of flaps for coverage of the skull.
· Reopening a preexisting craniotomy – can be complicated by dural adhesion to underlying brain surface.
· Entry into an aerated sinus – requires removal of mucosa and elimination of dead space to avoid infection.
· Dural tears – traumatic or iatrogenic, may require repair if they bleed despite attempts at tamponade.
· Dural sinus lacerations – an opening into a dural sinus can be the cause of rapid hemorrhage and exsanguinations.
· Vascular injuries – associated with a head injury (such as traumatic aneurysms) may have to be addressed in the course of a generic head trauma craniotomy.
· Open depressed skull fractures – with fragments depressed greater than the full calvarial thickness may require dural closure and reconstruction of the calvarium.
· Penetrating head injuries – do not require removal of bullets but potentially infective bone fragments should be removed if possible.
· Lobectomy – may be necessary (with or without a parenchymal hematoma mass) for control of ICP.
· Cranioplasty – is seldom but sometimes done in the course of a head trauma operation.
A. Repair of scalp injuries
Scalp wound closure objectives for the head trauma surgeon are: coverage and cosmesis. To achieve these objectives the surgical plan must address the depth of the lesion, its location, its relationship to the surgical incision, its size and shape, as well as the mechanism of injury. The presence of preexisting lesions of the skin or scalp may complicate skin incision, scalp division, or closure of a traumatic scalp lesion.
1. Depth of lesion
Techniques for closure are different depending on whether the lesion is confined to skin, extends to the galea, or includes the galea at its depth.
a) Surface (skin)
Lacerations no deeper than the dermis (white thick tissue) can be washed with an antibacterial solution containing iodine and covered with sterile dressings allowing for primary healing.
b) Subcutaneous (above galea)
Lesions deep to the dermis but superficial to the galea can be closed after thorough, vigorous irrigation, with interrupted 3-0 nylon sutures, or if on non-hair covered skin, with 5-0 nylon. A complex scalp laceration with more than one limb and an irregular contour extends down through the galea. The line or curve of the injury is smooth, the cut is clean, and the laceration lies in the path of the projected craniotomy scalp flap skin incision.
c) Subgaleal (full thickness)
Full thickness scalp wounds closure requires techniques not part of the generic craniotomy to: 1. expose viable tissue edges for re-approximation, 2. expand the area of a given piece of scalp, 3. swing a flap of scalp tissue from one location to cover a scalp defect in another.
2. Location of lesion
The location of a scalp laceration with respect to the hairline and cosmetically significant areas of the face, ears, and throat is a consideration in closure as is its relationship to the required craniotomy incision. The course of the scalp incision can sometimes be redirected to incorporate on closure part or all of a traumatic laceration.
a) Hairline
The skin of the forehead and face in front of the hairline should be approximated with the finest suture possible to avoid disfiguring scars. Interrupted “five-0” (00000)-nylon suture is a reasonable choice. The sutures should be placed between ½ and 1 cm apart. Lacerations that extend into the eyebrows should be closed without shaving (this hair does not grow back well if it does at all).
b) Skin incision
Lacerations to any depth that are in line with the skin incision with smooth edges are the easiest to incorporate into and close with the craniotomy scalp closure.
Lacerations in line with the skin incision but with jagged or necrotic edges require debridement prior to re-approximation. Starting back from the skin edge, where non-traumatized, viable skin begins, a ten or fifteen blade held perpendicular to the skin surface incises through all scalp layers to periosteum. The same procedure is performed along the opposing edge and re-approximation is then attempted. It may be necessary to cut out a small amount of viable skin in order to make the skin edge smooth for re-approximation.
Scalp lacerations behind the hairline superficial to the galea too far from the skin incision to be incorporated into it are closed with interrupted “3-0” (000) sutures. If the laceration extends down to and through the galea, absorbable sutures (such as Vicryl) are placed 1-2 cm apart with their knots buried below the galea.
3. Shape
The configuration and orientation of a scalp wound may be important in planning an appropriate closure especially when skin grafts and rotational flaps are part of the surgical treatment. The major consideration is preservation of blood supply to limbs of tissue separated on two or more sides from surrounding scalp. The vascular supply to the scalp runs primarily parallel to the course of the superficial temporal artery. Lacerations perpendicular to the course of the primary scalp arterial supply are most likely to compromise blood supply to distal scalp tissue and are most likely to be associated with necrosis or dehiscence following closure.
Devascularization with ischemia and impending necrosis is frequently manifest even at the time of an emergency head trauma craniotomy. Clearly necrotic tissue should be resected and measures taken (scalp relaxation or flap creation as described below). Dark or dusky skin suggests that tissue will ultimately die and degenerate. Confronted with such tenuous tissue the surgeon must decide whether to use it as part of the reapproximation or excise it and reapproximate clearly viable tissue further back from the skin edge. Excision is probably best if the dusky tissue has is likely devascularized according to its orientation with respect to the vascular supply of the scalp (parallel to the superficial temporal artery).
4. Size
Large scalp lacerations can pose problems of coverage especially when they result in isolated limbs of devascularized tissue. However, if the edges are viable and relatively smooth, reapproximation with galeal interrupted absorbable suture and skin staples is usually adequate with small risk of necrosis. Larger wounds (especially those obviously contaminated by embedded foreign bodies) require large volumes of vigorous irrigation with antibacterial solution.
5. Mechanism of injury
The condition of the scalp edges to be re-approximated as well as of contiguous tissue from which blood supply for healing will come depends on the mechanism of injury
a) Skin edges
The outcome of the scalp closure depends heavily on the condition of the tissue engaged. Macerated, contused, ischemic, or necrotic edges close only slowly and poorly with infection a frequent complication. The best closure is therefore that along edges of vital, well-vascularized scalp tissue.
b) Avulsion
Part of the scalp may be avulsed, or in the process of cutting back to dead skin a gap results which is too great to overcome with a small amount of tension applied by the galeal and skin sutures, to the scalp. Any more than the slightest amount of tension exerted by sutures results in compression of vascular channels through the scalp which ultimately causes ischemia, necrosis, and dehiscence of the closure. To avoid this, as little tension as possible should be placed across the repair line.
(1) Relaxation
A certain amount of relaxation of scalp tension results from separating the galea from the underlying periosteum in a plane through the loose areolar tissue between them. This if insufficient for re-apposition of the edges must be followed by extending the laceration such that the galea can be seen as the upper layers of scalp are lifted off of the loose areolar layer.
The tension of the galea tending to pull the scalp away from the re-apposition line can be reduced by making muliple linear cuts through the galea, oriented parallel to the line of apposition, approximately 1-5 to 2 cm apart. This freeing should initially be done in the direction where the galea is most readily accessible but may need to be done bilaterally.
(2) Flaps
Gaps that do not close with scoring of the galea may require “swinging” a flap of with re-approximation then of two lacerations: one traumatic, one iatrogenic. Larger gaps, even with swung flaps, are candidates for skin grafting. Some can be left to heal by primary intent, after a piece of fascia has been patched into the galeal layers.
(3) Grafts
Skin grafting of scalp lacerations is usually not done at the time of head trauma craniotomy in part because these wounds are usually contaminated with subsequent infection threatening the viability of any biologic covering.
c) Contiguous tissue