This week, I got to see some burn surgeries, as well as more neurosurgeries.
The first was a split thickness skin graft (STSG) for a patient who had a burn on her right calf. There was some healing around the edges of the burn wound, as evident from the new epidermis in which melanocytes were starting to produce melanin, and regions of epidermal budding. However, the burn site was too large for wound closure to occur naturally without a high risk of bacterial infection. The surgery first involved a tangential excision of the layer of eschar, which is essentially a thin white layer of denatured protein/scab on the site of injury, using a manual dermatome. This layer of dead tissue was removed to reduce the risk of bacterial infections. Next, an electric dermatome with a predetermined thickness setting of three thousandth of an inch was used to obtain a thin layer of epidermis from the patient's right thigh for the autograft. Vascular clips were then used to attach the graft to the injury site. Apparently, these clips will fall off on their own as the patient heals. The patient's leg is then put in a cast to prevent the graft from moving for several weeks, to allow innervation of the new tissue and structural connections to form.
The second burn surgery was on a patient who was the victim of an acid attack almost a year ago. There was extensive scarring to the right side of his neck, including a thick band of scar tissue which prevented him from fulling turning his head to the left.
For a little background on scar tissue, the deeper or more extensive the burn, the longer it takes to heal, and the more likely scarring will occur. If a burn wound heals completely within 17 days, it is unlikely to result in scarring. Otherwise, scar tissue begins to form about 2 - 3 months after injury. By about 6 months, scarring is at it's peak, and by the end of the first year, the scar tissue should be mature. The difference in immature and mature scar tissue is visually and palpably distinct. Immature scar tissue is deeper in color, and tends to be hard, as the scar tissue is well vascularized. Mature scar tissue, on the other hand, is lighter in color, and is soft, as it is no longer filled with blood.
In this patient, although the scar tissue on his neck was almost a year old, it was still highly vascularized as compared to the scars on his chest. While each individual rate of scarring varies, in this case, the immature scar tissue is more likely due to irritation from the hair growth from the patient's facial hair. During the surgery, a large piece of scar tissue from the patient's neck was removed. Scar tissue with facial hair on the patient's jaw and face was left in place, so that his facial hair would not look disproportionate when compared to his left side. Because the wound was deep, the scar tissue penetrated through to the dermis. As such, after the scar tissue was removed, a layer of Integra Dermal Regeneration Template was stapled in its place. This template comprises two layers - a cross-linked collagen and glycosaminoglycan matrix at the bottom that encourages dermal growth, and a silicone sheet above that acts as a temporary epidermis. A strip of material containing silver was placed over the template to reduced bacterial growth, and a sponge was placed over the silver-containing strip. An airtight covering was placed over the surgical site, and a vacuum pump was used to remove all the air from it. This pump is left on until the dermis regrows. The downside to this technique is that once the dermis regrows, a subsequent STSG operation is needed to replace the temporary silicone epidermis.
Moving over to pediatric neurosurgery, Dr. Souweidane operated on a child with a small hole at the back of the skull. To patch it up, a piece of skull of a comparable size was removed from a neighboring location. The bone was then flattened using a clamp. The piece of bone was then gently chiseled around its entire circumference parallel to its planer surface. After this, the chisel was then used to pry the bone in half, easily splitting it along its planar axes since the center of the bone is filled with structurally weaker trabecular bone as compared to the outer cortical bone. One piece was then returned to the donor site and sutured in place with biodegradable thread, while the other piece was attached to a piece of plastic that was molded to the contours of the recipient site, and then screwed in place with plastic screws.
Dr Souweidane also performed an encephaloduroarteriosynangiosis (EDAS) on a child with Moyamoya disease with obstructed internal carotid arteries. The procedure involved isolating a branch of the external carotid artery near the temporal region, removing a piece of the underlying skull and dura, placing the arterial branch on the brain, and suturing it to the dura, replacing the piece of skull, and suturing up the periosteum. To locate the arterial vessel of interest, a doppler probe was used to locate vessels, which were then compared to an MRI angiogram. Holes were made in the piece of bone for the arterial branch to thread in and out of the skull. Because the brain is so starved of blood flow, angiogenetic factors up-regulated, resulting in neoangiogensis occurring between the brain and the internalized arterial branch. This procedure is then repeated on the other temporal side of the patient. It takes up to a year before the success of the procedure can be determined.
I did see a patient briefly in the emergency department who had her arm crushed in a steam press. Both the epidermis and dermis were burnt off, and the vessels in running along the arm were clearly visible. However, in this instance, the bones and muscles of the patient's arm were also severely damaged. An amputation was thus required, as treating the skin would not prevent the dead muscle beneath from decomposing.
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