Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_557_Библиотеки_им_академика_М_И_Перельмана
.pdf
Chapter 5 Cranioplasty
https://t.me/medicina_free
A
C
Fig. 5.5 Acrylic cranioplasty by plastic sleeve molding technique. (A) Intraoperative view of right frontoparietal defect. (B) Molding of methyl
methacrylate to defect. (C) Postoperative result. From Yaremchuk MJ, Rubin JP. Surgical repair of major defects of the scalp and skull. In
Schmidek HH, ed: Operative Neurosurgical Techniques, 4th ed. Philadelphia, WB Saunders, 2000, with permission.
B
area to be augmented, leaving the head and two or three threads above the bone
surface. The acrylic is then poured over the screw so that it is incorporated in
the construct.
The implant may be perforated to allow the dura to be tented up to it. This
method lessens the potential for epidural collection. Perforations in the implant
also allow drainage and soft tissue ingrowth, which also aids in implant fixation.
Hydroxyapatite
Hydroxyapatite is available in a powdered form that, when mixed with water,
becomes a paste that is easily applied to regular surfaces. The paste sets in
approximately 20 minutes. Because of its low flexural resistance, it is recommended for use as an onlay material to improve contour. It has been used with
metallic mesh to reconstruct defects. In this application, Zins reported a high
complication rate of 42.8%, with some complications occurring as late as 4 years
postoperatively. The main problems observed at reoperation were fragmentation of the hydroxyapatite cement, exudation, and severe soft tissue inflammatory reaction.14 Others have cautioned about the use of this material for vault
reconstruction.15
58
Cranioplasty for full-thickness defects
https://t.me/medicina_free
Titanium mesh
Titanium mesh can be used alone to replace skull defects when precise restoration of skull contour is not paramount and brain volume can expand to the
inner surface of the implant eliminating intracranial dead space. Cranioplasties
utilizing mesh alone are susceptible to contour deformation when subjected to
blunt trauma.
A
Fig. 5.6 Acrylic cranioplasty by mesh-onlay technique. (A) Intraoperative view of titanium mesh spanning defect. (B) PMMA spread over
metallic template.
B
Prefabricated implants: CAD/CAM
Computed tomography (CT) imaging of skull defects provides digitized information that can be transferred to design software. Data describing the contour
along the edge of the defect and the surface characteristics of the normal cranium surrounding the defect can be used to design a custom-fit implant. The
electronic data describing the newly designed prosthesis are then used by a
computer-controlled manufacturing system to create a wax model, which is then
cast, or to directly mill raw material into the finished implant.
16,17
An alternative
method is for anatomically precise stereolithographic (SL) biomodels (i.e., exact
physical replicas) of the cranium to be constructed. Subsequently, each SL biomodel is used as a template for the construction of preliminary implant, which
is then inspected by the surgeon, physically or online, who either approves the
implant or requests further modifications. If approved, the final implant is then
prepared and packaged sterilely.
Prefabricated implants of various materials – including polymethylmethacrylate–polyhydroxyethylmethacrylate, porous polyethylene, and polymethylmethacrylate – are available. The use of custom prefabricated implants can
reduce operative time significantly.
When skull defects are large (greater than 6 cm in diameter) or when they
involve complex curvatures, such as the supraorbital rim, the author prefers
to reconstruct them with implants prefabricated using CT data. Use of these
implants has decreased operative time by at least 50%, more than justifying
their fabrication cost (Fig. 5.7).
59
Chapter 5 Cranioplasty
Cranium
Implant
Drain
Dura
Brain
https://t.me/medicina_free
A
C
D
B
E
F
Fig. 5.7 A 60-year-old woman presented with an exposed cranial implant. By history, an asymptomatic aneurysm was treated through a leftsided frontotemporal craniotomy. The craniotomy graft was lost to infection. A hydroxyapatite cement-and-mesh cranioplasty was performed
and was subsequently removed due to infection. Six months later, a custom HTR implant was fabricated by using three-dimensional CT data.
This became exposed. A CT scan was obtained, which showed communication between the frontal sinus and the implant. At surgery the
implant was removed and a rectus abdominis myocutaneous free ap was used to obliterate dead space in the wound, separate the frontal
sinus from the anticipated cranioplasty implant, and provide a closed soft tissue wound. Six months later, a tissue expander was placed in
the hair-bearing scalp. When the scalp was suciently expanded to provide hair-bearing scalp adequate to replace that lost to infection, the
expander was removed, a custom porous polyethylene implant was placed and covered with the expanded hair-bearing scalp. (A) Patient
with exposed implant. (B) Intraoperative view at time of implant removal. Arrow points to communication with frontal sinus. (C) Appearance
after rectus abdominis myocutaneous free ap wound closure. (D) Tissue expander used to expand hair-bearing scalp. (E) Skull model
obtained from three-dimensional CT scan data showing cranial defect. (F) Skull model and custom implant. (G) Appearance after custom
implant cranioplasty.
60
G
Lag screw fixation
https://t.me/medicina_free
Cranioplasty implants are traditionally fixed to the cranium with plates
and screws. A not uncommon etiology of implant exposure is the erosion of the overlying scalp over prominent plates and screws, as shown
in Fig. 5.5. As illustrated in Fig. 5.8, placing screws obliquely with the
implant–skull interface and countersinking of the fixation screw avoids
protrusion of the screw head above the implant surface. The position of
the channels for the screws is determined by certain attributes of the intact
cranium.
Intracranial drain access
An implant may also be designed to include a channel joining the intracranial
cavity with the cranial surface as shown in Fig. 5.8. The channel is of dimensions to allow passage of a drain into the intracranial cavity with the intention of evacuating fluids accumulating in the space between the brain and the
implant.
Functional cranioplasty
Drain
Implant
Dura
Cranium
Brain
Fig. 5.8 A CAD/CAM implant immobilized with lag screws. The screw
heads are countersunk to avoid prominence above the implant surface. A
channel for a drain to be placed between the dura and implant can also be
incorporated into the implant design.
FUNCTIONAL CRANIOPLASTY
Implantable neuromodulation devices treat CNS diseases such as movement
disorders, epilepsy, hydrocephalus, chronic pain, and are even proposed to be
used for cognitive enhancement.18 The current method of placement requires
device positioning above the skull, which not only produces a visible deformity but also compromises the vascularity of the overlying scalp, often resulting in device exposure and loss.19 Gordon et al.20 have developed cranial
implants manufactured by Longeviti (Hunt Valley, MD) and Matrix Surgical
(Atlanta, GA), which utilize the “dead space” within these implants to house
these devices.
61
Chapter 5 Cranioplasty
https://t.me/medicina_free
Drug-resistant epilepsy
The NeuroPace Neuromodulation System (NeuroPace Inc., Mountain View,
CA) is a device developed to treat drug-resistant epilepsy. This device
can be incorporated into a cranial implant as shown in Fig. 5.9. CT scan
data was used to create an implant that replaced a resorbed bone flap
while incorporating the NeuroPace device within the implant contour.
Intracerebral leads are placed for control of seizure foci not amenable to
antiseizure medication. After they are placed, they are connected to the
neurostimulator and the entire complex is placed within the laser-cut portion of the cranial implant. The PMMA implant is transparent allowing
visualization of the orientation of the stimulator and its leads as well as the
status of the operative field.
Fig. 5.9 Functional cranioplasty incorporating a device for treating
drug-resistant epilepsy. (A) Intraoperative photograph shows full
integration of the neuromodulation device within the implant. (B)
Panoramic intraoperative view shows maintenance of skull contour
with implant in place.
62
A
B
Cranioplasty for contour irregularities
https://t.me/medicina_free
Fig. 5.10 A functional implant system designed to contain a
shunt mechanism. (A) The ring implant is xed to the cranium
at the desired location and functions as a cutting guide for the
craniotomy and later as a housing for the functional implant. (B)
Three implants (showing dierent shunt construct possibilities)
are xed to the cutting-guided craniotomy defect.
A B
Shunt mechanism
A functional implant designed to house a shunt mechanism within its contours
is shown in Fig. 5.10. The ring implant is fixed to the cranium at the desired location and functions as a cutting guide. Various housings are fixed to the guided
craniotomy defect to house the functional implant. Video 5.1 demonstrates the
operative placement.
CRANIOPLASTY FOR CONTOUR IRREGULARITIES
Onlay cranioplasty is performed to refine the results of cranioplasties previously performed to reconstruct full-thickness defects, to correct surface irregularities resulting after posttraumatic reconstructions, or for purely aesthetic
reasons.
PMMA is the most frequently used material for onlay reconstructions of surface irregularities. It is immobilized by its insinuation into surface irregularities
or by encompassing a screw head placed above the skull surface.
Most often, the bicoronal flap is replaced before the PMMA is hardened and
the surface is molded through the overlying scalp. This allows the PMMA to
replace both hard tissue and soft tissue deficits with a resultant smooth skin–
surface contour.
When the frontal area is augmented for aesthetic concerns, a change in globe–
rim relations is the most frequent indication (Fig. 5.11). Aesthetic indications
often use a combination of implants and PMMA. Implants can help assure a
uniform thickness, defined projection, or symmetric complex curvature. PMMA
is used to create smooth transitions between the implants and the native skull
(Fig. 5.12).
63
Chapter 5 Cranioplasty
https://t.me/medicina_free
Fig. 5.11 A 25-year-old man underwent
augmentation of his supraorbital rims
to make his eyes appear less prominent.
Titanium screws were placed so that the
screw heads projected 5 mm beyond the
supraorbital rim. Porous polyethylene
implants were positioned laterally. PMMA
was used to cover the rim screws and the
porous polyethylene implants. Lateral
canthopexies were also performed. (A)
Preoperative frontal appearance. (B)
Postoperative frontal appearance. (C)
Preoperative lateral appearance. (D)
Postoperative lateral appearance. (E)
Intraoperative view from coronal approach.
Arrows point to screws at supraorbital
rim used to assure measured projection
of supraorbital rim PMMA onlay. (F)
Intraoperative lateral view.
A
B
64
C
E
D
F
Cranioplasty for contour irregularities
https://t.me/medicina_free
A
B
C
E
D
F
Fig. 5.12 A woman with Parry–Romberg syndrome underwent onlay rib frontal cranioplasty at age 21. The
grafts resorbed. At age 46 she underwent frontoorbital reconstruction with a custom porous polyethylene
implant. Her enophthalmos was corrected by implant augmentation of her internal orbit. (A) Preoperative
appearance. (B) Preoperative three-dimensional CT scan shows skeletal deciency. (C) Skull model obtained
from three-dimensional CT data. (D) Skull model with custom implant. (E) Postoperative appearance. (F)
Intraoperative view. There is no remnant of previously placed onlay bone grafts. (G) Intraoperative view
shows custom implant in place. (H) Intraoperative view shows PMMA used to feather implant native skull
G
H
65
Chapter 5 Cranioplasty
https://t.me/medicina_free
REFERENCES
1. Farkas LG, Hreczko TA, Katic MJ. Craniofacial norms in North American Caucasians from
birth (one year) to adulthood. Appendix A. In: Farkas LG, editor. Anthropometry of the head
and face. 2nd ed. New York: Raven Press; 1994.
2. Whitaker LA, Morales L, Farkas LG. Aesthetic surgery of the supraorbital ridge and forehead
structures. Plast Reconstr Surg 1986;78(1):23–32.
3. Bartlett SP, Wornom I, Whitaker LA. Evaluation of facial skeletal aesthetics and planning. Clin
Plast Surg 1991;18(1):1–9.
4. Pessa JE, Desvigne LD, Lambros VS, Nimerick J, Sugunan B, Zadoo VP. Changes in ocular
globe-to-orbital rim position with age: implication for aesthetic blepharoplasty of the lower
eyelids. Aesth Plast Surg 1999;23(5):337–42.
5. Marchac D. Relationship of the orbits to the upper eyelids. Clin Plast Surg 1981;8(4):717–24.
6. Grantham EG, Landis HP. Cranioplasty and posttraumatic syndrome. J Neurosurg 1948;5:19.
7. Carmichael FA. The reduction of hernia cerebri by tantalum cranioplasty. A preliminary
report. J Neurosurg 1945;2:379.
8. Tabaddor K, LaMorgese J. Complication of a large cranial defect. Case report. J Neurosurg
1976;44(4):506–8.
9. Stula D. The problem of “sinking skin-flap syndrome” in cranioplasty. J Craniomaxillofac Surg
1982;10(3):142–5.
10. Manson PN, Crawley WA, Hoopes JE. Frontal cranioplasty: risk factors and choice of cranial
vault reconstructive material. Plast Reconstr Surg 1986;77(6):888–904.
11. Hammon WM, Kempe LG. Methyl methacrylate cranioplasty: 13 years’ experience with 417
patients. Acta Neurochir 1971;25(1):69–77.
12. Rish BL, Dillon JD, Meirowsky AM, et al. Cranioplasty: a review of 1030 cases of penetrating
head injury. Neurosurgery 1979;4(5):381–5.
13. Stelnicki EJ, Ousterhout DK. Prevention of thermal tissue injury induced by the application of
polymethylmethacrylate to the calvarium. J Craniofac Surg 1996;7(3):192–5.
14. Zins JE, Moreira-Gonzalez A, Papay FA. Use of calcium-based bone cements in the repair of
large, full-thickness cranial defects: a caution. Plast Reconstr Surg 1946;120(5):1332–42.
15. Matic D, Phillips JH. A contraindication for the use of hydroxyapatite cement in the pediatric
population. Plast Reconstr Surg 2002;110(1):1–5.
16. Wehmoller MW, Eufinge H, Kruse D, Massberg W. CAD by processing of computed
tomography data and CAM of individually designed prostheses. Int J Oral Maxillofac Surg
1995;24:90–7.
17. Eufinger H, Wehmoller MW, Machtens E, et al. Reconstruction of craniofacial bone
defects with individual alloplastic implants based on CAD/CAM manipulated CT data. J
Craniomaxillofac Surg 1995;23:175–81.
18. Bergey GK, Morrell MJ, Mizrahi EM, Goldman A, King-Stephens D, Nair D, et al. Longterm treatment with responsive brain stimulation in adults with refractory partial seizures.
Neurology 2015;84(8):810–7.
19. Wei Z, Gordon CR, Bergey GK, Sacks JM, Anderson WS. Implant site infection and bone flap
osteomyelitis associated with the NeuroPace responsive neurostimulation system. World
Neurosurg 2016;88(687):e1–6.
20. Gordon CR, Santiago GF, Huang J, Bergey GK, Liu S, Armand M, Brem H, Anderson WS.
First in-human experience with complete integration of neuromodulation device within a
customized cranial implant. Oper Neurosurg 2018;15(1):39–45.
66
Video 5.1 InvisiShunt Implant. Courtesy of Longeviti Neuro.
https://t.me/medicina_free
66.e1
Соседние файлы в папке Библиотека им академика М.И. Перельмана