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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4430_Библиотеки_им_академика_М_И_Перельмана
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Chapter 5 Cranioplasty
Cranium
Implant
Drain
Dura
Brain
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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.
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G
Lag screw fixation
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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.
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Chapter 5 Cranioplasty
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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.
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A
B
Cranioplasty for contour irregularities
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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).
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Chapter 5 Cranioplasty
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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
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C
E
D
F
Cranioplasty for contour irregularities
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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
transition beneath extremely thin forehead skin.
G
H
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Chapter 5 Cranioplasty
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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.
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Video 5.1 InvisiShunt Implant. Courtesy of Longeviti Neuro.
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Chapter 6
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Temporal augmentation
Concavity in the temporal area is often referred to as “temporal hollowing.” It
reflects a deficiency in the bulk of the temporalis muscle, the temporal fat pad,
and/or an underlying bone defect (Fig. 6.1).
ETIOLOGY OF TEMPORAL HOLLOWING
When the temporal area has not been surgically violated, concavity gradually
appears with senescence.1 It may appear in patients with low body fat, hence less
temporal fat, and after massive weight loss. It may occur as a result of HIV-associated lipodystrophy and radiation-induced soft tissue atrophy. In other healthy
patients, prominent adjacent skeletal contour may diminish the relative projection of the temporal soft tissues. Therefore, augmenting the contours of the temporal area can have a rejuvenating and/or a balancing effect on facial appearance.
Both aesthetic and reconstructive procedures that involve the temporal area
may result in temporal hollowing. Aesthetic surgeries that access the midface
via separation of the temporal fascial planes can also result in depression in the
temporal fossa. Temporal depressions also occur after neurosurgical procedures
during temporal or pterional craniotomy where detachment of the temporalis
muscle from its origin at the temporal crest or the lateral orbital rim is required.
Reattachment of temporalis muscle often yields suboptimal results, leading to
significant depressions beneath the temporal line. Moreover, the deformity is
exaggerated by the overlying soft tissues that are thinned out due to atrophy
or posttraumatic scarring. Temporal augmentation can restore the presurgical
appearance in these patients.
Fig. 6.1 An example of temporal hollowing after a bicoronal
incisional neurosurgery procedure.
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Chapter 6 Temporal augmentation
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TREATMENT OPTIONS
Several procedures have been described to augment the contour of the temporal
area. These include the use of various alloplastic implants, free fat grafting, injection of various absorbable and permanent filler materials, and in some instances,
vascularized flaps.
Temporal augmentation with autologous fat grafting has been associated
with difficult irregularities.2 In fact, the temporal region is one of the subunits
with the lowest satisfaction rate after facial fat grafting.3 Patients with thick
skin generally experience the best results with fat injection; however, thick skin
is not a typical quality in patients with temporal hollowing due to senescence.
Besides skin irregularities and edema,2 other severe, but rare, complications
such as blindness and cerebral fat embolism have been reported.
knowledge of the clinical anatomy of the temporal region is crucial for the safe
performance of temporal fat grafting.
7
Similarly, temporal augmentation with filler materials (e.g., hyaluronic acid)
produces similar contour irregularities. Adopting the technique of diluting
calcium-based fillers for the dorsum of the hand, Lambros described a technique for filling the temples with highly diluted hyaluronic acid.2 This dilution
method allows the filler to be distributed more evenly in the temporal area,
resulting in a more satisfactory outcome.
2
Augmenting the temporal region with various alloplastic materials has
been described. Contour irregularities at the interface of the implant edge and
native anatomy are not uncommon. This chapter describes the senior author’s
use of polymethylmethacrylate (PMMA) to fill depressions in the temporal
area.8 In instances when no previous surgery has been performed or when the
temporal area has served as a dissection plane to access adjacent areas (e.g.,
subperiosteal facelift), the implant material is placed beneath the temporal
muscle through a limited incision in the hair-bearing scalp. When previous
reconstructive surgery has been performed in the temporal area, the surgical incision scars are used to access the area of depression for placement of
PMMA over the temporal muscle. The author’s techniques using PMMA to
reconstruct temporal contour depressions have been reliable, durable, and
relatively free of complications.
4–6
A thorough
OPERATIVE TECHNIQUE: AESTHETIC TEMPORAL AUGMENTATION
Access
A 5- to 6-cm vertical incision is made above the helix, within the hair-bearing temporal scalp. The scalp flap is undermined anteriorly for 2 to 3 cm
before the deep temporal fascia and the underlying temporalis muscle are
incised along the direction of the vertically oriented muscle fibers. The temporalis muscle is split and dissection is continued to reach the temporal
fossa (Fig. 6.2A).
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