Keywords scaphocephaly - superior sagittal sinus
Palavras-chave escafocefalia - seio sagital superior
Introduction
The premature fusion of the sagittal suture, known as scaphocephaly, remains the most
prevalent form of isolated single-suture synostosis, accounting for 40% to 60% of
all cases of craniosynostosis.[1 ]
[2 ] The cranium acquires an elongated form with an enhancement of anteroposterior (AP)
distance, which is typically accompanied by a bulging forehead and/or a prominent
occiput, due to the shape of the coronal and lambdoid sutures. The aim of surgery
is to oppose the abnormal longitudinal growth of the skull favoring its latero-lateral
enlargement.[3 ]
The first surgical treatment for sagittal craniosynostosis was performed by Lannelongue
in 1892, which consisted in a simple linear sagittal suture craniectomy.[1 ] Between 1969 and 1990, inadequacies in the results secondary to early reossification
led to modifications in this technique to more extensive calvarial reshaping operations,
such as the Renier H technique and Pi procedure.[2 ]
[4 ]
[5 ]
More recently, after 1990, there has been a renewed interest in simple linear sagittal
suturectomy with spring-assisted surgery or with minimally-invasive endoscopic procedures.
However, with the spring-assisted procedure, a second surgery is necessary to remove
the metal springs, and with the endoscopic approach, a molding helmet therapy is required
to obtain a good long-term cosmetic outcome.[6 ]
[7 ] The esthetic results are not immediately visible in the postoperative period with
both of these techniques.
There are many surgical options and opinions about the best operative treatment, but
no definitive guidelines have been established, and there is a lack of studies to
support or favor a particular surgical technique.[8 ]
The purpose of the present paper is to describe a modified technique of cranial vault
reconstruction, an open approach, that we have used at Centro Hospitalar Universitário
São João (CHUSJ) for scaphocephaly. Clinical observation and physical examination
with head measurements were the main parameters to propose surgery – elongated head,
manual palpation of a bony prominence over the sagittal suture, and biparietal and
bitemporal narrowing are the main criteria for early surgery.
With the present technical note, the surgery immediately enables the reduction of
the AP diameter of the skull, and does not require the use of a helmet.
Extensive blood loss is common in pediatric craniosynostosis reconstruction surgery.
Tranexamic acid (TXA) is increasingly used to reduce perioperative blood loss in various
settings, but data on its efficacy in children are limited.[9 ] Here, we also aimed to report the anesthetic approach with the use of TXA, and how
it has influenced our results, as far as blood loss is concerned, enabling the performance
of this surgery at earlier ages.
Materials and Methods
We designed a retrospective study to analyze the children with scaphocephaly who were
surgically treated by an individual team and with a modified technique of cranial
vault reconstruction, from January 2010 to December 2021 at CHUSJ.
Only children with isolated sagittal synostosis were included in the study, while
those diagnosed with closing of other cranial sutures in addition to the sagittal
and patients with syndromic or complex craniosynostosis were excluded.
All patients underwent a preoperative physical examination and three-dimensional computed
tomography (CT). The following determinants were evaluated: age at the time of the
surgery, gender, need for blood transfusion, use or not of TXA, and surgery complications.
Statistical Analysis
The continuous variables were expressed as mean, median, standard deviation, minimum,
and maximum values, whereas the categorical variables were reported as frequencies
and percentages. For the correlation analysis regarding the continuous variables,
with normal distribution or not, the Pearson coefficient and Spearman correlation
were used respectively. For the correlation analysis involving the categorical variables,
the Chi-squared test was used. Values of p < 0.05 were considered statistically significant. The IBM SPSS Statistics for Windows
(IBM Corp., Armonk, NY, United States) software, version 23.0, was used for the statistical
analyses.
Surgical Technique
The operation is performed with the patient in the prone position with the head positioned
on a horseshoe headrest to protect the eyes. The head is slightly elevated, retroflexed,
and we use antidecubitus gel cushion to protect the shoulders and hip. An air-warming
blanket is placed over the patient's body. The head is shaved in the operating theater
and the skin is thoroughly prepared with antiseptic-colored tincture.
We perform a skin scalp incision in the retrocoronal plane from one ear to the other.
A unique subgaleal and pericranium flap is elevated to visualize the calvarium from
the anterior fontanel region and coronal suture to the lambdoid suture. This one-layer flap helps to preserve the pericranium, which is important to further promote osteosynthesis.
Meticulous hemostasis of the soft tissue and bone is performed using bipolar cautery
and bone wax.
The modified technique of cranial vault reconstruction started with a classic sagittal
suturectomy by removing all the sagittal strip craniectomy of bone from the superior
sagittal sinus (SSS). With the present technical note, we additionally create 2 AP
rectangular structures by performing a strip craniotomy with 1.5 cm in width, parallel
and 1.5 cm next to the SSS, stuck by a posterior pedicle of bone to the lambdoid suture
but free of the coronal suture. With this maneuver, we create new parasagittal sutures
replacing the prematurely fused sagittal suture.
Before fixation, 1.5 cm of the anterior segment of bone of those 2 rectangular structures
parallel to the SSS are cut, to enable the immediate shortening of the AP diameter
of the skull ([Fig. 1 ]).
Fig. 1 Sagittal suturectomy and creation of two anteroposterior (AP) rectangular structures
with 1.5 cm in width, parallel to the superior sagittal sinus (SSS), stuck by a posterior
pedicle of bone and free of the coronal suture. Cut of 1.5 cm of the anterior segment
of bone of the two rectangular structures parallel to the SSS (blue arrow).
Laterally, on the parietal bones, toward the squamosal sutures, parallel barrel stave
osteotomies with 0.5 to 1 cm in width are performed, as well as removal of the most
anterior precoronal bone barrel on each side.
Then, a force-compressing maneuver shortens the AP skull distance and the 2 rectangular
structures, parallel to the SSS, advance toward the frontal bone and are fixed with
absorbable 2/0 stitches in this new position ([Fig. 2 ]).
Fig. 2 Left side: cranial vault before the fixation and reduction of the AP cranial diameter;
right side: after the force-compressing maneuver and fixation with immediate reduction
of the AP cranial diameter.
With the 1.5-cm osteotomy and fixation, we immediately reduce the AP diameter. The
extent of calvary shortening in the AP diameter is notorious since then, with correspondent
widening in latero-lateral cranial diameter.
Finally, we put a mesh plate (SonicWeld Rx, KLS Martin Group, Tuttlingen, Baden-Wuerttemberg,
Germany) over the SSS, which is fixed anteriorly and posteriorly with pins (SonicPins
Rx, KLS Martin Group). These mesh and pins are made from poly-D,
L-Lactic Acid (PDLLA), which is a synthetic total absorbable and osteoinductive material ([Fig. 3 ]). The mesh can be easily and flexibly adapted to the bone surface after softening
in a water bath heated to 60° C, and once cooled down, the material reliably retains
its new shape, turning rigid again.
Fig. 3 Mesh plate (SonicWeld Rx, KLS Martin Group) over the SSS (blue arrow).
The periosteal and subcutaneous flap and skin incision are then closed; a subgaleal
drain is not used.
Results
In total, 47 (42 male and 5 female) patients underwent to the same surgical technique
performed by the same surgical team. All patients underwent preoperative CT scans,
but, as a matter of routine, postoperative CT scans were not performed, unless the
patient showed signs of complications.
In the whole sample, the surgical procedure was performed at an average age of 11 ± 2.72
months. Before the use of TXA (before 2019), the mean age of the children at the time
of the surgery was of 12 ± 2.93 months. After 2019, the mean age of the children was
of 10 ± 2.31 months.
Blood transfusion during the surgical intervention was needed in 25 patients (53%),
and 22 patients (46.8%) did not need blood transfusion. Regarding TXA, it was used
in 14 patients (30%). and 33 patients (70.2%) did not receive it. None of the 14 patients
who received TXA needed blood transfusions. Of the 33 patients who did not receive
TXA, 8 did not need a blood transfusion, but 25 did ([Table 1 ]). With the Chi-Square test, we reported a statistically significant association
between the use of TXA and blood transfusion (p < 0.0001), with a decreased need for blood transfusion with the use of TXA.
Table 1
Crosstabulation of blood transfusion and administration of tranexamic acid
Tranexamic acid
Total
No
Yes
Blood transfusion
No
8
14
22
Yes
25
0
25
Total
33
14
47
No intraoperative complication for the proposed operative technique was identified.
We reported 2 postoperative complications (4.26%): 1 wound infection with no need
of revision surgery and 1 case of cervical cellulitis which was resolved with antibiotic
therapy. The average postoperative follow-up was of 11 ± 3.7 (minimum: 6; maximum:
16) months.
Discussion
The one intraoperative advantage of an open cranial vault reconstruction is related
to the large exposition of the skull, which enables the safe removal of the sagittal
strip craniectomy of bone from the SSS. This enables a safer control of the SSS and
the possibility of controlling any dural tears that might occur.
With our modified technique, first we create 2 rectangular bone pillars parallel to
the SSS and remove 1.5 cm of the anterior segment of bone of those rectangular structures
for frontal fixation. With this technical note, we immediately reduce the AP diameter
of the skull, with cosmetic correction visible at the end of the surgery. The location
and the number of the parietal barrel stave osteotomies can be easily tailored on
the deformed cranium, enabling a targeted enlargement in the regions where the narrowing
is greater. The surgical planning can be made in a digital workstation or even manufacturing
some cutting guides (KLS Martin Group).
Despite the minimally-invasive nature of endoscopic surgery, it also carries some
surgical risks and difficulties during the procedure. The detachment of the dura mater
from the inner surface of bones in the craniotomy area can be difficult due to the
small opening, increasing the risk of durotomies. Hemostasis is another important
problem in this kind of procedure, and it should be performed at each stage during
the surgery. There is a high risk of damage to the SSS and its repair can be complex
in a minimally-invasive approach. It is important to note that a successful long-term
outcome with endoscopic repair is critically dependent on postoperative molding with
helmet (orthotic) therapy to augment the cranial index, which increases the costs
associated with the procedure as well as its complications, such as alopecia.[7 ]
Spring-assisted cranioplasty has been proposed as an alternative to total calvarial
remodeling. However, some of the major drawbacks include the need for a second procedure
for removal, the lack of published long-term follow-up, and the fact that, in groups
of older patients, further remodeling surgery is required.[10 ]
With the type of technique herein described, there is no need for any postoperative
or preoperative molding therapy or later surgeries; therefore, further treatment is
not required.
Comparing our modified technique of cranial vault reconstruction with other extensive
calvarial reshaping operations, such as the Renier H technique and the Pi procedure, we create new parasagittal sutures replacing the prematurely fused one
and we immediately reduce the AP diameter of the skull. With the unique application
of the mesh plate over the SSS, we can protect it from traumatic brain injury, which
is so common at these ages. Additionally, it is a reinforcement of the bone suture
performed to obtain the shortening of the AP diameter of the skull. This technique
with this type of mesh and pins has never been described before, and the patients
do not need further surgeries to remove the material incorporated.
Reducing blood loss and transfusion requirements has been an endless question in this
type of cranial vault reconstruction.[11 ]
[12 ] Tranexamic acid is an antifibrinolytic drug which has demonstrated a significant
reduction in perioperative blood loss in many pediatric surgical procedures. Interest
in using TXA in craniosynostosis surgery has risen since the publication of randomized
controlled studies in 2011.[9 ] Goobie et al.[9 ] stated that TXA is effective in reducing blood loss and transfusion requirements
in children undergoing craniosynostosis surgery; they reported a mean blood loss of
65 mL in the group that received TXA, and a mean blood loss of 119 mL among the patients
who did not received TXA
In the sample of the present study, we observed a statistically significant association
between the use of TXA and blood transfusion, with a decreased of need for blood transfusion
with the use of TXA (p < 0.0001). According to Martin et al.,[13 ] TXA administration decreased blood loss both during and after surgery, reduced the
volume of red-blood-cell transfusions, and resulted in complete elimination of the
transfusion of other blood products, such as platelets and fresh frozen plasma. In
most of the articles reviewed, all patients, even those who were administered TXA,[1 ]
[3 ]
[4 ]
[5 ]
[9 ]
[13 ]
[14 ]
[15 ] received some type of transfusion, even if in smaller amounts than the group that
did not receive TXA. In the sample of the present study, none of the patients who
received TXA (N = 14) underwent any type of blood product transfusion ([Table 1 ]).
In the present study, with the administration of TXA, we reduced the mean age of the
child at the time of surgery to 10 ± 2.31 months, and, according to the literature,[16 ] we know that we can achieve better cognitive and cosmetic results with earlier surgery.
Therefore, the use of TXA may help to reduce the need for blood transfusion during
and after the surgery and promote earlier surgery.
It is important to underline the importance of an experienced surgical team. The morbidity
of the procedure, in the present study, was very low (of 4.26%), and there were no
cases of mortality. According to Kajdic et al.,[17 ] the mortality and morbidity rate is of 0.1%, and it may reach up to 50% in the case
of severe blood loss.
Conclusion
The modified technique of cranial vault reconstruction for scaphocephaly herein described
is a safe procedure, which enables the immediate reduction of the AP diameter of the
skull, and no further therapies are needed. It also results in a head with a normal
appearance right after the procedure. The wide decompression of the brain and remodeling
of the skull that can be obtained with the procedure are the most rewarding surgical
results. With the combination of a careful anesthesiologic protocol, we were able
to perform this surgery at early ages, requiring no blood transfusions.
