REVIEW URRENT C OPINION
Latest trends in minimally invasive synostosis surgery: a review Claire Sanger, Lisa David, and Louis Argenta
Purpose of review To present the current surgical options for minimally invasive surgery for treatment of craniosynostosis. Recent findings Minimally invasive procedures are well tolerated treatment options for patients with craniosynostosis. Suturectomy and helmet therapy is a treatment option for scaphocephaly with minimal blood loss and length of hospital stay. Spring-mediated cranioplasty is, in addition, a well tolerated and effective treatment option for scaphocephaly. Summary In patients with multiple suture craniosynostosis, surgical techniques that utilize spring-assisted surgery can provide decreased morbidity with better bone formation made available for a second operation. Continued basic science research and clinical studies will expand the use and provide further minimally invasive procedures to infants with craniosynostosis. Keywords craniosynostosis, endoscopic surgery, minimally invasive, scaphocephaly, synostosis
INTRODUCTION Craniosynostosis is the premature fusion of one or more sutures of the calvarium. The premature fusion of the cranial bones can be an isolated event or part of a craniofacial syndrome. The pathophysiology of this process was first described by Virchow over 150 years ago. The shape of the skull is dictated by the suture that is fused, which restricts growth in the perpendicular direction, thus forcing expansion in the opposite direction [1]. Since this first description, there have been competing theories to the cause of the fusion. Recent research done by Longaker and coworkers [2,3] revealed that the cause was more likely multifactorial with disruptions in the regulation of growth factors modifying the interaction between the dura and overlying suture. Linear craniotomies were among the first described surgical techniques in 1892 for premature fusion of the cranial bones [4,5]. This provided an immediate release to the restricted growth of the brain, but the correction was not sustained because of the rapid refusion of the skull. This was combated with placing polyethylene sheets and Zenker solution in the site of the resected bone. These measures were not successful because bone grew around the foreign material, causing both deformity and refusion. Although refusion was less likely the www.co-otolaryngology.com
substances were linked to sarcoma formation and disruption of the blood–brain barrier, respectively [6,7]. In the late 1960s, Tessier presented his techniques in treating adult skulls with aggressive surgical cranial remodeling. This aggressive treatment was necessary in the older age group as the dynamic force of a growing brain and reossification after 1 year of age would not aid in the repair. These were the factors that Marchac and Jane [8,9] took into consideration and used to the patient’s benefit by operating during infancy. Unfortunately, the concept that the brain would expand to correct the skull deformity often proved untrue and the deformity recurred. The floating forehead and pi-plasty techniques were instituted for the treatment of craniosynostosis by this group, and are still used by some surgeons today with modification. These were effective in addressing the prematurely fused sutures and Wake Forest Baptist Medical School, Department of Plastic and Reconstruction Surgery, North Carolina, USA Correspondence to Dr Claire Sanger, Wake Forest Baptist Medical Center, Medical Center, Boulevard, Winston-Salem, NC 27517, USA. Tel: +1 336 713 0200; e-mail: [email protected] Curr Opin Otolaryngol Head Neck Surg 2014, 22:316–321 DOI:10.1097/MOO.0000000000000069 Volume 22 Number 4 August 2014
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Minimally invasive synostosis surgery: a review Sanger et al.
improving the skull shape. However, the extent of the repair was limited by the amount of correction achieved in the operating room because of the change in force vectors and an increase in intracranial pressure. Radical repositioning of skull segments was practiced by most surgeons from the 1980s through approximately 2000 because of disappointment with results of conservative surgery. Less aggressive procedures reappeared clinically in the early 2000s. In 1986, Persing et al. [10] achieved successful distraction of cranial bones in a rabbit model; although it was not sustained, it allowed the technique to be reevaluated. Lauritzen et al. [11] opened the door for minimally invasive cranial reshaping in 1998 when they showed that stainless steel springs could be used to enhance skull reshaping over time referred to as spring-assisted surgery (SAS). Lauritzen demonstrated that the distracting forces of the springs allowed postoperative correction over time, which addressed the correction previously limited in the operating room. In addition, these results were maintained over time. Thus, the era of SAS began and gave way to more minimally invasive procedures for the treatment of craniosynostosis. There are two basic procedures to discuss for current surgical management for craniosynostosis utilizing minimally invasive techniques: endoscopic suture release and spring-assisted cranioplasty.
ENDOSCOPIC SUTURAL RELEASE AND HELMET MOLDING SAGITTAL SYNOSTOSIS Premature fusion of the sagittal suture is the most common form of craniosynostosis and leads to scaphocephaly, which presents with an elongated narrow head. There can also be occipital narrowing, coronal banding, and frontal bossing depending on the time of fusion, the severity, extent of the suture involved, and age of the patient at presentation. The sagittal suture is normally not expected to fuse until around 22 years of age. Premature fusion can be detected as early as at birth but typically presents within the first year of life. Vicari [12] presented his work with the treatment of sagittal synostosis with the aid of endoscopic visualization in 1994 at the American Society of Plastic and Reconstructive Surgeons Presymposium. The results were good, but narrowing of the cranium recurred in many cases. A few years later, endoscopic suture release with postoperative helmet molding was performed by Barone and Jimenez [13] for sagittal synostosis and is still performed today. The use of a molding helmet to put pressure on the skull in the anterior–posterior dimension and
expand the skull laterally helped to improve results. Their experience over a 16-year period showed a total of 256 patients treated for sagittal synostosis with endoscopic-assisted techniques and postoperative cranial orthotic therapy. The ideal age for this technique is less than 3 months, but infants between 3 and 6 months of age are still good candidates. If an infant presents between 6 and 9 months of age with a mild deformity, this technique can be considered. The younger age group is optimal because the bone is thinner, there is less blood loss, and the brain growth is more rapid, all of which contributes to a superior result in correction of the skull shape and decrease in morbidity. If an infant presents between 6 and 9 months of age with a severe deformity or is older than 9 months of age, this treatment is no longer an option [14 ]. Only the technical highlights will be described. The technique is done with the patient in the sphinx position. An incision is made across the midline posterior to the anterior fontanelle and anterior to the lambda. A 08 rigid endoscope designed specifically for this procedure is used for visualization. A combination of a burr hole, rongeurs, and the rigid endoscope is used to resect the sagittal suture from the dura. Lateral paramedian osteotomies are made bilaterally anterior to the lambdoid and posterior to the coronal sutures to aid in decreasing the length of the skull. The width of bone resected is inversely proportional to the age of the patient and ranges from 2 to 6 cm. Generally, the patients do not require blood transfusions and are discharged to home on the first postoperative day. Within the first week, a customized helmet is constructed to restrict growth in the anterior–posterior direction and allow expansion in the biparietal direction, and is prescribed for continual use up to 12 months after surgery [14 ,15,16 ]. The use of a helmet requiring periodic readjustments is difficult for many patients. Failure to wear the helmet as required lessened the ultimate success of the procedure. This often required more than one helmet before correction. &
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CORONAL SYNOSTOSIS Unicoronal synostosis is the second most common form of craniosynostosis and can cause significant skull and facial asymmetry. A common presentation includes flattening of the frontal bone on the side of the premature fusion with ipsilateral supraorbital rim involvement, ipsilateral orbital deviation laterally, ipsilateral occipital flattening, and contralateral nasal deviation. Jimenez and Barone show 15 years of experience with 100 patients treated for coronal craniosynostosis with the same principles described previously.
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For these patients, a 2-cm incision is made between the anterior fontanelle and the squamosal on the affected side. The endoscope is utilized for visualization to make an osteotomy of the bone just posterior to the coronal suture. Postoperatively, all the patients are placed in a custom helmet for molding [16 ]. Again, prolonged wearing of a helmet with periodic readjustments is necessary to achieve optimal results. Further published work by Rodgers over a 7-year period with 173 patients treated with this technique for craniosynostosis shows very similar results [17]. The craniofacial team at Joe DiMaggio Children’s Hospital recognized the lack of long-term correction of the supraorbital rim and lack of orbital symmetry when only suturectomy and a helmet are utilized for correction. Their team showed a 5-year experience with 10 patients who underwent surgical correction for nonsyndromic unicoronal synostosis with the addition of frontal and orbital rim advancement with a minimally invasive technique by using the endoscope. This surgery is conducted before 4 months of age. Three small incisions are made (near the anterior fontanelle and bilateral superior to the helix of the ear). The dissection is done in the subperiosteal plane with the temporalis muscle elevated with the scalp to reduce the risk of postoperative temporal hollowing. The endoscope provides visualization. Osteotomies are performed with a combination of Mayo scissor and the ultrasonic bone cutter where appropriate. After the synostosed suture is removed at a width of 3 cm, a linear craniotomy anterior to the contralateral coronal suture frees the attachment to the frontal bone. Additional osteotomies are performed on the affected side to allow for frontal orbital advancement. The metopic suture is used to hinge the bone segment with absorbable plates [18]. The ultrasonic bone cutter and endoscope have reduced the need for blood transfusion and limited the hospital stay to between 2 and 3 days. &
TECHNIQUE ADVANTAGES This technique has several positive points for the patients when compared with the traditional cranial vault remodeling procedures. Only one surgery is required and can be completed in an hour by experienced surgeons. There is no hardware implanted that needs to be removed or that could lead to complications. The need for a blood transfusion is not expected as the blood loss is minimal. The patient only requires up to three nights in the hospital for coronal synostosis. The procedure is tolerated by very young infants and therefore can incorporate the growing brain as an aid to achieving correction. 318
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TECHNIQUE DISADVANTAGES There is a learning curve for the use of the endoscope, and if bleeding occurs, the procedure would have to be converted to an open case. This procedure is only an option if the surgery is conducted in a narrow time frame. Thus, a subset of patients will not be eligible for this technique. There is no distracting force and as such this technique requires the external force of the helmet to be the key factor in obtaining correction in the skull shape. Because of the customized nature of the helmet and rapid skull growth in this age group, it is possible that more than one helmet will be required, which will increase the cost. The surgeon’s and infant’s success is predicated on compliance from the caregivers to keep the helmet on for the duration of the course prescribed. Many are not able or willing to have their child in a helmet as long as needed to obtain adequate correction. This technique is limited for coronal synostosis as significant advancement is often needed to obtain symmetry. The use of this technique without a postoperative helmet cannot be advised as an option for the reasons that our forefathers showed a century ago specifically for the high rate of recurrence and need for reoperation [19 ]. &
SPRING-ASSISTED CRANIOPLASTY Spring-assisted surgery was developed by Lauritzen in an effort to use the dynamic principles of distraction for continued correction over time to minimize intracranial risk and improve long-term outcomes. His first use was for a patient with turricephaly, but the benefits were quickly recognized and instituted for sagittal synostosis. In order to gain approval for use by the Food and Drug Administration (FDA) in the United States, studies with a rabbit model were conducted by David and led to FDA approval for use in infants. The concept of the spring surgery is similar to the principle involved in distraction osteogenesis shown by many in the long bones and then adapted by McCarthy [20,21] for mandibular distraction.
SAGITTAL SYNOSTOSIS In 2008, Lauritzen reported his first 100 SAS patients treated for craniosynostosis. Thirty-five of the first 100 patients were treated for sagittal synostosis. For this procedure, the patient is placed in the sphinx position. A lazy S incision is made across the midline from the anterior fontanelle to the posterior fontanelle. The entire sagittal suture is excised at a 1 cm width from the anterior fontanelle to the lambda posteriorly. The custom-fabricated stainless steel Volume 22 Number 4 August 2014
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springs are placed in the bone gap with one placed anteriorly and the other placed posteriorly with the springs bisecting in the middle. The age range for the study was 2.5–8 months, with an average time to removal of the spring being 7 months. The wire was 1.2 mm thick and 16 cm long [22]. The Wake Forest University group reported similar results of their 8-year experience for treating 90 infants with sagittal synostosis using SAS. Springs were placed at a mean age of 4.4 months and removed at a mean age of 8.8 months. The strength of the springs ranged from 5.5 to 9.5 N with a mean force of 6.9 N [23,24]. The springs used at Wake Forest are 1.28 mm thick and 15 cm long. The surgical time for both teams was dramatically lower than for cranial vault remodeling with a mean of 30 min for the Wake Forest team. The craniofacial team at the Christchurch Hospital in New Zealand showed similar successful results [25]. Over the past 3 years the endoscope has allowed a significantly smaller W-shaped incision at the midpoint with excellent anterior and posterior visualization and placement of the springs. The stainless steel springs are now commercially available. The second procedure involves percutaneous removal of the springs, and the patient is typically discharged from the recovery room.
CORONAL SYNOSTOSIS The craniofacial team in Sweden reported their experience with treating bicoronal synostosis with the use of SAS; it was done with an open approach through a bicoronal incision. For some of the cases, a combination of compressive and distracting springs was used for reshaping. Intracranial monitoring was utilized if compressive springs were utilized. A combination of osteotomies of the frontal and parietal bones was conducted with compressive forces to reduce the prominence, although springs placed in the lambdoid sutures will create expansion posteriorly while reducing the cranial height and width. The springs were removed on average 6 months later [22,26].
METOPIC SYNOSTOSIS The springs have been incorporated for treatment of metopic synostosis, although with an open approach. The patient is placed in the supine position. After the appropriate osteotomies are made through the synostosed suture, nasofrontal suture, and frontal bone, the spring is inserted into two holes positioned low in the frontal bone on either side of the metopic osteotomy. This provides gradual distraction and optimal correction [22,27,28].
A stop wire is used around the spring to prevent hypertelorism.
MULTISUTURE SYNOSTOSIS It is clear that the risk of increased intracranial pressure for infants with premature fusion of multiple sutures can be as high as 80%. It is ideal to obtain release before 1 year of life, and in severe cases, it is imperative to treat a Chiari malformation secondary to increased intracranial pressures. The traditional method of treatment before SAS was aggressive craniectomy of all the involved areas of the calvarium. With the advent of the springs, the posterior vault can be expanded by the springs within the first few months of life. As the pressure subsides, the child lays down bone into the gaps that were created by the distraction pressure. This prepares the infant for a full vault remodeling several months later when there is more stable bone available. This is commonly used with patients who have Apert and Crouzon syndrome, and the technique has been successfully done in several craniofacial centers throughout the world [22,29,30 –32 ,33]. There are requirements for instituting SAS for a single treatment modality for craniosynostosis or an adjunct to additional procedures. The bone needs to be thick enough to withstand the force of the spring. If the bone is too thin, it will break or the spring will migrate through the bone. The spring needs to be constructed with a force that is great enough to cause distraction but not so great that it bends the bone upward creating injury to the dura. Therefore, the patient’s age and bone thickness need to be taken into account. Preoperative models fashioned from a three-dimensional computed tomography (CT) scan can be helpful. There are a number of studies from several centers showing the safety and long-term efficacy of spring-mediated cranioplasty [22–29,30 –32 ,33–40]. &
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TECHNIQUE ADVANTAGES This technique has several positive points for patients when compared with the traditional cranial vault remodeling procedures. The blood loss is minimal, and no blood transfusions are usually required for single suture repair. The patient requires only one overnight stay in the hospital for placement of the springs. The second procedure for removal of the springs is a same-day procedure. The use of a molding helmet is not necessary. SAS can be incorporated as a first-line treatment for immediate release in cases of kleeblattschadel deformity or multisuture involvement, although osteogenesis occurs allowing for a better cranial vault remodeling when the
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infant is older. The endoscope can be used to further decrease the risks and scarring.
preoperative models to be fabricated whenever needed [44].
TECHNIQUE DISADVANTAGES
SUMMARY
There is a learning curve for selecting the appropriate spring strength and size, but standards have been established as guidelines and references and commercially fabricated springs are available. There is a defined time frame that this procedure can be offered to patients. There is a small risk of spring dislodgement, sagittal sinus tear [41], erosion, lack of adequate force, and lack of correction. A second surgery is required to remove the springs.
Minimally invasive surgery is becoming more possible with advanced technology, and this includes treatment for craniosynostosis. This surgery provides a technique to release the synostosis when the infant is less than a year and can remodel the cranial bone. The morbidities of the surgery are reduced with a decrease in blood loss, intensive care admission, and length of hospital stay recurrence.
CONCLUSION
Acknowledgements None.
Whitaker performed a transcontinental survey that included the time from 1968 to 1978. There were a total of 421 reported intracranial operations with a complication rate of 25.7% and a mortality rate of 2.2%. These were the pioneering years for this surgery, but showed that improvements were needed [42]. The open techniques for craniosynostosis have provided patients with successful treatments for the past 50 years. There are many advantages to these procedures, but we must continue to seek safer ways of providing care to our patients. The Internet and social media have empowered parents to be more informed about the surgical treatment options. Our challenge is to further educate parents for the treatment option that is the best for their child, by taking into account all of the factors discussed above. An initial work-up may involve several steps to prepare these patients for surgery. Consideration should be given for those children who may benefit from enrollment in the craniofacial team. Among those are patients being treated for craniofacial syndromes, multisuture involvement, or when a genetic disorder is identified. This helps provide continuity of care and support for both the patient and parents. A genetic consult should be considered when there is a familial history for craniofacial anomalies or for multisuture involvement. Ophthalmologic examination by a pediatric ophthalmologist or neuro-ophthalmologist should be obtained if there are questions about intracranial pressure, multisuture involvement, or for older children. Neurodevelopmental screening should be considered for infants with isolated craniosynostosis and is recommended for syndromic conditions or multisuture involvement [43]. Three-dimensional CT scans of the skull will confirm premature fusion, may reveal an additional suture involved, reveal an intracranial abnormality, and allow for 320
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Conflicts of interest The authors have no conflicts of interest to declare.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Virchow R. Uber den cretinismus, namentlich in Franken, und uber pathologiside Schadeelformen. Verh Phys Med Gesamle Wurzberg 1851; 2:26. 2. Warren SM, Longaker MT. The pathogenesis of craniosynostosis in the fetus. Yonsei Med J 2001; 42:646–659. 3. Warren SM, Greenwald JA, Spector JA, et al. New developments in cranial suture research. Plast Reconstr Surg 2001; 107:523–540. 4. Lane LC. Pioneer craniectomy for relief of mental imbecility due to premature sutural closure and microcephalus. JAMA 1892; 18:49–50. 5. Lannelongue J. De la craniectomie dans la microcephalie [The craniectomy in microcephaly]. CR Acad Sci 1890; 110:1382. 6. Bering E, McLaurin R, Lloyd J, et al. The production of tumors in rats by the implantation of pure polyethylene. Cancer Res 1955; 15:300. 7. McComb JG, Withers GJ, Davis RL. Cortical damage from Zenker’s solution applied to the dura mater. Neurosurgery 1981; 8:68–71. 8. Marchac D, Renier D, Broumand S. Timing of treatment for craniosynostosis and faciocraniosynostosis: a 20-year experience. Br J Plastic Surg 1994; 47:211–222. 9. Jane JA, Edgerton MT, Futrell JW, et al. Immediate correction of sagittal synostosis. J Neurosurg 1978; 49:705–710. 10. Persing JA, Babler W, Nagorsky MJ, et al. Skull expansion in experimental craniosynostosis. Plast Reconstr Surg 1986; 78:594–603. 11. Lauritzen C, Sugawara Y, Kocabalkan O, Olsson R. Spring mediated dynamic craniofacial reshaping: case report. Scand J Plast Reconstr Surg Hand Surg 1998; 32:331–338. 12. Vicari F. Endoscopic correction of sagittal craniosynostosis. Presented at the American Society of Plastic and Reconstructive Surgeons, Presymposium, San Diego, California, 1994. 13. Barone CM, Jimenez DF. Endoscopic craniectomy for early correction of craniosynostosis. Plast Reconstr Surg 1999; 104:1965–1973. 14. Jimenez DF, Barone CM. Endoscopic technique for sagittal synostosis. Childs & Nerv Syst 2012; 289:1333–1339. Describes the endoscopic technique for sagittal and coronal synostosis with the use of a molding helmet postoperatively described by the surgeons who first popularized the technique. 15. Jimenez DF, Barone CM, Cartwright CC, et al. Early management of craniosynostosis using endoscopic-assisted strip craniectomies and cranial orthotic molding therapy. Pediatrics 2002; 110:97–104. 16. Jimenez DF, Barone CM. Endoscopic technique for coronal synostosis. & Childs Nerv Syst 2012; 289:1429–1432. Describes the endoscopic technique for sagittal and coronal synostosis with the use of a molding helmet postoperatively described by the surgeons who first popularized the technique. 17. Berry-Candelario J, Ridgway EB, Grondin RT, et al. Endoscope-assisted strip craniectomy and postoperative helmet therapy for treatment of craniosynostosis. Neurosurg Focus 2011; 31:E5.
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Minimally invasive synostosis surgery: a review Sanger et al. 18. Stelnicki E, Heger I, Brooks CJ, et al. Endoscopic release of unicoronal craniosynostosis. J Craniofac Surg 2009; 20:93–97. 19. Mutchnick IS, Maugans TA. Nonendoscopic, minimally invasive calvarial vault & remodeling without postoperative helmeting for sagittal synostosis. J Neurosurg Pediatr 2012; 9:222–227. Explains how to perform a minimally invasive calvarial vault cranioplasty without the use of a molding helmet postoperatively. 20. McCarthy JG. The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg 1994; 21:625. 21. McCarthy JG, Schreiber J, Karp N, et al. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg 1992; 89:1–8. 22. Lauritzen CG, Davis C, Ivarsson A, et al. The evolving role of springs in craniofacial surgery: the first 100 clinical cases. Plast Reconstr Surg 2008; 121:545–554. 23. David LR, Plikaitis CM, Couture D, et al. Outcome analysis of our first 75 springassisted surgeries for scaphocephaly. J Craniofac Surg 2010; 21:3–9. 24. Pyle J, Glazier S, Couture D, et al. Spring-assisted surgery-a surgeon’s manual for the manufacture and utilization of springs in craniofacial surgery. J Craniofac Surg 2009; 20:1962–1968. 25. Mackenzie KA, Davis C, Yang A, MacFarlane MR. Evolution of surgery for sagittal synostosis: the role of new technologies. J Craniofac Surg 2009; 20:129–133. 26. Tovetja¨rn R, Maltese G, Ko¨lby L, et al. Spring-assisted cranioplasty for bicoronal synostosis. J Craniofac Surg 2012; 23:977–981. 27. Maltese G, Tarnow P, Lauritzen CG. Spring-assisted correction of hypotelorism in metopic synostosis. Plast Reconstr Surg 2007; 119:977–984. 28. Davis C, Lauritzen CG. Frontobasal suture distraction corrects hypotelorism in metopic synostosis. J Craniofac Surg 2009; 20:121–124. 29. Marucci DD, Dunaway DJ, Jones BM, Hayward RD. Raised intracranial pressure in Apert syndrome. Plast Reconstr Surg 2008; 122:1162–1168. 30. de Jong T, van Veelen MLC, Mathijssen IMJ. Spring-assisted posterior vault & expansion in multisuture craniosynostosis. Childs Nerv Syst 2013; 29:815– 820. Shows the important technique for releasing the posterior cranial vault in cases with multisuture synostosis. 31. Arnaud E, Marchac A, Jeblaoui Y, et al. Spring-assisted posterior skull & expansion without osteotomies. Childs Nerv Syst 2012; 28:1545–1549. Describes how spring-mediated cranioplasty without an osteotomy can achieve expansion.
32. Tunc¸bilek G, Kaykc¸og˘lu A, Bozkurt G, Akalan N. Spring-mediated cranioplasty in patients with multiple-suture synostosis and cloverleaf skull deformity. J Craniofac Surg 2012; 23:374–377. Describes the use of springs in cases with multisuture involvement and cloverleaf skull deformity. 33. Davis C, MacFarlane MR, Wickremesekera A. Occipital expansion without osteotomies in Apert syndrome. Childs Nerv Syst 2010; 26:1543– 1548. 34. Davis C, Windh P, Lauritzen CG. Adaptation of the cranium to spring cranioplasty forces. Childs Nerv Syst 2010; 26:367–371. 35. Taylor JA, Maugans TA. Comparison of spring-mediated cranioplasty to minimally invasive strip craniectomy and barrel staving for early treatment of sagittal craniosynostosis. J Craniofac Surg 2011; 22:1225–1229. 36. Guimara˜es-Ferreira J, Gewalli F, David L, et al. Spring-mediated cranioplasty compared with the modified pi-plasty for sagittal synostosis. Scand J Plast Reconstr Surg Hand Surg 2003; 37:208–215. 37. Ririe DG, David LR, Glazier SS, et al. Surgical advancement influences perioperative care: a comparison of two surgical techniques for sagittal craniosynostosis repair. Anesth Analg 2003; 97:699–703. 38. Windh P, Davis C, Sanger C, et al. Spring-assisted cranioplasty vs pi-plasty for sagittal synostosis–a long term follow-up study. J Craniofac Surg 2008; 19:59–64. 39. Davis C, Windh P, Lauritzen CG. Spring-assisted cranioplasty alters the growth vectors of adjacent cranial sutures. Plast Reconstr Surg 2009; 123:470–474. 40. van Veelen ML, Mathijssen IM. Spring-assisted correction of sagittal suture synostosis. Childs Nerv Syst 2012; 28:1347–1351. 41. Lin F, Wong VH, Ekanayake G, et al. Delayed sagittal sinus tear: a complication of spring cranioplasty for sagittal craniosynostosis. J Craniofac Surg 2012; 23:1382–1384. 42. Whitaker LA, Munro IR, Salyer KE, et al. Combined report of problems and complications in 793 craniofacial operations. Plast Reconstr Surg 1979; 64:198–203. 43. Speltz ML, Kapp-Simon K, Collett B, et al. Neurodevelopment of infants with single-suture craniosynostosis: presurgery comparisons with case-matched controls. Plast Reconstr Surg 2007; 119:1874–1881. 44. Danelson KA, Gordon ES, David LR, Stitzel JD. Using a three dimensional model of the pediatric skull for pre-operative planning in the treatment of craniosynostosis – biomed. Biomed Sci Instrum 2009; 45:358–363.
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Latest trends in minimally invasive synostosis surgery: a review Claire Sanger, Lisa David, and Louis Argenta
Purpose of review To present the current surgical options for minimally invasive surgery for treatment of craniosynostosis. Recent findings Minimally invasive procedures are well tolerated treatment options for patients with craniosynostosis. Suturectomy and helmet therapy is a treatment option for scaphocephaly with minimal blood loss and length of hospital stay. Spring-mediated cranioplasty is, in addition, a well tolerated and effective treatment option for scaphocephaly. Summary In patients with multiple suture craniosynostosis, surgical techniques that utilize spring-assisted surgery can provide decreased morbidity with better bone formation made available for a second operation. Continued basic science research and clinical studies will expand the use and provide further minimally invasive procedures to infants with craniosynostosis. Keywords craniosynostosis, endoscopic surgery, minimally invasive, scaphocephaly, synostosis
INTRODUCTION Craniosynostosis is the premature fusion of one or more sutures of the calvarium. The premature fusion of the cranial bones can be an isolated event or part of a craniofacial syndrome. The pathophysiology of this process was first described by Virchow over 150 years ago. The shape of the skull is dictated by the suture that is fused, which restricts growth in the perpendicular direction, thus forcing expansion in the opposite direction [1]. Since this first description, there have been competing theories to the cause of the fusion. Recent research done by Longaker and coworkers [2,3] revealed that the cause was more likely multifactorial with disruptions in the regulation of growth factors modifying the interaction between the dura and overlying suture. Linear craniotomies were among the first described surgical techniques in 1892 for premature fusion of the cranial bones [4,5]. This provided an immediate release to the restricted growth of the brain, but the correction was not sustained because of the rapid refusion of the skull. This was combated with placing polyethylene sheets and Zenker solution in the site of the resected bone. These measures were not successful because bone grew around the foreign material, causing both deformity and refusion. Although refusion was less likely the www.co-otolaryngology.com
substances were linked to sarcoma formation and disruption of the blood–brain barrier, respectively [6,7]. In the late 1960s, Tessier presented his techniques in treating adult skulls with aggressive surgical cranial remodeling. This aggressive treatment was necessary in the older age group as the dynamic force of a growing brain and reossification after 1 year of age would not aid in the repair. These were the factors that Marchac and Jane [8,9] took into consideration and used to the patient’s benefit by operating during infancy. Unfortunately, the concept that the brain would expand to correct the skull deformity often proved untrue and the deformity recurred. The floating forehead and pi-plasty techniques were instituted for the treatment of craniosynostosis by this group, and are still used by some surgeons today with modification. These were effective in addressing the prematurely fused sutures and Wake Forest Baptist Medical School, Department of Plastic and Reconstruction Surgery, North Carolina, USA Correspondence to Dr Claire Sanger, Wake Forest Baptist Medical Center, Medical Center, Boulevard, Winston-Salem, NC 27517, USA. Tel: +1 336 713 0200; e-mail: [email protected] Curr Opin Otolaryngol Head Neck Surg 2014, 22:316–321 DOI:10.1097/MOO.0000000000000069 Volume 22 Number 4 August 2014
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Minimally invasive synostosis surgery: a review Sanger et al.
improving the skull shape. However, the extent of the repair was limited by the amount of correction achieved in the operating room because of the change in force vectors and an increase in intracranial pressure. Radical repositioning of skull segments was practiced by most surgeons from the 1980s through approximately 2000 because of disappointment with results of conservative surgery. Less aggressive procedures reappeared clinically in the early 2000s. In 1986, Persing et al. [10] achieved successful distraction of cranial bones in a rabbit model; although it was not sustained, it allowed the technique to be reevaluated. Lauritzen et al. [11] opened the door for minimally invasive cranial reshaping in 1998 when they showed that stainless steel springs could be used to enhance skull reshaping over time referred to as spring-assisted surgery (SAS). Lauritzen demonstrated that the distracting forces of the springs allowed postoperative correction over time, which addressed the correction previously limited in the operating room. In addition, these results were maintained over time. Thus, the era of SAS began and gave way to more minimally invasive procedures for the treatment of craniosynostosis. There are two basic procedures to discuss for current surgical management for craniosynostosis utilizing minimally invasive techniques: endoscopic suture release and spring-assisted cranioplasty.
ENDOSCOPIC SUTURAL RELEASE AND HELMET MOLDING SAGITTAL SYNOSTOSIS Premature fusion of the sagittal suture is the most common form of craniosynostosis and leads to scaphocephaly, which presents with an elongated narrow head. There can also be occipital narrowing, coronal banding, and frontal bossing depending on the time of fusion, the severity, extent of the suture involved, and age of the patient at presentation. The sagittal suture is normally not expected to fuse until around 22 years of age. Premature fusion can be detected as early as at birth but typically presents within the first year of life. Vicari [12] presented his work with the treatment of sagittal synostosis with the aid of endoscopic visualization in 1994 at the American Society of Plastic and Reconstructive Surgeons Presymposium. The results were good, but narrowing of the cranium recurred in many cases. A few years later, endoscopic suture release with postoperative helmet molding was performed by Barone and Jimenez [13] for sagittal synostosis and is still performed today. The use of a molding helmet to put pressure on the skull in the anterior–posterior dimension and
expand the skull laterally helped to improve results. Their experience over a 16-year period showed a total of 256 patients treated for sagittal synostosis with endoscopic-assisted techniques and postoperative cranial orthotic therapy. The ideal age for this technique is less than 3 months, but infants between 3 and 6 months of age are still good candidates. If an infant presents between 6 and 9 months of age with a mild deformity, this technique can be considered. The younger age group is optimal because the bone is thinner, there is less blood loss, and the brain growth is more rapid, all of which contributes to a superior result in correction of the skull shape and decrease in morbidity. If an infant presents between 6 and 9 months of age with a severe deformity or is older than 9 months of age, this treatment is no longer an option [14 ]. Only the technical highlights will be described. The technique is done with the patient in the sphinx position. An incision is made across the midline posterior to the anterior fontanelle and anterior to the lambda. A 08 rigid endoscope designed specifically for this procedure is used for visualization. A combination of a burr hole, rongeurs, and the rigid endoscope is used to resect the sagittal suture from the dura. Lateral paramedian osteotomies are made bilaterally anterior to the lambdoid and posterior to the coronal sutures to aid in decreasing the length of the skull. The width of bone resected is inversely proportional to the age of the patient and ranges from 2 to 6 cm. Generally, the patients do not require blood transfusions and are discharged to home on the first postoperative day. Within the first week, a customized helmet is constructed to restrict growth in the anterior–posterior direction and allow expansion in the biparietal direction, and is prescribed for continual use up to 12 months after surgery [14 ,15,16 ]. The use of a helmet requiring periodic readjustments is difficult for many patients. Failure to wear the helmet as required lessened the ultimate success of the procedure. This often required more than one helmet before correction. &
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CORONAL SYNOSTOSIS Unicoronal synostosis is the second most common form of craniosynostosis and can cause significant skull and facial asymmetry. A common presentation includes flattening of the frontal bone on the side of the premature fusion with ipsilateral supraorbital rim involvement, ipsilateral orbital deviation laterally, ipsilateral occipital flattening, and contralateral nasal deviation. Jimenez and Barone show 15 years of experience with 100 patients treated for coronal craniosynostosis with the same principles described previously.
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For these patients, a 2-cm incision is made between the anterior fontanelle and the squamosal on the affected side. The endoscope is utilized for visualization to make an osteotomy of the bone just posterior to the coronal suture. Postoperatively, all the patients are placed in a custom helmet for molding [16 ]. Again, prolonged wearing of a helmet with periodic readjustments is necessary to achieve optimal results. Further published work by Rodgers over a 7-year period with 173 patients treated with this technique for craniosynostosis shows very similar results [17]. The craniofacial team at Joe DiMaggio Children’s Hospital recognized the lack of long-term correction of the supraorbital rim and lack of orbital symmetry when only suturectomy and a helmet are utilized for correction. Their team showed a 5-year experience with 10 patients who underwent surgical correction for nonsyndromic unicoronal synostosis with the addition of frontal and orbital rim advancement with a minimally invasive technique by using the endoscope. This surgery is conducted before 4 months of age. Three small incisions are made (near the anterior fontanelle and bilateral superior to the helix of the ear). The dissection is done in the subperiosteal plane with the temporalis muscle elevated with the scalp to reduce the risk of postoperative temporal hollowing. The endoscope provides visualization. Osteotomies are performed with a combination of Mayo scissor and the ultrasonic bone cutter where appropriate. After the synostosed suture is removed at a width of 3 cm, a linear craniotomy anterior to the contralateral coronal suture frees the attachment to the frontal bone. Additional osteotomies are performed on the affected side to allow for frontal orbital advancement. The metopic suture is used to hinge the bone segment with absorbable plates [18]. The ultrasonic bone cutter and endoscope have reduced the need for blood transfusion and limited the hospital stay to between 2 and 3 days. &
TECHNIQUE ADVANTAGES This technique has several positive points for the patients when compared with the traditional cranial vault remodeling procedures. Only one surgery is required and can be completed in an hour by experienced surgeons. There is no hardware implanted that needs to be removed or that could lead to complications. The need for a blood transfusion is not expected as the blood loss is minimal. The patient only requires up to three nights in the hospital for coronal synostosis. The procedure is tolerated by very young infants and therefore can incorporate the growing brain as an aid to achieving correction. 318
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TECHNIQUE DISADVANTAGES There is a learning curve for the use of the endoscope, and if bleeding occurs, the procedure would have to be converted to an open case. This procedure is only an option if the surgery is conducted in a narrow time frame. Thus, a subset of patients will not be eligible for this technique. There is no distracting force and as such this technique requires the external force of the helmet to be the key factor in obtaining correction in the skull shape. Because of the customized nature of the helmet and rapid skull growth in this age group, it is possible that more than one helmet will be required, which will increase the cost. The surgeon’s and infant’s success is predicated on compliance from the caregivers to keep the helmet on for the duration of the course prescribed. Many are not able or willing to have their child in a helmet as long as needed to obtain adequate correction. This technique is limited for coronal synostosis as significant advancement is often needed to obtain symmetry. The use of this technique without a postoperative helmet cannot be advised as an option for the reasons that our forefathers showed a century ago specifically for the high rate of recurrence and need for reoperation [19 ]. &
SPRING-ASSISTED CRANIOPLASTY Spring-assisted surgery was developed by Lauritzen in an effort to use the dynamic principles of distraction for continued correction over time to minimize intracranial risk and improve long-term outcomes. His first use was for a patient with turricephaly, but the benefits were quickly recognized and instituted for sagittal synostosis. In order to gain approval for use by the Food and Drug Administration (FDA) in the United States, studies with a rabbit model were conducted by David and led to FDA approval for use in infants. The concept of the spring surgery is similar to the principle involved in distraction osteogenesis shown by many in the long bones and then adapted by McCarthy [20,21] for mandibular distraction.
SAGITTAL SYNOSTOSIS In 2008, Lauritzen reported his first 100 SAS patients treated for craniosynostosis. Thirty-five of the first 100 patients were treated for sagittal synostosis. For this procedure, the patient is placed in the sphinx position. A lazy S incision is made across the midline from the anterior fontanelle to the posterior fontanelle. The entire sagittal suture is excised at a 1 cm width from the anterior fontanelle to the lambda posteriorly. The custom-fabricated stainless steel Volume 22 Number 4 August 2014
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springs are placed in the bone gap with one placed anteriorly and the other placed posteriorly with the springs bisecting in the middle. The age range for the study was 2.5–8 months, with an average time to removal of the spring being 7 months. The wire was 1.2 mm thick and 16 cm long [22]. The Wake Forest University group reported similar results of their 8-year experience for treating 90 infants with sagittal synostosis using SAS. Springs were placed at a mean age of 4.4 months and removed at a mean age of 8.8 months. The strength of the springs ranged from 5.5 to 9.5 N with a mean force of 6.9 N [23,24]. The springs used at Wake Forest are 1.28 mm thick and 15 cm long. The surgical time for both teams was dramatically lower than for cranial vault remodeling with a mean of 30 min for the Wake Forest team. The craniofacial team at the Christchurch Hospital in New Zealand showed similar successful results [25]. Over the past 3 years the endoscope has allowed a significantly smaller W-shaped incision at the midpoint with excellent anterior and posterior visualization and placement of the springs. The stainless steel springs are now commercially available. The second procedure involves percutaneous removal of the springs, and the patient is typically discharged from the recovery room.
CORONAL SYNOSTOSIS The craniofacial team in Sweden reported their experience with treating bicoronal synostosis with the use of SAS; it was done with an open approach through a bicoronal incision. For some of the cases, a combination of compressive and distracting springs was used for reshaping. Intracranial monitoring was utilized if compressive springs were utilized. A combination of osteotomies of the frontal and parietal bones was conducted with compressive forces to reduce the prominence, although springs placed in the lambdoid sutures will create expansion posteriorly while reducing the cranial height and width. The springs were removed on average 6 months later [22,26].
METOPIC SYNOSTOSIS The springs have been incorporated for treatment of metopic synostosis, although with an open approach. The patient is placed in the supine position. After the appropriate osteotomies are made through the synostosed suture, nasofrontal suture, and frontal bone, the spring is inserted into two holes positioned low in the frontal bone on either side of the metopic osteotomy. This provides gradual distraction and optimal correction [22,27,28].
A stop wire is used around the spring to prevent hypertelorism.
MULTISUTURE SYNOSTOSIS It is clear that the risk of increased intracranial pressure for infants with premature fusion of multiple sutures can be as high as 80%. It is ideal to obtain release before 1 year of life, and in severe cases, it is imperative to treat a Chiari malformation secondary to increased intracranial pressures. The traditional method of treatment before SAS was aggressive craniectomy of all the involved areas of the calvarium. With the advent of the springs, the posterior vault can be expanded by the springs within the first few months of life. As the pressure subsides, the child lays down bone into the gaps that were created by the distraction pressure. This prepares the infant for a full vault remodeling several months later when there is more stable bone available. This is commonly used with patients who have Apert and Crouzon syndrome, and the technique has been successfully done in several craniofacial centers throughout the world [22,29,30 –32 ,33]. There are requirements for instituting SAS for a single treatment modality for craniosynostosis or an adjunct to additional procedures. The bone needs to be thick enough to withstand the force of the spring. If the bone is too thin, it will break or the spring will migrate through the bone. The spring needs to be constructed with a force that is great enough to cause distraction but not so great that it bends the bone upward creating injury to the dura. Therefore, the patient’s age and bone thickness need to be taken into account. Preoperative models fashioned from a three-dimensional computed tomography (CT) scan can be helpful. There are a number of studies from several centers showing the safety and long-term efficacy of spring-mediated cranioplasty [22–29,30 –32 ,33–40]. &
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TECHNIQUE ADVANTAGES This technique has several positive points for patients when compared with the traditional cranial vault remodeling procedures. The blood loss is minimal, and no blood transfusions are usually required for single suture repair. The patient requires only one overnight stay in the hospital for placement of the springs. The second procedure for removal of the springs is a same-day procedure. The use of a molding helmet is not necessary. SAS can be incorporated as a first-line treatment for immediate release in cases of kleeblattschadel deformity or multisuture involvement, although osteogenesis occurs allowing for a better cranial vault remodeling when the
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infant is older. The endoscope can be used to further decrease the risks and scarring.
preoperative models to be fabricated whenever needed [44].
TECHNIQUE DISADVANTAGES
SUMMARY
There is a learning curve for selecting the appropriate spring strength and size, but standards have been established as guidelines and references and commercially fabricated springs are available. There is a defined time frame that this procedure can be offered to patients. There is a small risk of spring dislodgement, sagittal sinus tear [41], erosion, lack of adequate force, and lack of correction. A second surgery is required to remove the springs.
Minimally invasive surgery is becoming more possible with advanced technology, and this includes treatment for craniosynostosis. This surgery provides a technique to release the synostosis when the infant is less than a year and can remodel the cranial bone. The morbidities of the surgery are reduced with a decrease in blood loss, intensive care admission, and length of hospital stay recurrence.
CONCLUSION
Acknowledgements None.
Whitaker performed a transcontinental survey that included the time from 1968 to 1978. There were a total of 421 reported intracranial operations with a complication rate of 25.7% and a mortality rate of 2.2%. These were the pioneering years for this surgery, but showed that improvements were needed [42]. The open techniques for craniosynostosis have provided patients with successful treatments for the past 50 years. There are many advantages to these procedures, but we must continue to seek safer ways of providing care to our patients. The Internet and social media have empowered parents to be more informed about the surgical treatment options. Our challenge is to further educate parents for the treatment option that is the best for their child, by taking into account all of the factors discussed above. An initial work-up may involve several steps to prepare these patients for surgery. Consideration should be given for those children who may benefit from enrollment in the craniofacial team. Among those are patients being treated for craniofacial syndromes, multisuture involvement, or when a genetic disorder is identified. This helps provide continuity of care and support for both the patient and parents. A genetic consult should be considered when there is a familial history for craniofacial anomalies or for multisuture involvement. Ophthalmologic examination by a pediatric ophthalmologist or neuro-ophthalmologist should be obtained if there are questions about intracranial pressure, multisuture involvement, or for older children. Neurodevelopmental screening should be considered for infants with isolated craniosynostosis and is recommended for syndromic conditions or multisuture involvement [43]. Three-dimensional CT scans of the skull will confirm premature fusion, may reveal an additional suture involved, reveal an intracranial abnormality, and allow for 320
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Conflicts of interest The authors have no conflicts of interest to declare.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Virchow R. Uber den cretinismus, namentlich in Franken, und uber pathologiside Schadeelformen. Verh Phys Med Gesamle Wurzberg 1851; 2:26. 2. Warren SM, Longaker MT. The pathogenesis of craniosynostosis in the fetus. Yonsei Med J 2001; 42:646–659. 3. Warren SM, Greenwald JA, Spector JA, et al. New developments in cranial suture research. Plast Reconstr Surg 2001; 107:523–540. 4. Lane LC. Pioneer craniectomy for relief of mental imbecility due to premature sutural closure and microcephalus. JAMA 1892; 18:49–50. 5. Lannelongue J. De la craniectomie dans la microcephalie [The craniectomy in microcephaly]. CR Acad Sci 1890; 110:1382. 6. Bering E, McLaurin R, Lloyd J, et al. The production of tumors in rats by the implantation of pure polyethylene. Cancer Res 1955; 15:300. 7. McComb JG, Withers GJ, Davis RL. Cortical damage from Zenker’s solution applied to the dura mater. Neurosurgery 1981; 8:68–71. 8. Marchac D, Renier D, Broumand S. Timing of treatment for craniosynostosis and faciocraniosynostosis: a 20-year experience. Br J Plastic Surg 1994; 47:211–222. 9. Jane JA, Edgerton MT, Futrell JW, et al. Immediate correction of sagittal synostosis. J Neurosurg 1978; 49:705–710. 10. Persing JA, Babler W, Nagorsky MJ, et al. Skull expansion in experimental craniosynostosis. Plast Reconstr Surg 1986; 78:594–603. 11. Lauritzen C, Sugawara Y, Kocabalkan O, Olsson R. Spring mediated dynamic craniofacial reshaping: case report. Scand J Plast Reconstr Surg Hand Surg 1998; 32:331–338. 12. Vicari F. Endoscopic correction of sagittal craniosynostosis. Presented at the American Society of Plastic and Reconstructive Surgeons, Presymposium, San Diego, California, 1994. 13. Barone CM, Jimenez DF. Endoscopic craniectomy for early correction of craniosynostosis. Plast Reconstr Surg 1999; 104:1965–1973. 14. Jimenez DF, Barone CM. Endoscopic technique for sagittal synostosis. Childs & Nerv Syst 2012; 289:1333–1339. Describes the endoscopic technique for sagittal and coronal synostosis with the use of a molding helmet postoperatively described by the surgeons who first popularized the technique. 15. Jimenez DF, Barone CM, Cartwright CC, et al. Early management of craniosynostosis using endoscopic-assisted strip craniectomies and cranial orthotic molding therapy. Pediatrics 2002; 110:97–104. 16. Jimenez DF, Barone CM. Endoscopic technique for coronal synostosis. & Childs Nerv Syst 2012; 289:1429–1432. Describes the endoscopic technique for sagittal and coronal synostosis with the use of a molding helmet postoperatively described by the surgeons who first popularized the technique. 17. Berry-Candelario J, Ridgway EB, Grondin RT, et al. Endoscope-assisted strip craniectomy and postoperative helmet therapy for treatment of craniosynostosis. Neurosurg Focus 2011; 31:E5.
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