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The endoscopic‐assisted trephination approach for repair of frontal sinus cerebrospinal fluid leaks

2012; Wiley; Volume: 123; Issue: 2 Linguagem: Inglês

10.1002/lary.23499

1531-4995

Daniel L. Crozier, Peter H. Hwang, Parul Goyal,

Craniofacial Disorders and Treatments

Endoscopic techniques have been used extensively for the treatment of sinonasal skull base defects and resulting cerebrospinal fluid (CSF) leaks.1-4 Endoscopic surgery allows for improved visualization, high success rates, reduced morbidity, and shorter hospital stays.5 Most ethmoid and sphenoid skull base defects can be repaired endoscopically, but endoscopic repair of frontal sinus defects remains challenging.6 For that reason, many frontal sinus defects have typically been approached by way of a frontal craniotomy or frontal osteoplastic approach.7 This article describes the use of a frontal sinus trephination for the management of frontal sinus skull base defects. The trephination technique can allow direct access to most portions of the frontal sinus, allowing straightforward exposure for the treatment of many types of frontal sinus pathologies and skull base defects.8-11 A retrospective review was preformed of cases of frontal sinus CSF leaks managed using a frontal trephination approach from 2006–2011. IRB approval was obtained. In most instances, the frontal recess is explored endoscopically to determine whether the defect would be accessible using endonasal techniques alone. The external procedure is performed for extensive defects or defects that were too superior or lateral to be repaired using endonasal techniques alone. Computerized navigation is typically used to localize the defect site and identify the optimum location of frontal sinus entry. The skin incision is made along skin creases or along the brow in the area overlying the skull base defect. Subperiosteal dissection is performed and a 4 mm-cutting burr is then used to enter the sinus. The entry point is enlarged further with the drill or with Kerrison punches (Fig. 1A). (A) Intraoperative picture demonstrating incision and entry into the right frontal sinus with a 4-mm cutting burr. (B) Picture of the patient's surgical site incision closure demonstrates no forehead irregularity. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] An endoscope is then introduced through the trephination site. The repair is accomplished using techniques similar to those used for ethmoid and sphenoid defects. This includes reduction of any encephaloceles, defining the edges of the defect, and placing necessary grafting material. Graft materials typically used in our practice include septal bone and nasal floor mucosa. After satisfactory repair has been performed, the frontal sinus outflow tract is inspected for any signs of obstruction or disruption with an angled scope. The bony defect in the anterior table of the frontal sinus is inspected. Trephination sites larger than 1 cm in diameter are reconstructed to avoid frontal contour irregularities. Cranial titanium mesh is cut to the appropriate size and is secured with self-drilling screws. A meticulous closure of the skin concludes the procedure (Fig. 1B). Lumbar drains are not routinely used in our practice. A 27-year-old male presented with CSF rhinorrhea resulting from a fracture along the posterior table of the left frontal sinus, frontal recess, and ethmoid roof. The patient's rhinorrhea was found to be B2 transferrin positive. The patient was then offered surgical repair of the defect. The frontal sinus outflow tract portion of the defect was exposed using a Draf 2A approach. CT guided navigation and intrathecal fluorescein were used. The frontal sinus defect extended superiorly to the top of the frontal sinus and could not be exposed endoscopically using the Draf 2A technique (Fig. 2A–C). CSF was leaking along the entire length of the defect and the operating surgeon felt that the superior aspect of the defect would not be reachable endoscopically even if a Draf III procedure was performed. Therefore, a Draf III procedure was not performed and a frontal trephination was performed. Free mucosal grafts were used to repair both the frontal and ethmoid portions of the skull base defect. Follow-up has demonstrated no recurrent CSF leak. A CT obtained 40 months after repair shows a well-healed and aerated frontal sinus (Fig. 2D). (A) Axial CT image showing the left skull base fracture beginning in the frontal sinus outflow tract. (B) Coronal CT image following the fracture into the mid-left frontal sinus. (C) Coronal CT image revealing the superior and lateral extent of the left frontal skull base fracture. (D) Axial CT scan showing a reconstructed anterior table and functional frontal sinus three years after reconstruction of skull base defect. A 21-year-old male sustained facial fractures during a motor vehicle accident. A small fracture of the posterior frontal sinus table was managed conservatively because the patient did not have a CSF leak (Fig. 3A). The patient presented 2 years later after an episode of ascending bacterial meningitis. Imaging of the skull base revealed a defect in the right frontal sinus (Fig. 3B). An endoscopic frontal sinusotomy (Draf 2A procedure) revealed the defect, but it became evident that there was a larger area of dehiscence with additional brain herniation further superiorly in the sinus. A frontal trephination approach was used to obtain direct access to the majority of the frontal sinus for thorough exploration and exposure. Two defects were identified. A bone graft was placed intracranially and a mucosal graft was placed in the frontal sinus (Fig. 3C). The patient has not had any further clear nasal drainage or episodes of meningitis after 3 years of follow-up. (A) Axial CT image showing fractures of the right posterior frontal sinus table. (B) Coronal CT image showing a right frontal sinus skull base defect, diagnosed after a bout of meningitis. (C) Intraoperative endoscopic picture of the skull base defect repaired with septal bone and a mucosal graft in place, the arrow points to the frontal sinus outflow tract as viewed from above with an angled scope. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] A 52-year-old female presented with spontaneous clear rhinorrhea and a left middle meatal mass. CT demonstrated a large frontal sinus posterior table defect with associated frontal and ethmoid encephalocele (Fig. 4A–B). Endoscopic visualization of the middle meatus revealed a large soft tissue mass consistent with an encephalocele. After the ethmoid area was dissected, attempts were made to cauterize and reduce the herniated brain tissue. The amount of tissue was large enough that it could not be effectively cauterized and reduced back into the frontal sinus. The surgeons did not want to resect the tissue using sharp instruments from below without adequately cauterizing the encephalocele as it protruded through the skull base defect into the frontal sinus. Therefore, the trephination procedure was chosen as the safest way to cauterize and resect the encephalocele. The encephalocele was cauterized and resected through the trephination. The defect was repaired using a bone graft and a mucosal graft. Titanium mesh was used to cover the defect in the frontal sinus anterior table. There has been no recurrent CSF leak after a follow-up period of 5 years. (A) Coronal CT image showing complete opacification of the left frontal sinus due to the presence of a large encephalocele. (B) Axial CT image showing a frontal sinus posterior table defect and an opacified left frontal sinus. 5 (A) Axial CT image showing defect of posterior table of the left frontal sinus with near complete opacification. Vascular clips from previous neurosurgical procedure noted. (B) More superior axial image showing the extent of the posterior table defect. (C) Coronal CT image showing a defect in the roof of the left frontal sinus with associated pneumocephalus. A 76-year-old male had undergone a transorbital frontal craniotomy for treatment of a right intracranial aneurysm. During the surgery the posterior table of the left frontal sinus was removed for better exposure, and the dura was repaired with grafting material and tissue glue. The frontal sinus defect was occluded with bone wax. The patient developed clear rhinorrhea 2 months after surgery. A CT scan showed a left posterior frontal sinus table defect (Fig. 5A–C). Operative repair was performed using a frontal sinus trephination approach. In this case the defect was large and superior enough to justify the trephination technique as our initial surgical exposure. A large amount of bone wax was found in the sinus at the site of the defect. The defect was 2 cm in diameter. Septal bone and nasal floor mucosa were used to repair the defect. Endonasal evaluation revealed a patent frontal sinus outflow tract at the end of the operation. The patient has done well without any recurrent CSF leak at 12 month follow-up. The management of sinonasal CSF leaks has evolved significantly with the use of endoscopic surgical techniques. Endoscopic techniques allow for accurate localization, excellent visualization, and high success rates. Success rates with endoscopic repair of skull base defects have been reported to be as high as 98%.12 While the majority of the sinonasal skull base can be adequately accessed using endoscopic techniques, obtaining endoscopic access to certain portions of the frontal sinus skull base remains difficult. The narrow dimensions of the frontal recess can prevent wide endoscopic exposure of frontal sinus lumen.1 For these reasons, frontal craniotomy and frontal sinus obliteration have often been used for the management of frontal sinus skull base defects.1, 12-14 Despite the advances in endoscopic surgical techniques, even recent literature has advocated these external approaches as first-line procedures for repairing defects of the frontal sinus.6, 7, 12-14 These external techniques can have a number of disadvantages, including external incisions, extensive dissection, risk of intraoperative complications, asymmetric forehead contours, chronic pain, and risk for delayed mucocele.15-17 Extended endoscopic approaches such as the endoscopic modified Lothrop procedure have been used for the management of frontal sinus skull base defects.18 The wide exposure allowed can improve access to the medial and inferior aspects of the frontal sinus, allowing surgeons to perform endoscopic repair of frontal sinus CSF leaks in these regions. However, even an endoscopic-modified Lothrop approach may not allow adequate access to the superior and lateral portions of the frontal sinus. In a cadaveric study by Becker et al., the superior most aspect of the frontal sinus could not be reached even with a Draf 3 procedure. These authors showed that the lateral aspect of the frontal sinus can be visualized and reached with instruments simultaneously only 54% of the time.19 In addition, endonasal techniques may sometimes not allow adequate access if dural manipulation or underlay graft placement are necessary. The current article describes the use of an extended frontal sinus trephination approach for the management of frontal sinus skull base defects. While this technique requires an external incision, the morbidity is significantly less than the morbidity associated with frontal craniotomy or frontal sinus obliteration. Advantages of the technique include excellent exposure of all aspects of the frontal sinus, ability to perform a precise layered closure of the defect, and ability to maintain a functional frontal sinus. Previous reports have described the use of the frontal sinus trephination technique for the treatment of mucoceles, type IV cells, and fibrous dysplasia.10 The cases presented in this article demonstrate that the technique can be applied to defects of various sizes, locations, and etiologies. The endoscopic trephination approach is straightforward, and allows the surgeon to directly access frontal sinus defects with ease. Using the extended trephination technique, the entry into the frontal sinus is often large enough to lead to an anterior table contour irregularity if no reconstruction is performed. In each case presented, reconstruction was performed using titanium mesh. The mesh is easy to place and has not been associated with any post-operative complications. Follow-up as shown excellent cosmesis in all of the patients. The trephination is typically made in a location that optimizes access to the relevant portion of the frontal sinus. This can place the supraorbital neurovascular bundle at risk for injury. Placing the incision away from the region of the nerve and using blunt dissection can help prevent direct injury. Any postoperative forehead hypesthesia is typically temporary as long as direct injury to the neurovascular bundle is avoided. None of the patients in this series had any long term sensory deficits along the surgical sites. The cases presented in this article are used to illustrate situations in which the trephination approach was useful. The surgeons used their best judgment in determining the optimal surgical technique and felt that the trephination technique would allow the best chance of successful repair in the cases presented. Completely endonasal techniques may be preferable in many situations, and some surgeons may have chosen to perform more extensive endonasal dissection before performing any external procedures. However, the trephination technique can be useful if a surgeon is uncomfortable with extended endonasal techniques such as the Draf 3 frontal sinusotomy. In addition, experienced endoscopic surgeons may find the trephination technique to be a useful way to obtain direct access to certain portions of the frontal sinus. An important limitation of this article is that a small number of patients were treated with the techniques described. It may be difficult to generalize the findings to all patients with frontal sinus skull base defects. However, the cases presented do demonstrate that the trephination technique is useful in properly selected situations. A graduated approach can be helpful in selecting the best approach for any given frontal sinus defect. Many frontal sinus defects, especially those located inferiorly and medially in the frontal sinus, may be amenable to completely endoscopic repair using traditional frontal sinusotomy or Draf 3 frontal sinusotomy techniques. The large majority of defects not accessible using endonasal techniques can be repaired using the trephination technique outlined in this article. Patients with comminuted defects may best be managed with frontal craniotomy or frontal sinus obliteration.