Frontal sinus cranialization
Cranialization refers to the removal of the posterior table of the frontal sinus with occlusion of the inlet into the frontonasal ducts and allowing the neural structures, mainly frontal lobes of the brain and the intact dura, to move directly posterior to the anterior table of the frontal bone 1).
Frontal sinus cranialization with closure via bifrontal pericranial flaps is the gold standard for separating the nasofrontal recess from the intracranial cavity for posterior table defects. Despite the high success rate, cerebrospinal fluid (CSF) leak may persist and is particularly challenging when vascularized reconstructive options from the bicoronal incision are exhausted.
For appropriately selected patients with extensive frontal injuries, cranialization is a procedure that provides an excellent margin of long-term safety and a satisfactory esthetic outcome. Individual surgeons will continue to differ at times as to the appropriate management of a particular frontal injury. Nevertheless, for the most severe of these, cranialization continues to be the definitive treatment 2).
In the case series of Donath and Sindwani indications included extensive frontal sinus fractures involving the posterior table (78.9%), mucocele (10.5%), arteriovenous malformation (5.3%), and frontal bone osteomyelitis (5.3%). 3).
For Calis et al. it seems that isolated anterior table fractures with a maximum amount of displacement of less than 4.5 mm can be treated conservatively without leading to contour deformities. CSF leakage in the acute setting might not always require cranialization and this may spontaneously resolve within 10 days. Cranialization should be considered whenever CSF leakage lasts longer than 10 days 4).
For Echo et al. the first step in assessing frontal sinus fractures involves the assessment of the posterior table of the frontal sinus and determining the need for cranialization. Criteria for cranialization include severe posterior table fracture, CSF leak greater than 1 to 2 weeks, or in any situation where a craniotomy is otherwise indicated. Any patient who meets these criteria would undergo a cranialization of the frontal sinus, obliteration of the nasofrontal outflow tracts, and reconstruction of the anterior table 5).
Using a pedicle vascularized pericranial flap as an extra layer and an autologous fence above the dura adds more protection to the brain. This flap may reduce the risk of CSF leak and perioperative infections and improve the overall results. Yet, more prospective and randomized trials are recommended 6).
Cranialization of the frontal sinus appears to be a good option for the prevention of secondary mucocele development after open excision of benign frontal sinus lesions 7).
A retrospective review of 3 patients (all male; ages 42, 43, and 69 yr) with persistent CSF leak despite frontal sinus cranialization and repair with bifrontal pericranium was performed. Etiology of injury was traumatic in 2 patients and iatrogenic in 1 patient after anaplastic meningioma treatment. To create space for the flap and repair the nasofrontal ducts, endoscopic Draf III (Case 1, 3) or Draf IIb left frontal sinusotomy (Case 2) was performed. The forearm flap was harvested, passed through a Caldwell-Luc exposure, and placed within the Draf frontal sinustomy. The flap vessels were tunneled to the left neck and anastomosed to the facial vessels by the mandibular notch.
Intraoperatively, the flaps were well-seated and provided a watertight seal. Postoperative hospital courses were uncomplicated. There were no new CSF leaks or flap necrosis at 12, 14, and 16 mo.
Endoscopic endonasal free flap reconstruction through a Draf procedure is a novel viable option for persistent CSF leak after failed frontal sinus cranialization 8).
Soto et al. presented the outcome data from 28 cases of frontal sinus trauma due to gunshot wounds. There was a statistically significant difference (P = 0.049) in the type reconstructive strategy employed with each type of flap, with pericranial flaps primarily used in cranialization, temporal grafts were more likely to be used in obliteration, and free flaps were more likely to be used in cranialization. The overall major complication rate was 52% (P = 0.248), with the most common acute major complication being cerebrospinal fluid leak (39%) and the major chronic was an abscess (23.5%).
This report explores the management of frontal sinus trauma and presents short-term outcomes of treatment for penetrating gunshot wounds at a tertiary referral center 9).
Shin et al. suggested a combination flap of galea and reverse temporalis muscle as a method for reconstruction of huge skull base defect.
From 2016 to 2019, a retrospective review was conducted, assessing 7 patients with bone defect which is not just opening of frontal sinus but extends to frontal sinus and cribriform plate. Reconstructions were done by combination of galeal flap and reverse temporalis muscle flap transposition.
Defects were caused by nasal cavity tumor with intracranial extension or brain tumor with nasal cavity extension. There was no major complication in every case. During the follow up period, no patient had signs of complication such as ascending infection, herniation and CSF rhinorrhea. Postoperative radiologic images of all patients that were taken at least 6 months after the surgery showed that flaps maintained the lining and the volume well.
Conventional reconstruction of skull base defect with galeal flap is not effective enough to cover the large sized defect. In conclusion, galeal flap in combination with reverse temporalis muscle flap can effectively block the communication of nasal cavity and intracranium 10).
19 patients underwent (bilateral) frontal sinus cranialization with the pericranial flap between 2000 and 2005. Indications included extensive frontal sinus fractures involving the posterior table (78.9%), mucocele (10.5%), arteriovenous malformation (5.3%), and frontal bone osteomyelitis (5.3%). There were no intraoperative complications. A postoperative cerebrospinal fluid leak occurred in one patient with extensive skull base injuries. This was repaired endoscopically. Follow-up ranged from 9 to 55 months.
The pericranial flap is easily harvested and versatile. Using this vascularized tissue during cranialization affords added protection by providing an extra barrier between the intracranial cavity and the frontal bone and sinonasal tract. This technique is inexpensive, safe, and effective and should be considered when cranialization of the frontal sinus is performed 11).
A 47-year-old man with adenoid cystic carcinoma who underwent secondary reconstruction of the frontal bone with a split-iliac crest bone flap based on the deep circumflex iliac artery. The patient’s course following an initial ablative procedure was complicated by recurrent periorbital cellulitis, radiation, and eventual recurrence of the malignancy. Reconstructive requirements included restoration of the superior orbital rim, cranialization of the frontal sinus, and reconstruction of a sizeable frontal bone defect. In this setting, the iliac crest served as an excellent reconstructive option owing to its natural curvature and large surface area. The split-iliac crest deep circumflex iliac artery bone flap offers a robust and valuable reconstructive option for calvarial defects in hostile surgical fields 12).