Abstract
Objectives In the setting of craniotomy, complications after traversing the frontal sinus can lead to mucocele formation and frontal sinusitis. We review the etiology of frontal sinus violation, timeline to mucocele development, intraoperative management of the violated sinus, and treatment of frontal mucoceles.
Design Case series in conjunction with a literature review.
Participants A total of 35 patients were included in this meta-analysis. Nine of these patients were treated at a tertiary academic medical center between 2005 and 2014. The remaining patients were identified through a literature review for which 2,763 articles were identified, of which 4 articles met inclusion criteria.
Main Outcomes Measures Etiology of frontal violation, timeline to mucocele development, and method of management.
Results The overall interval from initial frontal sinus violation until mucocele identification was 14.5 years, with a range of 3 months to 36 years. The most common cause of mucocele formation was obstruction of the frontal recess with incomplete removal of the frontal sinus mucosa. The majority of patients were successfully managed with an endoscopic endonasal approach.
Conclusions Violation of the frontal sinus during craniotomy can result in mucocele formation as an early or late sequela. Image guidance may help avoid unnecessary frontal sinus violation. Mucoceles may develop decades after the initial frontal sinus violation, and long-term follow-up with imaging is recommended. While the endoscopic endonasal approach is usually the preferred method to treat these lesions, it may be necessary to perform obliteration or cranialization in unique situations.
Keywords: frontal sinusitis, craniotomy, mucocele, frontal sinus mucocele, craniotomy complications
Introduction
Mucoceles are benign, mucus-filled lesions covered with pseudostratified columnar epithelium. Sinonasal mucoceles usually originate secondary to blockage of the sinus drainage pathway, typically in the setting of chronic inflammation, infection, trauma, or prior surgery. 1 The frontal sinus may be violated during craniotomy with intracranial entrapment of sinus mucosa or obstruction of frontal sinus outflow due to scar formation. Signs and symptoms of a frontoethmoidal mucocele include pain, swelling, aesthetic deformity, and erosion of the surrounding bone. 2 Advanced disease can be associated with diplopia, ptosis, vision loss, meningitis, or brain abscess. While there is no universally accepted method for the management of frontal sinus mucoceles, standard practices include endoscopic marsupialization, frontal sinus obliteration, and cranialization. 3 4
This study analyzes nine patients managed at our institution with a history of frontal sinus violation after craniotomy and subsequent development of mucoceles. In addition, we performed a meta-analysis through a PubMed search using the search terms “frontal sinus mucocele,” “frontal craniotomy complication,” and “frontal sinusitis.” Based on this data, we make recommendations on how to avoid frontal sinusitis in the setting of craniotomy and manage this condition.
Materials and Methods
Patients in the case series all presented to the Thomas Jefferson University Hospital between 2005 and 2014 with a mucocele after a frontal sinus violation through a craniotomy initially performed at another institution. Surgical management was performed by our skull base team consisting of a neurosurgeon and otolaryngologist.
In addition, we performed a meta-analysis through a PubMed search using the search terms “frontal sinus mucocele,” “frontal craniotomy complication,” and “frontal sinusitis,” which yielded 2,763 articles. Of these articles, four manuscripts, consisting of 26 patients, met our inclusion criteria of examining frontal sinus mucocele formation after craniotomy ( Fig. 1 ).
Fig. 1.
Flow diagram of the literature review.
Results
Retrospective analysis revealed nine patients at our institution with a history of frontal sinus violation and subsequent mucocele formation. The average time from the initial frontal sinus violation to presentation was 14.5 years (range: 3 months to 36 years), with most patients presenting with headache symptoms. All of the mucoceles were successfully addressed through an endoscopic endonasal approach, except in one patient who developed lateral orbital and frontal bone osteomyelitis and subdural empyema that required craniotomy for debridement and frontal sinus repair ( Fig. 2 ). This patient had previously undergone an “eyebrow” approach craniotomy with a violation of the anterior and posterior lateral walls of the frontal sinus with titanium reconstruction of the anterior wall.
Fig. 2.
(A) Computed tomography (CT) demonstrating violation of the anterior and posterior walls of the frontal sinus with lateral sinusitis. (B) Obstruction of the right frontal recess. (C) Delayed magnetic resonance imaging (MRI) demonstrating worsening frontal sinusitis with leptomeningeal enhancement. (D) Subdural restricted diffusion indicative of empyema.
Review of the literature yielded four articles, with a combined total of 26 patients who met the inclusion criteria of our meta-analysis. Indications for the initial craniotomy were skull base tumors, aneurysm, craniofacial deformity, and arteriovenous malformation. Patients with chronic rhinosinusitis or those who initially underwent surgery for frontal sinusitis were excluded. The average time from craniotomy to mucocele presentation for these four articles was 13.9 years (range: 0.3–35 years). Yoshioka 5 reported on six patients, with an average time from craniotomy to presentation of 20.7 years. Meetze et al 6 reported their finding of delayed frontal sinus mucocele formation in six patients, with an interval of 14.8 years. Chandra et al 7 reviewed a series of patients who underwent a frontal sinus obliteration after craniotomy, developing mucoceles 10.5 years later. Schramm and Maroon 8 also reported six cases of mucocele formation after craniotomy at an average interval of 5.6 years.
The overall average time interval between frontal sinus violation and frontal sinus mucocele presentation for this meta-analysis was 14.5 years, with a range of 3 months to 36 years ( Tables 1 and 2 ).
Table 1. Meta-analysis of cases reviewed from the Jefferson experience, as well as Yoshioka, Chandra et al, Schramm and Maroon, and Meetze et al.
| Case | Indication for craniotomy | Treatment of frontal sinus violation following craniotomy | Age, Sex | Years from craniotomy | Presenting symptoms | Recurrence | Follow-up period (months) | Management of frontal sinus pathology | |
|---|---|---|---|---|---|---|---|---|---|
| Jefferson experience | 1 | Crouzon's syndrome | None | 58, F | 36 | Eye swelling, headache | No | 22 | Endoscopic marsupialization |
| 2 | Osteoma | None | 72, F | 20 | Forehead swelling, nasal discharge | No | 8 | Endoscopic marsupialization | |
| 3 | Brain abscess | Cranialization | 48, M | 20 | Postnasal drip, headache | No | 6 | Endoscopic marsupialization | |
| 4 | Unknown | None | 55, M | 11 | Eye and eyelid swelling | Yes | 5 | Endoscopic marsupialization | |
| 5 | Mucopyocele | Cranialization | 71, F | 6 | Headache and facial pain | Yes | 73 | Endoscopic marsupialization | |
| 6 | Optic nerve tumor | None | 71, F | 3 | Periorbital pain, vertigo | Yes | 21 | Endoscopic marsupialization | |
| 7 | Meningioma | Cranialization | 38, M | 7 | Periorbital cellulitis, frontal sinusitis | No | 24 | Endoscopic marsupialization | |
| 8 | Frontal sinus fracture | Cranialization | 36, M | 3 | Headache and frontal sinusitis | No | Endoscopic marsupialization | ||
| 9 | Frontal sinus fracture | None | 53, M | 30 | Proptosis and progressive loss of vision | No | 1 | Endoscopic marsupialization | |
| Yoshioka, 2014 | 10 | Brain tumor | Cranialization with methyl methacrylate | 47, F | 12 | Forehead swelling and mucopyocele | No | 60 | Cranialization with staged cranioplasty with hydroxyapatite |
| 11 | Brain tumor | Unknown | 48, M | 21 | Purulent discharge from a forehead fistula | No | 48 | Cranialization with staged cranioplasty with hydroxyapatite | |
| 12 | Brain tumor | Obliteration with methyl methacrylate | 58, F | 20 | Purulent discharge from a forehead fistula | No | 40 | Cranialization with staged cranioplasty with hydroxyapatite | |
| 13 | Subarachnoid hemorrhage | Unknown | 77, M | 25 | Purulent discharge from a forehead fistula | No | 17 | Cranialization with staged cranioplasty with hydroxyapatite | |
| 14 | Subarachnoid hemorrhage | Unknown | 66, F | 20 | Purulent discharge from a forehead fistula |
No | 14 | Cranialization with staged cranioplasty with hydroxyapatite | |
| 15 | Subarachnoid hemorrhage | Unknown | 61, M | 26 | Purulent discharge from a forehead fistula | No | 12 | Cranialization with staged cranioplasty with hydroxyapatite | |
| 16 | Frontal sinus fracture | Obliteration with methyl methacrylate | 43, M | 25 | Purulent discharge from a forehead fistula | No | 50 | Cranialization with staged cranioplasty with hydroxyapatite | |
| 17 | Frontal sinus fracture | Obliteration with methyl methacrylate | 71, M | 35 | Purulent discharge from a forehead fistula | No | 43 | Cranialization with staged cranioplasty with hydroxyapatite | |
| Chandra et al, 2004 | 18 | Mucocele | Fat obliteration | 75, M | 10 | – | Yes | 31 | Endoscopic marsupialization |
| 19 | Sarcoid | Fat obliteration | 34, M | 7 | – | No | 10 | Endoscopic marsupialization | |
| 20 | Aneurysm | Fat obliteration | 47, M | 20 | – | Yes | 23 | Endoscopic marsupialization | |
| 21 | Arteriovenous malformation | Fat obliteration | 65, F | 19 | – | No | 7 | Endoscopic marsupialization | |
| 22 | Osteoma | Fat obliteration | 43, F | 17 | – | No | 5 | Endoscopic marsupialization | |
| 23 | Frontal sinus fracture | Fat obliteration with bone cement | 61, M | 0.4 | Frontal mucocele and proptosis | No | 21 | Endoscopic marsupialization | |
| 24 | Frontal sinus fracture | Fat obliteration | 39, M | 0.3 | Persistent headaches and sinus infections | No | 8 | Endoscopic marsupialization | |
| Schramm and Maroon, 1979 | 25 | Aneurysm | None | 42, M | 2 | Headaches, frontal swelling, and cellulitis with mucopyocele | No | – | Fat obliteration |
| 26 | Pituitary tumor | None | 47, M | 3 | Headache and mucopyocele | Yes | – | Fat obliteration | |
| 27 | Aneurysm | None | 44, M | 4 | Frontal swelling and pain | Yes | 36 | Fat obliteration | |
| 28 | Frontal sinus fracture | None | 48, M | 2 | Cellulitis of orbit and frontal mucopyocele | No | 24 | Fat obliteration | |
| 29 | Aneurysm | None | 26, M | 3 | Frontal swelling with mucopyocele | Yes | 24 | Incision and drainage with washout | |
| 30 | Frontal sinus fracture | None | 42, M | 20 | Orbitofrontal mucocele and osteomyelitis with headaches and pain | No | 24 | staged cranioplasty with frontal exenteration | |
| Meetze et al, 2004 | Case | Indications for craniotomy | Management of frontal sinus following craniotomy a | Average Age | Average time from craniotomy | Presenting symptoms | Recurrence | Average time for follow up (months) | Management of frontal sinus pathology |
| 31 | Brain tumor | Unknown | 31.3 | 14.8 | Headaches, frontal edema, and cellulitis | No | 27 | Endoscopic marsupialization with possible combined trephine | |
| 32 | Brain tumor | Unknown | |||||||
| 33 | Arteriovenous malformation | Cranialization | |||||||
| 34 | Aneurysm | Fat obliteration | |||||||
| 35 | Craniofacial deformity | Bone obliteration |
Items in this column do not correspond precisely with the respective indications for craniotomy in the previous column. This information was not evident in the source article.
Abbreviations: F, female; M, male.
Table 2. Summary of Table 1 .
| Indications for Craniotomy | Total number of patients | Management of frontal sinus following Craniotomy | Total number of males | Total number of females | Average age (years) | Average time from frontal violation until complication (years) | Average time for follow-up (months) | ||
|---|---|---|---|---|---|---|---|---|---|
| Frontal sinus fracture | 8 | 35 | None | 11 | 23 | 12 | 42.1 | 14.5 | 24.4 |
| Aneurysm | 5 | ||||||||
| Brain tumor | 5 | Fat obliteration | 8 | ||||||
| Subarachnoid hemorrhage | 3 | Unknown | 6 | ||||||
| Arteriovenous malformation | 2 | Cranialization | 5 | ||||||
| Craniofacial deformity | 2 | Obliteration with methyl methacrylate | 3 | ||||||
| Mucopyocele | 2 | ||||||||
| Osteoma | 2 | Cranialization with methyl methacrylate | 1 | ||||||
| Brain abscess | 1 | ||||||||
| Optic nerve tumor | 1 | ||||||||
| Meningioma | 1 | Bone obliteration | 1 | ||||||
| Pituitary tumor | 1 | ||||||||
| Sarcoid | 1 | ||||||||
| Unknown | 1 | ||||||||
Discussion
Frontal sinus mucoceles arise from a variety of etiologies, with frontal sinus traumatic fracture or sinus violation during craniotomy representing two precipitating factors. The incidence of inadvertent frontal sinus violation during a craniotomy and optimal means of managing such violations remains uncertain. Careful long-term follow-up is necessary, as complications are typically significantly delayed.
Mucocele formation can occur in the early postoperative period or decades later as our results demonstrate a range of 3 months to 36 years (mean: 14.5 years). The best way to prevent frontal sinus mucocele formation is to avoid entering the frontal sinus when performing a craniotomy. In the age of image guidance, the surgeon can better delineate the anatomical boundaries of the frontal sinus and avoid this structure when possible. However, when the frontal sinus is disrupted, either purposefully or inadvertently, outflow obstruction of the frontal sinus must be avoided unless the entirety of the frontal sinus mucosa has been exenterated. Yoshioka 5 identified that each of his revision procedures for delayed mucocele formation occurred when the frontal recess had been “plugged” at the time of initial surgery with incomplete removal of the frontal sinus mucosa. He recommended management with complete cranialization of the frontal sinus and mucosal exenteration followed by frontal sinus recess obliteration. Failure to fully obliterate the frontal sinus recesses allows for direct communication between the sinus and intracranial cavity potentially, leading to postoperative pneumocephalus and infection ( Fig. 3 ).
Fig. 3.
(A) Postoperative computed tomography (CT) demonstrating incomplete frontal recess obliteration with persistent aeration of the frontal sinus. (B) CT showing resultant tension pneumocephalus.
In the setting of limited frontal sinus bony violation without significant mucosal disruption, extensive cranialization and exenteration of the mucosa is likely not necessary as the drainage pathway for the mucous secretion from the frontal sinus remains undisturbed. When the mucosa has been disrupted, careful reconstruction of the frontal sinus cavity will generally prevent long-term intracranial mucocele formation as long as the frontal outflow tract remains undisturbed. A vascularized pericranial graft represents the ideal reconstruction material for a cranialized frontal sinus, although this material is not always available or viable at the time of closure. Reconstruction with hydroxyapatite or bone cement should be avoided as these materials have been associated with high rates of infection when employed in the region of the sinuses. Furthermore, the patient may require an endoscopic procedure to reestablish a functional frontal outflow tract, and these materials are difficult to remove. After significant frontal sinus violation, we prefer cranialization as opposed to obliteration in most situations. In the case of obliteration, we find that complete removal of sinus mucosa is difficult, and retained mucosa may lead to mucocele formation. Moreover, surveillance and treatment of an obliterated frontal sinus are challenging.
There are a variety of options for the management of frontal sinus mucoceles. Most contemporary surgeons consider marsupialization through an endoscopic endonasal approach to be the procedure of choice as it has the least morbidity ( Fig. 4 ). 4 In Courson et al's meta-analysis of patients with frontal sinus mucoceles, patients were successfully treated with an endoscopic endonasal approach with equal efficacy and decreased morbidity as compared with open craniotomy. Our experience echoes the results of Meetze et al, as we were also able to effectively treat nearly all patients through an endoscopic approach. The endoscopic endonasal approach may be precluded if the mucocele is too far lateral above the orbit or if the frontal sinus has been obliterated by material that cannot be easily removed through the nose. Additionally, an endoscopic approach is contraindicated if there is neurologic tissue obstructing instrumentation of the frontal sinus or in the setting of brain abscess or epidural/subdural empyema.
Fig. 4.
Right frontal sinus mucocele treated through an endoscopic endonasal approach. (A) Coronal computed tomography (CT) sinus. (B) T1 postcontrast coronal magnetic resonance imaging (MRI) of the brain. (C) Axial CT of the sinus.
Mucoceles may develop decades after the initial frontal sinus violation. Our meta-analysis identified that the average time to presentation was 14.5 years, with a range of 3 months to 36 years. It would be reasonable to perform imaging, either a computed tomography (CT) or magnetic resonance imaging (MRI) scan, in the first few years, which may be obtained as part of routine surveillance for the initial intracranial lesion. Delayed imaging at 5 to 15 years with a CT or MRI would seem prudent to identify late mucocele formation. The proposed method of surveillance parallels the recommendations for surveillance of frontal sinus fracture repair. 9 10 11 Furthermore, follow-up with an otolaryngologist to perform nasal endoscopy and review imaging may help prevent complications from mucocele formation, such as orbital and intracranial infections.
Conclusion
Violation of the frontal sinus, through either craniotomy or fracture, can result in a mucocele as an early or late sequela. Image guidance may help avoid unnecessary frontal sinus violation during a craniotomy. Mucoceles may develop decades after the initial frontal sinus violation, and long-term follow-up with imaging and an otolaryngologist is recommended to care for these patients. While the endoscopic endonasal approach is usually the preferred method to treat these lesions, it may be necessary to perform obliteration or cranialization in unique situations.
Footnotes
Conflict of Interest None.
References
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