In this article, the historical context and current application of external frontal sinus procedures are discussed. In particular, the frontal trephine, frontoethmoidectomy, and osteoplastic flap are described.
Key points
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External frontal sinus surgery primarily involves 3 different surgical procedures: frontal trephination, external frontoethmoidectomy, and osteoplastic flap.
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Preserve or improve drainage from frontal sinus by maintaining patency of the frontal drainage pathway.
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Attain long-term success for obliteration or cranialization of the sinuses, if necessary.
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Achieve an aesthetic outcome by preserving the natural contour of the forehead, nose, and orbit as well as minimizing scar formation.
Preoperative planning and preparation
A thorough history and physical examination of patients is an important step in preoperative planning. The history should include chronicity, frequency, severity, and progression of symptoms. Because frontal sinusitis often occurs in the setting of acute or chronic rhinosinusitis, and may be exacerbated by allergic rhinitis or other types of rhinitis, it is prudent to inquire about any history of allergies or medications, including antibiotics, steroids, or immunomodulators. Any previous medical treatments or surgeries should be explored, and any history of trauma should be discussed. Attention should be paid to signs of possible orbital or intracranial complications, including changes in vision, neck stiffness, and headache.
On physical examination, vitals and a basic head and neck examination is expected. Attention should be directed toward any signs of ocular or intracranial involvement including cellulitis, erosion of the frontal bone (Pott puffy tumor), previous surgery, or scars. For example, decrease in visual acuity, gaze palsies, meningeal signs, changes in cranial nerve function, or changes in mental status should raise suspicion for complications of frontal sinus disease. Nasal endoscopy is a helpful and, arguably, required part of the physical examination. This procedure is important for possibly obtaining cultures and looking for anatomic abnormalities or previous surgery, signs of polyps, or other masses.
Laboratory testing is certainly a helpful adjunct to the evaluation of patients. A complete blood count can reveal an abnormal white count or a left shift, and a basic metabolic panel can detect electrolyte abnormalities or dehydration. If patients are likely to need an operative procedure, a coagulation panel (prothrombin time, partial thromboplastin time) may be helpful. Allergy testing or immunologic tests may be helpful in the outpatient setting to detect allergens or immunodeficiencies but is unlikely to be helpful in the acute setting. Nasal cultures, when collected successfully, are important for guiding antibiotic therapy; cerebrospinal fluid (CSF) or blood cultures are certainly recommended if patients show signs of altered mental status or sepsis.
A variety of radiographic tools are available. The most basic tool is a radiograph of the sinuses. This radiograph may show the general anatomy of the sinuses. If an osteoplastic flap is planned, the 6-foot occipitofrontal (Caldwell) view may be useful. At present, most physicians would order a computed tomography (CT) of the paranasal sinuses as the first step. This modality provides the most information about bony anatomy, opacification, or air-fluid levels in each of the sinuses. If obtained with contrast, it can also detect abscesses or fluid collections. MRI will provide soft tissue information but is usually not the first modality to be obtained unless there is a contraindication to CT scan. Both CT and MRI may also be accessed for surgical navigation.
Preoperative planning and preparation
A thorough history and physical examination of patients is an important step in preoperative planning. The history should include chronicity, frequency, severity, and progression of symptoms. Because frontal sinusitis often occurs in the setting of acute or chronic rhinosinusitis, and may be exacerbated by allergic rhinitis or other types of rhinitis, it is prudent to inquire about any history of allergies or medications, including antibiotics, steroids, or immunomodulators. Any previous medical treatments or surgeries should be explored, and any history of trauma should be discussed. Attention should be paid to signs of possible orbital or intracranial complications, including changes in vision, neck stiffness, and headache.
On physical examination, vitals and a basic head and neck examination is expected. Attention should be directed toward any signs of ocular or intracranial involvement including cellulitis, erosion of the frontal bone (Pott puffy tumor), previous surgery, or scars. For example, decrease in visual acuity, gaze palsies, meningeal signs, changes in cranial nerve function, or changes in mental status should raise suspicion for complications of frontal sinus disease. Nasal endoscopy is a helpful and, arguably, required part of the physical examination. This procedure is important for possibly obtaining cultures and looking for anatomic abnormalities or previous surgery, signs of polyps, or other masses.
Laboratory testing is certainly a helpful adjunct to the evaluation of patients. A complete blood count can reveal an abnormal white count or a left shift, and a basic metabolic panel can detect electrolyte abnormalities or dehydration. If patients are likely to need an operative procedure, a coagulation panel (prothrombin time, partial thromboplastin time) may be helpful. Allergy testing or immunologic tests may be helpful in the outpatient setting to detect allergens or immunodeficiencies but is unlikely to be helpful in the acute setting. Nasal cultures, when collected successfully, are important for guiding antibiotic therapy; cerebrospinal fluid (CSF) or blood cultures are certainly recommended if patients show signs of altered mental status or sepsis.
A variety of radiographic tools are available. The most basic tool is a radiograph of the sinuses. This radiograph may show the general anatomy of the sinuses. If an osteoplastic flap is planned, the 6-foot occipitofrontal (Caldwell) view may be useful. At present, most physicians would order a computed tomography (CT) of the paranasal sinuses as the first step. This modality provides the most information about bony anatomy, opacification, or air-fluid levels in each of the sinuses. If obtained with contrast, it can also detect abscesses or fluid collections. MRI will provide soft tissue information but is usually not the first modality to be obtained unless there is a contraindication to CT scan. Both CT and MRI may also be accessed for surgical navigation.
Patient positioning
For any external approach to the frontal sinus, whether or not endoscopic technique is also anticipated, patients should be placed in the supine position. Turning 90° to 180° can facilitate surgical navigation or the coronal approach. In some cases, if the neurosurgical team is involved or if surgical navigation headset interferes with the surgical approach, the patients’ head may be secured with a Mayfield skull clamp, which can also be registered to image guidance technologies.
Procedural approach
Before the surgical procedure, the surgeon must optimize the operative conditions to minimize complications.
When approaching the frontal sinus externally, eye protection is essential. This protection can be done via a tarsorrhaphy, corneal shield, or taping the eyes closed with adhesive tape.
Decongestion of the nasal mucosa can help facilitate the visualization and opening of the frontal sinus outflow tract. If the endoscopic approach is also anticipated, decongestion of the nose with oxymetazoline or epinephrine can help with visualization and hemostasis.
Local anesthetic can be used in combination with epinephrine along the incision line and along the dissection plane to improve hemostasis and for patient comfort, particularly if the nature of the patients’ situation permits or requires that procedure be performed without general anesthesia.
If preferred, surgical navigation may be used in conjunction with these procedures, although it is not required.
External frontal sinus surgery
Introduction
Technological advances have made the endonasal approach the dominant method of frontal sinus surgery, eclipsing the more aggressive external procedures. However, they all have a specific role in contemporary rhinologic surgery. The 6 procedures described in this article are linked with endonasal surgery and use endoscopes adjunctively. Clinical experience over a century has refined them with regard to indications, clinical efficacy, and cosmetic result. Increasing uses of frontal trephination has expanded the role of endoscopic frontal sinusotomy in the management of chronic inflammatory disease and is essential for control of acute suppuration. The external frontoethmoidectomy is essentially a transorbital approach that can be used selectively for frontal, ethmoid, skull base, or orbital disease. It is indispensable for control of orbital infections and hemorrhages. In select cases it can be used in place of an osteoplastic flap. The frontal osteoplastic flap is the most invasive procedure and is reserved for inflammatory disease that has failed intranasal and external procedures; it is also used for disease processes of the frontal sinus that cannot be accessed or completely removed transnasally. It must be remembered that although chronic sinusitis is the most common condition treated, the frontal sinus is the host of diverse lesions, including mucoceles, allergic fungal sinusitis, osteomyelitis, as well as neoplasms, pneumatoceles, encephaloceles, and traumatic injuries. Accordingly, in undertaking the treatment of frontal sinus disease, one must make concessions: first that one procedure or approach cannot treat all diseases and second that there is a subset of patients who defy long-term cure.
Even the most experienced endoscopic surgeons retain them in the surgical armamentarium for the complete treatment of frontal sinus disease. As an example, Hahn and colleagues reported that of 717 procedures in 683 patients done for inflammatory disease, in the period from 2004 to 2008, at the University of Pennsylvania, 5.3% underwent external procedures, consisting of 24 osteoplastic flaps and 14 trephines. These procedures were most often used when the frontal recess was stenosed by osteoneogenesis from previous surgeries.
Frontal trephine
Introduction
The frontal trephine had its origin as a direct method of evacuating purulent material from an acutely infected sinus or one with chronic infection and osteomyelitis. With the shift from external to endoscopic surgery for the management of frontal sinus disease, it became apparent that the purely transnasal approach could not completely address the complex anatomy and diverse pathology of the frontal sinus. The frontal trephine now serves as a secondary tool, expanding the scope and treatment of cases previously requiring an osteoplastic flap.
Its present reincarnation is called mini-trephination and uses endoscopic visualization and instruments. Even the most experienced endoscopic surgeons recognize its value in managing difficult primary and revision cases. Seiberling and colleagues reported that 188 trephinations were made during 80 modified Lothrop procedures and 108 frontal sinusotomies over an 8-year period at the University of Adelaide, South Australia with a complication rate of 5.4%. In their series, indications included extensive polyposis, fungal sinusitis, aberrant ethmoid air cells, or a stenosed outflow tract. The combined use has been referred to as the above-and-below approach.
History
In 1884, Ogston published the first external approach to the frontal sinus in which he performed a trephine through the anterior table and created a drainage pathway into the nose through the anterior ethmoid air cells. Luc performed a similar procedure in 1896. The procedure is reminiscent of what is done today for an acute frontal sinusitis whereby the purulent secretions are evacuated externally and an endonasal drainage pathway is created.
Indications
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Acute frontal sinusitis: Acute sinusitis with an air-fluid level within the frontal sinus is a major indication, especially when there is radiographic evidence of dural enhancement or suggestion of an epidural abscess ( Fig. 1 ). Intense nasal congestion may preclude safe intranasal drainage and a patent sinusotomy by endoscopic surgery alone.
Fig. 1
Axial ( A ) and coronal ( B ) CT with subgaleal and epidural abscess secondary to frontal sinusitis.
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Chronic frontal sinusitis or frontal osteomyelitis: Chronic sinusitis with an air-fluid level that has not responded to medical therapy and endoscopic surgery is especially difficult to access; trephination is helpful if orbital or intracranial ( Fig. 2 ).
Fig. 2
Frontal sinus with dense secretions aspirated through trephine.
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Biopsy of frontal sinus lesions: Trephination provides a direct route for biopsy of lesions within the frontal sinus that are not accessible with an endonasal approach.
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Repair of frontal sinus fractures: Depressed fractures of the anterior table can be elevated through a trephine with a curved clamp or sound, with placement of a balloon catheter inside the sinus if the fracture segments are unstable ( Fig. 3 ).
Fig. 3
( A ) Anterior table fracture reduced through trephine and ( B ) stabilized with balloon catheter.
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Expanding the scope of endoscopic frontal sinusotomy:
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It facilitates the opening and removal of agger nasi cells and type III and IV frontal cells that extend into the frontal sinus ( Fig. 4 ).
Fig. 4
Type IV cell in left frontal sinus.
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It facilitates the drainage of an infected interseptal frontal air cell.
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It can be used for frontal sinus septectomy to drain a sinus with an obstructive outflow tract into the normal unobstructed side.
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With a developmentally narrow outflow tract or one that is contracted by osteoneogenesis or fibrosis, placement of contrast materials and retrograde cannulation into the nose can be performed with a malleable probe, permitting safe creation of a Draf IIb procedure.
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It can provide access laterally to facilitate endoscopic frontal sinusotomy drainage of a sequestered lateral supraorbital ethmoid or septated frontal sinus mucocele.
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Other subsidiary uses are to facilitate management of nasal polyposis, for postoperative irrigation after frontal sinusotomy ( Fig. 5 ), and to facilitate stent placement ( Fig. 6 ).
Fig. 5
Frontal trephine with irrigating tube in place.
Fig. 6
Polymeric silicone tube placement through trephine after complete endoscopic sinusotomy.
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Technique
In the preantibiotic era, opening into a chronically infected frontal sinus was through the floor of the sinus, not only because it was the thinnest wall but it also lacked diploe through which infection could spread. Over the years, this technique has been preserved for the indications listed previously. It can be safely performed through a 1.5-cm opening at, or slightly anterior, to the medial aspect of the eyebrow. An incision is made down to the periosteum, and hemostasis is achieved with bipolar cautery. After the periosteum is incised and elevated, an opening is made with a 4-mm cutting burr at the junction of the medial and superior orbital walls, at the anterior border of the supraorbital ridge. The bone is thinned to a blue lining through which the sinus can be visualized and safely opened; enlargement with Kerrison-type punches is performed depending on the size of the opening required. After the sinus contents are aspirated and cultured, an endoscope can be inserted to visualize all the recesses of the sinus. If a trephine is performed for infection, a thin rubber catheter can be inserted for drainage and irrigation. The incision is then closed with 4-0 deep absorbable sutures and a continuous 6-0 nylon or polypropylene suture for the skin.
Complications
Careful evaluation of a multi-planar CT scan is essential to evaluate the depth of the sinus and location of the intersinus septum to avoid misplacement of the trephine opening. The position of the incision should not be within the eyebrow as an area of alopecia may develop. Careful layered closure should produce an imperceptible incision line. The trephine should be placed at the medial-most portion of the supraorbital ridge, as placement further laterally may injure the supratrochlear or supraorbital nerves with regional paresthesias. Misplacement laterally can also cause injury to the trochlea with diplopia developing from disturbance of the superior oblique muscle ( Fig. 7 ).
External frontoethmoidectomy
Introduction
The keystone to the management of inflammatory frontal sinus disease is restoration of its outflow tract. Technological advances in instrumentation, imaging, and navigational devices have led endonasal endoscopic surgery to be the preferred method to accomplish this. Nevertheless, frontal sinus anatomy, postoperative healing, and the type and extent of disease do not permit an endoscopic technique universally. The role of external surgery has been shifted to be an adjunct to endonasal procedures because of the limitations cited earlier. Moreover, it is the principal method of addressing the orbital and intracranial complications of sinus disease and may serve as an alternative to osteoplastic flap for the management of tumors, mucoceles, and fungal sinusitis.
The term external frontoethmoidectomy is being used generically for the operative management of orbital, skull base, ethmoid, and frontal disease, selectively or collectively, through a transfacial approach. In all applications, it is necessary to know the precise anatomy of the medial orbit and its relationship to the adjacent paranasal sinuses. The key structures to be recognized are the medial canthal ligament, the lacrimal sac and fossa, the ethmoidal blood vessels, and the trochlea. Frontal sinusotomy, ethmoidectomy, and orbitotomy can be performed without disruption of the nasofrontal duct, depending on the pathology.
History
Jansen in 1902, and Ritter in 1906, reported a transorbital approach to the frontal sinus by removing the ethmoid sinuses and creating a common cavity into the nasal cavity. In 1908, Knapp essentially described the external frontoethmoidectomy in its present form. An excision under the eyebrow was carried to the lateral side of the nose between the mid dorsum and medial canthus. The periosteum was elevated and the lacrimal sac was displaced, permitting removal of the floor of the frontal sinus and the ethmoid labyrinth, with placement of a drainage tube into the nose. A study of 100 skulls demonstrated the anatomy of the trochlea and that by re-apposition of the periosteum its normal position could be maintained without the development of diplopia. In 1921, Lynch reported his results with 15 operations in the United States and Howarth with more than 200 cases in England. Paradoxically, Lynch gained eponymic fame for devising the procedure, and the classic contribution of Knapp is generally overlooked. Lynch removed the floor of the frontal sinus, stripped all the mucosa, and drained the frontal sinuses. Howarth removed the entire floor of the frontal sinus, retained the mucosa, and performed a complete ethmoidectomy. Both surgeons used rubber tube drainage into the nose.
Indications
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Chronic frontal sinusitis: The management of chronic frontal sinusitis has undergone a massive paradigm shift from open to endonasal surgery. In addition to technological advances and better understanding of the pathophysiology, new procedures have been devised to enlarge the frontal sinus outflow tract to compensate for postoperative narrowing. These procedures have been notably the work of Draf and include unilateral outflow enlargement and the resurrection of the Lothrop procedure as a purely endonasal method to conjoin both sinus outflow tracts into a common opening. In a small number of cases, the anatomy of the frontal sinus (especially the anteroposterior width) may limit endoscopic instrumentation. The external approach with stenting may eliminate or precede the use of an osteoplastic flap. With a small frontal sinus, it is possible to remove all the chronically diseased mucosa and obliterate the cavity. It provides wider access to mucoceles, often eliminating an osteoplastic flap.
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Drainage of orbital abscesses: Subperiosteal and intraconal suppurative disease can be rapidly and directly drained. Intraorbital pressure can be reduced as needed by incising the periorbita and removal of the bone of the medial orbital wall to increase orbital volume. Disease in the ethmoid sinus, which is the usual cause of this complication, can also be treated at this time ( Fig. 8 ).
