Although endoscopes were first used by Hirschmann, in 1903,  the development of the rigid endoscope by H. H. Hopkins and its use in maxillary sinus surgery, reported in 1989 by Hopkins and Kapang, were instrumental to our current understanding of sinus disease.
With the use of the endoscope, an understanding of mucociliary clearance patterns from the sinuses was obtained. The anatomy of the sinuses and the ostia were also better visualized with the endoscope, and the relationships between the intranasal and paranasal structures were better understood. 
Go to Acute Sinusitis, for more complete information on this topic.
In infancy, the ethmoidal sinuses are developed, and they expand during early childhood.  The sinuses are paired and are divided into anterior and posterior ethmoidal air cells. This division is provided by the basal lamella of the middle turbinate. In an adult, the average length of the sinus is 4-5 cm. The height is approximately 3 cm. The sinus widens from anterior to posterior, expanding from 0.5 cm anteriorly to 1.5 cm posteriorly.
The frontal, lacrimal, palatine, sphenoid, and maxillary bones contribute to the walls of the ethmoid sinus.  Medially, the ethmoid sinus is demarcated by the lamina papyracea, which forms the medial wall of the orbit and the lateral nasal wall. Superiorly, it is demarcated by the fovea ethmoidalis. [5, 6] The infundibulum of the ethmoid represents a cleft that is demarcated by the uncinate process on its medial side and the lamina papyracea on its lateral side.  It connects the inferior aspect of the hiatus semilunaris with the superomedial aspect of the maxillary sinus.
The uncinate process is a bony, curved prominence extending from the lateral nasal wall superiorly to the inferior turbinate. The ostiomeatal complex denotes the ultimate pathway for the secretions from the anterior ethmoidal air cells.
Inferiorly, the hiatus semilunaris is the shortest distance from the free posterior margin of the uncinate process to the anterior aspect of the bulla ethmoidalis. Superiorly, it is a space between the lateral aspect of the middle turbinate and the superior aspect of the bulla ethmoidalis.  The anterior air cells drain into the middle meatus, and the posterior air cells drain into the superior meatus.
A retrospective study by Crovetto-Martínez et al indicated that odontogenic maxillary sinusitis frequently spreads to the anterior ethmoid sinus but that such involvement does not reduce the success of functional endoscopic sinus surgery. The study included 55 patients with odontogenic sinusitis who were treated with functional endoscopic sinus surgery, with the sinusitis extending to the anterior ethmoid sinus in 52.7% of cases. The investigators determined that 92.3% of the patients with odontogenic sinusitis alone were cured by surgery (middle meatal antrostomy), compared with 96.5% of those with anterior ethmoid sinus involvement (middle meatal antrostomy plus anterior ethmoidectomy). 
Ethmoid sinusitis can spread outside of the borders of the sinus and cause an orbital cellulitis, orbital subperiosteal abscess, orbital abscess, superior orbital fissure syndrome, or cavernous sinus thrombosis. This last condition can result in limited ocular motility, proptosis, and loss of vision and can be life threatening.
Intracranial complications from sinusitis are fortunately rare but can have high morbidity and mortality. These complications include meningitis, thrombophlebitis of the superior sagittal sinus, and abscess formation. Yeh et al reported a case of intracranial abscess in a 17-year-old patient after surgical treatment for ethmoiditis.  Osteitis and osteomyelitis have also been observed. Mucoceles and pyoceles can occur.
Indications for Surgery
The typical case of acute ethmoid sinusitis is treated with medical therapy. Medical treatment can reduce the inflammation and edema of the mucosa, alleviate the pain, combat the infection, open the ostia of the sinuses, and restore normal mucociliary secretions. Moreover, improved antibiotic penetration of the sinuses may reduce the need for surgical intervention.
In a retrospective study by Mahalingam-Dhingra et al, pediatric patients who had orbital cellulitis were 4.8 times more likely to require surgery if they had concomitant ethmoiditis. 
Surgery is indicated in the following instances:
Sinusitis that is not responsive to medical management
Rapidly progressing sinusitis
Sinusitis that creates an abscess either in the sinus or in adjacent areas, such as the orbit or brain
Sinusitis that compromises the survival of the patient
A study by Stokken et al indicated that pediatric patients who require surgery for complications of acute bacterial sinusitis are more likely to have ethmoid and frontal sinus involvement than are children who undergo surgery for chronic rhinosinusitis. The study, which included 27 patients with a complication of acute bacterial sinusitis and 77 patients with chronic rhinosinusitis, all of whom underwent sinus surgery, also found differences in culture results between the two groups. 
Surgical intervention for acute ethmoid sinusitis is contraindicated in poor surgical candidates who are unable to undergo the risks of anesthesia.
Most often, the surgery is performed under general anesthesia. The desire to perform the surgery under local anesthesia with monitored anesthesia sedation must be carefully considered, because hemorrhage in a partially sedated patient with no protection of the airway can be difficult to manage. However, the surgical method chosen, degree of surgery required, and experience of the surgeon are all qualifying factors.
Bleeding dyscrasias may also be a relative contraindication to surgery.
Lawson stated that patients with a defect in the lamina papyracea, fovea ethmoidalis, or the cribriform plate should not have an ethmoidectomy from the intranasal approach.  However, not all surgeons agree.
Preoperative CT Scan
Computed tomography (CT) scans should be obtained to determine the extent of the ethmoidectomy needed. The degree of surgery required is determined by the extent of the disease and not by a simple categorization or technique, such as limiting the surgery only to the anterior ethmoidal air cells, as in the Messerklinger technique, or performing a complete sphenoethmoidectomy, as in the Wigand approach. 
The use of image guidance systems that correlate the intraoperative position of the instrumentation with the CT-scan anatomy may reduce complications in adjacent structures during the more posterior dissection.
An ethmoidectomy is performed using one of 3 major approaches: the external ethmoidectomy, the intranasal (endoscopic) ethmoidectomy, and the transantral ethmoidectomy. Each approach has advantages and disadvantages.
The ultimate decision as to which approach to use depends on the surgeon's preference and the extent of the disease. However, the transantral approach is the least used for isolated ethmoid sinusitis. Depending on the extent of the disease, more than 1 approach may be combined during the surgical intervention.
Regardless of the approach used, the surgeon must be familiar with the anatomy and aware of all pertinent landmarks to reduce the risk of complications. Attention must be paid to avoid violating the cribriform plate or inadvertently entering the orbit. Avoiding injury to the septal mucosa, especially if the endoscopic approach is used, will diminish bleeding that otherwise would obscure the view.
If bleeding is a problem, it must be controlled with cautery, thrombin, Gelfilm, Gelfoam, Surgicel, or Merocel, or with packing containing cocaine, adrenaline, phenylephrine, or oxymetazoline.
This surgery can be performed under monitored anesthesia care or general anesthesia. General anesthesia may be preferred, because manipulating the globe can be uncomfortable to the patient. An incision approximately 2.5-3 cm long is made in a curvilinear fashion. It is positioned at the midpoint between the medial canthus and the middle of the anterior nasal bone. The skin is incised, and the dissection is carried down to the periosteum. If the angular artery is transected, it is cauterized or ligated. Dissection is carried subperiosteally to the posterior lacrimal crest, avoiding damage to the lacrimal excretory structures.
The medial canthal tendon may need to be released to allow for easier access to this area; if this is done, care must be taken to reposition it correctly. The posterior crest may need to be removed. Care must be taken not to extend the dissection superiorly to the frontoethmoidal suture, as this demarcates the cranial fossa.
The anterior ethmoidal artery lies at the level of this suture, 20 mm posterior to the posterior lacrimal crest. The posterior ethmoidal artery is also at this level, another 10 mm posterior, and the optic nerve is found 5 mm further back from the posterior ethmoidal artery. If needed, the anterior ethmoidal artery can be ligated.
The anterior cells are removed. The posterior cells can also be approached and treated as needed with ligation of the posterior ethmoidal artery if required. A drain is often placed and can be used in the postoperative period for lavage of the sinus. The medial canthal tendon is repositioned if needed, the periosteum can be closed or left open, and the skin is closed in layers.
This surgery can be performed with the patient under monitored anesthesia care or general anesthesia. Pledgets soaked in 4% cocaine or a combination of 4% lidocaine and 0.25% oxymetazoline are passed into the nasal cavity to anesthetize and decongest the mucosa. A local anesthetic containing 1% lidocaine and 1:100,000 epinephrine is injected into the mucosa of the middle turbinate, septum, and lateral wall. Hand instruments or powered instrumentation are used. If present, polyps are resected.
If the middle turbinate is obstructing the ostial area, such as with a concha bullosa, it can be partially resected. When manipulating the middle turbinate, care must be taken not to fracture the cribriform plate, which is just medial to the attachment of the turbinate, because this will cause a cerebrospinal fluid (CSF) leak.
The uncinate process and infundibulum are approached. An incision is made in the infundibulum and the uncinate process is resected. The mucosa can be incised with a sickle blade and removed with forceps. A loop curette or other noncutting instrument can be used to gently break into the anterior cells of the sinus. The cells are opened with biting instruments. Posteriorly, the dissection ends at the sphenoid sinus. Dissecting this far posterior in isolated anterior disease may not be necessary.
If the sphenoid sinus is involved, it must also be surgically addressed. The frontoethmoidal suture lies at approximately the level of the pupils, but this can be less reliable with a patient under general anesthesia. Complications from improper dissection of the sphenoid sinus can involve the optic nerve and carotid artery, with disastrous consequences.
Culture can be obtained and material sent for pathologic examination as warranted. The nasal area is then packed with antibiotic ointment–coated gauze.
This surgery can be performed under monitored anesthesia sedation or general anesthesia. A Caldwell-Luc approach is used. Once the maxillary sinus has been entered, the medial and superior walls of the maxillary sinus are identified. At the midpoint of the medial wall, the bulla ethmoidalis may be seen bulging into the maxillary sinus.
A curette is used to enter this area, which is enlarged with a Kerrison rongeur or other bone cutting instruments. This allows access to most of the anterior cells, but the most anterior cells may be difficult to reach. The posterior cells off the ethmoid sinus can also be reached.
Balloon sinuplasty has been used in chronic sinusitis involving the frontal sphenoid and maxillary sinuses. The ethmoid sinuses are less well suited for this owing to their anatomy. 
The microflow drug-eluting stent has been used successfully in chronic ethmoiditis. 
Outcome and Follow-up
Most patients who undergo ethmoidectomy for acute ethmoid sinusitis obtain resolution of the disease. However, chronic sinusitis and other problems can occur. Improvement following ethmoidectomy has ranged from 46-98%.  The success rate for the external approach has ranged from 70-93%, and for the endoscopic approach, from 46-98%.
The postoperative course and care of the patient will to some extent depend on the approach used. All patients are maintained on antibiotic therapy and pain medication. Culture results can be used to adjust the antimicrobial regime as needed. Once the prognosis has improved, steroid usage can be considered. Patients are instructed to avoid nose blowing for up to 1 week.
In the external approach, the drain is usually removed in 48-72 hours. It can also be used to lavage the sinus; however, the authors do not do this. The skin sutures are removed in approximately 7 days. Topical nasal decongestants are used for 3 days after surgery and then discontinued. The patient then uses nasal saline mist for 1 week.
In the endoscopic approach, the packing is removed within 48-72 hours. Topical nasal decongestants are used for 3 days after surgery and then discontinued. The patient then uses nasal saline mist for 1 week. Repeat nasal endoscopic examination and debridement in the postoperative period are usually necessary.
In the transantral approach, the patient rinses with an antiseptic mouthwash after each meal and at bedtime to maintain the hygiene of the mouth. The sutures are dissolvable. Topical nasal decongestants are used for 3 days after surgery and then discontinued. The patient then uses nasal saline mist for 1 week.
All patients have a follow-up visit the first day after surgery. Further follow-up visits are scheduled according to the surgical approach used and the patient’s degree of illness.
Overall, the complication rate for ethmoid sinus surgery has been reported to be 2-17%. 
External approach complications
The external approach allows for visualization of the orbital contents and is a unilateral approach that will result in a cutaneous scar that could lead to medial canthal webbing, telecanthus, and medial canthal dystopia, especially if the medial canthal tendon is released and not properly repositioned.
In the external approach, periorbital edema, injury to the extraocular muscles with diplopia, paresthesias in the distribution of the supraorbital, supratrochlear and infratrochlear nerve distributions, and blepharoptosis can also occur. The globe also can be injured. Blindness can occur from either a hematoma or excessive pressure on the globe, occluding the central retinal artery during the surgery.
Endoscopic approach complications
The endoscopic approach allows for access to both ethmoid sinuses, but it requires that the surgeon be facile with an endoscope. This approach can cause an orbital hematoma and blindness. Diplopia can occur if an extraocular muscle, usually the medial rectus, is injured. Atrophic rhinitis has also been reported.  More worrisome are the rare, but unfortunate, reports of blindness due to resection of the optic nerve.
CSF leaks can also occur. Most will resolve with conservative treatment; however, if a leak is extensive and noted at the time of surgery, it should be addressed and repaired with dura, fat, mucosa, and/or fibrin glue. Synechia and ostial closure can also occur. Often, the synechia can occur between the turbinate and the septum. If it occurs between the turbinate and the lateral wall, blockage of the ostium can result.  Pituitary apoplexy has also been reported. 
Transantral approach complications
The transantral approach does allow for access through the maxillary sinus and is a unilateral approach, but it provides restricted access to the most anterior ethmoidal air cells. In the transantral approach, damage to the dentition, oral-antral fistula formation, paresthesias in the distribution of the infraorbital nerve, and paresthesias in the gingivobuccal sulcus and alveolar ridge can also occur.