Transantral approach

Transcription

1 13. Describe the external approaches to the ethmoid sinuses External ethmoidectomy: external ethmoidectomy is accomplished through a Lynch incisionsmall skin incision between the nasal bridge and the eye. The scar from the incision can be extremely well hidden using various plastic surgery techniques. In general, this technique has been fully replaced by endoscopic trans nasal techniques that do not require an incision on the facial skin. However, this technique can still be useful in some special circumstances. Two examples include acute bacterial sinusitis which causes an abscess in the eye and requires surgical drainage and severe arterial nose bleeds which require surgical ligation of the anterior ethmoid artery. To be sure, both of these stated operations can be accomplished endoscopically, however, endoscopic operations in these circumstances often require special equipment like image guidance, trained nursing crews and technicians, special surgical tools including customized hand instruments and cautery, and microdebriders. Sometimes, these types of procedures are also urgent or emergent. The external ethmoidectomy approach is sometimes the safest and most direct, quickest method to accomplish surgery in some conditions. Finally, the external ethmoidectomy is still sometimes used as an approach by skull base surgeons when addressing problems like tumors requiring surgery or cerebrospinal fluid leak repair 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 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. Transantral approach 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.

2 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. 14. List the indications for osteoplastic flap in the management of frontal sinus disease. Describe the procedure. From emed 1) reserved for chronic cases of refractory frontal sinusitis or for those accompanied by intracranial complications. Conservative medical management and/or surgical drainage procedures must be performed prior to the consideration of obliteration. The presence of hypoplastic frontal sinuses is a contraindication to the obliteration procedure. The particular advantages of the osteoplastic flap procedure are the excellent visualization of the sinus, an ability to correct problems of the posterior table and dura, the elimination of the need to establish a frontonasal communication, and an overall low failure rate. A drawback of the osteoplastic flap procedure is difficulty in postoperative follow-up, because the sinus is obliterated. Nonetheless, the osteoplastic flap procedure remains the criterion standard in chronic refractory or recurrent acute frontal sinusitis. Current modifications include the use of a pericranial flap and cancellous bone grafts. In osteoplastic frontal sinus obliteration, the following 3 approaches are possible: The coronal approach The midline forehead approach The brow incision approach The coronal incision is useful and cosmetically acceptable if the patient is not balding, but it involves more blood loss. The midline forehead incision is incorporated into a patient's forehead wrinkles, if present. The brow incision is the least cosmetically acceptable and may cause postoperative pain, anesthesia, or paresthesias. A Caldwell-Luc image obtained preoperatively at a distance of 6 feet provides a template for the frontal sinus, which is used intraoperatively after it is sterilized. Ipsilateral tarsorrhaphy also should be performed to protect the globe. After one of the 3 approaches is used, the frontal periosteum is cleaned of subcutaneous tissues. The template aids in outlining the frontal sinus. The periosteum is then incised 5 mm above the outline of the sinus and elevated to just below the sinus outline. A power saw is used to cut into the sinus by beveling the saw blade downward and inward. The template helps to ensure that the bone cuts are in the frontal sinus and do not enter the anterior cranial fossa inadvertently. Small cuts above the glabella may be necessary to weaken the frontonasal suture. The osteoplastic flap is then fractured forward from above, exposing the contents of the frontal sinus and allowing meticulous removal of all sinus mucosa and/or the removal of the intersinus septum.

3 The sinus is commonly drilled out with a polishing burr to ensure adequate bone exposure and complete removal of mucosa in preparation for the fat graft. If the posterior table of the frontal sinus is involved with osteomyelitis or is absent because of an expanding frontal sinus mucocele, it can be removed, allowing the dura to move forward to occupy the frontal sinus space (ie, cranialization of the frontal sinus). Generally, the posterior frontal sinus is intact, and after complete removal of mucosa, it can be packed with fat or other materials before replacing the ostiomeatal flap and suturing the periosteum and the incision in layers. A variety of substances can be used, including Gelfoam, Teflon, fat, paraffin, silastic sponge, and cartilage. Autogenous fat, typically harvested from subcutaneous abdominal adipose tissue, is currently the preferred substance for obliteration, because it is thought to prevent osteoneogenesis and impede regrowth of the mucoperiosteum. In addition, the fat revascularizes and, thus, is theoretically more resistant to postoperative infection than other substances. The drawbacks to autogenous fat use include donor site morbidity. Adequate obliteration can also be achieved with osteoneogenesis, allowing the sinus to obliterate itself after the inner bony cortex and mucosa is removed and a transfrontal ethmoidectomy is performed. This technique obviously avoids donor site morbidity. A study demonstrated the value of magnetic resonance imaging (MRI) in the follow-up of patients after obliteration, in that MRI results can be used to differentiate the distribution of fatty and fibrous tissue. The review, of patients undergoing frontal sinus obliteration with adipose tissue, had a 12-year follow-up period. In the study, a 10.2% incidence of persistent changes in frontal contouring and a 9.8% incidence of mucocele were documented with MRI results. The images also showed a significant decrease in the amount of adipose tissue with time, as revealed by a median half-life of 15.4 months. 15. What is a Lothrop procedure? The Lothrop or Chaput-Meyer technique is used mainly for chronic, bilateral frontal sinusitis, but modifications are used in the treatment of acute infection. The external technique involves resection of the intersinus septum, superior nasal septum, and medial frontal sinus floor, connecting the 2 outflow tracts and thereby creating a large frontonasal communication. Drainage via the healthy side of the sinus can be used to treat unilateral frontal sinus disease. This operation is more effective than others in eradicating persistent frontal sinus disease, although it can be used in treating acute frontal sinusitis. One of the disadvantages of this procedure is that it causes medial collapse of the orbital soft tissues, which may result in stenosis of the nasofrontal communication. Also, the procedure is technically difficult, and the cribriform plate is directly posterior to the dissection, increasing the risk of intracranial injury. Draf: from UTMB Dr. Wolfgang Draf popularized three endoscopic procedures to the frontal sinus termed Draf types I, II and III. The endoscopic frontal recess approach (Draf type I) procedure is indicated when frontal sinus disease persists despite more conservative endoscopic approaches directed at the infundibulum

4 and anterior ethmoid region. This procedure involves complete removal of the anterior ethmoid cells and uncinate process surrounding the frontal recess to the frontal ostium. Obstructing frontal cells, if present, are removed. The frontal sinus ostium may then drain into a patent frontal recess. The endoscopic frontal sinusotomy, or Draf II procedure, is indicated for patients with severe forms of chronic frontal sinus disease that have failed after endoscopic frontal recess approach. This extended drainage procedure involves resection of the floor of the frontal sinus from the nasal septum medially, to the lamina papyracea laterally. The dissection involves removal of the anterior face of the frontal recess. Thus, the frontal sinus ostium is enlarged to its maximum dimension. This procedure can be very difficult to distinguish from the endoscopic frontal recess approach (Draf I) on coronal postoperative imaging. Evaluation of multiple consecutive coronal images or sagittal reformatted images can demonstrate extensive removal of the anterior face of the frontal recess and frontal sinus floor when compared to the frontal recess approach. The endoscopic frontal sinusotomy (Draf II) procedure can be easily distinguished from the Draf III procedure by the lack of resection of the superior nasal septum and entire frontal sinus floor. The modified Lothrop procedure, or Draf III procedure, may also be referred to as median drainage. This procedure, in its present form, was first described in the mid-1990s and has been gaining popularity among rhinologists. Indications include the most severe forms of chronic frontal sinusitis where osteoplastic flap with obliteration is the only alternative. This procedure involves removal of the inferior portion of the interfrontal septum, the superior part of the nasal septum, and the frontal sinus floor to the orbit laterally. The lamina papyracea and posterior walls of the frontal sinus remain intact. Authors in Japan compared long term results with the Draf II and III procedures and concluded that the Draf III allows for better long term patency of the frontal sinus. 16. Discuss the anatomy and classification of the frontal cells. American Journal of Rhinology 2003;17:163. Link to images of these: Pneumatization of the frontal sinus extends into the squamous part of the frontal bone and posteriorly into the orbital part of the frontal bone to form a supraorbital cell. The inner plate of the frontal sinus is compact bone, while the outer plate is cancellous bone. Pneumatization in the agger nasi region is variable; the following 4 variations have been described: Type I - A single frontal recess cell above the agger nasi cell Type II - A tier of cells in the frontal recess above the agger nasi cell Type III - A single large cell pneumatized into the frontal sinus Type IV - A single isolated cell within the frontal sinus Am J Rhinol May Jun;17(3): Coronal computed tomography analysis of frontal cells. Meyer TK, Kocak M, Smith MM, Smith TL.

5 Source Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. Abstract BACKGROUND: Described by Schaefer in 1916, frontal cells have been implicated as a cause of frontal recess obstruction. In this cross-sectional study, we determine the prevalence of frontal cells and other anatomic variants and examine their relationships. METHODS: Coronal computed tomography scans of the sinuses performed from January 2000 to June 2001 were evaluated for frontal cells, other anatomic variants, and sinus disease. Of 1009 scans evaluated, 768 scans were included for data collection. Frontal cells were classified. RESULTS: In this population, 20.4% of individuals had frontal cells (14.9% had type I, 3.1% had type II, 1.7% had type III, and 2.1% had type IV). The presence of frontal cells was positively associated with hyperpneumatization of the frontal sinus (p = 0.01) and negatively associated with hypopneumatization of the frontal sinus (p < 0.01). Individuals with frontal cells had an increased prevalence of concha bullosa compared with individuals without frontal cells (41.4% versus 24.1%, p < 0.01). The prevalence of frontal mucosal thickening was increased in individuals with type III and type IV cells compared with individuals without frontal cells (38.5 and 69.0% versus 17.1%, p = 0.04 and p < 0.01). CONCLUSION: The prevalence of frontal cells among a population undergoing sinus computed tomography is 20.4%. Frontal cells are associated with other variants of sinonasal pneumatization and should be suspected when these variants are noted. The presence of frontal cells does not invariably lead to frontal sinusitis but may contribute to the mechanical obstruction of the frontal recess and should be appropriately addressed during the surgical management of frontal sinusitis.