AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Acute sphenoid sinusitis is relatively uncommon; comparatively, chronic sphenoid sinusitis is more common. Signs and symptoms are often subtle; therefore, the diagnosis can be difficult to make. However, early diagnosis and treatment are essential because the disease can be rapidly progressive and complications can be devastating. Complications arise from the relationship of the sphenoid sinus to vital vascular, neurologic, and optic structures. Treatment is initially medical; surgery is reserved for unresponsive disease and impending complications. Surgical treatment involves opening the sphenoid sinus, establishing drainage, and obtaining material for culture. Endoscopic methods of sphenoidotomy are now accepted, and several approaches have been described. Open approaches, including an external ethmoidectomy or transseptal approach, can also be used. The outcome of sphenoid sinusitis is highly dependent on the speed of diagnosis.

History of the Procedure

The sphenoid sinus has been described as the forgotten sinus or neglected sinus because of its anatomical location and the difficulty in diagnosing disease there. Diseases of the sphenoid often were determined only when complications arose. With the advent of modern imaging techniques and a higher index of suspicion, diseases of the sphenoid are much more easily found and treated. Modern imaging, antibiotic, and surgical options have changed the presentation and, often, the treatment of acute sphenoid sinusitis.

Problem

According to the American Academy of Otolaryngology—Head and Neck Surgery (AAO-HNS) task force on rhinosinusitis, sinusitis is defined as an inflammatory response involving mucous membranes of the nasal cavity and paranasal sinuses, fluids within these cavities, and/or bone. The condition is classified as acute if it persists for 4 weeks or fewer. In contrast, a subacute infection is defined as lasting 4-12 weeks, and a chronic infection persists for more than 12 weeks.

When this inflammatory response occurs in the sphenoid sinus, the result is sphenoid sinusitis or sphenoiditis. The disease may be limited to the sphenoid sinus or, more commonly, may involve multiple sinuses or pansinusitis.

Frequency

Sphenoid sinusitis often occurs in the context of pansinusitis. In the preantibiotic era, Teed reported an incidence of sphenoid involvement of 33% in patients with pansinusitis. A 1977 study by Wisberger and Dedo suggested that in the antibiotic era, incidence decreased to 8%. Isolated sphenoid sinusitis is much less common. Lew reported a 2.7% incidence in patients hospitalized for sinusitis in a 12-year period. Of these incidences, only one half had acute disease. Hnatuk et al suggest that the incidence is actually much lower, and that sphenoid sinusitis represents fewer than 1% of all cases of sinusitis.

Etiology

The microbiology of acute sphenoid sinusitis differs from that of uncomplicated maxillary sinusitis. Whereas maxillary sinusitis is caused predominantly by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, sphenoid sinusitis has a different profile. Gram-positive organisms predominate, with Staphylococcus aureus most common, followed by Streptococcus pneumoniae. Chronic sphenoid sinusitis can be caused by both gram-negative and gram-positive organisms, anaerobes, and mixed flora, which are more common. Fungal disease also must be considered, especially in the context of a patient who is immunocompromised.

Pathophysiology

The pathophysiology of sphenoid sinusitis involves blockage of sinus ostia and impaired mucociliary clearance leading to stasis and secondary bacterial infection. Several predisposing factors have been implicated. Anatomic differences include variations in the position of the intersinus septum and small or abnormally placed ostia. Blunt, penetrating, or surgical trauma can alter drainage patterns as well as allow entry of pathogenic organisms. Swimming or diving with forceful water entry through the nose also has been implicated in causing disease. Immunosuppression due to long-term steroids, diabetes, or radiotherapy can predispose patients to this disease, as can obstruction of sinus ostia by polyps or tumor.

Clinical

Patients with acute sphenoid sinusitis often present with vague nonlocalizing symptoms. Headache is the most common symptom; almost all patients in various studies complain of headache. Although the vertex headache is classic, the pain also can be retroorbital, parietooccipital, or frontal. In general, the headache is described as severe, interfering with sleep, and not relieved by narcotics. Fever and purulent rhinorrhea often are noted, and hypoesthesia of the trigeminal nerve may be present in select cases. Neurologic and ophthalmologic findings suggest impending complications. Decreased mental status, lethargy, and seizures point to intracranial extension or meningitis. Ophthalmologic findings may include abducens nerve palsy or hypoesthesia of V1 and/or V2. Chemosis, proptosis, ptosis, diplopia, or decreased visual acuity and ophthalmoplegia may be noted.

Maintain a high index of suspicion for sphenoid sinusitis. A review by Hnatuk et al reported that 78% of cases of sphenoid sinusitis were initially misdiagnosed. Evaluate patients with severe progressive headache, with or without fever, for sphenoid sinusitis. Thoroughly investigate signs of orbital or neurologic complications.

Disease in the sphenoid sinus is not always inflammatory in nature. Consider a broad differential diagnosis in a patient with clinical suggestion of sphenoid disease and imaging studies consistent with sphenoid opacification. Isolated sphenoid lesions, for example, merit special consideration. In his review of 132 cases of isolated sphenoid disease, Lawson found that, while inflammatory disease predominates, neoplasms, fibroosseous disease, and other entities were significant.

In addition to acute and chronic sinusitis, inflammatory diseases included mucoceles, polyps, retention cysts, and fungal disease. Neoplasms included benign tumors, such as inverting papilloma, myxofibroma, plasmocytoma, and schwannoma. Salivary gland malignancies, such as adenoid cystic carcinoma and epidermoid carcinoma, were present, as well as malignancies including squamous cell, melanoma, and hemangiopericytoma.

Extension from adjacent sites, such as the nasopharynx and pituitary, was noted, as was metastatic disease from the prostate, kidney, and tonsil. Several cases of fibrous dysplasia and ossifying fibroma were observed.

Miscellaneous entities including foreign bodies, encephaloceles, and even an internal carotid aneurysm were also included. In general, although many clinical cases of sphenoid disease may be inflammatory in nature, consider other entities.

INDICATIONS

Section 3 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

In general, start medical treatment of acute sphenoid sinusitis once the diagnosis is made. Institute antibiotics and decongestants for 24 hours, and, if the patient does not improve over this time course, schedule surgical therapy. If the patient has evidence of complications, undertake urgent surgical decompression.

Some individuals advocate early and aggressive surgical and medical treatment for acute sphenoid sinusitis. Hnatuk comments on the aggressive nature of the disease and concludes that nonoperative medical management is not indicated. These conclusions are based on a small number of patients, all in their teenage years.

RELEVANT ANATOMY

Section 4 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

The sphenoid sinus is the most posterior of the paranasal sinuses. It is a paired structure, divided asymmetrically by an intersinus septum. Pneumatization begins at age 3 years and progresses rapidly between ages 5 and 7 years. Various degrees of pneumatization exist. While the sphenoid most commonly is fully pneumatized, the structure can be only partially aerated or can be filled completely with bone. Pneumatization also may occur in the bones adjacent to the sinus, such as the greater wing of the sphenoid bone or the vomer or palatine bones.

The anterior wall of the sphenoid is adjacent to the sphenoethmoidal recess. The floor of the sinus contributes to the roof of the nasopharynx. Posterior to the sphenoid is the clivus. The inferior aspect where it articulates with the vomer is known as the sphenoid rostrum. The pituitary gland sits superior to the sinus. The sphenoid ostium is membranous but surrounded by bone. It lies approximately 30° from the nasal floor and 7 cm from the nasal vestibule.

Lateral to the sphenoid sinus lies the cavernous sinus. The close proximity of the sphenoid to the structures within the cavernous sinus accounts for much of the danger of acute sphenoiditis. Within the cavernous sinus lies the internal carotid artery as well as cranial nerves (CN) II, III, IV, and VI and V3. These structures may lie adjacent to the sphenoid and cause indentations within the wall. The internal carotid artery can be observed indenting the posteroinferior surface of the lateral wall. Cadaver studies have shown that the bony covering is thin in 71% of patients and absent in 4% of patients.

The optic nerve also has a significant relationship to the sphenoid sinus. As the optic nerve travels within the optic canal, it passes over the anterolateral region of the sphenoid roof. The bony covering over the nerve has been noted to be absent in 4% of individuals.

CONTRAINDICATIONS

Section 5 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Very few contraindications to urgent surgical decompression of the sphenoid sinus exist if a patient is having complications or is unresponsive to medical management. Unstable vital signs or excessive bleeding might require waiting until these problems can be temporized. Chronic medical conditions might preclude general anesthesia. If the sphenoid sinus is the underlying problem, however, decompression is beneficial.

WORKUP

Section 6 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Lab Studies

• Include WBC count and differential in the laboratory evaluation. Findings of leukocytosis with a left shift suggest acute infection.
• Blood cultures may help identify a pathogen.
• Perform a lumbar puncture if meningitis is suggested.

Imaging Studies

• CT scan
• • In the workup of a patient with suggested sphenoid sinusitis, imaging studies are the mainstay of diagnosis. CT scan establishes the presence of sphenoid disease and provides information on bony erosion. An air-fluid level usually is observed in acute disease, while complete opacification is more common in chronic disease. A globular opacity filling the cavity is likely to be a retention cyst or polyp; however, further studies may be needed to rule out a rare encephalocele or aneurysm.
  • In the setting of acute sinusitis, a CT scan establishes the anatomy of the sphenoid, including the size of the cavity and the intersinus septum. The presence of pansinusitis can be determined. Identify the internal carotid artery, pituitary, and optic nerve.
• MRI
• • MRI is useful in evaluating the relationship of the sphenoid to its surrounding structures. While CT scan is useful in showing bony erosion, MRI is better for imaging of soft tissues. Several CT scan findings require further workup with MRI. Bony erosion requires an MRI to differentiate mucoceles from tumors. An image with low density on T1 images and high density on T2 is characteristic of a mucocele. Tumors tend to show intermediate density in T1 and T2 images. Fungal sinusitis can be identified by signal voids within the sinus. A mixed signal pattern, in contrast, is typical of fibroosseous orders. Any extrasinus extension in conjunction with bony erosion is likely to be a malignancy. Partial opacification of the sphenoid may occasionally represent an internal carotid artery aneurysm or encephalocele.
  • In the setting of acute sphenoid sinusitis, MRI is valuable in evaluating patients with neurologic or visual complaints for evidence of complications. The structures surrounding the sphenoid (eg, dura, optic nerve, cavernous sinus) are demonstrated. Cavernous sinus thrombosis, in particular, can be identified.
• Magnetic resonance angiography (MRA) can be used to confirm the diagnosis of cavernous sinus thrombosis.

TREATMENT

Section 7 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Medical therapy

Initial treatment of a patient with uncomplicated sphenoiditis begins with medical therapy. Once the diagnosis is made, begin administration of broad-spectrum antibiotics. Also add topical and systemic decongestants to the regimen. Try medical treatment for 24 hours. If the patient does not improve over this time course, schedule surgical therapy; if the patient has evidence of complications, undertake urgent surgical decompression.

Sethi described an interesting modification of this algorithm. Daily endoscopic decongestion and assessment of the sphenoethmoidal recess was performed, allowing direct evaluation of the anatomy. Three of the 8 patients in this study did well with this regimen, while 5 patients did not improve and required surgery.

Surgical therapy

The goals of surgery are to identify the sphenoid ostium, enlarge it, and establish drainage. Diseased mucosa should be removed and cultures should be obtained. Many surgical approaches have been described. The classic approaches include transseptal, transantral, intranasal, and external, but endoscopic surgery is now commonly used.

Preoperative details

Preoperatively, review the imaging studies to determine bony anatomy and areas of disease. Decide the approach to the sphenoid sinus based on associated disease as well as surgeon preference.

Intraoperative details

When operating on the sphenoid sinus, be aware of the relationship of the sphenoid to the surrounding structures. The anterior wall of the sphenoid is approximately 7 cm from the anterior nasal spine and 30 degrees off the nasal floor. The distance to the posterior sphenoid wall is approximated by measuring the distance to the posterior nasopharynx, which is about 9 cm. The carotid artery and optic nerve may be observed indenting the lateral walls of the sphenoid sinus. The carotid artery is dehiscent in 4% of patients and covered with only a thin bony covering in 71% of patients. The optic nerve is found in the superolateral aspect of the sinus, also dehiscent in 4% of patients. A margin of safety can be obtained by staying medial and inferior when opening and exploring the sphenoid.

Transseptal transsphenoidal approach

Many approaches to the sphenoid have been described. Among the earliest was the transseptal transsphenoidal approach, described by Cushing and Hirsh in 1910 in the context of pituitary tumor resection. This approach was repopularized by Hardy in the 1950s and is still in use today. The transseptal approaches can be via sublabial incision, external rhinoplasty incision, or alar incision. The sublabial incision is most common because of the relative ease of the procedure, midline exposure, and lack of external scar. However, oral contamination is a disadvantage.

For the sublabial approach, inject lidocaine with epinephrine into the upper buccal sulcus, septum, and floor of nose. Make an incision in the upper sulcus and carry the incision down to bone. Elevate the periosteum to the piriform aperture laterally and elevate the anterior nasal spine medially. Elevate a mucoperichondrial flap on one side of the septum and the nasal floor bilaterally, leaving the contralateral septal mucosa intact. Disarticulate the septum at the bony-cartilaginous junction, and remove the perpendicular plate to expose the sphenoid rostrum. Following placement of a pituitary speculum, fluoroscopy can be used if needed to confirm placement. Enter the sphenoid sinus in the midline with an operating microscope.

Transantral approach

The transantral approach also has been used for sphenoid disease. For this approach, make a sublabial canine fossa incision. Open the anterior maxillary sinus wall and address any antral disease. Remove the nasoantral wall exposing the middle turbinate. Use the middle turbinate as a guide to the sphenoid ostium, which is found superior and medial to the posterior aspect of the middle turbinate. Then, open the anterior sphenoid wall.

Intranasal approach

Another classic approach is the intranasal approach. Perform typical nasal decongestion; then, fracture the middle turbinate medially. Perform an ethmoidectomy followed by lateralization of the posterior attachment of the middle turbinate. Identify the sphenoid ostium medially to the middle turbinate, enter it, and enlarge it toward the midline. Remove the posterior ethmoid cells to create a common cavity between the sphenoid sinus and the posterior ethmoid. External sphenoethmoidectomy is used infrequently because an external incision is needed.

Endoscopic approach

The advent of endoscopic sinus surgery has dramatically changed the approach to sphenoid disease. Endoscopic approaches provide excellent visualization of the anatomy and disease process. Advantages include reduced operating time, minimal blood loss, and decreased morbidity compared to classic techniques. In a recent article, Metson commented on the widespread popularity of endoscopy and went on to evaluate the efficacy of the endoscopic approach. Metson deemed it effective and safe in the treatment of sphenoid sinusitis.

Transethmoidal approach

If sinus disease involves both the sphenoid and the ethmoid sinuses, a transethmoidal approach is taken. Medialize the middle turbinate to visualize the uncinate process. Remove the uncinate, and identify and open the ethmoid bulla. Then, perform an anterior and posterior ethmoidectomy. The sphenoid sinus is located medial and inferior to the posterior ethmoid air cells. Use a probe to approximate the anterior wall of the sphenoid at 7 cm from the nasal spine and 30° off the nasal floor. Enlarge the opening while taking care to stay medial and inferior in order to avoid the vital structures. The distance to the posterior nasopharyngeal wall approximates the posterior wall of the sinus and usually measures 9 cm.

Transnasal approach

If isolated sphenoid disease is present, a transnasal approach can be used. Displace the middle turbinate laterally and pass the endoscope along the septum until the superior turbinate is identified. Transect and remove the superior aspect of the superior turbinate. Identify the sphenoid ostium in the area between the remnant and the septum. Inferiorly enlarge the ostium. An endoscope can then be passed directly into the sphenoid sinus to evaluate the location of the carotid artery and optic nerve. With these structures identified, the ostium can be enlarged further. A diameter of 5-10 mm is advocated to reduce the likelihood of recurrent obstruction.

Alternate approach to isolated sphenoid disease

Stankiewicz describes an alternate approach to isolated sphenoid disease. He advocates fracturing the middle turbinate towards the septum. Make incisions in the anterior superior and posterior inferior portion of the middle turbinate, and remove this tissue. The basal lamella remains intact as a landmark. With a probe, measure the distance to the sphenoid ostium; then, enter the sphenoid.

Postoperative details

Postoperatively, continue administration of broad-spectrum antibiotics. Adjust antibiotic choices when culture results are available. Closely monitor the patient for complications of the sinus disease as well as the procedure.

Follow-up

Acute sphenoid sinusitis should respond to medical and surgical management as described above. Monitor patients who develop complications of sphenoid sinusitis for progression or resolution of their symptoms. Patients who develop repeated episodes of sphenoid sinusitis may have an anatomic predisposition, such as a narrowed ostium, and may require surgery. Chronic sphenoid sinusitis is a different entity and may respond to medical or surgical treatment. In contrast to acute sphenoiditis, chronic disease is not considered a medical emergency.

COMPLICATIONS

Section 8 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Complications of acute sphenoid sinusitis relate to the vital structures that surround the sinus. Expansion into surrounding structures, local osteitis, or thrombophlebitis in draining vessels may cause complications. Orbital cellulitis, orbital abscess, and orbital fissure syndrome occur from extension towards the orbit; cavernous sinus thrombosis and blindness may occur. Meningitis, epidural, and subdural abscess result from intracranial extension. Carotid artery thrombosis also may occur, though very infrequently. The close proximity of the sphenoid to the pituitary can lead, in some cases, to hypopituitarism.

The sinus surgery itself has potential complications, again based on the vital structures that surround the sphenoid sinus. Intraoperative complications are predominantly vascular in nature and include persistent hemorrhage from the carotid artery or, infrequently, the cavernous sinus. Retrobulbar hemorrhage with proptosis and visual compromise requires urgent ophthalmological consultation and lateral canthotomy. Persistent hemorrhage from the sphenoid or cavernous sinus may require angiography to localize and control bleeding.

Postoperative complications may be nasal, neurologic, or vascular in nature. Long-term complications include cosmetic deformities; septal perforations may occur and are predominantly related to approach. In the perioperative state, epistaxis is also a risk. Neural structures, including the optic nerve or any structures running through the cavernous sinus, may be damaged during surgery. Cranial nerves that control extraocular movements (ie, CN III, IV, VI) are at risk, as are the ophthalmic (ie, V1) and maxillary (ie, V2) branches of CN V. Cerebrospinal fluid leak is possible if the roof of the sphenoid is violated. Hemorrhage from the internal carotid artery or cavernous sinus is a devastating complication that may occur intraoperatively or postoperatively. Immediately evaluate any unexplained mental status changes or excessive bleeding.

OUTCOME AND PROGNOSIS

Section 9 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Outcome and prognosis for sphenoid sinusitis depend highly on early diagnosis. Lew concluded that treatment delay inevitably led to serious morbidity and mortality. In his study, 9 out of 15 patients had a delay in treatment. Four patients died, and 4 had irreversible cranial nerve injury. Kibbelwhite et al came to similar conclusions. In their study of 14 patients with acute sphenoid sinusitis, 57% of the patients had signs of neurologic or ophthalmologic complications, and 29% of the patients were left with permanent disabilities. A delay in diagnosis led to an 80% morbidity rate. The conclusion is that early diagnosis is essential. If properly treated, patients with acute sphenoid sinusitis can improve without complications.

FUTURE AND CONTROVERSIES

Section 10 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Controversies exist in several areas. Administration of broad-spectrum antibiotics is necessary. The choice of antibiotics is not clear. Suggestions in the literature have included gentamicin, chloramphenicol, nafcillin, penicillin, and metronidazole. Direct antibiotic therapy at the likely pathogens, including Staphylococcus aureus and Streptococcus pneumoniae. Consider a drug that crosses the blood-brain barrier if complications are present or seem likely. Adjust antibiotics to cultures when available. Steroid use is generally not indicated.

Acute sphenoid sinusitis can be a devastating disease if not diagnosed quickly. CT scans lead to earlier diagnosis and treatment. Endoscopic approaches to drainage are safe and effective. The combination of these 2 modalities should result in improved outcome and prognosis. In addition, image guidance systems are being used more frequently in sinus surgery. The use of image guidance systems in diseases of the sphenoid is especially helpful and adds an extra dimension of safety to the procedure.

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

• Abramovich S, Smelt GJ. Acute sphenoiditis, alone and in concert. J Laryngol Otol. Aug 1982;96(8):751-7. [Medline].
• Dale BA, Mackenzie IJ. The complications of sphenoid sinusitis. J Laryngol Otol. Jul 1983;97(7):661-70. [Medline].
• Deans JA, Welch AR. Acute isolated sphenoid sinusitis: a disease with complications. J Laryngol Otol. Dec 1991;105(12):1072-4. [Medline].
• Grillone GA, Kasnica P. Isolated sphenoid sinus disease. Otolaryngol Clin North Am. 2004;37(2):435-451.
• Hnatuk LA, Macdonald RE, Papsin BC. Isolated sphenoid sinusitis: the Toronto Hospital for Sick Children experience and review of the literature. J Otolaryngol. Feb 1994;23(1):36-41. [Medline].
• Holt GR, Standefer JA, Brown WE Jr. Infectious diseases of the sphenoid sinus. Laryngoscope. Mar 1984;94(3):330-5. [Medline].
• Hsu YC, Su CY, Hsu RF. Abducens palsy in acute isolated sphenoid fungal sinusitis. J Otolaryngol. 2004;33(5):319-321.
• Kibblewhite DJ, Cleland J, Mintz DR. Acute sphenoid sinusitis: management strategies. J Otolaryngol. Jun 1988;17(4):159-63. [Medline].
• Lawson W, Reino AJ. Isolated sphenoid sinus disease: an analysis of 132 cases. Laryngoscope. Dec 1997;107(12 Pt 1):1590-5. [Medline].
• Lew D, Southwick FS, Montgomery WW. Sphenoid sinusitis. A review of 30 cases. N Engl J Med. Nov 10 1983;309(19):1149-54. [Medline].
• Metson R, Gliklich RE. Endoscopic treatment of sphenoid sinusitis. Otolaryngol Head Neck Surg. Jun 1996;114(6):736-44. [Medline].
• Postma GN, Chole RA, Nemzek WR. Reversible blindness secondary to acute sphenoid sinusitis. Otolaryngol Head Neck Surg. Jun 1995;112(6):742-6. [Medline].
• Sethi DS. Isolated sphenoid lesions: diagnosis and management. Otolaryngol Head Neck Surg. May 1999;120(5):730-6. [Medline].
• Stankiewicz JA. The endoscopic approach to the sphenoid sinus. Laryngoscope. Feb 1989;99(2):218-21. [Medline].
• Tan HK, Ong YK. Acute isolated sphenoid sinusitis. Ann Acad Med Singaore. 2004;33(5):656-659.
• Turgut S, Ozcan KM, Celikkanat S. Isolated sphenoid sinusitis. Rhinology. Sep 1997;35(3):132-5. [Medline].
• Weiss RL, Bailey BJ. Approaches to the sphenoid. In: Bailey BJ, ed. Head and Neck Surgery - Otolaryngology. 2nd ed. Philadelphia, Pa:. Lippincott-Raven;1998:485-495.

Article Last Updated: Dec 20, 2006