Introduction:
The sphenoid bone is the pivotal facial bone that occupies central importance regarding the clinical aspects of all skull base surgeries in the field of oral and maxillofacial surgery. The sphenoid sinus is a hollow and important vital structure of the facial skeleton that is present only in primates. This sinus tends to develop and complete its formation postnatally, reaching its complete adult size usually by the age of 12 years in the case of humans. The extent of pneumatization of the sinus is highly variable based on individual facial structure and the weight of the facial skeleton in individuals. During functional endoscopic surgeries, the endoscopic surgeon or the maxillofacial surgeon often has to approach the boundaries of the sella turcica (a cavity present in sphenoid bone). The different important anatomical structures like the optic nerve (nerve to the eye), planum sphenoidal (front part of the sphenoid bone), tuberculum, or the lateral sellar orbital junction are located near this area. Because of its proximity to surrounding vital nerve structures and sinuses such as the optic nerve, vidian nerve (nerve of the pterygoid canal), maxillary nerve (nerve to the upper jaw bone), oculomotor nerve (nerve to the eyeballs), trochlear nerve (nerve to the eyeballs), and abducens nerves (the sixth cranial nerve), great care is taken on behalf of the endoscopic or maxillofacial surgeon while performing a routine adenoidectomy (surgery to remove adenoid glands) procedure or surgeries such as rhinosinusitis (surgery for infected sinus lining) surgeries or for eliminating skull base lesions or tumors. During surgical procedures, there is a chance of leakage of cerebrospinal fluid. Also, the cavernous sinuses and the internal carotid arteries, which are the major structures in the human skull present close to this region. These are the focal points from which untreated lesions can spread in affected patients; even cancers can spread at a faster pace than in the other parts of the body.
What Are the Symptoms of Sphenoid Sinus Pathologies?
The pathologies that occur in the sphenoid sinus itself are quite rare or uncommon. In very rare cases where isolated pathologies are occurring specifically only in the sphenoid sinus. The patients would usually complain of the following clinical symptoms or presentations, such as
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Nasal discharge.
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Post nasal drip.
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Headaches of varying intensity or other non-specific symptoms of the head and neck region.
potential complications of leaving sphenoidal sinusitis infections can lead to the development of a range of lesions, from simple mucocele to skull base lesions or lesions spreading up to or involving the cavernous sinus or even cranial neuropathies.
How to Evaluate Sphenoid Sinus?
As per current research, the primary tumors or cancers that originate or occur in the sphenoid sinus itself are quite rare as per case reports. Most often, it may be the adjoining or secondary cancers or tumors that are invading the sphenoid sinus.
Such serious or chronic lesions can be detected by the modality of a multidetector computed tomography (CT) scan or through magnetic resonance imaging (MRI). These are the two major imaging modalities that are currently used in the diagnosis of any lesions about the sphenoid sinus and also hold crucial importance in monitoring the patient's health status by preventing post-operative complications (after surgical intervention).
How to Access Sphenoid Sinus?
In comparison to rhinosinusitis surgeries that require the surgeon to have a broad visualization of skull base structures, sphenoidotomy (minimally invasive surgery for sphenoid sinus) which is recommended only for sphenoid sinus or adjacent anatomic disturbances, lesions, or diseases requires very minimal surgical intervention by the endoscopic, oral, and maxillofacial surgeon. To access any skull base lesions near the sphenoid bone or the sinus, the surgeon would usually require a minimal visual field of the interspinous septum and the skull base. neuroendoscopic procedures often require the elimination of bone present within the sphenoid sinus to access the skull base.
How to Prevent Injury During Surgical Procedures?
Functional endoscopic sinus surgery is one of the most common surgical procedures and is much more likely to injure the anatomical vital structures that are present adjacent to the sphenoid sinus. Furthermore, based on the individual facial skeleton, the degree of pneumatization of the sphenoid sinus would tend to vary from individual to individual. Hence, dental surgeons recommend a detailed CBCT (cone-beam computed tomography) sinus examination, which is the most suitable radiographic modality for studying these anatomic variations. This helps understand the regional sinus anatomy of the individual to avoid pre and post-surgical complications. In modern-day dentistry, cone-beam computed tomography (CBCT) is the most convenient and suitable modality either for assessment of the sinus anatomy, for presurgical planning or placement of dental implants, for treatment of facial sinuses, or even for studying or analyzing and diagnosing the infections of the orofacial region.
Because the sphenoid sinus is primarily located quite deep in the skull and has vital nerve and sinus boundaries, compared to the remaining sinuses of the face such as the frontal, ethmoidal, or maxillary sinus (that are more accessible in terms of surgical approach), the sphenoid sinus usually remains a complicated and partially inaccessible paranasal sinus. The vital structures of the internal carotid artery (ICA), optic nerve (ON), and vidian canals (VC) are always considered, and their boundaries are identified and studied before the maxillofacial surgeon performs the required surgical procedure on the affected patient. Iatrogenic injuries to the sinus wall or the boundaries of the sinus or a breach in the anatomic structures call for immediate or emergency management to prevent post-operative complications and functional disabilities in the patients. The priority in any approach to the sphenoid sinus is, hence, firstly, safe access to the sella, which is in turn influenced by the pattern of pneumatization within the sphenoid sinus. It is also important to note that recurrent or chronic sinusitis infections are easily caused in many individuals owing to these anatomic variations.
Conclusion:
Hence, it is conclusive as per medical research currently that surgical intervention is required to eliminate the skull base lesions or infections or diseases of the surrounding anatomic structures to the sphenoid sinus. Such procedures are a clinical challenge to the endoscopic or the maxillofacial surgeon. Care should also be taken by the maxillofacial surgeon or the endoscopic surgeon to avoid any sort of injury to the lateral, posterior, or superior walls of the sphenoid sinus. This is because it can pose the greatest risk of an inadvertent leak of cerebrospinal fluid (CSF). It is these anatomical variations of the sphenoid sinus that pose the greatest complexity to the maxillofacial surgeon in terms of approach.
