Endoscopic Skull Base Surgery
Skull base surgery has been transformed by the development of endoscopic endonasal surgery. These techniques were initially developed for paranasal sinus surgery, but their indications have been gradually extended to include endoscopic resection of pituitary tumours, and then lesions of the clivus, olfactory cleft, planum sphenoidale, but also the petrous apex, or infratemporal fossa.
Endoscopic endonasal surgery provides access to almost all regions of the skull base situated anterior to the foramen magnum Tumours are the lesions primarily concerned, but cerebrospinal fluid (CSF) leaks of traumatic or other origin, certain chronic infections and congenital malformations are also accessible to endoscopic surgery.
The use of endoscopic techniques in the management of benign tumours: pituitary adenomas, craniopharyngiomas, but also inverted papillomas and nasopharyngeal fibromas, cholesterol granuloma of the petrous apex and petrous apicitis, congenital malformations (meningoencephaloceles), or CSF leaks.
- Excellent three dimensional view
- Easy manipulation of zoom and focus features
- Speculum protects the mucosa from instruments injury
- Better manipulability of instruments
Facial pain, Headache, Dizziness, Visual problems, Numbness, Weakness of the face, Hearing loss or ringing in the ears, Nasal congestion, or frequent sinus infections.
For endoscopic endonasal surgery, rigid rod-lens endoscopes are used for better quality of vision, since these endoscopes are smaller than the normal endoscope. The endoscope has an eyepiece for the surgeon, but it is rarely used because it requires the surgeon to be in a fixed position. Instead, a video camera broadcasts the image to a monitor that shows the surgical field.
Surgical approaches to the anterior skull base
The transnasal approach is used when the surgeon needs to access the roof of the nasal cavity, the clivus, or the odontoid. This approach is used to remove chordomas, chondrosarcoma, inflammatory lesions of the clivus, or metastasis in the cervical spine region. The anterior septum or posterior septum is removed so that the surgeon can use both sides of the nose. One side can be used for a microscope and the other side for a surgical instrument, or both sides can be used for surgical instruments.
This procedure allows the surgeon to access the sellar space, or sella turcica. The sella is a cradle where the pituitary gland sits. Under normal circumstances, a surgeon would use this approach on a patient with a pituitary adenoma. The surgeon starts with the transnasal approach prior to using the transsphenoidal approach. This allows access to the sphenoid ostium and sphenoid sinus. The sphenoid ostium is located on the anterosuperior surface of the sphenoid sinus. The anterior wall of the sphenoid sinus and the sphenoid rostrumis then removed to allow the surgeon a panoramic view of the surgical area. The lateral approach is then used to reach the medial cavernous sinus and petrous apex. Lastly, the inferior approach is used to reach the superior clivus.
The transpterygoidal approach enters through the posterior edge of the maxillary sinus ostium and posterior wall of the maxillary sinus. This involves penetrating three separate sinus cavities: the ethmoid sinus, thesphenoidal sinus, and the maxillary sinus. Surgeons use this method to reach the cavernous sinus, lateral sphenoid sinus, infra temporal fossa, pterygoid fossa, and the petrous apex. Surgery includes a uninectomy (removal of the osteomeatal complex), a medial maxillectomy (removal of maxilla), a ethmoidectomy (removal of ethmoid cells and/or ethmoid bone), a sphenoidectomy (removal of part of sphenoid), and removal of the maxillary sinus and the palatine bone. The posterior septum is also removed at the beginning to allow use of both nostrils.
This approach makes a surgical corridor from the frontal sinus to the sphenoid sinus. This is done by the complete removal of the ethmoid bone, which allows a surgeon to expose the roof of the ethmoid, and the medial orbital wall. This procedure is often successful in the removal of small encephaloceles of the ethmoid osteomas of the ethmoid sinus wall or small olfactory groove meningiomas. However, with larger tumors or lesions, one of the other approaches listed above is required.