Endoscopic Transnasal Neurosurgery

Author: ,

Endoscopic surgery of the pituitary gland, sella turcica, clivus and anterior skull base

The limited possibilities of microsurgery in terms of illumination, depth of field, and vision are especially pronounced in the process of transnasal/transsphenoidal access to the pituitary gland, the sella turcica, and the clivus: we are talking about a narrow, associated with the anatomical boundaries of the nasal cavity, access to processes at a depth (as a rule, more than 10 cm), which, moreover, are often not illuminated and not reached along a straight optical line, but spread at an angle of 30 to 45 degrees (!) to the transnasal approach, such as, for example, pituitary tumors. The processes can develop in this case both parasellar and retrosellar or, in the case of tumors of the clivus, stretch laterally. The limited part of the light reaching the depth in the forward direction and the shallow depth of field of the microscope at the required high magnification necessitate a microscopic invasive "binasal" transseptal approach through cleavage of the nasal septum, which in 30% of patients leads partly to prolonged postoperative complaints (complaints associated with the necessary nasal tamponade, nasal breathing disorders, nosebleeds, hyperemia, anosmia). Perforation of the nasal septum, which occurs in over 10% of all cases, complicates follow-up control, and therefore ENT specialists avoid transseptal access in favor of the endoscopic method.

The sublabial method using upper lip anesthesia is obsolete from a microsurgical point of view.

In this case, endoscopy has a decisive advantage in terms of the least ("adequate") invasiveness with the maximum surgical efficiency: endoscopically, mononasal access is possible; atraumatic surgery through the existing, slightly stretched normal nasal cavity, without the need to dissect the nasal septum and traumatize the mucous tissue or perform resection. Through the sinus of the sphenoid bone, to which there is easy and quick access, tumors of the pituitary gland and the area adjacent to the sella turcica, as well as the anterior part of the clivus (or transethmoid area) and the midline of the anterior base of the skull, except the sinus frontalis, give an ideal endoscopic image. With instruments very similar to microsurgical ones, and thanks to a better view, and even more radical treatment of pathologies is possible, while at the same time more gentle conditions for anatomical structures: with the help of optics with an angle of 30 * and 45 ° degrees, capable of 180 ° rotation, a view is possible under an angle of 180 ° "around the corner", while the suprasellar proliferation of pituitary tumors, as well as lateral tumor remnants, even behind the carotid artery (a. carotis) are radically removed under the supervision and under sparing conditions for the diaphragm of the Turkish saddle (diaphragma sellae). Further, endoscopy will allow for the reconstruction of open cavities (base of the sella turcica, sinuses of the sphenoid bone, frontal basal defects) and restoration of the intranasal space; tamponades that cause discomfort to patients become unnecessary, and the patient's hospitalization time is reduced.

The complexity of the endoscopic method of neurosurgical surgery lies, especially at the initial stage, in the fact that it is necessary to operate "bypassing the endoscope": to achieve accuracy, the endoscope must be fixed with a holder at an ideal working distance in front of the lesion, so that there is no need to constantly hold it in one hand and with the help of instruments, insert and remove (danger of damage to the mucous tissue, deliberate inaccuracy in the static position of the hand). Therefore, we use optics with an eyepiece directed into the sector that is already difficult to manipulate due to the optical fiber cable and work with bayonet-shaped instruments that can be kept at a distance from the endoscope. Therefore, these instruments should have bent in both directions (0 ° and 180 °, if necessary 90 °) instrumental heads (dissectors, chisels, curettes), since only one side of the fixed endoscope can be operated (i.e., the right side of the leading hands of a neurosurgeon).

In contrast to other comparative methods of transnasal endoscopic operations according to JHO and CAPPABIANCA, we, therefore, prefer the use of a speculum for nasal access, which specifically meets the endoscopic and mononasal requirements: slight roundness, if necessary using a blunt trocar, makes it possible to insert the instrument nasally up to the sphenoid bone ( control transillumination or neuronavigation!) without injury to the mucous membrane or resection of the turbinate. After visualization of the base of the sphenoid bone, only the posterior bony part of the nasal septum (adjacent to the base of the sphenoid bone) is broken to the opposite side through the mirror hole. By positioning the mirror (lateral X-ray position control), a quick change of instruments and optics is possible without contact with the mucous tissue and, accordingly, without the risk of bleeding; the mucous tissue at the base of the sinus of the sphenoid bone is only pulled, not removed, and finally takes its previous position. Then, in the same way, the nasal septum is placed in its original place (starting from the opposite side of the nasal cavity, using the little finger or dissector).

The operation in the clivus is carried out similarly, however, through an autopsy under the sella turcica, for which, in addition to a drill, an ultrasound system developed by us can be used, thanks to which it is possible to remove pituitary tumors, pathological processes in the clivus and tumors of the anterior skull base in a gentle manner. While liquorrhea from the sella turcica can in most cases be closed by periumbilical fat, resections in the anterior base of the skull, as well as the treatment of frontal basal fractures, require more laborious reconstruction involving fascia, muscles, and an artificial meninges.