Endoscopic endonasal surgery: New perspectives in recurrent and residual pituitary adenomas

The study by Alahmadi et al. discusses the suitability of the endoscopic endonasal approach in recurrent or residual tumors and compares the endoscopic approach with the previous microscopic approach, suggesting that inadequate exposure is a cause of incomplete tumor removal. With regard to the first point, the conclusions of Alahmadi et al., supported by their experience, are noteworthy; endoscopic endonasal surgery is safe and effective, and the low complication rate encourages its use in reinterventions. Reinterventions using the microscopic transseptal approach may be difficult right from the beginning of the procedure. The scarring process may make the septal route extremely difficult, leading to a chain of errors that, in association with the anatomic distortion, may favor disorientation. Conversely, the endoscopic technique is an endonasal procedure and is not affected by septal problems resulting from previous surgery. Furthermore, the learning curve of endoscopic surgeons depends on the knowledge of the anatomy of the region. Anatomic knowledge, associated with the panoramic view of the endoscope, which allows the exposure of many anatomic landmarks, is of paramount importance in avoiding errors of orientation. These are the main reasons why the endoscopic technique is more suitable for reinterventions. Instruments, such as a navigation system can help in anatomic orientation. However, in our opinion, to be used safely, it should not serve as a substitute for anatomic knowledge, but as a confirmation of previous anatomic recognition. The second point, the comparison of the endoscopic with the microscopic approach, is more open to criticism. We agree with the remark that limited exposure, sphenoidal and/or sellar, is a factor favoring the incomplete removal of primary adenomas. However, this defect is not exclusive to the microscopic approach. A comparison between the endoscopic and the microscopic technique based on cases with incomplete tumor resection is misleading. In agreement with Alahmadi et al., these microscopic cases are not to be considered representative of the microscopic approach in general. In addition to the debatable comparison, the fact remains that inadequate exposure, sphenoidal and/or sellar, is an error regardless of the technique. Concerning the results of the study it is surprising that, even when correct exposure was obtained in residual tumors, gross total removal was obtained in only 41% of the cases, whereas in recurrent tumors, the percentage of removal was 70%. Therefore, it appears that surgical management of an adenoma with aggressive behavior inducing a true recurrence may be more satisfactory than the surgical management of a tumor remnant, independent of its biology. This discrepancy may be partially explained by assuming that the residual tumors were mainly located in the cavernous sinus and keeping in mind that Alahmadi et al. refrained from surgery in the cavernous sinus. Nevertheless, if surgery was carried out, it means that components within the cavernous sinus were symptomatic and/or were growing, even if radiosurgical treatment was carried out. If and when this occurs, the chance to resect the tumor is less than 50%. Therefore, every effort should be made to prevent this severe condition. We are against not operating in the cavernous sinus in the case of pituitary adenomas. We believe that radiosurgery is a useful procedure. However, we believe that it should follow resection of the tumor but not be used as a substitute for this procedure. The abstention, which we criticize, is the consequence of disillusionment after the morbidity observed 30 years ago when craniotomic cavernous sinus surgery was in vogue. Since that time, great improvement in knowledge, technique, and instrumentation has occurred. We have learned that, in selected patients, cavernous sinus surgery is safe and effective (1). Selection criteria depend on the nature of the tumor and its location with respect to the dural plane. Adenomas are the prototype of tumors amenable to surgery because they do not infiltrate vessels and/or nerves, and because they are generally soft and removable by simple suction. Furthermore, when a parasellar tumor is extradural, it can be resected using an extradural approach, such as the endoscopic extended transsphenoidal approach, which is a minimally invasive approach. Returning to the excellent study of Alahmadi et al., some operative suggestions are useful to improve the surgical management of residual and recurrent pituitary adenomas. Furthermore, it points out the poorer surgical outcome of remnants with respect to recurrences, particularly if located in the cavernous sinus. This suggestion may contribute to changing the prevailing attitude toward surgery in the cavernous sinus; lack of intervention is not justifiable owing to the current innovations in this type of surgery, especially after the advent of extended endoscopic endonasal surgery.