Endoscopic anatomical study on anterior communicating artery aneurysm surgery by endonasal transphenoidal approach

The study provide the anatomic basis for endonasal transphenoidal approach of anterior
communicating artery aneurysm clipping by neuroendoscopy. The approach is significant
and can be applied to clinic widely for several reasons: Firstly, endonasal transphenoidal
approach by neuroendoscopy is more minimally invasive, and it can both relieve the
pain and shorten the hospitalization time, most of all, it can reduce the postoperative
complications. Secondly, neuroedoscopy can provide a more broad and clear surgical
field, which can be safer than microscope operative surgery. Thirdly, the rupture
of intracranial aneurysm occupies the third in cerebral vascular accident, second
to cerebral thrombosis and cerebral hemorrhage of hypertension. According to statistics,
more than 80 % of spontaneous subarachnoid hemorrhage is caused by aneurysm rupture.
While accident of anterior communicating artery aneurysm is about 35 % of intracranial
aneurysms 6], 7].

Anterior communicating artery has important physiological functions, it can balance
and compensate blood flow between bilateral hemispheres. Anterior communicating artery
is adjacent to the third ventricle, hypothalamus, optic chiasm, and Heubner artery
and other important structures. If any important structure injured in surgery, it
can lead to serious complications, such as dysfunction, coma or even death. The most
popular craniotomy approach for anterior communicating artery aneurysm is pterional
and interhemispheric approach. Pterional approach is fit for exposing A1 and blocking
blood flow conveniently in surgery. Interhemispheric approach is fit for anterior
communicating artery aneurysm pointing to the rear and front. Both of them have their
limitations and surgical injury. The pterional requires separation of sylvian fissure,
pulling the frontal lobe, or even removal of part gyrus rectus to complete the surgery,
and damage to gyrus rectus can cause the recent memory impairment 8]. Li JP, Zhao JZ and Wang S report 59 patients with surgical clipping of anterior
communicating artery aneurysm of which 12 (20.34 %) patients have different parts
of the brain tissue infarction 9].

In recent years, as the endoscopic techniques become mature and the equipments improve
better, we find that transsphenoidal surgery is much better than craniotomy 10], and begin to resect sellar tumors transsphenoidal approach with neuroendoscopy 11]–14]. Based on anatomical study, we found that it is easy to get to the sellar region
and observe the important structures clearly. There are several advantages of endoscopic
endonasal transphenoidal surgery for anterior communicating artery aneurysm. Firstly,
avoid scars caused by craniotomy. Secondly, no need to stretch or resect the brain.
Thirdly, by neuroendoscopy we can clearly observe the optic nerve, optic chiasm, cisterna
lamina terminalis, bilateral arteriae cerebri anterior, part of frontal lobe gyri
rectus and the anterior communicating artery complex. So after blocking A1 of anterior
cerebral artery, we can clearly see the anterior communicating artery complex and
clip the aneurysm safely. But there are also some problems of the endoscopic endonasal
transphenoidal surgery for clipping of anterior communicating artery aneurysm. Firstly,
Postoperative cerebrospinal fluid rhinorrhea: The closure of dura is very important
in operation, despite the skull base reconstruction can prevent the occurrence of
cerebrospinal fluid rhinorrhea 15], inevitably some patients still have this complication. For these patients, we can
take some measures, such as lumbosacral cerebrospinal fluid external drainage, strengthen
anti-infective therapy, most of them can be cured. If these treatments were ineffective,
cerebrospinal fluid rhinorrhea repair can be considered. Secondly, select indications
for surgery strictly. If the top of anterior communicating artery aneurysm points
to anterior inferior, this surgical approach can get to the top of anterior communicating
artery aneurysm firstly, so it is difficult to control bleeding when the aneurysm
rupture. If the top of anterior communicating artery aneurysm points to posterosuperior,
it is difficult to see the surrounding vital structures of aneurysm. If decompressive
craniectomy or haematoma elimination is needed, we should consider carefully in accordance
with the patient. Thirdly, it is difficult to control bleeding, so cooperation and
special equipments should be required in surgery. Such as special plier can help place
aneurysm clip on it, and endoscope holder can help liberate the hands of operator.