RESUMO
Background: Vertebral artery is a medium sized artery which has long, tortuous course through neck and cranium.It is highly protected by bony and muscular structures because it provides the vascularization to importantintracranial structures. During cervical spine movements, it is exposed to large shear and tensile forces at theexit from second cervical vertebra. A reduction in blood flow in vertebral artery may occur due to many congenitaland structural factors which will cause ischemia and various neurological symptoms. Vertebral artery tearsafter blows to the head and neck are usually associated with basal subarachnoid haemorrhage with a rapidlyfatal outcome. Aim of study was to study histomorphometric variations in four segments of vertebral artery.Material and methods: All four segments of vertebral arteries each having 0.5 cm long of both sides werecollected from 30 cadavers. Outer and inner diameters were measured. Tissues were processed and stained byVerhoeff’s Van Geison and Masson Trichrome. Slides were scanned by “IS capture software” under 10 Xmagnifications.Results: Outer diameter of left vertebral artery was 3.598± 0.32mm and that of right was 3.286± 0.33mm. Innerdiameter of left vertebral artery was 3.19± 0.30 mm and right was 2.86± 0.26mm. Diameter of 1st and 3rd part ofvertebral artery was more than 2nd and 4th part. Internal elastic lamina was thick and prominent in 4th part.External elastic membrane was prominent in 1st, 2nd, and 3rd part, but it is completely absent or represented bysparse fibrils in 4th part of vertebral artery.Conclusion: Left vertebral artery was found to be dominant than the right.Internal elastic lamina was mainelastic constituent of 4th part of vertebral artery, so damage to it may cause vascular pathologies likeatherosclerosis, aneurysm etc.
RESUMO
The bipolar coagulator has been frequently used in reducing the size of aneurismal neck or dissecting the aneurismal sac. However the effects of bipolar current on the wall of vessels have not been adequately documented. The author studied the histopathological changes of the renal arterial wall after bipolar coagulation. Thirty one Sprague-Dawley strain rats of both sexes and of various age were used. Under penthobarbital anesthesia, the left renal artery was coagulated with bipolar forcep just distal to it's origin from the aorta. The rats were divided into two groups:Group A was coagulated for two seconds:Group B for one second. The coagulation sites of vessels were examined grossly and microscopically in three and six months, respectively. The results were summarized as followings: 1) In both three and six months groups:the internal elastic membrane and elastic fibers were destructed, fragmented and thinned;the medial smooth muscle cells were damaged and decreased in number. 2) While the endothelial cells were severely desquamated and scattered in three months group, but there was an evidence of partial regeneration of endothelium and reduction of inflammatory reaction in six months group. Fibrosis was more augmented in six month group than three month group. 3) Between group A and B, There weemed to be no definite discrepancy in histopathological findings. 4) Pseudoaneurysms were developed in 72.2% of three months group and in 61.5% of six months group, but there was no significant statistical difference in the rate of pseudoaneurysm formation between the two groups(p>0.05, chi2=0.393). 5) Above findings suggest that the pseudoaneurysm which might be produced by bipolar coagulation of vessels in the neurosurgical operation, would be progressed to the true aneurysm if continuous hemodynamic factors are exerted upon the pseudoaneurysm. Therefore, it is desirable that the bipolar current should be used very catiously during the surgery of cerebrovascular disease.