Surgical Anatomy of the Vertebrobasilar Territory and Posterior Circle of Willis

BACKGROUND: In the present era of microscopic and neuroendoscopic procedures; the surgical anatomy of the skull base vessels has gained increased significance. The pattern of the vertebrobasilar arterial complex and the posterior circle of Willis (COW) in Nigerians has not been previously reported despite various variants of these complexes existing in different populations. OBJECTIVE: To review and document the size; distribution and anomalies of the vertebrobasilar territory and posterior COW pattern in a Nigerian set of brains. Methods: The target population for this study was a group of Nigerian adults 18 years and above. Specimens from patients with an ante-mortem or post-mortem evidence of meningitis or atherosclerosis were excluded. The size; distribution and anomalies of the vertebrobasilar artery; its branches; and the posterior COW were defined in 50 brains. RESULTS: The male: female ratio was 1.9:1 and a mean age of 44 years. Statistical analysis showed significant differences between the sizes of posterior inferior cerebellar arteries and anterior inferior cerebellar arteries (Student's t = -30.189; p-value = 0.000). Fifty-six percent of the brains had no anomalies. Thirty anomalies were noted in posterior COW compared with six in the vertebrobasilar territory. There were no aneurysms in all the specimens studied. CONCLUSION: Anomalies in the region of the posterior COW are commoner than the vertebrobasilar territory and the region of the posterior communicating artery is the most common site of anomalies in the posterior COW territory. These variations should be taken into account during skull base and carotid surgeries; and cerebral angiography

Intrascrotal anomalies related to testicular torsion in nigerians: an anatomical study

Objective: The abnormalities that predispose to torsion are often bilateral. They include horizontally lying testis; bell-clapper deformity (BCD); long mesorchium; well-developed spiral cremasteric muscle and ectopic testis. The pattern and incidence of intrascrotal anomalies that predispose to testicular anomalies in Nigerians have not been studied. Our objective was to define and document this. Material and Methods: The scrotal sacs of fifty cadaver scrotums and inguinal canals from patients aged between 35 and 57 years (mean age: 42 years) were examined. The parameters studied were the location (scrotal or canalicular); alignment (horizontal; vertical); mesorchium (height and width); cremasteric muscle development (well or poorly developed) and parietal tunica vaginalis investment of the testis (normal; intermediate or BCD). Results: Forty-nine testes had descended to the scrotal position; all were anchored by the ligamentum testis. The canalicular position was noted to be present in one cadaver. Forty-eight testes lay vertically. 16of the testes had BCD; while intermediate tunica investment was noted in 12. The most common type of epididymal and testicular relationship was Type I (84). The mesorchium was normal in all specimens examined. Conclusion: The most common anomaly in our study was that of tunica investment; and this is usually bilateral. The need for bilateral orchiopexy in cases of testicular torsion is further strengthened since the anatomic anomalies are usually bilateral