Hypoplasia of Fourth Part of Vertebral Artery and Its Clinical Significance.

Introduction: The anatomical and morphological variation of vertebral artery has clinical importance not only to the performance of interventional or surgical procedure itself but also to ensure circulation to the hindbrain. Aim of the Study: To analyze the morphological and morphometric variations of the fourth part of vertebral arteries. Materials and Methods: The present study was conducted in the Department of Anatomy, Vinayaka Mission's Kirupananda Variyar Medical College and Hospitals, Salem, Tamil Nadu, India. Fifteen adult human brains' specimens acquired from embalmed human cadavers were utilized for the study. Morphology and morphometric analysis of the fourth part of vertebral arteries were done to demonstrate the variations. Vernier caliper was used for morphometric analysis. Results: The mean diameter of the fourth part of the left vertebral artery has been larger in size than the right vertebral artery with a mean of 2.55 mm ± 0.30 mm. In one specimen, the fourth part of the left vertebral artery was very narrow with a diameter of 0.1 mm and the right vertebral artery measured 0.4 mm. Conclusion: Hypoplasia of the fourth part of the vertebral artery is a contributing factor in acute ischemia of the brain. Morphological variations of the vertebral artery are considered as an etiological factor for conditions such as atherosclerosis, infarction, vascular malformations, transient ischemic attack and syndromes such as Wallenberg's and Medial Medullary syndrome. Vascular variations usually subject for controversy, and detailed knowledge of such variations serves as a key role in procedures such as magnetic resonance imaging, computed tomography, and neurovascular surgeries. The study will be done extensively to support the anatomical and morphological variations of vertebral arteries to make fruitful clinical implications.