Anatomy of Neck and Blood Supply of Brain
Sudhir K. Gupta in Forensic Pathology of Asphyxial Deaths, 2022
The carotid arterial system and the vertebral arterial system (Figures 2.35 and 2.36) contribute to the arterial blood supply of the brain. Left and right common carotid arteries arise from arch of aorta and brachiocephalic trunk respectively. At the superior border of thyroid cartilage, external and internal carotid arteries arise from the common carotid arteries, with the internal carotid being more medially placed. The internal carotid artery in its intracranial course divides into anterior and middle a cerebral artery which provides the anterior cerebral circulation of brain. The posterior cerebral circulation is mainly by the vertebral arteries. Vertebral arteries traverse the foramen transversarium of cervical vertebra and enter the skull through the foramen magnum where they join to form the basilar artery and posterior cerebral arteries are their terminal branches.
Central nervous system
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha in Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
The brain is supplied with blood from two sources. The bilateral internal carotid arteries arise from the bifurcation of the common carotid arteries in the neck and branch off to form the left and right anterior and middle cerebral arteries, which supply the forebrain. The vertebral arteries arise from the subclavian arteries and come together at the level of the pons to form the midline basilar artery. The posterior cerebral, basilar and vertebral arteries supply the posterior circulation of the brain, comprising posterior cortex, the midbrain and the brainstem. Cerebellum is also supplied by dorsolateral arteries such as the posterior inferior cerebellar artery (PICA) and the anterior inferior cerebellar artery (AICA) and superior cerebellar artery. An arterial ring called the circle of Willis connects the anterior and posterior cerebral circulation; thus, in the event of loss of blood supply to one area of the brain, it may be possible for blood to be supplied via a different arterial route.
Cerebrovascular Disease
John W. Scadding, Nicholas A. Losseff in Clinical Neurology, 2011
Stroke can be defined as a focal neurological deficit resulting from a disturbance of the cerebral circulation lasting more than 24 hours (or causing early death). Transient ischaemic attack (TIA) is defined identically, except that the symptoms last less than 24 hours. This timing distinction is completely arbitrary and significantly out of date. An alternative description has been proposed which requires acute imaging, preferably magnetic resonance imaging (MRI), to exclude an infarct as a cause of the transient symptoms. In this definition, if the brain scan shows a relevant acute infarct, then the event is called an ‘ischaemic stroke’, however short the duration of the symptoms. The latter definition is widely used in research studies, but is not currently common in clinical use.
Ocular ischaemia: signs, symptoms, and clinical considerations for primary eye care practitioners
Published in Clinical and Experimental Optometry, 2022
Michael Kalloniatis, Henrietta Wang, Paula Katalinic, Angelica Ly, Warren Apel, Lisa Nivison-Smith, Katherine F Kalloniatis
Cerebral circulation is maintained through an efficient blood supply involving the carotid and vertebral arteries and anastomoses forming the Circle of Willis. The sequelae of impaired cerebral circulation leads to transient ischaemic attacks (TIA) or completed strokes: both events are serious medical conditions. Based on the Classification and Outline of Cerebrovascular Diseases II,7 completed strokes are defined as prolonged neurological deficit that are relatively stable with a duration of over three weeks. On the other hand, TIAs were previously defined as brief episodes of focal cerebral ischaemia lasting less than 24 hours and not associated with a permanent infarct.8 Studies showed that 30-50% of the TIAs within the 24-hour time frame had brain injury in MRI studies and a new definition was developed: ‘a brief episode of neurological dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of acute infarction’.9–11 However, even the new proposed definition had a one-hour time frame and may not accurately distinguish between patients with or without acute cerebral infarction and thus the writing committee endorsed the revised definition for a TIA as ‘a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction’.11 Based upon the new TIA definition, an ischaemic stroke is ‘an infarction of central nervous system tissue’.11 Unlike TIAs, ischaemic strokes may be symptomatic or silent.
Variability across countries for brain death determination in adults
Published in Brain Injury, 2023
Fang Yuan, Huiping Li, Tao Pan, Wanxin Wen, Lixin Wang, Shibiao Wu
Somatosensory evoked potentials (SEPs) test examines lemniscal pathways in the hemispheres and brainstem, and it was reported to be a reliable test for brain death determination with a sensitivity of 87.4%-100% (18–20). The examination of cerebral circulation provides an alternative evaluation of brain function. TCD is recognized as one of the three confirmatory tests in Chinese criteria of brain death. However, TCD is reported to a lower sensitivity (73%-78%) than EEG and SEPs (19,21). The diagnostic performance of ancillary tests may vary depending on the criteria of brain death in different countries, but our study suggests that such differences are small. Although we reported a higher sensitivity of 84.3%-86.0% for TCD, our finding that EEG and SEP have higher sensitivities than TCD is consistent with previous studies (19,21). Therefore, the results of EEG and SEP results should be given more weight than TCD, whether in China, USA, or Europe. Besides, TCD is limited by the penetrability of transtemporal windows and interexaminer variability. MR and CT angiography were proposed to assist brain death determination (22,23). However, angiography requires higher cost and the transfer of patients out of intensive care unit which generates potential safety hazards.
A study of oxidative stress in migraine with special reference to prophylactic therapy
Published in International Journal of Neuroscience, 2018
Gyanesh M. Tripathi, Jayantee Kalita, Usha K. Misra
The pathophysiology of migraine involves CSD, neurogenic inflammation and vasodilatation. Vasoactive controls of cerebral microcirculation are modulated by the release of oxygen free radicals which may play a role in migraine pathophysiology. Products of oxygen metabolism such as hydrogen peroxide and hydroxyl radicals may mediate some physiological vasodilator responses in cerebral circulation. Aura is regarded to be due to vasoconstriction and cortical hypoxia [21]. In our study, the patients with migraine with aura had higher level of oxidative stress evidenced by significantly increased LPO levels but the levels of antioxidants GSH, GST and TAC were not significantly altered. The role of oxidative stress at the time of aura has been reported by only a few studies [21,33]. Migraine with aura is less common in Indian patients compared to Western (3% vs. 30%) [35], which may be due to genetic differences.