Electroencephalogram and cerebral blood flow diagram:
The discharge phenomenon of brain nerve cells is called EEG, which is detected and amplified by electronic instruments, and the pattern recorded is EEG. EEG examination has its unique value in the diagnosis of epilepsy. Abnormal changes of EEG will also occur in the process of stroke.
For example, the EEG in the acute phase of cerebral hemorrhage often shows generalized high amplitude slow waves, and then the focal area is limited δ Wave. Subarachnoid hemorrhage, common α The wave slows down, the wave amplitude decreases, and the dispersion appears δ Wave.
Cerebral infarction has different EEG changes according to its infarct location. The internal carotid artery system is occluded, and the EEG shows that the innervation area of the middle cerebral artery appears δ Wave sum θ Wave, mainly on the ipsilateral side, but also on the contralateral side; Middle cerebral artery occlusion can have significant slow waves on the side of the lesion for a long time or no change in EEG; The occlusion of anterior and posterior cerebral arteries may have localized EEG abnormalities, but they are mild; Basilar artery occlusion showed normal EEG.
Cerebral blood flow diagram, also known as electroencephalogram, can indirectly judge the blood flow by tracing the changes of vascular impedance. When internal carotid artery thrombosis occurs in stroke patients, it can affect the cerebral blood flow diagram, and the wave flag on the lesion side is low, and the double beat wave is reduced or disappeared. When the common carotid artery on the diseased side was compressed, the amplitude of the diseased side did not change, while when the common carotid artery on the uninjured side was compressed, the amplitude of the diseased side further decreased.
The development of the electroencephalogram (EEG) and cerebral blood flow (CBF)
The development of the electroencephalogram (EEG) and cerebral blood flow (CBF) measurement techniques has been a journey of scientific discovery and technological advancement, each contributing to our understanding of brain function and pathology.
Electroencephalogram (EEG):
The history of EEG traces back to the early 20th century when scientists first began to explore the electrical activity of the brain. In 1924, German psychiatrist and physiologist Hans Berger made a breakthrough by recording the first human EEG. Berger’s work was based on earlier discoveries by British scientist Richard Caton, who in 1875 observed and recorded electrical phenomena of the brain using animals.
Berger’s invention allowed for the non-invasive monitoring of brain waves, which are fluctuations in voltage caused by the electrical activity of neurons. His initial recordings were of alpha waves, a type of brainwave associated with relaxation. Over the years, the technology has evolved, with improvements in electrode design, signal amplification, and data analysis techniques. The introduction of computerized systems in the 1960s and 1970s further enhanced the sensitivity and resolution of EEG, making it a valuable tool in clinical settings for diagnosing epilepsy, sleep disorders, and other neurological conditions.
Cerebral Blood Flow (CBF):
The study of cerebral blood flow has a similarly rich history, with early investigations focusing on the mechanisms of blood supply to the brain. In the 19th century, French physiologist Claude Bernard made significant contributions to the understanding of the vascular system and the role of blood in maintaining homeostasis.
Modern techniques for measuring CBF began to emerge in the mid-20th century. One of the earliest methods involved the use of radioactive isotopes, which were injected into the bloodstream and their passage through the brain monitored. This technique, known as radioactive xenon inhalation, provided a way to estimate regional CBF.
In the 1970s, the development of positron emission tomography (PET) and later, functional magnetic resonance imaging (fMRI) revolutionized the field. These imaging techniques allow for non-invasive, real-time visualization of blood flow and oxygenation changes in the brain, providing insights into brain function and metabolism. PET uses radioactive tracers to map blood flow, while fMRI measures changes in blood oxygenation level dependent (BOLD) signals, which are related to neural activity and blood flow.
Both EEG and CBF measurement techniques continue to evolve, with ongoing research focusing on improving spatial and temporal resolution, enhancing the understanding of brain dynamics, and developing new applications in clinical practice and research. These technologies are crucial for advancing our knowledge of brain disorders and for developing more effective treatments.
