Migraine |
Cortical spreading depression (CSD) or spreading depolarization (SD) is a wave of electrophysiological hyperactivity followed by a wave of inhibition. [3] Spreading depolarization describes a phenomenon characterized by the appearance of depolarization waves of the neurons and neuroglia [4] that propagates across the cortex at a velocity of 1.5–9.5 mm/min. [5] [6] [7] [8]
CSD can be induced by hypoxic conditions and facilitates neuronal death in energy-compromised tissue. [9] CSD has also been implicated in migraine aura, where CSD is assumed to ascend in well-nourished tissue and is typically benign in most cases, although it may increase the probability in migraine patients to develop a stroke. [10]
Spreading depolarization within brainstem tissues regulating functions crucial for life has been implicated in sudden unexpected death in epilepsy, by way of ion channel mutations such as those seen in Dravet syndrome, a particularly severe form of childhood epilepsy that appears to carry an unusually high risk of SUDEP (sudden unexpected death in epilepsy).
Although the terms cortical spreading depression and spreading depolarization are often used as synonyms, a study found spreading depolarizations can produce variable effects on cortical activity in humans and rats, ranging from depressed to booming activity depending on SD depth. [11]
Neuroscientists use the term cortical spreading depression to represent at least one of the following cortical processes:[ citation needed ]
The scintillating scotoma of migraine in humans may be related to the neurophysiologic phenomenon termed the spreading depression of Leão. [13]
Increased extracellular potassium ion concentration and excitatory glutamate contribute to the initiation and propagation of cortical spreading depression, which is the underlying cause of migraine aura. [14]
Chronic daily administration of migraine prophylactic drugs (topiramate, valproate, propranolol, amitriptyline, and methysergide) dose-dependently suppressed frequency of CSD induced by continuous cortical application of 1 M KCl solution. [15] However lamotrigine (a drug with specific anti-aura action, but no efficacy in migraine in general) has a marked suppressive effect which correlates with its rather selective action on the migraine aura. Valproate and riboflavin were shown to have no effect on the triggering of cortical spreading depression though they are effective in migraine without aura. [16] Taken together, these results are compatible with a causal role of cortical spreading depression in migraine with aura, but not in migraine without aura.[ citation needed ]
The folded structure of the cerebral cortex is capable of irregular and complex CSD propagation patterns. The irregularities of the folded cortex and the vasculature promote the presence of re-entrance waves, such as spirals and reverberating waves. [7] The expansion of the wave then is less predictable and it is affected by the concentration of different molecules and gradients on the cortex.[ citation needed ]
Its triggers and propagation mechanisms, as well as clinical manifestations of CSD, are a therapeutic target to reduce brain damage after a stroke or brain lesion. [17] [18] [19]
Migraine is a genetically-influenced complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea and light and sound sensitivity. Other characterizing symptoms may include nausea, vomiting, cognitive dysfunction, allodynia, and dizziness. Exacerbation of headache symptoms during physical activity is another distinguishing feature.
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of neural integration in the central nervous system, and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is the part of the brain responsible for cognition.
Alice in Wonderland Syndrome (AIWS), also known as Todd's Syndrome or Dysmetropsia, is a neurological disorder that distorts perception. People with this syndrome may experience distortions in their visual perception of objects, such as appearing smaller (micropsia) or larger (macropsia), or appearing to be closer (pelopsia) or farther (teleopsia) than they are. Distortion may also occur for senses other than vision.
Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or colored dots across the whole visual field.
A cortical column is a group of neurons forming a cylindrical structure through the cerebral cortex of the brain perpendicular to the cortical surface. The structure was first identified by Vernon Benjamin Mountcastle in 1957. He later identified minicolumns as the basic units of the neocortex which were arranged into columns. Each contains the same types of neurons, connectivity, and firing properties. Columns are also called hypercolumn, macrocolumn, functional column or sometimes cortical module. Neurons within a minicolumn (microcolumn) encode similar features, whereas a hypercolumn "denotes a unit containing a full set of values for any given set of receptive field parameters". A cortical module is defined as either synonymous with a hypercolumn (Mountcastle) or as a tissue block of multiple overlapping hypercolumns.
The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to language switching. It is located bilaterally, roughly at the upper sides of the temporal lobes – in humans, curving down and onto the medial surface, on the superior temporal plane, within the lateral sulcus and comprising parts of the transverse temporal gyri, and the superior temporal gyrus, including the planum polare and planum temporale.
In neuroanatomy, a gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci. Gyri and sulci create the folded appearance of the brain in humans and other mammals.
An aura is a perceptual disturbance experienced by some with epilepsy or migraine. An epileptic aura is actually a minor seizure.
Familial hemiplegic migraine (FHM) is an autosomal dominant type of hemiplegic migraine that typically includes weakness of half the body which can last for hours, days, or weeks. It can be accompanied by other symptoms, such as ataxia, coma, and paralysis. Migraine attacks may be provoked by minor head trauma. Some cases of minor head trauma in patients with hemiplegic migraine can develop into delayed cerebral edema, a life-threatening medical emergency. Clinical overlap occurs in some FHM patients with episodic ataxia type 2 and spinocerebellar ataxia type 6, benign familial infantile epilepsy, and alternating hemiplegia of childhood.
Aristides Azevedo Pacheco Leão was a Brazilian neurophysiologist, researcher and university professor.
FreeSurfer is brain imaging software originally developed by Bruce Fischl, Anders Dale, Martin Sereno, and Doug Greve. Development and maintenance of FreeSurfer is now the primary responsibility of the Laboratory for Computational Neuroimaging at the Athinoula A. Martinos Center for Biomedical Imaging. FreeSurfer contains a set of programs with a common focus of analyzing magnetic resonance imaging (MRI) scans of brain tissue. It is an important tool in functional brain mapping and contains tools to conduct both volume based and surface based analysis. FreeSurfer includes tools for the reconstruction of topologically correct and geometrically accurate models of both the gray/white and pial surfaces, for measuring cortical thickness, surface area and folding, and for computing inter-subject registration based on the pattern of cortical folds.
In neuroanatomy, a sulcus is a shallow depression or groove in the cerebral cortex. One or more sulci surround a gyrus, a ridge on the surface of the cortex, creating the characteristic folded appearance of the brain in humans and most other mammals. The larger sulci are also called fissures. The cortex develops in the fetal stage of corticogenesis, preceding the cortical folding stage known as gyrification.
Scintillating scotoma is a common visual aura that was first described by 19th-century physician Hubert Airy (1838–1903). Originating from the brain, it may precede a migraine headache, but can also occur acephalgically, also known as visual migraine or migraine aura. It is often confused with retinal migraine, which originates in the eyeball or socket.
Martinotti cells are small multipolar neurons with short branching dendrites. They are scattered throughout various layers of the cerebral cortex, sending their axons up to the cortical layer I where they form axonal arborization. The arbors transgress multiple columns in layer VI and make contacts with the distal tuft dendrites of pyramidal cells. Martinotti cells express somatostatin and sometimes calbindin, but not parvalbumin or vasoactive intestinal peptide. Furthermore, Martinotti cells in layer V have been shown to express the nicotinic acetylcholine receptor α2 subunit (Chrna2).
Spike-and-wave is a pattern of the electroencephalogram (EEG) typically observed during epileptic seizures. A spike-and-wave discharge is a regular, symmetrical, generalized EEG pattern seen particularly during absence epilepsy, also known as ‘petit mal’ epilepsy. The basic mechanisms underlying these patterns are complex and involve part of the cerebral cortex, the thalamocortical network, and intrinsic neuronal mechanisms.
Retinal migraine is a retinal disease often accompanied by migraine headache and typically affects only one eye. It is caused by ischaemia or vascular spasm in or behind the affected eye.
The trigeminovascular system (TVS) refers to neurons and their axonal projections within the trigeminal nerve that project to the cranial meninges and meningeal blood vessels residing on the brain's surface. The term, introduced in 1983 denotes also the neuropeptides contained within axons that are released into the meninges to target vessels and surrounding cells.
Illusory palinopsia is a subtype of palinopsia, a visual disturbance defined as the persistence or recurrence of a visual image after the stimulus has been removed. Palinopsia is a broad term describing a heterogeneous group of symptoms, which is divided into hallucinatory palinopsia and illusory palinopsia. Illusory palinopsia is likely due to sustained awareness of a stimulus and is similar to a visual illusion: the distorted perception of a real external stimulus.
A migrainous infarction is a rare type of ischaemic stroke which occurs in correspondence with migraine aura symptoms. Symptoms include headaches, visual disturbances, strange sensations and dysphasia, all of which gradually worsen causing neurological changes which ultimately increase the risk of an ischaemic stroke. Typically, women under the age of 45 who experience migraine with aura (MA) are at the greatest risk for developing migrainous infarction, especially when combined with smoking and use of oral contraceptives.
Martin Johannes Lauritzen is a Danish neuroscientist. He is a Professor of Translational Neurobiology at the Department of Neuroscience, University of Copenhagen, Denmark and also a Professor of Clinical Neurophysiology at the Department of Neurophysiology, Rigshospitalet.
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