An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness, to shaking movements involving only part of the body with variable levels of consciousness, to a subtle momentary loss of awareness. These episodes usually last less than two minutes and it takes some time to return to normal. Loss of bladder control may occur.
A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combination of two conscious states of brain wakefulness and REM sleep. They are distinguishable from several related phenomena, such as dreaming, which does not involve wakefulness; pseudohallucination, which does not mimic real perception, and is accurately perceived as unreal; illusion, which involves distorted or misinterpreted real perception; and mental imagery, which does not mimic real perception, and is under voluntary control. Hallucinations also differ from "delusional perceptions", in which a correctly sensed and interpreted stimulus is given some additional significance.
Micropsia is a condition affecting human visual perception in which objects are perceived to be smaller than they actually are. Micropsia can be caused by optical factors, by distortion of images in the eye, by changes in the brain, and from psychological factors. Dissociative phenomena are linked with micropsia, which may be the result of brain-lateralization disturbance.
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.
The claustrum is a thin sheet of neurons and supporting glial cells, that connects to the cerebral cortex and subcortical regions including the amygdala, hippocampus and thalamus of the brain. It is located between the insular cortex laterally and the putamen medially, encased by the extreme and external capsules respectively. Blood to the claustrum is supplied by the middle cerebral artery. It is considered to be the most densely connected structure in the brain, and thus hypothesized to allow for the integration of various cortical inputs such as vision, sound and touch, into one experience. Other hypotheses suggest that the claustrum plays a role in salience processing, to direct attention towards the most behaviorally relevant stimuli amongst the background noise. The claustrum is difficult to study given the limited number of individuals with claustral lesions and the poor resolution of neuroimaging.
A headache is often present in patients with epilepsy. If the headache occurs in the vicinity of a seizure, it is defined as peri-ictal headache, which can occur either before (pre-ictal) or after (post-ictal) the seizure, to which the term ictal refers. An ictal headache itself may or may not be an epileptic manifestation. In the first case it is defined as ictal epileptic headache or simply epileptic headache. It is a real painful seizure, that can remain isolated or be followed by other manifestations of the seizure. On the other hand, the ictal non-epileptic headache is a headache that occurs during a seizure but it is not due to an epileptic mechanism. When the headache does not occur in the vicinity of a seizure it is defined as inter-ictal headache. In this case it is a disorder autonomous from epilepsy, that is a comorbidity.
Visual snow syndrome (VSS) is a form of visual hallucination that is characterized by the perception of small, flickering dots throughout the entire visual field. It is present in all conditions of illumination. The dots remain individual and do not clump together or change in size. Visual snow exists in one of two forms: the pulse type and the broadband type.
Acephalgic migraine is a neurological syndrome. It is a relatively uncommon variant of migraine in which the patient may experience some migraine symptoms such as aura, nausea, photophobia, and hemiparesis, but does not experience headache. It is generally classified as an event fulfilling the conditions of migraine with aura with no headache. It is sometimes distinguished from visual-only migraine aura without headache, also called ocular migraine.
In the field of neurology, temporal lobe epilepsy is an enduring brain disorder that causes unprovoked seizures from the temporal lobe. Temporal lobe epilepsy is the most common type of focal onset epilepsy among adults. Seizure symptoms and behavior distinguish seizures arising from the medial temporal lobe from seizures arising from the lateral (neocortical) temporal lobe. Memory and psychiatric comorbidities may occur. Diagnosis relies on electroencephalographic (EEG) and neuroimaging studies. Anticonvulsant medications, epilepsy surgery and dietary treatments may improve seizure control.
Frontal lobe epilepsy (FLE) is a neurological disorder that is characterized by brief, recurring seizures arising in the frontal lobes of the brain, that often occur during sleep. It is the second most common type of epilepsy after temporal lobe epilepsy (TLE), and is related to the temporal form in that both forms are characterized by partial (focal) seizures.
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.
In the field of neurology, seizure types are categories of seizures defined by seizure behavior, symptoms, and diagnostic tests. The International League Against Epilepsy (ILAE) 2017 classification of seizures is the internationally recognized standard for identifying seizure types. The ILAE 2017 classification of seizures is a revision of the prior ILAE 1981 classification of seizures. Distinguishing between seizure types is important since different types of seizures may have different causes, outcomes, and treatments.
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.
Migralepsy is a rare condition in which a migraine is followed, within an hour period, by an epileptic seizure. Because of the similarities in signs, symptoms, and treatments of both conditions, such as the neurological basis, the psychological issues, and the autonomic distress that is created from them, they individually increase the likelihood of causing the other. However, also because of the sameness, they are often misdiagnosed for each other, as migralepsy rarely occurs.
Abdominal aura, also known as visceral aura and epigastric aura, is a type of somatosensory aura that typically manifests as abdominal discomfort in the form of nausea, malaise, hunger, or pain. Abdominal aura is typically associated with epilepsy, especially temporal lobe epilepsy, and it can also be used in the context of migraine. The term is used to distinguish it from other types of somatosensory aura, notably visual disturbances and paraesthesia. The abdominal aura can be classified as a somatic hallucination. Pathophysiologically, the abdominal aura is associated with aberrant neuronal discharges in sensory cortical areas representing the abdominal viscera.
Idiopathic childhood occipital epilepsy of Gastaut (ICOE-G) is a pure but rare form of idiopathic occipital epilepsy that affects otherwise normal children and adolescents. It is classified amongst benign idiopathic childhood focal epilepsies such as rolandic epilepsy and Panayiotopoulos syndrome.
Hallucinatory palinopsia is a subtype of palinopsia, a visual disturbance defined as the persistent or recurrence of a visual image after the stimulus has been removed. Palinopsia is a broad term describing a group of symptoms which is divided into hallucinatory palinopsia and illusory palinopsia. Hallucinatory palinopsia refers to the projection of an already-encoded visual memory and is similar to a complex visual hallucination: the creation of a formed visual image where none exists.
Cerebral diplopia or polyopia describes seeing two or more images arranged in ordered rows, columns, or diagonals after fixation on a stimulus. The polyopic images occur monocular bilaterally and binocularly, differentiating it from ocular diplopia or polyopia. The number of duplicated images can range from one to hundreds. Some patients report difficulty in distinguishing the replicated images from the real images, while others report that the false images differ in size, intensity, or color. Cerebral polyopia is sometimes confused with palinopsia, in which multiple images appear while watching an object. However, in cerebral polyopia, the duplicated images are of a stationary object which are perceived even after the object is removed from the visual field. Movement of the original object causes all of the duplicated images to move, or the polyopic images disappear during motion. In palinoptic polyopia, movement causes each polyopic image to leave an image in its wake, creating hundreds of persistent images (entomopia).
Occipital epilepsy is a neurological disorder that arises from excessive neural activity in the occipital lobe of the brain that may or may not be symptomatic. Occipital lobe epilepsy is fairly rare, and may sometimes be misdiagnosed as migraine when symptomatic. Epileptic seizures are the result of synchronized neural activity that is excessive, and may stem from a failure of inhibitory neurons to regulate properly.
Musicogenic seizure, also known as music-induced seizure, is a rare type of seizure, with an estimated prevalence of 1 in 10,000,000 individuals, that arises from disorganized or abnormal brain electrical activity when a person hears or is exposed to a specific type of sound or musical stimuli. There are challenges when diagnosing a music-induced seizure due to the broad scope of triggers, and time delay between a stimulus and seizure. In addition, the causes of musicogenic seizures are not well-established as solely limited cases and research have been discovered and conducted respectively. Nevertheless, the current understanding of the mechanism behind musicogenic seizure is that music triggers the part of the brain that is responsible for evoking an emotion associated with that music. Dysfunction in this system leads to an abnormal release of dopamine, eventually inducing seizure.
