Aura | |
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Artist's depiction of zig-zag lines experienced as part of a migraine aura phenomenon | |
Specialty | Neurology, neuro-ophthalmology |
Types | Scintillating scotoma |
Differential diagnosis | Persistent aura without infarction, retinal migraine, visual snow |
An aura is a perceptual disturbance experienced by some with epilepsy or migraine. An epileptic aura is actually a minor seizure. [1]
Epileptic and migraine auras are due to the involvement of specific areas of the brain, which are those that determine the symptoms of the aura. Therefore, if the visual area is affected, the aura will consist of visual symptoms, while if a sensory one, then sensory symptoms will occur.
Epileptic auras are subjective sensory or psychic phenomena due to a focal seizure, i.e. a seizure that originates from that area of the brain responsible for the function which then expresses itself with the symptoms of the aura. It is important because it makes it clear where the alteration causing the seizure is located. An epileptic aura is in most cases followed by other manifestations of a seizure, for example a convulsion, since the epileptic discharge spreads to other parts of the brain. Rarely it remains isolated. Auras, when they occur, allow some people who have epilepsy time to prevent injury to themselves and/or others when they lose consciousness.
The aura of migraine is visual in the vast majority of cases, because dysfunction starts from the visual cortex. The aura is usually followed, after a time varying from minutes to an hour, by the migraine headache. However, the migraine aura can manifest itself in isolation, that is, without being followed by headache. The aura can stay for the duration of the migraine; depending on the type of aura, it can leave the person disoriented and confused. It is common for people with migraines to experience more than one type of aura during the migraine. Some people who have auras have the same type of aura every time.
Auras can also be confused with sudden onset of panic, panic attacks or anxiety attacks, which creates difficulties in diagnosis. The differential diagnosis of patients who experience symptoms of paresthesias, derealization, dizziness, chest pain, tremors, and palpitations can be quite challenging. [2]
An epileptic aura is the consequence of the activation of functional cortex by abnormal neuronal discharge. [3] In addition to being a warning sign for an impending seizure, the nature of an aura can give insight into the localization and lateralization of the seizure or migraine. [4] [5]
The most common auras include motor, somatosensory, visual, and auditory symptoms. [6] The activation in the brain during an aura can spread through multiple regions continuously or discontinuously, on the same side or to both sides. [7]
Auras are particularly common in focal seizures. If the motor cortex is involved in the overstimulation of neurons, motor auras can result. Likewise, somatosensory auras (such as tingling, numbness, and pain) can result if the somatosensory cortex is involved. When the primary somatosensory cortex is activated, more discrete parts on the opposite side of the body and the secondary somatosensory areas result in symptoms ipsilateral to the seizure focus. [8] [9]
Visual auras can be simple or complex. Simple visual symptoms can include static, flashing, or moving lights/shapes/colors caused mostly by abnormal activity in the primary visual cortex. Complex visual auras can include people, scenes, and objects which results from stimulation of the temporo-occipital junction and is lateralized to one hemifield. Auditory auras can also be simple (ringing, buzzing) or complex (voices, music). Simple symptoms can occur from activation in the primary auditory cortex and complex symptoms from the temporo-occipital cortex at the location of the auditory association areas. [10]
An aura sensation can include one or a combination of the following:
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 compelling sense of reality. 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.
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 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.
Psychogenic non-epileptic seizures (PNES), also referred to as pseudoseizures, non-epileptic attack disorder (NEAD), functional seizures, or dissociative seizures, are episodes resembling an epileptic seizure but without the characteristic electrical discharges associated with epilepsy. PNES fall under the category of disorders known as functional neurological disorders (FND), also known as conversion disorders, and are typically treated by psychologists or psychiatrists. PNES has previously been called stress seizures and hysterical seizures, but these terms have fallen out of favor.
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.
Focal seizures are seizures that affect initially only one hemisphere of the brain. The brain is divided into two hemispheres, each consisting of four lobes – the frontal, temporal, parietal and occipital lobes. A focal seizure is generated in and affects just one part of the brain – a whole hemisphere or part of a lobe. Symptoms will vary according to where the seizure occurs. When seizures occur in the frontal lobe, the patient may experience a wave-like sensation in the head. When seizures occur in the temporal lobe, a feeling of déjà vu may be experienced. When seizures are localized to the parietal lobe, a numbness or tingling may occur. With seizures occurring in the occipital lobe, visual disturbances or hallucinations have been reported.
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.
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.