Focal seizures (also called partial seizures and localized seizures) are
seizure
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 los ...
s which 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 frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betwe ...
the patient may experience a wave-like sensation in the head. When seizures occur in the
temporal lobe
The temporal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe ...
, a feeling of
déjà vu
''Déjà vu'' ( , ; "already seen") is a French loanword for the phenomenon of feeling as though one has lived through the present situation before.Schnider, Armin. (2008). ''The Confabulating Mind: How the Brain Creates Reality''. Oxford Univer ...
may be experienced. When seizures are localized to the
parietal lobe
The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integrates sensory informa ...
, a
numbness
Hypoesthesia or numbness is a common side effect of various medical conditions that manifests as a reduced sense of touch or sensation, or a partial loss of sensitivity to sensory stimuli. In everyday speech this is generally referred to as num ...
or
tingling
Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias ar ...
may occur. With seizures occurring in the
occipital lobe
The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head".
The occipital lobe is the vi ...
, visual disturbances or hallucinations have been reported.
, Epilepsy Society - Are all seizures the same.
Types
As of 2017, focal seizures are split into two main categories, ''focal onset aware'', and ''focal onset impaired awareness''.
What was previously termed a ''secondary generalised seizure'' is now termed a ''focal to bilateral seizure''.
In focal onset aware seizures, a small part of one of the lobes may be affected and the person remains conscious. This can often be a precursor to a larger focal onset impaired awareness seizure. When this is the case, the focal aware seizure is usually called an
aura (symptom), aura.
A focal impaired awareness seizure affects a larger part of the hemisphere and the person may lose consciousness.
If a focal seizure spreads from one hemisphere to the other side of the brain, this will give rise to a ''focal to bilateral seizure''.
The person will become unconscious and may experience a
tonic clonic seizure
Tonic may refer to:
*Tonic water, a drink traditionally containing quinine
*Soft drink, a carbonated beverage
*Tonic (physiology), the response of a muscle fiber or nerve ending typified by slow, continuous action
* Tonic syllable, the stressed syl ...
. When people have multiple focal seizures they generally have a condition known as
temporal lobe epilepsy
Temporal lobe epilepsy (TLE) is a chronic disorder of the nervous system which is characterized by recurrent, unprovoked focal seizures that originate in the temporal lobe of the brain and last about one or two minutes. TLE is the most common f ...
. (A
generalized seizure
Generalized epilepsy is a form of epilepsy characterised by generalised seizures with no apparent cause. Generalized seizures, as opposed to focal seizures, are a type of seizure that impairs consciousness and distorts the electrical activity of t ...
is one that involves both sides of the brain from the onset.)
Simple partial seizures
Simple partial seizures are
seizure
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 los ...
s which affect only a small region of the brain, often the
temporal lobes
The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe is involved in pro ...
or structures found there, such as the
hippocampi. People who have focal aware seizures remain conscious.
Focal aware seizures often precede larger focal impaired awareness seizures, where the abnormal electrical activity spreads to a larger area of the brain. This can result in a
tonic-clonic seizure.
Presentation
Simple partial seizures are a very subjective experience, and the symptoms vary greatly between people. Since symptoms can be subtle, diagnosis can be delayed by months or years. The symptoms of these seizures can also be misconstrued as auras, especially for epilepsy patients with multiple types of seizure diagnosis. This is due to the varying locations of the brain in which the seizures originate (e.g.,
Rolandic). A simple partial seizure may go unnoticed by others or shrugged off by the patient as merely a "funny turn." Focal aware seizures usually start suddenly and are very brief, typically lasting 60 to 120 seconds.
Some common symptoms of a simple partial seizure, when the person is awake, are:
* preserved consciousness
* sudden and inexplicable feelings of fear, anger, sadness, happiness or nausea
* sensations of falling or movement
* experiencing of unusual feelings or sensations
* altered sense of hearing, smelling, tasting, seeing, and tactile perception (sensory
illusion
An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people.
Illusions may o ...
s or
hallucinations
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 combinatio ...
), or feeling as though the environment is not real (
derealization
Derealization is an alteration in the perception of the external world, causing those with the condition to perceive it as unreal, distant, distorted or falsified. Other symptoms include feeling as if one's environment is lacking in spontaneity, ...
) or dissociation from the environment or self (
depersonalization
Depersonalization can consist of a detachment within the self, regarding one's mind or body, or being a detached observer of oneself. Subjects feel they have changed and that the world has become vague, dreamlike, less real, lacking in significa ...
)
* a sense of spatial distortion—things close by may appear to be at a distance
*
déjà vu
''Déjà vu'' ( , ; "already seen") is a French loanword for the phenomenon of feeling as though one has lived through the present situation before.Schnider, Armin. (2008). ''The Confabulating Mind: How the Brain Creates Reality''. Oxford Univer ...
(familiarity) or
jamais vu
In psychology, ''jamais vu'' ( , , ), a French loanword meaning "never seen", is the phenomenon of experiencing a situation that one recognizes in some fashion, but that nonetheless seems novel and unfamiliar.
Overview
Jamais vu is often desc ...
(unfamiliarity)
* laboured speech or inability to speak at all
* usually the event is remembered in detail
When a seizure occurs during sleep, the person will often become semi-conscious and act out a dream they were having while engaging with the real environment as normal. Objects and people usually appear normal or only slightly distorted to them, and will be able to communicate with them on an otherwise normal level. However, since the person is still acting in a dream-like state, they will assimilate any hallucinations or delusions into their communication, often speaking to a hallucinatory person or speaking of events or thoughts pertaining to their dream or a hallucination.
While-asleep symptoms include:
* onset usually in
REM sleep
Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream viv ...
* dream-like state
* appearance of full consciousness
* hallucinations or delusions
* behavior or visions typical in dreams
* ability to engage with the environment and other people as in full consciousness, though often behaving abnormally, erratically, or failing to be coherent
* complete amnesia or assimilating the memory as though it was a normal dream on regaining full consciousness
* dreams of daily life that appear as if they happened in reality, and can cause disorientation upon awakening
Although hallucinations may occur during focal aware seizures they are differentiated from psychotic symptoms by the fact that the person is usually aware that the hallucinations are not real.
Jacksonian march
Jacksonian march or Jacksonian seizure is a phenomenon where a simple partial seizure spreads from the
distal
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
part of the limb toward the
ipsilateral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
face (on same side of body). They involve a progression of the location of the
seizure
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 los ...
in the brain, which leads to a "march" of the motor presentation of symptoms.
Jacksonian seizures are initiated with abnormal electrical activity within the
primary motor cortex
The primary motor cortex (Brodmann area 4) is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region of the motor system and works in association with other motor areas including premotor co ...
. They are unique in that they travel through the primary motor cortex in succession, affecting the corresponding
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
s, often beginning with the fingers. This is felt as a tingling sensation, or a feeling of waves through the fingers when touched together. It then affects the hand and moves on to more proximal areas on the same side of body. Symptoms often associated with a Jacksonian seizure are sudden head and eye movements, tingling, numbness, smacking of the lips, and sudden muscle contractions. Most of the time any one of these actions can be seen as normal movements, without being associated with the seizure occurring. They occur at no particular moment and last only briefly. They may result in secondary generalized seizure involving both hemispheres. They can also start at the feet, manifesting as
tingling or pins and needles, and there are painful cramps in the foot muscles, due to the signals from the brain. Because it is a partial seizure, the
postictal state
The postictal state is the altered state of consciousness after an epileptic seizure. It usually lasts between 5 and 30 minutes, but sometimes longer in the case of larger or more severe seizures, and is characterized by drowsiness, confusion, nau ...
is of normal consciousness.
Jacksonian seizures are named after their discoverer,
John Hughlings Jackson
John Hughlings Jackson, FRS (4 April 1835 – 7 October 1911) was an English neurologist. He is best known for his research on epilepsy.
Biography
He was born at Providence Green, Green Hammerton, near Harrogate, Yorkshire, the youngest so ...
, an
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ide ...
neurologist
Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal c ...
, whose studies led to the discovery of the seizures' initiation point (in the primary motor cortex) in 1863.
Complex partial seizures
A complex partial seizure is a seizure that is associated with unilateral
cerebral hemisphere
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...
involvement and causes
impairment of
awareness
Awareness is the state of being conscious of something. More specifically, it is the ability to directly know and perceive, to feel, or to be cognizant of events. Another definition describes it as a state wherein a subject is aware of some inform ...
or responsiveness, i.e. alteration of consciousness.
Presentation
Complex partial seizures are often preceded by an
aura (symptom), aura.
[Trescher, William H., and Ronald P. Lescher 2000, p. 1749.] The seizure aura is a focal aware seizure.
The aura may manifest itself as a feeling of
déjà vu
''Déjà vu'' ( , ; "already seen") is a French loanword for the phenomenon of feeling as though one has lived through the present situation before.Schnider, Armin. (2008). ''The Confabulating Mind: How the Brain Creates Reality''. Oxford Univer ...
,
jamais vu
In psychology, ''jamais vu'' ( , , ), a French loanword meaning "never seen", is the phenomenon of experiencing a situation that one recognizes in some fashion, but that nonetheless seems novel and unfamiliar.
Overview
Jamais vu is often desc ...
, fear,
euphoria
Euphoria ( ) is the experience (or affect) of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, laughter, listening to or making music and da ...
or
depersonalization
Depersonalization can consist of a detachment within the self, regarding one's mind or body, or being a detached observer of oneself. Subjects feel they have changed and that the world has become vague, dreamlike, less real, lacking in significa ...
.
[Murro, Anthony M. 2006.] The aura might also occur as a visual disturbance, such as
tunnel vision
Tunnel vision is the loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision.
Causes
Tunnel vision can be caused by:
Eyeglass users
Eyeglass users experience tunnel vision t ...
or a change in the perceived size of objects. Once consciousness is impaired, the person may display
automatisms, such as lip smacking, chewing or swallowing.
There may also be loss of memory (
amnesia
Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use ...
) surrounding the seizural event.
The person may still be able to perform routine tasks such as walking, although such movements are not purposeful or planned. Witnesses may not recognize that anything is wrong. The person may or may not even realize that they experienced a seizure.
Complex partial seizures might arise from any
lobe
Lobe may refer to:
People with the name
* Lobe (surname)
Science and healthcare
* Lobe (anatomy)
* Lobe, a large-scale structure of a radio galaxy
* Glacial lobe, a lobe-shaped glacier
* Lobation, a characteristic of the nucleus of certain biolo ...
of the brain.
They most commonly arise from the
mesial
This is a list of definitions of commonly used terms of location and direction in dentistry. This set of terms provides orientation within the oral cavity, much as anatomical terms of location provide orientation throughout the body.
Terms
...
temporal lobe
The temporal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe ...
, particularly the
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verteb ...
,
hippocampus
The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, a ...
, and
neocortical
The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, sp ...
regions. A common associated brain abnormality is
mesial temporal sclerosis
Hippocampal sclerosis (HS) or mesial temporal sclerosis (MTS) is a Neuropathology, neuropathological condition with severe neuronal cell loss and gliosis in the hippocampus, specifically in the Cornu Ammonis area 1, CA-1 (Cornu Ammonis area 1) and ...
.
Mesial temporal sclerosis is a specific pattern of hippocampal neuronal loss accompanied by hippocampal
gliosis
Gliosis is a nonspecific reactive change of glial cells in response to damage to the central nervous system (CNS). In most cases, gliosis involves the proliferation or hypertrophy of several different types of glial cells, including astrocytes, ...
and atrophy. Complex partial seizures occur when excessive and synchronous electrical brain activity causes the impaired awareness and responsiveness. The abnormal electrical activity might spread to the rest of the brain and cause a ''focal to bilateral seizure'' or a generalized
tonic–clonic seizure.
[Trescher, William H., and Ronald P. Lescher 2000, p. 1747.] The newer classification of 2017 groups only focal and generalized seizures, and generalized seizures are those that involve both sides of the brain from the onset.
References
External links
{{Seizures and epilepsy
Seizure types