| Focal seizure | |
|---|---|
| Other names | Partial seizures, localized seizures |
| Specialty |
Neurology 
|
Focal seizures (also called partial seizures and localized seizures) are seizures 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 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.
What happens during a focal seizure depends on which area (lobe) of the brain is affected. Also if the seizure spreads to affect other areas. Some people just experience one symptom during a focal seizure, while others have several.
1) Frontal Lobes- The frontal lobes are responsible for cognitive functions like intelligence personality, emotions, concentration, problem-solving and body movements. The symptoms of frontal lobe seizures can sometimes be mistaken for mental health problems. Some people who have frontal lobe seizures only have them in their sleep. The awareness may or may not be affected.
Symptoms of seizures in the frontal lobes can include:
- Pelvic thrusting, kicking, pedalling, thrashing or rocking movements.
- Screaming, swearing or laughing
- Urinary incontinence
- Head or eyes turning to one side
- Unusual body movements
- Twitching, jerking or stiffening of muscles in one area of the body
2) Occipital lobes-The occipital lobes are responsible for processing visual information. Occipital lobe seizure symptoms include:
- Seeing flashing lights
- Seeing colours or simple patterns
- Seeing more complex images
- Not being able to see as well as usual, or not being able to see at all
- Having eye movements that can’t control, such as your eyes closing.
- Repeated blinking
3) Parietal Lobes-The parietal lobes help in spatial perception, language processing, and interpreting the signals from our senses of touch, vision and hearing. Seizures starting in the parietal lobe often spread to involve other lobes. The parietal lobe symptoms include:
- Having feelings of numbness
- Tingling
- Prickling, crawling or electric-shock sensations
- Sensations of burning
- Sensations of cold or pain
- Feeling like the body is moving or floating (full or partial)
- Sexual sensations
- Difficulty understanding language, reading, writing, or doing simple maths
- Seeing things as bigger or smaller than they really are
4) Temporal Lobes- The temporal lobe is responsible for things like memory, hearing and understanding language. The temporal lobe seizures start in one or other of the temporal lobes. Seizures starting in the temporal lobes are usually, focal impaired awareness seizures but not all the time. The seizure starts being aware of what’s happening, and then lose awareness as the seizures goes on. Symptoms of seizures in the temporal lobes include:
- Feeling frightened
- Feeling like what’s happening has happened before (deja vu)
- Hearing things that aren’t there
- Experiencing an unpleasant taste or smell
- Having a rising sensation in your stomach
- Lip smacking
- Repeated swallowing or chewing
- Changes to your skin tone or heart rate
- Automatic behaviours such as fidgeting, undressing, running or walking
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.
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. When people have multiple focal seizures they generally have a condition known as temporal lobe epilepsy. (A generalized seizure is one that involves both sides of the brain from the onset.)
Simple partial seizures
Simple partial seizures are seizures which affect only a small region of the brain, often the temporal lobes 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. Simple focal seizures, also known as auras. It occurs in one area on one side of the brain but may spread from there.
- Motor- A simple focal seizure with motor symptoms will affect muscle activity, causing jerking movements of a foot, the face, an arm, or another part of the body. Physicians can diagnose which side of the brain is affected by observing which side of the body experiences symptoms since the left brain controls the right side of the body and the right brain controls the left.
- Sensory- A simple focal seizure with autonomic symptoms affects the part of the brain responsible for involuntary functions. These seizures may cause changes in blood pressure, heart rhythm, or bowel or bladder function.
- Psychic- Some simple focal seizures strike parts of the brain that trigger emotions or memories of previous experiences, causing feelings of fear, anxiety, or déjà vu (the illusory feeling that something has been experienced before).
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 illusions or hallucinations), or feeling as though the environment is not real (derealization) or dissociation from the environment or self (depersonalization)
- a sense of spatial distortion—things close by may appear to be at a distance
- déjà vu (familiarity) or jamais vu (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
- 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 part of the limb toward the ipsilateral face (on same side of body). They involve a progression of the location of the seizure 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. They are unique in that they travel through the primary motor cortex in succession, affecting the corresponding muscles, 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 is of normal consciousness. Jacksonian seizures are named after their discoverer, John Hughlings Jackson, an English neurologist, 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 involvement and causes impairment of awareness or responsiveness, i.e. alteration of consciousness.
Presentation
Complex partial seizures are often preceded by an aura. The seizure aura is a focal aware seizure. The aura may manifest itself as a feeling of déjà vu, jamais vu, fear, euphoria or depersonalization. The aura might also occur as a visual disturbance, such as tunnel vision 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) 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 of the brain. They most commonly arise from the mesial temporal lobe, particularly the amygdala, hippocampus, and neocortical regions. A common associated brain abnormality is mesial temporal sclerosis. Mesial temporal sclerosis is a specific pattern of hippocampal neuronal loss accompanied by hippocampal gliosis 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. 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.
Symptoms
The focal seizure disturbs one part of the brain, the symptoms depending on the specific incident. Some people with focal seizures can experience an aura. Auras can be the initial symptoms of a focal seizure.
The possible symptoms of focal seizures include:
- Muscle contractions, followed by relaxation.
- Unusual head movements.
- Unusual eye movements
- Numbness
- Tingling or a feeling of something crawling on the skin
- Rapid heart rate or pulse
- Repetitive movements (lip smacking, chewing, swallowing)
- Sweating
- Nausea
- Flushed face
- Hallucinations
- Dilated pupils, vision changes
- Mood changes
- Blackouts
- Focal aware seizures-The feature of these seizures is the awareness of them when it happens. Auras that happen with these are the seizure itself.
- Focal impaired awareness seizures- These disrupt the awareness of what is happening. The aura happens before any disruption in the awareness. These usually last no more than three minutes. It is the most common of all seizures. About 36% of all seizures are this type.
- Focal to bilateral tonic-clonic seizure- These used to be called generalized tonic-clonic seizures. These seizures involve full body muscle movements and convulsions.
- Focal motor symptoms- It causes unconscious or involuntary movements. These often affect the face, hands and toes on one side. They can involve twitching or jerking muscle movements, uncontrolled tightening up of muscles, and automatic movements. Focal motor symptoms can also spread across an affected body part and to other parts of the body. These seizures start in a small area and spread to the entire body parts. It sometimes continues to other body parts or the face. After focal motor symptoms happen, many people have paralysis in their affected body parts. It is known as “Todd paralysis,” which is temporary, but it can last several hours.
- Focal sensory symptoms- It causes involuntary movements which is unconscious. These frequently disturb the face, hands and toes. They can involve twitching or jerking muscle movements, and automatic movements. Also uncontrolled tightening up of muscles. These seizures start in a small area and spread to the entire body parts. It sometimes continues to other body parts or the face. After focal motor symptoms happen, many people have paralysis (Todd paralysis) in their affected body parts. If an aura affects neurons in parts of your brain connected to your senses, the neurons can mistakenly act like they’re getting real input. These kinds of symptoms, known as hallucinations, can affect all five of your senses.
-Visual: Seeing bright lights, flashes, or distortions in how objects look (they appear bigger or smaller).
-Hearing: Hearing unexpected or non-specific sounds and noises.
Smell: Smelling something that isn’t there; usually happens suddenly and unexpectedly.
Taste: Also usually sudden and unexpected; these are often non-specific, like something metallic, sour, or bitter.
Touch: Strange feelings on or underneath your skin in a specific body part; may feel like pins and needles, tingling or crawling, or even heat or pain.
*Focal autonomic symptoms-Auras can distress body structures that brain runs mechanically. Some examples include:
-Sweating
-Making too much saliva or drooling.
-Skin colour changes (either pale or turning red)
-Gastric uprising
*Focal cognitive symptoms- Auras cause deviations in an emotional state, the examples are:
- Negative emotions- Fear, anxiety, agitation, or anger
- Positive emotions- Joy, excitement, or uncontrollable laughter.
- Disruptions in reality- Dream-like feelings or flashbacks.
- Déjá vu- When a new experience somehow feels familiar.
Causes
Focal seizures can happen for many reasons. There are diverse circumstances and states that can cause focal seizures. Some of the possible of focal seizures are:
- Liver or kidney failure
- Very high blood pressure
- Use of illegal drugs
- Brain infections
- Brain and head injuries
- Congenital brain defects
- Stroke
- Poisoning or venomous bites
- Low blood sugar
- Withdrawal from drugs or alcohol
- Phenylketonuria (a genetic disorder)
- Aneurysms
- Arrhythmias (Irregular heart rhythms)
- Brain tumors (including cancer)
- Cerebral hypoxia
- Concussion
- Degenerative brain diseases (Alzheimer’s disease or frontotemporal dementia)
- Eclampsia
- Electrolyte problems, especially low sodium (hyponatremia), calcium or magnesium.
- High Fevers
- Genetic disorders
- Hormone-related changes
- Encephalitis or meningitis
- Inflammation
- Insomnia
- Metabolic problems
- Problems with your brain structure
- Sepsis