Focal seizures

Clinic

• Also called Partial / Localized seizures
• They are seizures which affect initially only one hemisphere
• Symptoms will vary according to where the seizure occurs.
  • Frontal lobe: Wave-like sensation in the head.
  • Temporal lobe: Déjà vu
  • Parietal lobe: Numbness or tingling
  • Occipital lobe: Visual disturbances / Hallucinations

Types

Two main categories,

1. Focal onset aware: 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.
2. Focal onset impaired awareness, which was previously termed a secondary generalized seizure is now termed a focal to bilateral seizure. It 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.

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
• Sensory illusions or hallucinations
• Derealization: Experiencing of unusual feelings or sensations
• Depersonalization
• 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.

Automatism

• It refers to a set of brief unconscious behaviors.
• These typically last for several seconds to minutes or sometimes longer, a time during which the subject is unaware of his/her actions.
• This type of automatic behaviour often occurs in certain types of epilepsy, such as complex partial seizures in those with temporal lobe epilepsy, or as a side effect of certain medications, such as zolpidem.

Variations

• There are varying degrees of automatism. Some may include simple gestures, such as finger rubbing, lip smacking, chewing, or swallowing, or more complex actions, such as sleepwalking behaviors.
• Others may include speech, which may or may not be coherent or sensible. The subject may or may not remain conscious otherwise throughout the episode. Those who remain conscious may be fully aware of their other actions at the time, but unaware of their automatism.
• In some more complex automatisms, the subject enters into the behaviors of sleepwalking while fully awake up until the moment it starts. In these episodes, which can last for longer periods of time, the subject proceeds to engage in activities they routinely perform, such as cooking, showering, or driving along a familiar route, or may even carry on conversation.
• Following the episode, the subject regains consciousness, often feeling disoriented, and has no memory of the incident.

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.^{[better source needed]} 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.