Focal seizures

Clinic

• Also called Partial / Localized seizures since they initially affect only one hemisphere.
  • 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, according to the level of consciousness:

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: Also named focal to bilateral seizure. It affects a larger part of the hemisphere and the person may lose consciousness.

Points

• 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.

Simple partial seizures

• They affect only a small region of brain, often the temporal lobes or hippocampus, but it may leads to tonic-clonic seizure.
• 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

While-asleep focal seizures

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.

• 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

Note

• Although hallucinations may occur during focal aware seizures they are differentiated from psychosis by the fact that the person is usually aware that the hallucinations are not real.
• There is no convulsive entity, so what is the difference between RBD and While-asleep focal seizures?

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.
• Etiology:
  • Certain types of epilepsy, such as complex partial seizures in temporal lobe epilepsy
  • Side effect of certain medications such as zolpidem.

Variations

• Simple gestures such as finger rubbing, lip smacking, chewing, or swallowing
• Complex actions such as sleepwalking
• Coherent / Sensible or incoherent speech
• 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 Somnambulism 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.
• Seizure aura is itself a focal aware seizure. It may manifest itself as a feeling of
  • Déjà vu/ Jamais vu
  • Fear
  • Euphoria
  • Depersonalization
  • Visual disturbance, such as tunnel vision or a change in the perceived size of objects.
  • If consciousness is impaired, the person may display automatisms, such as lip smacking, chewing or swallowing
  • Amnesia maybe occured surrounding the seizural event
  • He 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.

Pathology

• Complex partial seizures might arise from any lobe of brain, 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.