EEG findings in patients with Neurological Disorders

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EEG findings in patients with Neurological
Disorders

• Instructor
• Dr. Gharibzadeh
• By
• Fahime Sheikhzadeh

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Electrodes for recording EEG

• A  Ear lobe, C  Central, Pg  Nasopharyngeal,
  P  Parietal,
• F  Frontal, Fp  Frontal Polar, O  Occipital.

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American Electroencephalographic Society
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Normal EEG

• This EEG displays the activity of an awake state
  showing normal amplitudes, frequencies,
  waveforms similar features between hemispheres
  and no epileptiform activity.

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Disorders

• Here we discuss in EEG finding in these
  neurological disorders
• Epilepsy
• Tumors
• Coma

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Epilepsy

• Epilepsy is a common chronic neurological
  disorder that is characterized by recurrent
  unprovoked seizures. These seizures are transient
  signs and/or symptoms due to abnormal, excessive
  or synchronous neuronal activity in the brain.
• Epilepsy should not be understood as a single
  disorder, but rather as a group of syndromes with
  vastly divergent symptoms but all involving
  episodic abnormal electrical activity in the
  brain.

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Ictal, Post-Ictal, Inter-Ictal

• Ictal refers to a physiologic state or event such
  as a seizure, stroke or headache. In
  electroencephalography, or EEG, the recording
  during an actual seizure is said to be "ictal".
  Post-ictal refers to the state after the event.
  Inter-ictal refers to the state between events.
  Inter-ictal EEG discharges are those abnormal
  waveforms not associated with seizure symptoms.

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The types of epilepsy

• Generalized
• Partial
• Simple-partial
  Complex-partial

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The types of epilepsy

• Generalized
• Generalized seizures affect the entire brain
  at once
• Partial
• Partial seizures affect only a small part of
  the brain. As the partial seizure develops, it
  may remain localized to a small part of the brain
  or it may spread and affect the entire brain. In
  either case it is still called a partial seizure
  because it began in only part of the brain.

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Epilepsy Classifications

• Grand mal epilepsy
• Petit mal epilepsy
• Focal epilepsy (Partial epilepsy)

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EEG in different kinds of epilepsies
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Grand mal epilepsy

• Tonic-clonic seizures (also known as Grand Mal
  Seizures, though this term is now discouraged and
  rarely used in a clinical setting) are a type of
  generalized seizure affecting the whole brain.
  Tonic-clonic seizures are the seizure type most
  commonly associated with epilepsy and seizures in
  general, though it is a misconception that they
  are the only type.

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EEG finding in Grand mal epilepsy

• In patients with Grand mal (tonic-clonic)
  seizures, generalized, bilaterally synchronous
  spike discharges, or bursts of spike wave or poly
  spike wave activity, or both may be seen
  inter-ictally.
• The earliest change during a tonic-clonic
  convulsion is often the appearance of
  generalized low voltage fast activity. This
  activity then becomes slower, more conspicuous,
  and more extensive in distribution and depending
  on recording technique, may take the form of
  multiple spike or repetitive sharp wave
  discharges that have a frequency of about 10 Hz
  and are seen during the tonic phase of the attack.

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EEG Traces of Generalized Epilepsy
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Grand mal epilepsy

• Paroxysmal, generalized, bilaterally
  synchronous spike-wave and poly spike wave
  discharges seen interictally in the EEG of
  62-year olds woman with tonic-clonic seizures.

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Petit mal epilepsy

• Absence seizures are one of several kinds of
  seizures. These seizures are sometimes referred
  to as petit mal seizures, which is an older term.
• In absence seizures, the person may appear to be
  staring into space with or without jerking or
  twitching movements of the eye muscles. These
  periods last for seconds, or even tense of
  seconds. Those experiencing absence seizures
  sometimes move from one location to another
  without any purpose.

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EEG finding in Petit mal epilepsy

• In patients with Petit mal (Absence) seizures,
  this epileptiform activity consist of
  well-organized 2.5 to 3 Hz spike-wave discharges,
  which may be seen both inter-ictally and ictally.
• The frequency of the complexes is often a little
  faster than 3 Hz at onset and tends to slow to
  about 2 Hz before terminating.

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Petit mal epilepsy

• Paroxysmal, generalized, bilaterally
  synchronous and symmetric 2.5 to 3 Hz spike-wave
  activity recorded inter-ictally in the EEG of a
  patient with absence (petit mal) seizures.

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Progression of Absence Seizure
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Focal (Partial) epilepsy

• Focal seizures (also called partial seizures) are
  seizures which affect only a small part of the
  brain, and are split into two main categories
  simple partial seizures and complex partial
  seizures
• A simple partial seizure will often be a
  precursor to a larger seizure such as a complex
  partial seizure, or a tonic-clonic seizure. When
  this is the case, the simple partial seizure is
  usually called an aura.
• Focal seizures are common in temporal lobe
  epilepsy.

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EEG findings in Focal (Partial) epilepsy

• The interictal EEG findings may vary considerably
  at different times in patients with focal
  epilepsy, especially in those with complex
  symptomatology.
• In some patients with partial seizures, and
  especially those with elementary symptomatology,
  the scalp recorded EEG shows no change during the
  ictal event. More commonly, however, the EEG
  shows localized discharges or more diffuse
  changes during the ictal period.

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Focal (Partial) epilepsy

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Focal (Partial) epilepsy

• EEG of a 13 years old boy with frequent
  attacks of dimming out. A burst of repetitive
  spikes is seen to occur in the right temporal
  region during this time he experienced an attack.

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Tumors

• Tumors may affect the EEG by causing compression,
  displacement, or destruction of nervous tissue.

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Tumors

• This abnormalities depend at
• Part
• Size
• Rate of growth of the tumor
• Age

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EEG findings in Cerebral lesion

• Depression of electrical activity over a discrete
  region of the brain
• The presence of a focal polymorphic slow wave
  disturbance.

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Tumors

• Polymorphic slow wave activity in the left
  frontal region in the EEG of a 62 years ld man
  with a glioma

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Coma

• Altered state of consciousness may result from
  many causes, it is therefore not surprising that
  the EEG findings in comatose patients are
  variable.

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EEG findings in Comatose patients

• A change in electro cerebral activity can be
  expected to occur following stimulation of a
  patients with a mildly depressed level of
  consciousness this reactivity becomes
  inconstant, delayed, or lost as the depth of coma
  increases.
• With further progression, repeated stimulation
  may be needed to produce any EEG change, and
  finally the EEG becomes unresponsive.

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Coma

• EEG of a comatose child showing attenuation
  of the diffuse background slow activity in
  response to a sudden loud noise.

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Brain death
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Brains are Cool!!
Any Questions?