Revised: December 29, 2004

Glossary & Definitions of Diseases / Syndromes


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Encephalopathy (encephalo = inside of head, or brain; pathy = dysfunction) is a term for a non-specific diffuse brain dysfunction.  It is usually secondary to a systemic condition.

The Progress of the Illness is:
               Initial Stages:

    1. Impaired attention
    2. Confusion
    3. Disorientation



      Progressing on to:

    5. Stupor and coma
    6. or Coma of unknown origin/cause



      Associated symptoms may include:

    8. Agitation
    9. Hallucinations
    10. Myoclonus
    11. Asterixis
    12. Generalized seizures
The EEG may show various wave forms, ranging from normal to very slow. The EEG findings are related to the clinical condition of the patient, and can be of prognostic value.

EEG findings may include: Diffuse theta, diffuse delta, triphasic waves, sharp waves, spikes.

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Epilepsy is a dysfunction of the brain, usually paroxysmal in nature.  A true epileptic seizure is commonly associated with abnormal electrical discharge of the brain; although there are cases where this is not true.  Not all seizures, are epileptic in origin.

Epileptic seizures manifest themselves in different ways.  They can have physical, sensory, cognitive, and/or psychological  symptoms/components.    Epilepsy is classed using different systems.  Two classifications are shown here, but there are others.  Some classify them by inherited traits, some by localization of epileptogenic lesion, clnical manifestations (symptoms and/or what it looks like), the underlying mechanism or supposed cause, and the time of life during which attacks occur, including not only adult/child, but also nocturnal, diurnal, etc.

Basically, there are 3 types of epilepsy, which are defined by how much of the brain is involved, and what level of consciousness is apparent at the time of the seizure.  The first is generalized.  As the name implies, the whole brain is involved, the patient is not conscious during the seizure.  The other 2 are referred to as partial seizures, where only part of the brain is involved.  In simple partial seizures, the patient is aware that they are having a seizure, and is usually aware of their surroundings, as well.  In complex partial seizures, the patient suffers from a loss of consciousness.

Another style of classification is the "International Classification of Epilepsies and Epileptic Syndromes".  Because the document is quite lengthy, only the broader points will be listed here.

I.    Localization related
        A.    Idiopathic
        B.    Symptomatic: symptoms of great individual variability
II.    Generalized Epilepsies and Syndromes
        A.    Idiopathic, with age related onset
        B.    Idiopathic and/or symptomatic
        C.    Symptomatic
                1.    Non-specific etiology
                2.    Specific Sydromes
III.    Epilepsies and Sydromes undetermined as to whether thay are focal or generalized
        A.    With both generalized and focal seizures
        B.    Without unequivocal generalized or focal features.
IV.    Special Syndromes
        A.    Situation related seizures
        B.    Isolated, apparently unprovoked epileptic events
        C.    Epilepsies characterized by specific modes of seizure precipitation
        D.    Chronic progressive epilepsia partialis continua of children.
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A non-specific term which refers to a pain in the head, but offers no information as to quality, location, etc. Headaches are categorized by the International Headache Society Headache Classification, as below:

#  Migraine without aura
#  At least 5 "attacks"
        Duration: 4 72 hours (untreated)
        Pain characteristics (at least 2 of the following)
                a    Unilateral
                b    Pulsating
                c    Moderate-severe intensity (inhibits or prohibits daily activity)
                d    Increased with generalized physical activity, at least one of the following:
                        I    Nausea and vomiting
                        II    Photophobia and Phonophobia

      1. At least one of the following:
      1. History and examination do not suggest "organic" disorder
"Organic" disorder ruled out by appropriate imaging or other laboratory studies
The separation of migraine without aura from episodic tension type headache may be difficult, thus, at least 5 attacks are required for research purposes.

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A disease or dysfunction of the muscles.  Like the term neuropathy, it is a non-specific term.  The disease can strike anywhere in the muscular system.  There are 6 major categories of myopathies.  They are:

  1. Inflammatory myopathies
  2. Endocrine myopathies
  3. Metabolic myopathies (This includes mitochondrial encphalomyopathy)
  4. Toxic myopathies
  5. Congenital myopathies
  6. Muscular dystrophies
Although an EEG cannot be used to detect or diagnose myopathy, an NCS / EMG test can.
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In itself, the term neuropathy is non-specific. The term itself means a disease of the nerve. Neuropathy only refers to the peripheral nervous system, it is not used in reference to the central nervous system. There are five major types of neuropathy. Included among them are:

  • Metabolic neuropathies. Examples of these are alcoholic neuropathy, diabetic neuropathy, etc.
  • Traumatic neuropathies. Examples of these are compressive neuropathies, such as carpal tunnel syndrome, radial nerve entrapment (also referred to as Saturday Night Palsy), ulnar Neuropathy, and perennial neuropathy, which creates a dropped foot.
  • Toxic neuropathies: Related in many ways to metabolic neuropathies.
  • Degenerative neuropathies: So called because the nerve begins to physically break down. These are further classes into demyelinating and axonal neuropathies.
  • Inflammatory neuropathies: These are broadly broken down into acquired (such as AIDS), chronic (such as ALS), or hereditary. Hereditary is sometimes referred to as familial.
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There are different types of seizures.  Seizures can be convulsions, but convulsions are not necessarily seizures.