Fisch EEG Primer Chapter 20 Flashcards

Localized Slow Waves

1
Q

What is the cause of local slow waves?

A

circumscribed abnormality located superficially or deeply within a hemisphere (e.g. cerebral white matter). Usually has an acute or progressive course (ischemi or seizures, tumors, hemorrhage, abscess, migraine, hypertensive encephalopathy)

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2
Q

Focal slow waves consists of waves less than…

A

8Hz - usually only focally located but can rarely be over entire hemisphere

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3
Q

focal irregular delta activity is commonly referred to as…

A

focal polymorphic delta activity

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4
Q

what type of reactivity is typically seen with focal irregular delta activity?

A

little attenuation with eye opening and may NOT be facilitated by hyperventilation whereas surrounding theta activity MAY respond to these maneuvers - these areas are most conspicuous during transition between wakefulness and light sleep.

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5
Q

Structural lesions producing focal polymorphic delta activity typically demostrate

A

continous activity of variable waveform, amplitude, duration, and morphology that are persistent during sleep and eye opening maneuvers

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6
Q

What are some transient cerebral disorders that can cause focal slow waves?

A

TIA, migraine, hypertensive and metabolic encephalopathies, post ictal, head injuries

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7
Q

What is the time period of maximal slow wave activity following structural damage?

A

Immediately following damage

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8
Q

What is the spatial relationship between focal slow waves and underlying cerebral lesions?

A

superficial lesions are fairly precise indicators however can appear more lateral or anterior.

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9
Q

What are some other features of EEG in those with focal slow waves that will help in making a clinical diagnosis?

A
  • widespread asynchronous slow waves -usually from acute vascular or metabolic changes
  • bilaterally synchronous slow waves - usually deep midline structures (e.g. FIRDA - potential sign of pending herniaiton)
  • focal spike and sharp waves - possible ongoing epileptiform activity
  • asymmetry and reduced reactivity of the alpha rythym - posterior lesions
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10
Q

What are some degenerative disorder that can produced focal slowing?

A

Alzheimer’s disease, Jakob-creutzfeld, normal pressure hydrocephalus, porencephaly, tuberous sclerosis, holoprosencephaly, bilateral retrobulbar neuritis in children

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11
Q

What are some metabolic disorders that can produced focal slowing?

A

hypoglycemia, hypoxia, non-ketotic hyperglycemia, porphyria, vitamin B12 deficiency, Wilson’s disease

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12
Q

What are some cerebrovascular disorders that can produce focal slowing?

A

ischemia, embolism, hemorrhage, migraine especially if associated with unilateral neurological deficit, tia, chronic subdural, sah

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13
Q

What are some traumatic/ injuries that can produced focal slowing?

A

brain surgery, progressive traumatic encephalopathy, hemispherectomy

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14
Q

What is the significance of brain tumors and focal slowing?

A

AMONG THE MOST IMPORTANT CAUSES OF FOCAL SLOWING`

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