EEG Changes - Pathology

Question 1

Absence Seizures (Petit-Mal)

Answer 1

Regular 3 Hz Complexes

Question 2

Alzheimer’s Dementia

Answer 2

Rarely normal in advanced dementia

May be helpful in differentiating pseudodementia from dementia.

Question 3

Angelman’s Syndrome

Answer 3

1. EEG changes are notable by the age of 2.
2. Prolonged runs of high amplitude 2–3 Hz frontal activity with superimposed interictal epileptiform discharges – all ages
3. Occipital high amplitude rhythmic 4–6 Hz activity facilitated by eye closure, is seen under the age of 12 years.
4. There is no difference in EEG findings in AS patients with or
   without seizures

Question 4

Antisocial Personality Disorder

Answer 4

Increased incidence of EEG abnormalities in those with aggressive behaviour.

Question 5

ADHD

Answer 5

Up to 60% have EEG abnormalities (spike/spike-­waves)

Question 6

Borderline Personality Disorder

Answer 6

Borderline personality disorder Positive spikes: 14 and 6 per second seen in 25% of patients.

Question 7

CJD

Answer 7

Generalised periodic 1-­2 Hz sharp waves are seen in nearly 90% patients with sporadic CJD. Less often in familial/hormonal transplant-­related forms. NOT seen in a variant form.

Question 8

Closed Head Injuries

Answer 8

Focal slowing (sharply focal head trauma)

Focal delta slowing (subdural haematoma)

Question 9

Diffuse Atherosclerosis

Answer 9

Slowed alpha frequency and increased generalized theta slowing

Question 10

Herpes Simplex Encephalitis

Answer 10

Episodic discharges are recurring every 1-­‐‑3 seconds with variable focal waves over the temporal areas.

Question 11

Huntington’s Dementia

Answer 11

Initial loss of alpha, later flattened trace

Question 12

Infantile spasms (seen in
tuberous sclerosis)

Answer 12

Hypsarrhythmia [diffuse giant waves (high voltage, >400 microvolts) with a chaotic background of irregular, asynchronous multifocal spikes and sharp waves]. Clinical seizures are associated with a marked suppression of the background -­‐‑ called the electrodecremental response.

Question 13

Infectious Disorders

Answer 13

Diffuse, often synchronous, high voltage slowing (acute phase of encephalitis)

Question 14

Metabolic and Endocrine Disorders

Answer 14

Diffuse generalized slowing. Triphasic waves: 1.5 to 3.0 per second high-­voltage slow-­waves especially in hepatic encephalopathy

Question 15

Neurosyphilis

Answer 15

The non-­specific increase in slow waves occurring diffusely over the scalp

Question 16

Panic Disorder

Answer 16

Paroxysmal EEG changes consistent with partial seizure activity in one-­third; focal slowing in about 25% of patients

Question 17

Seizures

Answer 17

Generalized, hemispheric or focal spike/spike-wave discharge

Question 18

Stroke

Answer 18

Focal or regional delta activity

Question 19

Structural lesions

Answer 19

Focal slowing/focal spike activity