EEG basic to practice 2
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This document provides information about EEG waves and sleep patterns. It discusses the different types of EEG waves including delta, theta, alpha and beta waves. It describes normal sleep stages and the characteristic EEG patterns such as K complexes and sleep spindles. It also covers wave variants that can be seen with sleep and how age, consciousness level, medications and other factors can influence the EEG.
EEG basic to practice 2
- 2. To learn together FIRST One flower can give an odour enough than a bouquet But can’t give the colorful collection SECOND Our aim and objectives
- 5. BRAIN WAVES
- 6. EEG Waves • دايماتأتىالرياحبياتا • Delta waves – 1 – 3.5 Hz. • Theta wave -- 4 – 7.5 Hz. • Alpha wave -- 8 – 13 Hz. • Beta wave -- >13 Hz. (14 – 30 Hz.) »D T A B
- 7. One second
- 8. Alpha Rhythm أالمخ فى حاجة خر-اصحى-اتتأكد عنيك قفل–امهم لفرق • The starting point of analysing awake EEG • 8-13 Hz activity occurring during wakefulness • 20-60 mV, max over posterior head regions, Waxing & waning • Present when eyes closed; blocked by eye opening or alerting the patient • 8 Hz is reached by 3 years of age and progressively increases in a stepwise fashion until 9-12 Hz is reached by adolescence • Very stable in an individual, rarely varying by more than 0.5 Hz. • With drowsiness, alpha activity may decrease by 1-2 Hz • A difference of greater than 1 Hz between the two hemispheres is significant.( Ear referential montage) • 10% of adult have little or no alpha
- 11. Alpha block
- 12. NB • Unilateral failure of the alpha rhythm to attenuate reflects an ipsilateral abnormality (Bancaud’s phenomenon). • Normally, alpha frequencies may transiently increase immediately after eye closure (alpha squeak). • Alpha variants include forms that are one-half (slow alpha) • or two times the frequency with similar distribution and reactivity. (fast alpha) • Alertness results in the presence of alpha, and drowsiness does not. Paradoxical alpha
- 13. Mu Rhythm Arciform, apiculate negative and rounded positive phase (9-11) Hz. • - Intermingled with 20 Hz beta. C3,4 & Cz location. • - may be seen only on one side, and may be quite asymmetrical and asynchronous, despite the notable absence of an underlying structural lesion. • - Normal if other central rhythms symmetrical. • - Eyes open has no effects. • block with contralateral movement of an extremity. • - High voltage over skull defect – breach rhythm. • - Apiculate phase may resembles spikes.
- 17. Beta wave • Faster than alpha, present in the anterior head area. • Is a normal finding in the adult awake EEG and can sometimes be better seen when patient's eyes open. • Enhanced by drowsiness and some medication especially barbiturates.14 hz and above; 15-25 Hz most common. • - - Location: frontal – common; • central common mixed with Mu. • Posterior – fast alpha variant. • Diffuse – when abundant = medication effect • - Usually < 20 mV; occasionally 20-30 mV. • - Amplitude and distribution increases by: drowsiness, light sleep, REM, skull defect, medication especially benzodiazepines, barbiturates, chloral hydrate. • - Diffuse theta may accompany medication-induced excess beta.
- 19. Theta Rhythm • – Low voltage 4-7 hz diffuse theta a common component of normal recordings. • - May be seen at the onset of sleep, not a predominant rhythm in the normal alert adult EEG. • - More common in children and young adults than older adults. • The appearance of frontal theta can be facilitated by emotions, focused concentration, and during mental tasks. • Theta activity is normally enhanced by hyperventilation, drowsiness, and sleep. • Intermittent 4- to 5-Hz activity bitemporally, or even with a lateralized predominance (usually left > right), may occur in about one-third of the asymptomatic elderly and is not abnormal.
- 20. Lambda waves • O1,2 pricipally. Involve P3,4 & T5,6. • Bilateral synchronous; diphasic or triphasic. • Largest wave electropositive lasting 100- 200msec. • Evoked by scanning well-illuminated, patterned visual field. • Present in 50% of normal EEGs. • Blocked by white paper shuttle
- 22. DELTA waves • Less than 4 hz. • - Not a normal findings in the awake adult EEG. • - Normally found in the deeper stages of sleep. • - Hyperventilation Sequencies: Increase in diffuse theta. Rhythmic delta in bursts. Continuous rhythmic delta. • - Effect maximally anterior in most adolescents, adults maximum amplitude of delta bursts may shift from side-to-side. • - Multiples frequencies may create apiculate wave forms effect greatly in youth with maximum effort and low serum glucose. • - Effects subsides in 60-90secs. After HV. • - Post HV period may contain newly appearing focal delta or theta as abnormalities.
- 29. Stages of sleep EEG pattern Somatic or Behavioral changes Alert Alpha activity on eye closed Desynchronization on eye opening Respond to verbal commands I (Drowsiness) Alpha dropout and slowing & appearance of vertex waves & theta.POSTS Reduced HR & RR II (Light sleep) Sleep spindles, vertex sharp waves & K-complexes, POSTS Reduced HR & RR III ( Deep Sleep) Much slow theta- delta background K-complexes No spindles Reduced HR & RR
- 30. IV (very deep sleep) Synchronous delta waves, some K- complexes Reduced HR & RR REM sleep (paradoxical sleep) Desynchronization with faster frequencies Mixed frequencies HR, BP & RR irregular Marked hypotonia Rapid eye movement 50 – 60 /min. Dreaming threshold of arousal
- 33. Wave variants with sleep • Vertex (V) Waves • – Bilaterally synchronous. • - Maximum amplitude at vertex (Cz) extend to Fz, Pz, F3,4; C3,4; P3,4. • - May appear in sequencies; shifting asymmetries occur; • - . • - May be preceded and/or followed by smaller waves of opposite polarity. • - Highest amplitude and sharpest in youth; become more blunt with age. • - Appear principally in light sleep but also in awakefulness, drowsiness, and at onset of focal pathology.
- 34. Post Occipital Sharp Transients of Sleep (POSTs) • Sharp-contoured, mornophasic, surface-positive transients • Ocurring singly or in trains of 4-5 Hz over the occipital head regions • May have a similar appearance to the lambda waves during the awake record but are of higher voltage and longer duration • Usually bilaterally synchronous but may be asymmetric over the two sides • Predominantly seen during drowsiness and light sleep
- 35. POSTs
- 36. • Spindles – • Rhythmic or arciform waves. • - In 2-3 sec bursts, waxing and waning giving spindle shape. • - Bilaterally synchronous and symmetrical or asynchronous with symmetry of total spindle quantity. • - 13-14 Hz Cz, C3,4 with frontal spread in light stage 2 sleep. • - 10-12 Hz Fz, F3,4 in deeper stage 2 and stage 3 sleep.
- 37. Sleep Spindles
- 38. • K Complexes – • Diphasic waves (Initial brief wave; subsequent slow wave). • - + Spindles superimposed on slowed wave stage 2 sleep
- 42. Stages of sleep EEG pattern Somatic or Behavioral changes Alert Alpha activity on eye closed Desynchronization on eye opening Respond to verbal commands I (Drowsiness) Alpha dropout and slowing & appearance of vertex waves & theta.POSTS Reduced HR & RR II (Light sleep) Sleep spindles, vertex sharp waves & K-complexes, POSTS Reduced HR & RR III ( Deep Sleep) Much slow theta- delta background K-complexes No spindles Reduced HR & RR
- 43. IV (very deep sleep) Synchronous delta waves, some K- complexes Reduced HR & RR REM sleep (paradoxical sleep) Desynchronization with faster frequencies Mixed frequencies HR, BP & RR irregular Marked hypotonia Rapid eye movement 50 – 60 /min. Dreaming threshold of arousal
- 46. Wave variants with sleep • Vertex (V) Waves • – Bilaterally synchronous. • - Maximum amplitude at vertex (Cz) extend to Fz, Pz, F3,4; C3,4; P3,4. • - May appear in sequencies; shifting asymmetries occur; • - . • - May be preceded and/or followed by smaller waves of opposite polarity. • - Highest amplitude and sharpest in youth; become more blunt with age. • - Appear principally in light sleep but also in awakefulness, drowsiness, and at onset of focal pathology.
- 47. Post Occipital Sharp Transients of Sleep (POSTs) • Sharp-contoured, mornophasic, surface-positive transients • Ocurring singly or in trains of 4-5 Hz over the occipital head regions • May have a similar appearance to the lambda waves during the awake record but are of higher voltage and longer duration • Usually bilaterally synchronous but may be asymmetric over the two sides • Predominantly seen during drowsiness and light sleep
- 48. POSTs
- 49. • Spindles – • Rhythmic or arciform waves. • - In 2-3 sec bursts, waxing and waning giving spindle shape. • - Bilaterally synchronous and symmetrical or asynchronous with symmetry of total spindle quantity. • - 13-14 Hz Cz, C3,4 with frontal spread in light stage 2 sleep. • - 10-12 Hz Fz, F3,4 in deeper stage 2 and stage 3 sleep.
- 50. Sleep Spindles
- 51. • K Complexes – • Diphasic waves (Initial brief wave; subsequent slow wave). • - + Spindles superimposed on slowed wave stage 2 sleep
- 56. Factor influencing EEG • Age – Infancy – theta, delta wave – Child – alpha formation. – Adult – all four waves. • Level of consciousness (sleep) • Sedation • Hypocapnia (hyperventilation) slow & high amplitude waves. • Hypoglycemia • Hypothermia • Low glucocorticoids Slow waves
- 58. Hyperventillation • The usefulness of HV depends on vasoconstriction secondary to resultant decreased CO2 concentration, thus inducing relative cerebral ischemia and decreased glucose utilization. • A complain of lightheadedness or tingling in the extremities. • Even tetany secondary to hypocalcemia may occur with particularly vigorous HV. • The procedure is most effective in the young; in the elderly it has little effect. • The standard response is moderate to high-voltage, often rhythmic, delta and theta slowing with bifrontal preponderance • As a rule, HV is carried out for 3 minutes with vigorous exhalation at an increased but not particularly rapid rate. • Rapid HV moves little air and has correspondingly little effect. • After the conclusion of HV the record should return to baseline levels in about 1 minute • it is not performed in patients with pulmonary and cardiac disease.
- 60. Photic stimulation • easily carried out with strobe units that flash for 5– 10 seconds at frequencies typically between 1 and 35 Hz. • If the response to the flash train is 1 : 1 it is termed the fundamental. • It is not unusual to see harmonic (twice the flash frequency) and/or subharmonic (half the flash frequency) responses. • If photic driving is absent on one side, it may support a diagnosis of unilateral structural disease involving the occipital region (e.g., infarction in posterior cerebral artery territory).
- 63. Sleep deprived • Sleep deprivation is a powerful activator of epileptiform activity. • It is sometimes suggested that the subject stay up all night before his or her appointment the next morning, but a brief period of sleep may be permitted. • No caffeinated beverages are permitted, • Carry out HV early in the recording • One can expect an increase in or de novo appearance of focal epileptiform activity in about 30% of patients with epilepsy
- 65. 1. Frequency of brain waves in sequence of DTAB, same to age progression 2. Sleep changes very important, it is a source of confusion with pathology, and a source of abused EEG and AED.
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