EEG Sleep EEG definition It is record of

EEG & Sleep

EEG: definition • It is record of variations in brain potential • It is record of electrical activity of brain/neurons in different phases e. g. during sleep, wakefulness and epilepsy.

E. E. G • Carried out by placing electrodes on surface of scalp. • Sometimes placed directly on surface of cerebral cortex, e. g. , during neurosurgical operations or in experimental animals. • Such a record is called Electro. Corticogram (ECOG)

E. E. G • E. E. G was 1 st recorded by a German Psychiatrist Hans Berger. • There are 2 methods for EEG recording • Recording of EEG can be unipolar or bipolar. • In unipolar EEG, active electrode is placed on surface of scalp, while inactive or indifferent is placed at a distant point, like tip of 7 th cervical vertebra. • In bipolar EEG, both electrodes are active & placed on surface of scalp.

E. E. G • In routine E. E. G, 20 electrodes are placed on scalp at different points to record EEG. • In normal EEG, 4 types of waves can be seen: alpha, beta, theta & delta, in different phases. • Character of each wave is described as • 1 - its intensity/voltage 2 - frequency

Alpha waves: Waves of quiet wakefulness / waves of inattentiveness: • Frequency: 8 -13 / sec • Voltage: 50 micro-volts • Relaxed awareness These are recorded when a person is awake but mentally relaxed & inattentive, e. g. , lying comfortably in a quiet room, eyes are closed & person is mentally relaxed & inattentive.

Alpha waves: Waves of quiet wakefulness / waves of inattentiveness: • When a person opens eyes or the brain becomes active by thinking process or solving a problem, alpha waves disappear. • Frequency of alpha waves decreases by decreased body temperature, decreased glucocorticoid secretion, hypoglycemia & increase in p. CO 2. (due to cold temp. / empty stomach / during suffocation, one cant relax)

Alpha waves: Waves of quiet wakefulness / waves of inattentiveness: • Best recorded from parietal & occipital regions. • Thalamo-cortical connections are important for it.

Beta waves: waves of alertness / wakefulness / desynchronized waves • Frequency: 14 -80 cycles/sec • Amplitude / voltage: 20 microvolts. Awareness with concentrated attention • Recorded when brain is highly active. • Best recorded from parietal & frontal regions. • Recorded during REM sleep. • Appear on eye opening

Theta waves: • Frequency: 4 -7 / sec • Voltage: 10 microvolts • Best recorded from parietal & temporal regions. • Recorded during light sleep. • Recorded in adults during states of frustration & disappointment. • In children normally recorded in awake E. E. G. • Also recorded in brain disorders like Grand Mal Epilepsy. In degenerative brain disorders.

Delta Waves: • Very slow waves. • Frequency: 0. 5 - 3 / sec • Voltage: 100 microvolts • Recorded in deep & restful sleep. • Also recorded in coma, general anesthesia & in epilepsy. In organic brain disorders.

Brain waves in normal E. E. G

Physiological basis of E. E. G: • Electrical activity recorded in EEG, is mainly from superficial layers of cerebral cortex which have number of dendrites on which many nerve terminals synapse. • Some terminals are excitatory (EPSP is produced), some are inhibitory (IPSP is produced). • Electrical activity recorded in EEG, is summation of EPSPs & IPSPs

Physiological basis of E. E. G: • Amplitude of waves in EEG depends on how much the waves are synchronized / coordinated. • If waves are synchronized, there is increased amplitude. • If desynchronized, there are deflections in different directions & these neutralize each other, resulting into a small amplitude like in beta waves. • During each wave there is synchronous discharge/ activation of neurons.

Physiological basis of E. E. G: • Thalamo-cortical connections are important, mainly in recording of alpha waves. • If these fibers are cut, alpha waves disappear & delta waves appear.

Clinical use of E. E. G: • • EEG reflects functional state of brain. Recorded as an investigation in patients. Also recorded for research purpose. Recorded for many hours in epilepsy cases. • EEG machines are now computerized & there is automatic analysis of EEG.

Clinical use of E. E. G: • Helps to diagnose SOL (Space occupying lesion) in skull, which may be infective, neoplastic, traumatic or vascular. • It helps in diagnosis of epilepsy & its types. • It helps in diagnosis of psychopathic disorders.

Clinical use of E. E. G: • In Grand Mal epilepsy, there may be theta or delta waves (high voltage waves) in EEG. • In Petit Mal epilepsy, there is spike & dome pattern. • In Psychomotor epilepsy, mainly delta waves are seen.

Clinical use of E. E. G: • E. E. G silence is sure indication of brain death.

Epilepsy • Epilepsy (also called “seizures”) is characterized by uncontrolled excessive activity of either part or all of CNS. • Attack occurs when basal level of excitability of neurons crosses threshold. • Epilepsy can be classified into three major types: • grand mal epilepsy, petit mal epilepsy, and focal epilepsy.

Grand Mal Epilepsy/Generalized epilepsy • Grand mal epilepsy is characterized by extreme neuronal discharges in all areas of the brain cerebral cortex, deep parts of cerebrum, and brain stem. • Discharges transmitted into the spinal cord sometimes cause generalized tonic seizures of the entire body, followed by alternating tonic and spasmodic muscle contractions called tonic-clonic seizures

• • person bites his tongue difficulty in breathing & cyanosis urination and defecation can occur grand mal seizure lasts from a few sec to 3 to 4 min. It is also characterized by post seizure depression of the entire nervous system.

Factors which produce epilepsy • Strong emotional stimuli • Hyperventilation or alkalosis • Effects of some drugs e. g. phenylenetetrazole • High fever • Loud noises • Bright light • Traumatic lesion in any part of brain

Petit mal/Partial epilepsy • Person suddenly becomes unconscious. • Convulsions do not occur • Muscles of face show twitching & blinking of eyes • Afterwards person become normal • It occurs in late childhood • Absence syndrome/ absence epilepsy • Excitatory thalamocortical neurons

Focal Epilepsy • It involves only localized area of brain (cerebral cortex or deep parts of cerebrum) • The abnormality starts from a particular area and spreads to the adjacent area.

Focal Epilepsy • • • Two types 1 - Jacksonian epilepsy 2 - Psychomotor epilepsy Causes 1 - scar tissue in brain, 2 - Tumor, 3 - some destroyed part of brain tissue • In Jacks, as the wave of excitation spreads over motor cortex, it causes progressive march

• Of muscle contrations throughout the opposite side of body. • Beginning in mouth region and marching progressively downwards to legs.

Psychomotor epilepsy • It is characterized by emotional outburst such as abnormal rage, anxiety, fear or discomfort. • There is amnesia or confused mental state for some period. • The cause, are the abnormalities in temporal lobe & tumor in hypothalamus and limbic system.

SLEEP • “Period of inactivity during which there is unconsciousness from which person can be aroused by sensory & other stimuli”. • Unconsciousness during surgical anesthesia, epilepsy & coma should not be considered as sleep.

Lack of SLEEP • Sleep is essential for normal life. • It restores a balance between different parts of nervous system. If a person is not allowed to sleep for 2 -3 days, certain effects are seen: • Loss of concentration • Slow thought making • Loss of memory • irritability

Lack of SLEEP If insomnia is further prolonged, person may develop: • Dysarthria (defect of speech) • Tremors • Abnormal gait

Requirement of SLEEP Varies with age: • Infants: 20 -24 hrs • Young children: 12 hrs • Young adults: 7 -9 hrs • Old age: 5 -7 hrs

Relationship of SLEEP with ANS: During sleep, generally there is • Sympathetic inhibition & • Parasympathetic stimulation

Types of SLEEP • SLOW WAVE / Non. REM sleep / Delta wave sleep • REM sleep / paradoxical sleep

SLOW WAVE / Non-REM sleep / Delta wave sleep • Deep & restful sleep. • If a person is tired, he passes into deep sleep in 1 hr. • On average it constitutes 75% of total sleep during a night. • Dreams can be seen but are not remembered, so cannot be recalled. • Muscle tone decreases.

SLOW WAVE / Non-REM sleep / Delta wave sleep • • • Slowing of heart rate & respiratory rate BMR decrease There is GH secretion Pupillary constriction. Sleep walking (somnambulism) may be seen during slow wave sleep

REM sleep / paradoxical sleep • Occurs in periods lasting for 5 -30 min. • Each period is repeated at every 90 min. • There are 4 -6 periods of REM sleep during a night. • It constitutes 25% of total night sleep.

REM sleep / paradoxical sleep • Its duration is different in different age groups. • There is more REM sleep as age advances. • If a person is tired, less REM sleep at night. • If a person has taken rest during day time, more REM sleep at night.

REM sleep / paradoxical sleep • There is active dreaming & dreams can be recalled. • It is difficult to arouse the person from REM sleep as compared to non REM sleep but • Usually in the morning, person wakes up from REM sleep.

REM sleep / paradoxical sleep • During REM sleep, brain is highly active, so beta waves are recorded from EEG. • Muscle tone increases. • Rapid movement of eye. • Twitching in different parts of body. • Mild convulsions.

REM sleep / paradoxical sleep • Respiratory & heart rate becomes irregular during REM sleep. • Increased secretion of corticosteroid hormones. • In males, may be erection (parasympathetic stimulation) • Teeth grinding (BRUXISM) occurs. • Replacement of alpha rhythm by asynchronous rhythm on opening eye.

Replacement of alpha rhythm by asynchronous rhythm on opening eye:

Types of SLEEP • SLOW WAVE / Non-REM sleep / Delta wave sleep • REM sleep / paradoxical sleep • 75% sleep • 25% sleep • Dreaming without memory • Active dreaming with memory • Increased parasympathetic stimulation • Increased sympathetic stimulation • Decreased muscle tone • Bed-wetting in children • Increased muscle tone, muscle twitching & convulsions.

Types of SLEEP • SLOW WAVE / Non-REM • REM sleep / paradoxical sleep / Delta wave sleep • Decreased heart rate • Irregular heart rate • Decreased respiratory rate • Irregular respiratory rate • Pupil constriction • No constriction of pupil • Easy to arouse from sleep • Difficult to arouse from sleep, but gets up spontaneously in the morning • Brain is not active • Brain is active

Types of SLEEP • SLOW WAVE / Non- • REM sleep / paradoxical REM sleep / Delta sleep wave sleep • • Increased GH No erection No bruxism Sleep walking • Increased corticosteroid • Erection • Bruxism • No sleep walking

Changes in EEG when a person goes to sleep:

Mechanism of sleep • There is a cycle of wakefulness & sleep. • When a person is awake, gradually neurons in reticular activating system become less & less active & there is also activation of certain sleep centers. • This results into sleep.

Mechanism of sleep • During hours of sleep, neurons in reticular activating system become progressively more & more active, leading to wakefulness.

Sleep centers: • 1) LOCUS CERULEUS: Location: • At junction of midbrain & pons. • Neurons in this locus secrete nor epinephrine at nerve endings of nerve fibers. • Nerve fibers from these neurons pass to reticular formation.

Sleep centers: • This center (Locus Ceruleus) is involved in REM sleep, when brain is highly active. • So perhaps nor-epinephrine secreting neurons are involved (sympathetic stimulation in REM sleep) • Ach secreting neurons in reticular formation of upper brain-stem are also involved.

PGO spikes • In REM sleep there are PGO spikes (large phasic potentials in groups of 3 -5). • These spikes are due to Acetylcholine secreting neurons in this pathway of producing REM sleep. • Only the tone of neck muscles is dec. , other muscles keep their tone. • But at the same time there is locus ceruleus dependent inhibition of voluntary act.

Sleep centers: • 2) RAPHE MAGNUS NUCLEUS: • Midlinear nuclei in upper pons & lower medulla. • Fibers from here pass to reticular formation, hypothalamus, limbic system & also spinal cord. • These fibers synapse with pain-inhibitory neurons in dorsal horn of spinal cord (analgesia system).

Sleep centers: • There is release of serotonin at nerve endings of these fibers. • Raphe Magnus Nucleus is involved in Deep Slow Wave sleep (NREM sleep). • Serotonin inhibitors wakefulness. • Stimulation of SCN of Anterior hypothalamus, certain thalamic nuclei & portion of nucleus of tractus solitarius NREM sleep.

Muramyl dipeptide induced sleep: Experimental observation: • In animals kept awake for 2 -3 days, muramyl dipeptide & other sleep promoting factors are produced in CSF of brain stem which can be later detected in blood & urine. • When muramyl dipeptide is injected to some other animal, it immediately passes into sleep.

DISORDERS OF SLEEP: • • • 1) Somnambulism / sleep walking 2) Bedwetting in children 3) Bruxism 4) Insomnia 5) Narcolepsy 6) Sleep apnea

1) Somnambulism / sleep walking • Occurs during slow wave sleep / NREM. • More common in male children. • Episode of sleep walking may remain for many minutes. • Person walks with open eyes, obstacles are avoided during walking. • Person wakes up unaware of sleep walking.

2) Bedwetting in children • Also called Nocturnal enuresis. • May be due to parasympathetic dominance, as it occurs in slow wave sleep.

3) Bruxism • Teeth grinding • Occurs during active sleep (REM sleep)

4) Insomnia • Inability to sleep, although sufficient facilities & time is available for sleep. • Reason: Psychological or medical.

5) Narcolepsy: • There attacks of intense desire to sleep during day time • Person cannot resist to sleep in the day • Attack may last for seconds to minutes

Cause of Narcolepsy: Etiology: • Considered to be hypothalamic disorder Evidence: • Other features of hypothalamic disorders are present, e. g. , obesity, polyuria, sexual retardation.

6) Sleep apnea • During sleep, breathing stops suddenly. • May be repeated 100’s of times in severe cases. • When breathing stops, person wakes up, takes a few breaths & then tries to go to sleep.

6) Sleep apnea • In the morning, person is fatigued & drowsy. • There may be features of respiratory failure without respiratory disease.

6) Sleep apnea ETIOLOGY: • Exact cause ? ? POSSIBLE CAUSES: • Obesity • Airway obstruction • Disease of CNS

Story of sleep disorders: • Somoo (somnambulism / sleep walking) knocks mom’s bedroom door, while sleeping. • Complains of wetting his bed (bed-wetting) • Mom reacts by Bruxism / teeth grinding • Mom shouts: You disturbed my sleep, I cannot sleep at night because of you!! (insomnia) • Mom adds: I will now go to sleep at my work place in the day! (narcolepsy) • Mom continues: I am so tired, that I can hardly breathe (sleep apnea)