#STEEMGIGS TIL(today i learned) -"SYNCOPE"- PART-1

Hello everyone,
Today i learned about syncope and I would like to tell about it. As syncope is a big topic i will split it into parts.we have to know about our health problems that is my goal.
Thanks to @surpassinggoogle and @steemgigs for supporting minnows.

SYNCOPE-

It is a transient,self-limited loss of consciousness due to acute global impairment of cerebral blood flow

●The onset is rapid,duration brief, and recovery spontaneous and complete.
●A syncopal prodrome(presyncope) is common,although loss of consciousness may occur without any warning signals.
●Typical presyncopal symptoms include dizziness,lightheadedness or faintness,weakness,fatigue,and visual and auditory disturbances

PATHOPHYSIOLOGY

1. The upright posture imposes a unique physiologic stress upon humans;most,although not all,syncopal episodes occur from a standing position.there is pooling of 500-1000ml of blood in the lower extremities and splanchnic circulation after standing.
2. there is decrease in venous return to the heart and reduced ventricular filling that results in diminished cardiac output and blood pressure.
   These hemodynamic changes provoke a compensatory reflex response,initiated by the baroreceptors in the carotid sinus and aortic arch,resulting in increased sympathetic outflow and decreased vagal nerve activity.
3. This reflex increases peripheral resistance,venous return to the heart,and cardiac output and thus limits the fall in blood pressure.
4. If this response fails,as is the case chronically in orthostatic hypotension and transiently in neurally mediated syncope,cerebral hypoperfusion occurs.
5. syncope is aconsequence of global cerebral hypoperfusion and thua represents a failure of cerebral blood flow autoregulatory mechanisms.
6. The latency of autoregulatory response is 5-10s
7. typically cerebral blood flow ranges from 50 to 60ml/min per 100g brain tissue and remains relatively constant over perfusion pressures ranging from 50 to 150 mm Hg.
8. cessation of blood flow for 6-8s will result in loss of consciousness,while impairement of consciousness ensues when blood flow decreses to 25ml/min per 100g of brain tissue.
9. from the clinical point of view, a fall in systemic systolic blood pressure to ~50 mm Hg or lower will result in syncope.a decrease in cardiac output and/or systemic vascular resistance -thus underlies the pathophysiology of syncope.

EEG Changes
Two patterns of electroencephalographic(EEG) changes occur
■1st pattern- "slow-flat-slow" pattern-

In this normal background activity is replaced with high-amplitude slow delta waves.this is followed by sudden flattening of the EEG-a cessation or attenuation of cortical activity- followed by the return of slow waves,and then normal activity.

■2nd pattern- slow pattern-

It is characterized by increasing and decresing slow wave activity only.the EEG flattening that occurs in the slow-flat-slow pattern is a marker of more severe cerebral hypoperfusion.

Here is the pic of EEG pattern -
"Slow-flat-slow" pattern

There is lot of information is ahead to learn. We will see in next part ..

My special thanks to my supporters @schamangerbert @pundito @novacadian @amreshchandra @angelinafx and my friends @sonuuday and @vinaykumarr who are supporting me.

Thanks for reading
Yours @summisimeon