yeah this is very important how much ml you can withdraw safely more important question before
that is that never withdraw cs try to withdraw csf if there's raised intracranial pressure
this is raised intracranial intracranial pressure is contraindication to the lumbar puncture why
because if pressure in the cs if intracranial pressure is high maybe there's a big tumor or
swelling and as soon as from this area you pull the csf out brain will herniate
right through foramen magnum metallic will come down and maybe the lower part of tonsillar part
of the cerebellum and that all that gets crushed and patient dies is that right and how you know
that patient has really raised intracranial pressure before doing the lumbar puncture
because it is not written on the patient here that i have a raised
interactional pressure don't do lumbar puncture
usually we withdraw csf about 5 to 10 ml per bottle and usually we take about 3 bottles
is that right yeah but it should be better to keep it low yes please who will tell me
that how do you really know patient has raised intracranial pressure or not before you do the
lumbar puncture so you ask the patient do you have and do you think patient is going to tell you
yes anyone has good idea that how do you know that this raised intracranial pressure
there is a very dangerous black star with five points
number one patient has a history of headache and this headache is usually
present already when patients wake up any headache which is present already
when you wake up however mild it is it should be considered serious
is there any unexplained headache right when a person has already as soon as you wake up
you realize he has headache unexplained but if you have been hit by someone yesterday night
of course there's well-explained headache right so any unexplained headache right uh
that raises suspicion of the raised interaction depression because in lying down for a long time
right fluid accumulates there and if there's raised internal pressure that become further
raised and that produces headache number one number two is there is yes papal edema
you know what is papillardima okay let me tell you if you do ophthalmoscopy you know thermoscopy
right with the thermoscope you look through the pupil
on the retina is that right normally if you look at the retina it looks like this
what is this optic disc this is the point where optic nerve is attached with the eyeball or in
the retina am i clear optic disc now normally the margins of optic disc are very sharp and clear
if there is purple edema if up right if there is this is called papilla if
it is animators then there are no more clear they look like this the margins are blurred
due to edema and in raised intracranial pressure there is papilloedema raised intracranial pressure
may be due to severe meningitis inflammation of managers or due to encephalitis inflammation of
the brain or raised internal pressure may be due to tumors or raised intracranial pressure may be
due to hemorrhages or any space occupying lean and cranial cavity may lead to high intracranial
pressure and all these situations lumber puncture is contra indicated is that right someone can
explain why the patient develop papillardema due to when they have raised intracranial pressure
do you really want to know the answer we move forward that why raised interchangeable pressure
produces popular edema you want to know it okay then i have to draw a diagram
this thing may not be very relevant with this lecture but it is extremely relevant
with your career that every doctor should know that what are the important signs and symptoms
related with raised intracranial pressure right now popular edema why it develops
let me tell you okay this is i make central nervous system
this is central nervous system and what is this fluid around here if this is subarachnid space
what is this fluid csf is that right and whenever there is some tumor in the brain
or there is swelling of the brain or there's inflammation of the meninges under all these
things cranial cavity cannot expand so pressure in the cranial cavity goes up so intracranial
pressure is high now listen carefully uh what is this this is dura this is dura
matter i have not drawn the subrag for simplicity this is the dura mater now listen carefully
actually here is your eyeball this is your eyeball okay let me make it little bit beautiful
here should be length and suspensory ligament this is your eyeball is that right now
actually from here these are the neuronal this is the retina and from here what is this going out
optic nerve and optic nerve is of course connected with the central nervous system is that right
this is optic nerve going to the chasma that we'll discuss later these are the fibers of
optic nerve am i clear no problem in this diagram actually now this
is the beauty of understanding dura mater moves makes a sleeve around the optic nerve
if durameter is making a sleeve around the optic nerve then it means csf is also going around the
optic nerve up to this point
am i right i hope you'll never forget this diagram in your life
until you're going to deal with the patients that csf is around the optic nerve why because
optic nerve is covered by the biomatter and then it has subarachnoid matter and optic nerve has
a outer covering as dura mater and there's the special news optic nerve is not a nerve
it is a central nervous system track we wrongly call it nerve is that right optic nerve is not
typical peripheral nerve it is actually central nervous system track proof is that it is covered
by all the layers of central nervous system plus its myelin sheath of the optic nerve is
not made by schwann cell schwann cells are the myelinating cells the peripheral nervous system
optic nerve has myelinating cells of central nervous system and central nervous system tracks
are myelinated by oligodendrocyte optic nerve is also myelinated by oligodendrocyte peripheral
nerves are myelinated by schwann's health optic nerve is myelinated by oligodendrocyte
central nervous system tracks are myelinated by oligodendrocyte so diseases of oligodendrocyte
will make disease in the central track and also in optical and diseases of schwann cell will make
peripheral nerve diseases but not after canal now you understand the whole story now another thing
here is retinal artery going you must be knowing that retinal artery is the branch of ophthalmic
artery you know it already i suppose now retinal artery going to the retina but when it is going to
retinite passes through what area pierces the dura mater of the optic nerve passes through
subarachnid space retinal artery passes through csf then parameter end into what is this optic
nerve and then it supplies the retinal branches to the retina am i clear of course then there should
be retinal uh central retinal vein also this was central retinal artery central retinal vein
bring the blood out backward vein should drain and this also passes through all those areas
central retinal vein now you see this is central retinal artery of course blood is going in that
direction so it means central lateral artery and veins pass through subregnant space around the
optic nerve am i really clear to everyone now if there is due to any reason
if intracranial pressure is high you know cranial cavity is not an expandable cavity
so if someone develop tumor or big hemorrhage or someone develops a big infection in central
nervous system or swelling so pressure in the central you know due to that reason
when things swell up in inside the cranial cavity pressure in the csf will go down or up
so when pressure csf pressure will become high then cerebral spinal fluid which is around the
optic nerve that will have low pressure or high pressure high pressure is that really
clear now you imagine retinal artery is artery arterial system as compared to the venous system
arterial system is high pressure system low pressure system high pressure and as compared to
arteries venous system is low pressure pressure in the arteries is high and pressure in the veins is
low now you imagine if you have raised interchangeable pressure then csf is under high
pressure in the optic nerve retinal artery itself is a high pressure vessel in spite of high csf
it will still take the blood to the retina but retinal vein which is draining the blood back
is compressed by the high pressure of csf is that right let me show you this is the optics nav
a dura mater here it is what is this optic optic uh nerve
artery cannot be compressed by high pressure but vein can be compressed by
right and csf pressure here is very high
and raise endocrine pressure so when vein is compressed blood is going but
cannot drain well the pressure in the micro circulation of retina goes up and edema develops
and that leads to that funny papilla edema a demo accumulates especially around the optic
disc margin am i really clear and there's one more reason fluid of csf right it also tracks through
the nerve bundles and also goes over there that also add to the papillae edema but as a single
cause if you want to remember the single cause of mechanism of papilloedema you say papillardema
develops in cases of raised interactional pressure because that optic nerve has a sleeve of durometer
and subarachnoid space so optic nerve is all the time bathing in csf and the central retinal
arteries and central retinal vein pass through that space when there's a high intranal pressure
csf pressure is high high pressure of the csf compresses the retinal vein so drainage of retinal
fluid is not well and edema develops in the retina we specially accumulate around the optic desk
and optic does become edematous and we say patient as papal edema so it's so easy that you are doing
you are going to do lumbar puncture you just do of thermoscopy and look at optic disc if it
is its margins are blurred then please don't do lumber puncture patients life will also blur and
your professional carrier carrier may also blur is that clear that means that there is high pressure
yeah popular edema mean there's high pressure in the csf is that right so two features of
raised intracranial pressure i discussed number one was headache number two papillon
third feature of raised intracranial pressure is projectile vomiting
raised intracranial pressure right it disrupts the git regulating centers in medulla and vagus nerve
is disturbed you know vagus nerve is coming out of medulla do you know that okay that's good so
what really happens when raised interchangeable pressure is there right uh brain is little bit
herniating downward vagus nerve is disturbed and you know vagus nerve supplies the git and
control the motility of the git regulate so when it is firing too much patient may develop retro
propulsions and a vomiting which is projectile vomiting what is meant by the projectile vomiting
is that right that is projectile vomiting and he will be spared
don't be upset is that right i mean this type of vomiting is a characteristic in small
children very small children have normal vomiting projectile only mama knows is that right but when
we become adult our vomiting is really not that thank god not that projectile right but in adult
life if you redevelop your projectile vomiting maybe one of the reason is raised internal
pressure then another two more classic features of raised interchangeable pressure are progressively
rising blood pressure every hour you take the blood pressure of the patient it keeps on going
up and progressively falling pulse rate i will explain why patient has progressively rising blood
pressure and progressively falling pulse rate for example if raised internal pressure is there now
pulse may be 60 and after a few hours it may be 50 still after a few hours if it may become 40 why
because vegas is again irritated and vegas in cardio stimulant or cardio inhibitor
inhibitor so when heart rate is reduced of course pulse will go
down and why blood pressure goes up because when there's high pressure in central nervous system
then do you think blood can easily enter into central nervous system no so blood flow to central
nervous system reduces an ischemia develop an ischemia central nervous system produces immense
sympathetic overflow which constricts many vessels in the body and your blood pressure goes up
that is an attempt of the vessels of the body to construct and push the blood to ischemic brain
is that right but you want me to revise it okay listen cranial cavity cannot be
expanded it's a fixed cavity due to any reason if pressure in the cranial cavity become too much
do you think then blood which is going to central the system blood flow will increase to cns or
decrease when blood flow to cns will decrease the central nervous system will develop ischemia
when central our system develops significant ischemia it produces intense sympathetic overflow
sympathetic fiber fire and many vessels in the body constrict right in a way all the vessels are
squeezing the blood towards the central nervous system right so due to that reason if you take
blood pressure that will be high but due to over sympathetic stimulation heart rate does not go out
go up because vehicle stimulation is very swear which inhibits the heart rate
overrides the sympathetic stimulation to the heart rate sympathetic nervous system try to
stimulate the heart rate but parasympathetic definitely inhabits is that right so
if you come across a patient who complains of some headache which is specially present on lying down
you look at the
optic disc and you find this papillae edema projectile vomiting is there
and progressively blood pressure is going up and pulse rate is going down you must suspect
strongly that there's a raised interchangeable pressure and don't plan lumbar puncture am i okay