3. Physiology of normal
intracranial pressure
• The normal supine intracranial
pressure is 10–15 mmHg, measured
at a position equal to the level of the
foramen of Monro.
• The intracranial pressure is directly
related to the volume of the
intracranial contents within the skull.
4. the Monro–Kellie doctrine
• is that “the cranial cavity is a rigid
sphere filled to capacity with
noncompressible contents and that
an increase in the volume of one of
the constituents will lead to a rise in
intracranial pressure”.
6. Causes of increased volume of normal
intracranial constituents
• a space-occupying lesion: cerebral
tumor, abscess, intracranial
hematoma.
• cerebral edema: tumor, trauma.
• benign intracranial hypertension:
(pseudo tumor cerebri).
• hydrocephalus: due to any cause.
• vasodilatation due to hypercapnia:
sleep, high altitude.
8. volume to pressure relationship
is described in terms of compliance and
elastance of the intracranial space.
• Compliance: is V/P, is the amount of
‘give 'available within the intracranial
space.
• Elastance: is the inverse of compliance
and is the ‘resistance’ offered to
expansion of a mass or of the brain
itself.
9. Intracranial pressure
monitoring
• There are three ways to monitor pressure
in the skull (intracranial pressure).
10. 1.INTRAVENTRICULAR
CATHETER.
The intraventricular catheter is thought
to be the most accurate method. A
burr hole is drilled through the skull.
The catheter is inserted through the
brain into the lateral ventricle.
11. 2.SUBDURAL SCREW.
A subdural screw or bolt is a hollow
screw that is inserted through a hole
drilled in the skull. It is placed
through the dura mater. This allows
the sensor to record from inside the
subdural space.
12. 3.EPIDURAL SENSOR.
an epidural sensor is inserted between
the skull and dural tissue. Is placed
through a burr hole drilled in the
skull. This procedure is less invasive
than other methods, but it cannot
remove excess CSF.
13. Neurological symptoms and signs
of raised intracranial pressure
1. Headache: usually worse on
waking in the morning and is
relieved by vomiting.
2. Nausea and vomiting: usually
worse in the morning.
3. Drowsiness: is the most
important clinical feature of
raised intracranial pressure.
14. CONTINUE
4. Papillodema: is due to transmission
of the raised pressure along the
subarachnoid sheath of the optic
nerve.
5. Sixth nerve palsy, diplopia, false
localizing sign.
6. Signs of brain herniation.
7. In infants; tense, bulging fontanelle.
15. Systemic signs of raised ICP
Cushing triad of :
HYPERTENTION
RESPIRATORY
BRADYCARDIA
IRREGULARITY
16. TYPES OF BRAIN HERNIATION
1. Cingulate herniation(subfalcian
herniation); the cingulate gyrus in one
hemisphere is pushed under the falx
towards the other hemisphere.
2. Uncal herniation(transtentorial
herniation), the uncus and hippcampus
pushed to the midline towards the
tentorial edge causing the classical
ipsilateral 3rd nerve palsy, hemiparesis
(kernohan’s notch).
17. TYPES OF BRAIN HERNIATION
3. Central transtentorial herniation;
downward movement of hemispheres
and basal nuclei through the tentorial
opining.
4. Upward transtentorial herniation (
the inverted pressure cone), is a
variant of central herniation.
5. Cerebellar tonsils herniation through
the foramen magnum.
18.
19. MANAGEMNET OF INCREASED
ICP
1. Head elevation: to 30
degrees, insure that there is no
venous compression of internal
jugular vein.
2. Hypertonic solutions: like
mannitol, should be used for short
period because of rebound
phenomenon.
3. Diuretics:
furosemide(frosemide), has the
advantage of reducing ICP as well
20. Continue…
4. hyperventilation: with sedation and
intubation. The best method in
reducing ICP and the effect is
almost immediate. Hyperventilation
causes hypocapnea (reduces CSF
carbon dioxide which leads to CSF
alkalosis and eventually cerebral
vasoconstriction as well as cerebral
blood flow and volume).
21. Continue..
5. hypothermia: has a limited use.
Reduces cerebral oxygen
demand, cerebral blood flow, and
ICP.
Disadvantages are;
1. Cardiac arrhythmias.
2. seizure, drowsiness, and probably
coma during re-warming.
22. Continue..
6. Steroids; causes reduced CSF
production and edema.
More effective in brain tumor, no
important role in head trauma.
7. barbiturates: should be used only in
intensive care units, as they cause
hypotension and myocardial
depression.
23. Continue..
Surgical interventions:
8. Ventriculostomy, external drains and
shunt operations, CSF diversion
procedures. To manage one of the
intracranial contents, the CSF.
Can not be established in case of small
ventricles like in benign intracranial
hypertension.
24. Continue..
Craniotomy, craniectomy, lobectomy, a
nd removal of the space occupying
lesion, according to the cause of the
raised ICP.
This could be a palliative or a definitive
treatment.
25. Summary of Medical management
of raised intracranial pressure
■ Position head up 30º.
■ Avoid obstruction of venous drainage
from head.
■ Sedation +/– muscle relaxant.
■ Normocapnia 4.5–5.0 kPa.
■ Diuretics: furosemide and mannitol.
■ Seizure control.
■ Normothermia.
■ Sodium balance.
■ Barbiturates.
26. Summary of Surgical management
of raised intracranial pressure
■ Early evacuation of focal
haematomas: EDH, ASDH
■ Cerebrospinal fluid drainage via
ventriculostomy
■ Delayed evacuation of swelling
contusions
■ Decompressive craniectomy