What is Intracranial pressure (ICP)?

ICP Monitoring . credit teachmesurgery.com

What is Intracranial pressure (ICP)?

Intracranial pressure (ICP) refers to pressure within the skull. This can occur as a result of raised intracranial pressure, or from an underlying cause that results in an elevated brain tissue pressure. Raised Intracranial pressure is a serious problem that can damage your brain and lead to permanent impairment or death.

What are the signs and symptoms of raised intracranial pressure?

Raised intracranial pressure can cause

1. Headaches

2. Seizures

3. Changes in the level consciousness

4. Ipsilateral pupillary dilation 

5. Irregular respiration 

6. Bradycardia and hypertension 

7. Papilledema.

What are the causes of raised intracranial pressure?

It can occur by more than one cause including brain tumors, bleeding in the brain, fluid build-up around the brain (i.e., hydrocephalus), head injuries and certain diseases or infections (e.g., meningitis). This can  also occur from an underlying cause that results in an elevated brain tissue pressure. Raised Intracranial pressure is a serious problem that can damage your brain and lead to permanent impairment or death. Other causes are as follows:

1. Trauma 

2. Severe head injury 

3. Closed head injury 

4. Post-traumatic encephalopathy 

5. Hydrocephalus

For brain survival a continuous supply of oxygenated blood and glucose is necessary. Normally the cerebral blood flow is about 50 ml/minutes for every hundred gram of the brain tissue, if this below 20 ml per minute then schema results which have a bad consequences that can result infarction immediately unless promptly correctly

Flow depends on CPP which is cerebral perfusion pressure and this pressure is the difference between MAP and ICP. 

CPP(75-105>= MAP(90-110)-ICP(5-15)

Here 

Cerebral perfusion pressure (CPP)

Mean arterial pressure (MAP) 

Intracranial pressure (ICP).

What are the manifestations of raised ICP?

Normal intracranial pressure is 5-15 mmHg. Pressures above 20-25 mmHg are associated with worst outcomes. Various manifestation of raised ICP are given below

1. Changes in the level consciousness

This is Earliest manifestation which occurs due to depression of reticular formation. Other symptoms associated with acute rise in ICP are nausea, projectile vomiting, blurred/double vision.

2.Ipsilateral pupillary dilation 

This occurs when cause of raised ICP is a mass lesion. Temporal uncal herniation on the side of mass compresses oculomotor (third) nerve causing pupillary dilation on the side of mass lesion.

3.Irregular respiration 

Results from hypoperfusion of brain stem causing respiratory depression 

4. Bradycardia and hypertension 

Decreased cerebral perfusion leads to compensatory rise in blood pressure (hypertension). This is followed by baroreceptor response from carotid bodies leading to bradycardia.

5. Papilledema. 

Seen with chronically raised ICP

What is cushing triad?

Its triad of hypertension (HTN), bradycardia and irregular respiration. When this occurs the patient is said to coning and this can result in brainstem death if immediate intervention not taken

Head injury classification

what is Head injury classification according to Glasgow coma scale (GCS)?

Minor head injury	GCS 15 with signs of loss of conciouness (LOC)
Mild head injury	GCS 14 or 15 with signs LOC
Moderate head injury	GCS 9 - 13
Severe head injuary	GCS 3 - 8

 

In short

1) The most common initial manifestation of raised ICP is altered mental status

2) The most common initial sign of raised ICP in a comatose patient is irregular respiration followed by hypertension, which then induces compensatory bradycardia.

3) In case of a mass lesion causing compression of brain and raised intracranial pressure, lateralizing signs are seen such as pupillary dilation towards the side of lesion. Herniation is more abrupt with mass lesions. 

4) Signs of acutely rising ICP: Irregular respiration, hypertension and bradycardia 

5) Signs of chronically raised ICP: Papilledema 

6) In infants the signs of raised ICP include: increased head circumference, bulging fontanelle, prominent veins and in some cases "sun-set" sign (Parinaurd disease

Question

Now lets solve a question after reading the above article

Which of following is the most common initial manifestation of increased intracranial pressure?

A) Change of level of consciousness

B) Ipsilateral pupillary dilation 

C) Contralateral pupillary dilation

D) Bradycardia

E) Hypertension

Correct: A (Change of level of consciousness)