Chapter 6 - Head Trauma Flashcards
(112 cards)
1
Q
What % of prehospital trauma-related deaths involved head trauma?
A
90%
2
Q
What is the primary goal of someone who has a TBI (traumatic brain injury)?
A
To prevent secondary brain injury from inadequate oxygenation and hypoperfusion.
3
Q
The anterior fossa houses what?
A
The frontal lobes
4
Q
The middle fossa houses what?
A
The temporal lobes.
5
Q
The posterior fossa houses what?
A
The lower brainstem and cerebellum.
6
Q
Name the 3 layers of the meninges. (outside to in)
A
- The dura mater - tough and fibrous. 2 sublayers - the Periosteal Layer and Meningeal Layer.The large venous sinuses are housed in between these sublayers.
- Arachnoid mater
- Pia Mater (covers the brain)
7
Q
A
The superior sagittal sinus drains into the bilateral transverse and sigmoid sinuses.
8
Q
When consulting a neurosurgeon about a patient with TBI what information needs to be relayed?
A
- Age of patient
- Mechanism and time of injury
- Respiratory and cardiovascular status (Blood pressure and oxygen sats)
- Results of the neurological examination, including GCS score (with particular emphasis on the motor response, pupil size and reaction to light.
- Focal neurological deficits
- Presence and type of associated injuries
- Results of diagnostic studies, particularly CT scan (if available)
- Treatment of hypotension or hypoxia
9
Q
Meningeal arteries are located between what two surfaces?
A
Meningeal arteries lie between the dura and the internal surface of the skull (Epidural space)
10
Q
Describe the the anatomy of a epidural hematoma.
A
Skull fractures can lacerate middle meningeal arteries (most commonly the middle meningeal artery). An epidural hematoma will form.
11
Q
What two injuries can cause epidural hematomas?
A
- Skull fractures
- Injury to Dural sinuses (Sagital sinus etc.)
12
Q
How do you manage an epidural hematoma?
A
URGENTLY!!! They need to be evacuated by a neurosurgeon ASAP.
13
Q
How do subdural hematomas form?
A
Bridging veins that travel from the surface of the brain to the venous sinuses within the dura may tear. These then fill the subdural space (between the dura mater and the arachnoid mater).
14
Q
The pia mater is firmly attached to the surface of the brain. CSF fills the space between the watertight arachnoid mater and the pia mater (Subarachnoid space).
A
15
Q
Subarachnoid hemorrhages are frequently caused by ?
A
- Brain contusion
- Injury to the vessels at the base of the brain.
16
Q
The brain consists of what 3 structures?
A
- Cerebrum - right and left hemispheres and seperated by the falx cerebri.
- Cerebellum - responsible for coordination and balance.
-
Brain stem -
- Midbrain
- Pons
- Medulla.
17
Q
Which cerebral hemisphere contains the language centers in virtually all right handed people and 85% of left handed people?
A
The left hemisphere
18
Q
What functions does the frontal lobe control?
A
Executive functions, emotions, motor function and, on the dominant side, expression of speech.
19
Q
What functions does the parietal lobe control?
A
Sensory function and spatial orientation.
20
Q
What function does the temporal lobe control?
A
Memory functions
21
Q
What function does the occipital lobe control?
A
Vision.
22
Q
The midbrain and upper pons contain the ? activating system which is responsible for ?
A
- Reticular
- the state of alertness
23
Q
Where does the vital cardiorespiratory center preside?
A
In the medulla
24
Q
Where is CSF produced and reabsorbed?
A
It is produced in the choroid plexus in the lateral ventricles and is reabsorbed in the dural venous sinuses through the arachnoid granulation tissue.
NOTe: Blood in the CSF can inhibit reabsorption and can cause increased ICP
25
26
Which cranial nerve runs along the edge of the tentorium and can be compressed against it during temporal lobe herniation?
Cranial Nerve III
27
What is the physiological mechanism to explain a **blown** **pupil**?
**Parasympathetic** **fibers** from the **3rd** **cranial nerve constrict** the **pupil**. If these are compressed (e.g. herniation, hematoma) then they cannot act and you get **unopposed sympathetic** **activity**. i.e. **pupillary dilation**.
28
What's going on here?
The **tentorial notch** is **opening** that allows **passage** of the **brainstem** through the **tentorium**. The **Uncus** (medial part of the temporal lobe) is **herniating** (**uncal** **herniation**) through the **tentorial notch** and **compressing** the **corticospinal** (**pyramidal**) **tract** in the **midbrain,** which **crosses** at the **brainstem**. Therefore you will get in a **contralateral hemiparesis**.
29
What is the classic sign of **uncal** **herniation**?
Ipsilateral pupillary dilatation associated with contralateral hemiparesis.
30
What 3 physiological conepts related to head trauma?
1. Intracranial pressure - if elevated it can reduce cerebral perfusion and exacerbate ischaemia.
2. The Monro-Kellie Doctrine
3. Cerebral Blood Flow -cerebral blood flow can be reduced after comatose inducing TBI. This can lead to cerebral ischaemia.
31
What is the normal ICP at resting stage?
~10mmHg
32
What ICP is related to poor outcomes?
20mmHg
33
What is the Monro-Kellie Doctrine?
The **total volume** of the **intracranial** **contents** must **remain** **constant** because the **cranium** is a **rigid**, **nonexpansile** container.
**Venous blood** and **cerebrospinal** **fluid** may be **compressed** **out** of the **container**, **providing** a **degree** of **pressure buffering**.
Once, the **limit of displacement** of CSF and intravascular blood has been **reached**, **ICP** **rapidly increases**.
34
35
How is cerebral perfusion pressure (CPP) defined?
CPP = MAP - ICP
Mean arterial pressure
Incracrainal Pressure
36
What level of MAP (Mean arterial pressure) maintains a constant CBF? (a.k.a. **Pressure** **autoregulation)**
What will happen if the MAP is too low?
What will happen if the MAP is too high?
50 to 150mmHg
If the MAP is too low then ischaemia and infarction can occur.
If the MAP is too high, marked brain swelling will occur with elevated ICP.
37
What 4 factors can induce secondary brain injury?
1. Hypotension - need to maintain MAP
2. Hypoxia
3. Hypercapnia
4. Iatrogenic hypocapnia.
38
Does CPP always equate with or assure adequate CBF?
NO. Once ICP increases dramatically then blood flow to the brain can be compromised.
39
What are the classifications of head injury?
1. Minor = GCS 13-15
2. Moderate = GCS 9-12
3. Severe = GCS 3-8
40
**True** or **False**, we use the **worst motor response** to calculate the GCS score, because this is the most reliable?
**FALSE**. We use the **BEST** motor response score.
41
Describe the Glasgow Coma Score?
Remember Equation **E4V5M6**
Eye opening =
* 4 to sponteously
* 3 to speech
* 2 to pain
* 1 none
Verbal response
* 5 Oriented
* 4 Confused Speech
* 3 Inappropriate words
* 2 Incomprehensible sounds
* 1 None
Motor response
* 6 Obeys commands
* 5 Localizes pain
* 4 Withdrawal to pain
* 3 Abnormal flexion (decorticate)
* 2 Abnormal extension (decerebrate)
* 1 None (flaccid)
42
43
Skull fractures are divided into what two regions?
1/ Vault
* Linear or stellate
* Depressed/Non-depressed
* Open/closed
2/Basilar
* With/without CSF leak
* With/without 7th Nerve Palsy.
44
What are the clinical signs of a basilar skull fracture?
1. **Periorbital ecchymosis** (**racoon eyes**)
2. **Retroauricular ecchymosis** (**Battle**'s **sign**)
3. **CSF leakage** from **nose** or **ear** (**Rhinorrhea**/**Otorrhoea**)
4. **7th** and **8th nerve disfunction** (**Facial paralysis** and **hearing loss**.
45
Fractures that traverse the carotid canals can cause what?
What investigation can be useful?
1. Damage to **carotid arteries** (**dissection**, **pseudoaneurysm**, **thrombosis**)
2. **Cerebral angiography**
46
A linear vault fracture in concious patients increasese th elikelihood of an intracranial hematoma by roughly how many times?
400 times.
47
What are the 2 categories of uintracranial lesions?
Diffuse or Focal.
48
**Concussion** is a type of diffuse brain injury. What happens in concussion?
The patient will have a **transient**, **nonfocal neurologic** disturbance that often includes **loss** of **conciousness**. CT scan will often be normal.
49
What is a common cause of severe diffuse brain injury and how can it manifest on a CT scan?
**Hypoxic ischaemic insult secondary** to **prolonged** **apnea** or **shock**.
**CT** may initially appear normal but may appear **diffusely swollen** with **loss** of **normal gray**-**white** **distinction**.
50
What are **Diffuse Axonal Injuries** (**DAI**) and how do they manifest on CT?
**DAI** is a **severe** form of **diffuse brain injury**. **DAI** is a result of a **shearing injury** where there is a **high** **velocity** impact or **deceleration injury**. **Multiple** **punctate hemorrhages** are often seen throughout the **cerebral hemispheres inbetween** the **grey** and **white** **matter**.
51
Focal lesions consists of 4 types. What are they?
1. Epidural hematoma
2. Subdural hematoma
3. Contusion
4. Intracerebral hematoma
52
How common are epidural hematomas?
Uncommon. They occur in 0.5% of patients with brain injury & 9% in TBI who are comatose.
53
What shape are epidural hematomas and where are they most commonly located?
They are biconvex and are most commonly located over the temporal or temporoparietal region.
54
What do epidural hematomas often result from?
Skull fractures that cause the middle meningeal artery to tear.
55
How do epidural hematomas clinically present
Head injury with a **lucid interval** after injury but then neurological deterioration.
56
What are more common, epidural hematomas or subdural hematomas?
Subdural hematomas. They occur in 30% of individuals with severe brain injury.
57
Is the brain damage of an epidural hematoma or a subdural hematoma usually more severe?
Subdural hematoma brain damage is usually more severe due to concomitant parenchymal injury.
58
How common are cerebral contusions?
Cerebral contusions are common.
(Present in 20 to 30% of severe brain injuries)
59
Where do the majority of contusions occur?
In the frontal and temporal lobes.
60
Why should patients with contusion have a repeat CT scan within 24 hours of the intial scan?
Contusions can form a coalscent contusion with enough mass effect to require immediate surgical evacuation.
61
Define Minor traumatic brain injury (MTBI)
A history of disorientation, amnesia or transient loss of conciousness in a patient who is currently concious and talking. They will have a GCS score between 13-15.
62
What are some important parts of the history to take from a patient with a MTBI. (minor traumatic brain injury)
1. Name, sex, age, race, occupation
2. Mechanism of injury
3. Time of injury
4. Loss of conciousness - length of time unresponsive, any siezure activity and the subsequent level of alertness.
5. Duration of amnesia - both retrograde and antegrade.
6. Subsequent level of alertness
7. Headache - mild, moderate, severe.
63
What are the **high risks** for **neurosurgical** **intervention** that warrant a **CT** scan being done for **MTBI**?
1. **GCS** score **less than 15 at 2 hours** after injury.
2. **Suspected open** or **depressed** **skull** **fracture**.
3. Any sign of **basilar** **skull** **fracture** (e.g. hemotympanum, raccoon eyes, CSF otorrhea or rhinorrhea, Battle's sign)
4. **Vomiting (more than 2 episodes)**
5. Any more than **65 years**.
64
What are the **moderate** **risks** for neurosurgical intervention that warrant a **CT scan** being done for **MTBI**?
1. **Loss** of **conciousness** (**\>5** **minutes**)
2. **Amnesia** before impact (**\>30 minutes**)
3. **Dangerous mechanism** (e.g. pedestrian struck by motor vehicle, occupant ejected from vehicle, fall from heigh of more than 3 feet or 5 stairs)
65
If someone with an MTBI is being sent home what should you make sure happens?
That they are **sent home with a companion** who can **observe them for 24 hours** OR **advise them to return** to ED if they **develop** **headaches**, **decline** in **mental status** or **develp** **neurological deficits**.
66
Define moderate brain injury./
GCS 9-12
67
How shoud you manage a patient with mild brain injury?
1. Take a history (see other card)
2. General examination
3. Limited neuro exam
4. Imaging
5. Bloods - alcohol level and urine toxicology.
6. CT scan of head if indicated.
68
How should you manage someone with a moderate brain injury?
1. **History** and **examinations** same as mild head injury.
2. **CT scan**.
3. **Follow up CT scan within 24 hours** if condition worsens.
4. **90% of patients will improve** - discharge and follow up in clinic.
5. **10% will deteriorate** - manage as per severe brain injury protocal
69
What is the definition of a severe brain injury?
The patient will be unable to follow simple commands because of impaired consciousness (GCS score 3-8).
70
How do you manage someone with a severe brain injury?
1. **ABCDEs**
2. **Primary** **survey**
3. **Resuscitation**
4. **Secondary Survey** and **AMPLE**
5. **Admit** to **facility** for **definitive** neurosurgical care.
6. **Therapeutic** **agents **(**Mannitol**, **Moderate hyperventilation [PCO2 32-35mmHg],** **Hypertonic saline**)
7. **Neurologic reevaluation**
8. **GCS**
9. **Pupils**
10. Focal neurology
11. **CT Scan**
71
If you have a severe brain injury, hypotension and hypoxia on admission, what is your relative risk of dying?
75%
72
In severe head injury, how do you manage the airway and breathing?
1. **Endotracheal intubation early.**
2. **Ventilate** with **100% O2** until blood gas done.
3. **Oxygen** **Sats** of **\>98%** are desirable on pulse oximetry.
4. **Ventilation parameters**: **maintain** **PCO2** of ~**35mmHg**. **Normocarbia** is generally **preferred**.
5. **Hyperventilation** (**PCO2 \<32mmHg**) should be **cautisouly** **used** only when **acute neurological** **deterioration** has **occured**. **Hyperventilation causes a reduction in pCO2** and causes **cerebral** **vasoconstriction**. This can **promote cerebral** **ischaemia**. **Hyperventilation** will **LOWER ICP** until **emergent** **craniotomy** can be **performed**.
73
When does hypotension occur in a brain injury?
ONLY in the final stages when the medulla fails or there is concomitant spinal cord injury.
NOTE: intracranial haemorrhage cannot cause hemorrhagic shock.
74
What type of fluids should be used in order to establish euvolaemia in severe brain injuresi: hypotonic, isotonic or hypertonic fluids?
Isotonic solutions like Ringer's lactate or normal saline.
75
Can 5% dextrose be used for fluid resucitation in patients with severe brain injury?
No because hyperglycaemia can occur. Hyperglycaemia has been shown to be harmful to brain injury.
76
What can hyponatraemia cause to the brain?
It can cause brain swelling.
77
If someone is intoxicated, what must you make sure you don't do.
Do not miss a head injury!!!
78
The postictal state after a traumatic seizure can last for roughly how long?
**Minutes** to **hours**.
NOTES: this can make it **difficult** to **assess neurological** **state**.
79
How can motor response be ellicited in a comatose patient?
The **trapezius** **muscles** can be pinched, the **nail** **bed** can be pressed on or the **supraorbital ridge** can be presed on.
80
Should we test for doll;s eye movement or do the caloric test with ice water?
NO...leave that to a neurosurgeon.
NOTE: Doll's eye testing should never be tempted before a C-spine injury has been ruled out.
81
What neurological examination should be done before sedating a patient?
**GCS score** and **pupillary response**.
This is because **knowledge** of the patient's **clinical** **condition** is important for **determinding** **subsequent** **treatment**.
82
Sedation, in head injuries, should be avoided except....?
EXCEPT **when a patient's agitated state places him or her at risk.** The **shortest** **acting** **agents** are recommended.
83
What is a sign of temporal lobe herniation (uncal herniation)?
Dilation of the pupil and loss of pupillary response to light.
84
What are the significant and what are the crucial findings of CT scan?
**Significant Findings**
1. **Skull** **fractures**
2. **Subgaleal** **hematomas**.
3. **Scalp swelling**
**Crucial Findings**
1. **Intracranial hematoma**
2. **Contusions**
3. **Shift of the midline (mass effect)** - **a shift of 5mm or greater is often indicative of the need for surgery to evacuate the blood clot or contusion.**
4. **Obliteration of the basal cisterns**
85
If someone has a head injury and is either anticoagulated or is on antiplatelet therapy, what should be done?
1. INR
2. Rapid normalization of the anticoagulation.
86
Medical therapies for brain injury include...?
1. Intravenous fluids
2. Temporary Hyperventilation
3. Mannitol
4. Hypertonic saline
5. Barbiturates
6. Anticonvulsants.
87
What PCO2 levels correspond with normocarbia, hypocarbia and hypercarbia?
* **_Normocarbia - PCO2 ~35mmHg (4.7kPa)_**
* _**Hypocarbia/Hyperventilation **- **PCO2 25-30mmHg (3.3 to 4.7kPa) but aim for 28 to 32mmHg to be safer.**_ - Promotes vasoconstriction and thus used in acute increases of ICP)
* **Hypercarbia** - **PCO2 \>45** (promotes vasodilation & increases ICP)
88
What is mannitol used for?
To decrease ICP
89
How do you secondarily manage a severe head injury? (not diagnostic)
1. **Frequent** **serial** **neuro examination**.
2. **Normocarbia - PCO2 35+/- 3**
3. **Mannitol** and **PCO2 28-32 if deterioration.**
4. **Avoid PCO2 \<28**
5. **Address** **intracranial lesions** appropriately.
90
What preparation of mannitol is most commonly used?
20% solution (20g in 100ml solution).
91
When should mannitol NOT be given?
**In patients with hypotension.**
**Mannitol** **does** not **lower ICP in hypovolaemia** and is a potent **osmotic** **diuretic**.
92
How do you administer mannitol in a deteriorating euvolaemic patient with a severe head injury?
1. Give a bolus of 1g/kg rapidly over 5 minutes
2. Then transported immediately to CT scanner.
93
What is hypertonic saline used for?
To reduce ICP
94
How do mannitol and hypertonic saline compare when it comes to lowering ICP?
**They are just as effective.**
**Neither** will **adequately lower ICP** in **hypovolaemic** **patients**. HOWEVER, **hypertonic saline** is **preferred in** patients with **hypotension** because it **does NOT** act as a **diuretic**.
95
When should barbiturates NOT be used?
In severe head injury patients who have hypotension and hyopvolaemia.
NOTE: Hypotension can result from their use.
96
Why are barbiturates used and when should they not be used?
They are useful in reducing ICP refractory to other measures. They are not to be used in the acute resuscitative phase.
97
Why should barbiturates probably not be used if the patient will die?
They have a long half life and will prolong brain death.
98
What are the 3 factors that are linked to a high incidence of late epilepsy?
1. Seizures occuring in the first week.
2. Intracranial hematoma
3. A depressed skull fracture.
99
What effect does early anticonvulsant use have on long term traumatic seizure outcome?
None whatsoever. Purely used to control seizures.
100
What effect do anticonvulsants have on brain recovery?
They inhibit it. So use them carefully.
101
What anticonvulsants and in what doses are they used in patients with traumatic seizures?
**Phenytoin** and **Fosphenytoin**.
For **phenytoin**, a **loading dose** of **1 gram** is **given IV** at a rate **~50mg/min**.
Then **100mg/8 hours** **for maintenance** but **monitor** **serum levels** for optimal dosing.
102
What else can be used in addition to phenytoin for traumatic seizures?
**Diazepam** or **lorazepam**.
**GA** may also be required if still not controlled.
103
Why is it important to gain control over seizures early?
If prolonged seizures occur (30-60minutes) they can cause secondary brain injury.
104
How do you diagnose brain death/
1. GCS score of 3
2. Nonreactive pupils
3. Absent brainstem reflexes (Doll's eyes, no gag reflex etc)
4. No psontaneous ventilatory effort on formal apnea testing.
105
What do you need to exclude before diagnosing brain death?
Reversible conditions like hypothermia and barbiturate coma.
106
What head wounds may require surgical management?
1. **Scalp wounds** - clean and inspect. **CSF** **leakage** indicates a **dural tear**.
2. **Depressed skull fractures** - can be operated on to **elevate the fracture if the degree of depression is greater than the thickness of the adjacent skull** **or** it is **open** and **contaminated**.
3. **Intracranial mass lesions** - managed by neurosurgeon. May require emergency craniotomy if trained.
4. **Penetrating brain injuries** - **CT/CT angiography is recommended**. If non metalic then MRI can be useful. _**Prophylactic broad**-**spectrum** **antibiotics** should be **given**._
107
When is early ICP monitoring recommended in a penetrating brain injury?
1. When the clinician is **unable** to **assess** the **neurologic examination accurately**.
2. The **need to evacuate** a **mass lesion** is **unclear**.
3. **Imaging studies suggest elevated ICP**.
108
How should you treat someone with a small bullet entrance wound to the head?
Wound care and closure if there is no scalp devitalization and no major intracranial pathology.
109
If someone has a penetrating intracranial wound what should you do?
Leave it in place until the vascular surgeons review.
110
How is the primary survey performed for head injuries?
1. ABCDEs
2. Immobilize and stabilize C spine
3. Perform a brief neuro exam.
* Pupillary response
* GCS score
* Lateralizing signs.
111
How is the secondary survey performed in a patient that has a potential brain injury?
1. **Inspect** the **entire head**, **face** looking for **lacerations**, **CSF leakage** from **nose** and **ears**.
2. **Palpate** the entire head and face looking for **fractures** and **lacerations**.
3. **Inspect** the **scalp** lacerations for **brain tissue, depressed skull fractures, debris and CSF leaks.**
4. **Determine GCS score**, **pupillary response, best limb motor response, verbal response.**
5. **Examine** the **C-spine.**
6. **Document** the neurological injury.
7. **Reassess** for deterioration.
112
Describe the process of evaluating CT scans of the head?
1. **Confirm the patient.**
2. **Assess the scalp for contusions** or **swelling**.
3. **Assess for skull fractures** - **depressed skull** **fractures**, **open fractures**, **missile wounds** or **tracts**.
4. **Assess the gyri and sulci for symmetry.** If assymetrical consider subdural hematoma or epidural hematoma. (**Subdural hematomas** **more frequent** and can have associated **contusions** and **hematomas**. **Epidural** **hematomas** cause **midline shift**, **biconvex** and commonly over **temporal region**)
5. **Assess the cerebral hemispheres** - density, symmetry, **cerebral contusions(punctate areas of high density)**, **DAI** (diffuse axonal injury), intracerebral hematomas.
6. **Assess the ventricles** - decreased size if increased ICP.
7. **Assess midline shift** - **\>5mm or more requires surgical decompression.**
8. **Assess maxfacs structures** - **facial bones**, **sinuses**, **mastoid** air cells.
9. **Look** for the **4 C's of increased density**: **Contrast**, **Clot**, **Cellularity** (**tumor**), **Calcification** (**pineal gland, choroid plexus**)
