Brain, head injury and adjustment to chronic disability Flashcards
What are the functions of the frontal lobe?
Movement
Decision-making, Problem-solving
Concentration, Learning, Intellect
Language, Word associations
Memory for habits and activities
Abstract reasoning and planning
Control over emotional response
What are the main divisions of the frontal lobe?
Prefrontal cortex - planning of complex cognitive behaviours, personality expression
Premotor cortex
Primary motor cortex
What are the functions of parietal lobe?
Tactile sensory information
Somatosensory cortex
What are the functions of the occipital lone?
Visual processing and perception
Primary visual cortex
What are the functions of the temporal lobe?
Structures of the limbic system - olfactory cortex, amygdala and the hippocampus, organisation of sensory input, auditory perception, language and speech production, memory association and formation, sense of identity, behaviour
What are the compartments of brainstem?
- Medulla oblongata
- Pons
- Midbrain
Describe thalamus
Dual lobed mass of grey matter buried under the cerebral cortex
Connection between brainstem and cerebral cortex
Describe hypothalamus
Control centre for autonomic functions of the PNS
Connects to the endocrine NS
Directly influences the pituitary gland
What are the functions of the cerebellum and where is it located?
Regulation and coordination of movement, posture, muscle tone and balance
In inferior cranial fossa
What structures does the Tentorium Cerebelli divide?
Occipital lobes and cerebellum from the rest of the brain
What does the Falx Cerebri divide?
The cerebral hemispheres
Describe amygdala and its location
Almond-shaped groups of neurones located deep within the medial temporal lobes - processing memory of emotional reactions
Part of the limbic system - emotion, behaviour, long-term memory
What is the relation of the middle meningeal artery to the meningeal layers?
Found between dura and the skull - travels close by the the pterion is often damaged in skull fractures
What is the relationship of the cerebral arteries to the meningeal layers and spaces?
In the subarachnoid space
Describe the circle of Willis starting with the vertebral arteries?
The two vertebral arteries fuse to form the basilar artery - basilar artery branches: pontine a, superior cerebellar, posterior cerebral, anterior inferior cerebellar
Splits into 2 posterior communicating a - into these feed, the internal carotid a - gives of middle cerebral and anterior cerebral
The anterior cerebral arteries are connected by the anterior communicating artery
What is the relations of the venous sinuses to the meninges and spaces?
Venous sinuses are found between the 2 layers of dura: the endosteal layer and the meningeal layer
They are found in the sulci of the brain
How would the blood drain from the superficial prefrontal cortex?
To one of superior cerebral veins –> superior sagittal sinus –> transverse sinus –> sigmoid sinus –> internal jugular vain
How would the blood drain from deep parietal lobe?
Into inferior sagittal sinus –> straight sinus –> transverse sinus –> sigmoid –> internal jugular v
What is the Great cerebral vein (of Galen) and where does it drain?
Deep within the brain - close to the basal ganglia
Drains into the straight sinus
What is the cavernous sinus, what it contains, where it drains to and how many are they?
Sinus deep within the brain, drains the eyes, temporal lobes etc.
Contains some of the cranial nerves - I, III, IV, V
Drains to sigmoid sinus 2 - one in each hemisphere
Define the pterion
Common site of injury to the middle meningeal artery
The site of connection of the parietal, frontal, squamous temporal bone and greater wing of sphenoid
What are the 3 types of Intracranial Hematoma?
- Epidural Haematoma
- Subdural Haematoma
- Intracerebral Haematoma
Describe the ventricles of the brain superior to inferior
Anterior horns of lateral ventricles –> right and left lateral ventricles –> posterior horns of lateral ventricles –> temporal/inferior horn of lateral ventricle 3rd ventricle connects the lateral ventricles anteriorly and posteriorly
Connected to 4th ventricle by the aqueduct of the midbrain
What are the types of traumatic brain injury?
Primary and secondary –> primary usually leads to secondary
What is the difference between a primary and secondary head injury? - list types of each
Primary
- caused by the impact
- diffuse axonal injury
- focal lesions like lacerations, contusions and haemorrhage
Secondary
- an injury resulting from a process started by an impact
- infection
- hypoxia
- cerebral swelling
- ischemia
What are the types of primary brain injury?
Focal injuries (haematomas and contusion) Diffuse injuries
What are the common characteristics of intracranial Haematomas?
Slowly or rapidly progressing Progressively compressing brain structures and increasing ICP
What are the common signs and symptoms of focal injuries?
Localised to the site of impact Extent of damage is variable Symptoms: dependent on the area affected - weakness, headache
Describe the hallmarks of epidural haematoma
Collections of blood in the epidural space between cranium and the dura mater Vessels are susceptible to injury in skull fractures Mostly arterial bleeding - rapid and deterioration of function
Describe the hallmarks of subdural haematoma
Between dura and arachnoid mater Bridging vessels damaged Slower rate of formation (venous)
Describe the hallmarks of intracerebral haematoma
Within the brain matter and ventricles Common signs: severe headache followed by vomiting, collapse and coma
What are the characteristic distributions for cerebral contusions/polar injuries?
- Orbital surface of the frontal lobes
- Frontal poles
- Around the lateral sulcus
- Tips and inferior aspects of the temporal lobes
- Occipital poles and the cerebellum
What is a cerebral contusion?
Focal brain damage resulting from contact between bony protuberances of the skull base - brain moves within the skull and crashes into the bone
What is concussion?
Temporary disturbance in brain function as a result of trauma
What are the signs and symptoms of concussion?
Symptoms; headache, dizziness, memory disturbance, balance problems Signs: loss of consciousness, seizure activity, irritability and poor performance
Describe diffuse injuries
Movement within the cranial cavity causes widespread neuronal damage - mostly as diffuse axonal injury
Describe diffuse axonal injury
- Associated with coma - caused by stretching of axonal white matter resulting in function disruption - mostly microscopic damage caused by rotational acceleration of the brain - Axons, blood vessels, dendrites and glial cells are damaged
What are the changes caused by diffuse axonal injury on molecular level
Increased membrane permeability, marked influx of calcium, swelling of mitochondria, disruption of microtubules, alterations in axonal transport and accumulations of cytoskeletal components and membranous organelles –> axonal swelling within 3-6 hours
What is the subclassification of secondary brain injury?
Ischaemia, increased ICP and altered vascualar regulation, cerebral sweeping and infection - damage usually exceeds that of primary injury
What are the neurochemical changes caused by secondary brain injury?
Transient cell membrane disruption leading to a redistribution of ions and neurotransmitters - in acute phase there is release of glutamate from presynaptic terminal
Accumulation of intracellular Ca2+ which activates mitochondrial Ca2+ uptake –> oxidative stress and impair mitochondrial function
Describe the prevalence and symptoms of extradural haematoma
- Young adults
- Lucid interval
- Deterioration
What is the fatality in subdural haematomas and what is the determinant?
20%
Elderly and coexisting brain swelling
What is the mortality of contusion injuries?
High, most common of fatal head injuries
What is the grading of diffuse axonal injuries?
Grade I - III
- Grade I - cannot see anything microscopically
- Grade III - poor outcome or fatal, had no lucid interval
What can be ischaemia result of?
Raised ICP, hypoxaemia, reduced cerebral perfusion pressure
What are the characteristics of brain swelling?
- Adjacent to contusion
- One hemisphere in adults
- Most common to be fatal
- Oedema - increased water content
- Congestion - increase in blood volume
What is diffuse vascular injury?
Multiple small haemorrhages Death within minutes of injury Spreads through white matter
What happens in chronic subdural haematoma
Symptoms develop weeks after injury More common in older people because brain atrophy causes the brain to shrink away from the dura and stretch fragile bridging veins - These veins rupture, causing slow seepage of blood into the subdural space - Fibroblastic activity causes the haematoma to become capsulated - Sanguineous fluid in this encapsulated area has high osmotic pressure and draws in fluid from the surround subarachnoid space - Mass expands Æ exerts pressure on cranial contents
What is the result of cerebral hypoperfusion and hypoxaemia?
Lack of O2 and nutrients essential for cellular functioning and survival leading to ischaemic cascade
Describe the mechanism of ischaemic cascade
- Lack of oxygen – lack of ATP 2. Switch to anaerobic respiration producing lactic acid 3. Cell depolarisation 4. Calcium ions flow into cell – levels increase leading to ion pump failure 5. High calcium triggers release of glutamate 6. Glutamate triggers more calcium entry into cells 7. High calcium causes exotoxicity 8. Cell membrane broken down by phospholipases 9. Mitochondria break down 10. Apoptosis cascade initiated 11. Cell death – release of glutamate and toxins which affects nearby neurons Inflammatory response
What three things determine intracranial pressure?
Pressure-volume relationships with brain tissues, CSF and blood in intracranial cavity Monro-Kellie hypothesis, relates to reciprocal changes among the intracranial volumes Compliance of the brain
What are the percentages of brain tissue, blood and CSF within the skull?
Brain - 80% CSF- 10% Blood - 10%
Define intracranial pressure
The pressure exerted by the essentially incompressible tissue and fluid volumes of the three compartments contained within the skull
What is the normal intracranial pressure?
7 - 15 mmHg
Explain the Monroe-Kellie hypothesis
Compensatory response, an increase in one component can be offset by a reduction of the other two, it is called compliance as changes in volume are accommodated for without change in pressure - limited due to the rigidity of the skull
How does the volume can change to accommodate for increasing pressure?
Cerebral blood vessels can reduce volume via vasoconstriction CSF can move to the spinal cord In young children head circumference can increase
Define cerebral perfusion pressure
CPP = MAP/BP - Intracranial pressure
Define what is clouding of consciousness
Mild form of altered mental status in which the patient has inattention and reduced wakefulness
Define confusional state
More profound, disorientation, bewilderment and difficulty following commands
Define lethargy
Severe drowsiness, can be aroused by moderate stimuli and then drift back to sleep
Define obtundation
lessened interest in the environment, slowed responses to stimulation, tends to sleep more with drowsiness in between sleep states
Define stupor
only vigorous and repeated stimuli will arouse the individual, when left undisturbed, the patient will immediately lapse back to the unresponsive state
Define coma
state of unarousable unresponsiveness
What is the maximum scale in Glasgow Coma scale
15
What are the areas of assessment in GCS
Eye opening Best motor response Best verbal response
What are the grades in eye opening
4 - opens eyes spontaneously 3 - opens eyes to voice 2 - opens eyes to pain 1 - no eye opening
What are the grades in best motor response
6 - obeys command 5 - localizes to pain 4 - withdraws to pain 3 - abnormal flexor response 2 - abnormal extensor response 1 - no movement
What are the grades for best verbal response in GCS
5 - appropriate and oriented 4 - confused conversation 3 - inappropriate words 2 - incomprehensible sounds 1 - no sounds
Define the classifications of results of GCS
- Mild/Minor TBI: GCS 13-15; mortality 0.1% - Moderate TBI: GCS 9-12; mortality 10% - Severe TBI: GCS < 9; mortality 40%
What is the acute management of head injury
- Cardiopulmonary stabilisation is the first priory (Airway, Breathing, Circulation). Attention to the airway is vital, especially if there is potential damage to the respiratory centres in the medulla. - Check Disability - neurological examination → use GCS - Radiological screening (CT, MRI) must be quickly carried to find surgically correctable lesions. - Surgical intervention for depressed skull fractures, bleeding vessels and haematomas. - Management of ICP - craniectomy, CSF drainage devices. - Further therapy is individualised, seeking to maintain ICP, cerebral blood flow and cerebral oxygen utilisation within optimal ranges.
If neurons don’t regenerate easily - how does almost complete recovery occur in most brain injury patients?
Neuronal plasticity - recovery of tissue that has only been partially damaged - adaptation of uninjured tissue to undertake some of the function of the damaged tissue
What are the abilities of CNS for recovery?
Adult CNS neurones have limited ability to regenerate in contrast to PNS neurones → due to lack of factors which facilitate growth in the CNS and to the presence of factors which actively inhibit growth
What does neural plasticity involve?
Rewiring of existing neurones into new functional networks and the addition of new formed neurones
What are the long term outcomes of brain injury
- TBIs are major causes of morbidity and disability, having severe psychosocial factors. Disability and longterm neurologic function depends on the severity and location of trauma. Possible consequences: - Cognitive impairment - Hemiparesis - weakness on entire left or right side of the body. - Epilepsy - neurological disorder characterised by sudden, recurrent sensory disturbances, loss of consciousness and convulsions, associated with abnormal electrical activity of the brain. - Post-Traumatic Syndrome - this describes the vague complaints of headache, - Chronic Subdural Haematoma - Hydrocephalus - Chronic Traumatic Encephalopathy
What can cause olfactory nerve dysfunction?
Neurological lesion - commonly trauma - fracture passing through ethmoid bone
How do you test the optic nerve function?
Test for visual acuity, check visual fields and inspect optic disks Inspect size and shape of pupils - compare both sides - test reactions to light
What are the different results you can get in a Weber’s test - and what do they mean.
Equal sound in both ears - normal hearing Sound louder in right - left sensorineural problem Sound louder in left - right sensorineural problem
Does someone with an epidural heamatoma have a lucid period?
After the initial unconsciousness from the injury, they have a lucid period in which consciousness is regained.
What happens after the lucid interval in an epidural heamatoma?
Rapidly developing unconsciousness and focal symptoms related to the area of brain involved
Why are epidural haemorrhages more common in young people?
Because the dura mater is less firmly attached to the skull - so is more easily separated from the inner surface, allowing expansion of the heamatoma
What are the symptoms of an epidural heamatoma?
Ipsilateral symptoms - pupil dilation - eyes point down and out Contralateral symptoms - hemiparesis (from uncal herniation) - loss of visual field
What is the largest danger with a subdural (venous) heamatoma?
Venous blood collects more slowly - and may not be recognised and the patient is sent home
Name the time frames of acute, subacute and chronic subdural heamatomas.
Acute - symptoms witching 24 hours Subacute - symptoms seen from 2-10 days after injury Chronic -symptoms seen several weeks after injury
What’s the main clinical difference between a subdural and an epidural heamatoma.
No lucid interval
Which factors often lead to a high mortality rate for a heamatoma?
Increased ICP Loss of consciousness Delay in surgical removal Oedema Ischaemia
Why are subdural heamatomas more common in old people?
The brains in older people begin to atrophy causing the brain to shrink away from the dura and stretch the fragile bridge veins
What is vasogenic cerebral oedema?
Defective blood brain barrier around contusions or heamatomas allows extravasion of water, sodium and protein molecules to enter the brain
What is the difference between a missile and non-missile head injury?
Missile - open skull fracture Non-missile - base of skull fracture
What is the pathology of punch drunk syndrome?
Loss of pigment in Substantia Nigra Neurofibrillary tangles Amyloid plaques Cavum septum split
How is CPP related to ICP?
CPP=MAP-ICP - as ICP rises, the CPP will continually drop until it reaches a critical level - blood flow ceases when ICP reaches MAP
What is the minimum CPP required for adequate cerebral function?
70mmHg
Which three ways can a brain herniate?
Under falx cerebri Through tentorial notch Incisura of tentorium cerebelli
How does the brain normally compensate for a drop in BP, to keep CPP up?
Cerebrovascular autoregulation causes cerebral vasodilation
When should surgery be used to manage a haematoma?
Mass lesions with a greater than 5mm midline shift Intraparenchymal contusions with raised ICP
What is punch drunk syndrome?
Consists of cognitive impairment Pyramidal and extrapyramidal signs Little and often head injuries can eventually lead to one giant fuck up
Describe post-traumatic syndrome.
Describes vague complications of headache, dizziness and malaise Depression is prominent Prolonged symptoms
Describe the term sick role
A role of sanctioned deviance Rights - exempted from normal social roles, not blamed for illness Responsibilities - try to get better, to seek help and cooperate with help given
Describe the term ‘ilnness behaviour’
The way in which symptoms are perceived, evaluated, and acted upon by a person who recognises some pain, discomfort or other signs of organic malfunction
List 5 elements that have been identified as facilitating successful adjustment to chronic illness
Self-management strategies Maintains morale Problem focused Flexible Internal locus control Being able to express emotion Satisfaction and wellbeing in various life domains
What are the symptoms induced by cytokines activity in chronic illness?
Large number of non-specific symptoms: weakness, fatigue, lethargy, anorexia, psychological symptoms
How can interventions target cytokine activity in chronic illness?
Graded exercise and activity scheduling
What is locus of control?
The degree to which the person believes that control to influence events resides with themselves or others
What are the characteristics of internal locus of control
- Believe that they have agency in their behaviour and ability to influence the world about them - Better respond and manage their conditions
What are the characteristics of external locus of control
Believe that they have little control over events and that outcomes will be determined by others or by fate
What are the positive experiences of illness?
Increasing focus on this - Changed priorities - Improved health - better diet, stop smoking - Reappraising values - Adaptability - Creativity - Changes in life choice and relationships No triumph no tragedy
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