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