Neurological Assessment and Dysfunction Flashcards
Three signs of Cushing’s Triad
- Increasing blood pressure
- Bradycardia
- Irregular breathing patterns
Red flags for neurological deterioration include:
Increasing headache, decreased conscious state or orientation, confusion or irritability, seizures, slurred speech, neck pain, weakness or numbness, behaviour changes
Biot’s breath is…?
Irregular breathing with apnoeic episodes
Cushing’s Triad indicates ….?
Late signs of increased ICP and indicate that the brain is about to herniate.
Albumin resus in head injured patients
Is contraindicated due to increased mortality and association with increased ICP.
What is the sole energy substrate for the brain?
Glucose
3 systems responsible for maintain homeostasis
Neurological, endocrine & immune,
CNS consists of:
Spinal cord and the brain
CNS is responsible for:
Acquire, coordinate and disseminate information about the body and it’s environment.
The peripheral nervous system is composed of:
43 pairs of spinal nerves and 12 pairs of cranial nerves that emerge from the base of the brain.
How many neurons in the human brain?
100 billion
Two main classes of synapses:
Electrical and chemical
Function of electrical synapses
Permit direct, passive flow of electrical current from one neuron to another in the form of action potential.
Function of chemical synapses:
Enable cell to cell communication via the secretion of neurotransmitters
Function of myelin:
Increases conduction velocity
Guillian-Barre syndrome:
Demyelination of peripheral nerves, slowing conduction and may result in a conduction block.
Neurotransmitters are:
Chemical that act as messengers to relay information between neurons.
4 classes of neurotransmitters:
- Acetylcholine
- Biogenic amines
- Excitatory amino acids
- Neuropeptides
3 major divisions of the brain:
- Paired hemispheres of the cerebrum
- the brainstem
- the cerebellum
7 components of the brainstem:
- thalamus
- hypothalamus
- epithalamus
- subthalamus
- midbrain
- medulla oblongata
3 regions of the brain:
Forebrain, midbrain, hindbrain
Cerebrum description:
- Largest and most uppermost portion of the brain.
- Two hemispheres.
- 2x frontal, parietal, temporal and occipital lobes
Cerebrum functions:
Cortex (outer layer) is the site of conscious thought, memory, reasoning and abstract mental functions.
Diencephalon decription;
Between the cerebrum and the brainstem.
Contains thalamus and hypothalamus
Thalamus function:
Thalamus sorts redirects sensory input
Hypothalamus function:
Controls visceral, autonomic, endocrine and emotional function and the pituitary gland.
Midbrain function:
Reflex centres concerned with vision and hearing.
Basal ganglia function:
Planning and coordinating motor movements and posture,
Basal ganglia description:
The mass of grey matter in the midbrain beneath the cerebral hemispheres
Pons function:
Helps to regulate respiration +?
Cerebellum function:
Coordinates voluntary muscles, maintains balance and muscle tone, fine movement, position sense and integration of sensory input.
One fixed or dilated pupil may be indicative of
- An expanding or developing intracranial lesion, compressing the oculomotor nerve on the same side as the effect pupil
A sluggish pupil may be :
An early focal sign of an expanding intracranial lesion and raised ICP.
Approximate blood flow through the brain
750 mls/min
CPP formula:
MAP - ICP = CPP
Cerebral perfusion pressure - relationship to cerebral blood flow
CBF is a function of the pressure drop across the cerebral circulation
divided by
cerebral resistance
CPP serves as a rough index of
Cerebral blood flow
Normal cerebral perfusion pressure
70-100mmHg
When ICP and MAP are equal:
CPP is zero and CBF ceases
Cerebral autoregulation
Maintenance of constant CBF rate in face of changing MAP and CPP through alterations in cerebral vascular resistance (dilation and constriction of the vessels) within MAP 50-150mmHg
Effect of head injury on cerebral autoregulation
Alters vessel reactivity and the relationship between CPP and blood flow.
*CBF becomes passively dependent on changes in blood pressure
Effect of CO2 on CBF
Effect of O2 on CBF
Effect of pH on CBF
Effect of temperature on CBF
Effect of glucose on CBF
Why is oxygen of critical importance in cerebral metabolism?
Cerebral oedema
Abnormal accumulation of water or fluid, either local or generalised in the:
- intracellular space
- extracellular space
- or both
Cerebral oedema can cause:
Deterioration in brain function through the compression of tissue and blood vessels
Compression of cerebral blood vessels
Reduces oxygen delivery to the brain, causing cerebral ischaemia and a decrease in brain function.
Cerebral oedema can block the flow of:
CSF, causing an increase in ICP
3 main types of cerebral oedema
Vasogenic, cytotoxic, interstitial
Vasogenic oedema:
Cytotoxic oedema:
Interstitial oedema:
Preventing secondary injury of a head injury patient aims to:
- Control ICP
- Maintain cerebral oxygenation
- Minimise cerebral oxygen consumption
Aim of ICP monitoring:
Detect potentially harmful secondary insults early and apply appropriate preventative interventions.
Vasospasm post haemorrhage
Often occurs 4-14 days post haemorrhage, increasing chances of rebleeding
Stroke
Descriptive term for the sudden onset of acute neurological deficit persisting for more than 24 hours and caused by interruption of cerebral blood flow
Two types of stoke:
Ischaemic and haemorrhagic
2 Subtypes of haemorrhagic stroke:
Subarachnoid and intracerebral
Ischaemic stroke
Interruption of blood flow due to thrombotic of embolic event
Most common cause of cardiac emoboli
Atrial fibrillation
Ischaemic injury occurs when:
Cerebral blood flow is reduce to a level insufficient to maintain neuronal viability
Cerebral oedema can cause:
Intracranial hypertension
Cerebral oedema results from:
Loss of metabolic function of the cells, peaking at 4 days.
Common cause of death during the first week after stroke:
Cerebral oedema
Major acute complications of ischaemia stroke
- Secondary haemorrhage at the site of the stroke lesion
2. Seizures
Haemorrhagic conversion
Secondary haemorrhage at the site of the stroke lesion
Characteristic sign of an ischaemic stroke
Sudden onset of focal neurological signs persisting for more than 24 hours
