Neurological conditions Flashcards
What is the function of the blood brain barrier?
Helps maintain a stable environment required for normal brain function (brain tissue is very sensitive)
Regulates the passage of most ions and fluid between the blood and the brain tissue
Regulates entry and exit of nutrients and waste
What is the structure of the blood brain barrier?
Endothelium (tight junction)
Basement membrane with pericytes (Pericytes monitor and control influx of substances but pulling apart the membrane)
Macrophages
Polarised astrocytic feet (Completely surround the vessels and tightly control electrolytes)
What can and can’t cross the blood brain barrier?
Most low molecular weight non polarised molecules can pass through the BBB easily. Polarised ions will be repelled.
Water, O2, CO2 and glucose can cross easily however ions such and calcium that would normally follow water cannot because they are polarised.
Many drugs can easily cross the BBB (cociane, nicotine, opiates etc.), many medications cannot (such as dopamine)
A limited number of pathogens can cross but immunosupressed patients may be more succeptible. Many viruses can cross but bacteria crossing is less common
How is CSF tested?
With a lumbar puncture (“spinal tap”)
The pt is led on their side with their knees to their chest to spread out their vertebrae and a 22G needle is inserted between L3/L4 OR L4/L5.
Most commonly used in meningitis diagnosis but medication can also be delivered this way (e.g. anaesthetics for child birth, antibiotics, cancer medication)
What causes menigococcal septicaemia?
Neisseria meningitidis
12 seroproups identified, 6 known to cause epidemics
What is the effect of meningitis on the CSF?
Increased pressure
Increased white blood cells
Increased protein
Decreased glucose
What is the circle of Willis?
The circle of Willis is a junction of several important arteries at the bottom part of the brain.
What is the cerebral ischaemic cascade and what main pathology does it lead to?
-Na+ and K+ pump dysfunction
-Na+ and Ca+ pump dysfunction
-Cytotoxic oedema
-Mitochondrial dysfunction
Excitiotoxicity
Degradative enzymes
BBB breakdown
Free radicals
How does the cerebral ischaemic cascade lead to cytotoxic oedema?
With a reduced blood supply the brain tissue turns to anaerobic respiration and acidosis (mitochondrial dysfunction). This is very inefficient and eventually the hypoxia will lead to a failure of first sodium then potassium pumps. The cell will fill with sodium and calcium, attracting the surrounding water from the extra-cellular fluid into the cell causing it to swell.
What happens to glutamate in the cerebral ischaemic cascade?
Glutamate binds to ionotropic receptors (iGluRs), promoting a major influx of calcium. This calcium overload triggers phospholipases and proteases that degrade essential membranes and proteins
What are iGluRs?
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that are activated by the neurotransmitter glutamate
What percentage of strokes are ischaemic?
87%
What percentage of strokes are haemorrhagic?
13%
What percentage of strokes are subarachnoid haemorrhage?
3%
What percentage of strokes are intracranial haemorrhages?
10%
What risk factors are more associated with haemorrhagic strokes?
Taking blood thinners
Arteriovenous malformations (AVMs)
What risk factors are more associated with ischaemic strokes?
Any increased risk of clot formation e.g.
Coronary heart disease
Atrial fibrillation
Heart valve disease
Carotid artery disease
Sickle cell disease
DVT
Contraceptive pill
Long hospital stay/bed-bound periods
etc.
What risk factors are shared between ischaemic and haemorrhagic strokes?
High blood pressure
Diabetes
High blood cholesterol
Poor lifestyle (Obesity, smoking, drinking, drugs etc.)
Age
Family history
Sex
Other medical conditions (sleep apnea, kidney disease, migraine headaches)
What is asphasia?
Changes in speech commonly caused by strokes
What is the timeframe for it to be classed as a TIA and not a full stroke?
24 hours
What can you use to assess risk if you suspect a patient has had a TIA?
ABCD2 scale
What can you use to differentiate between strokes and stroke mimics?
Rosier scale
What percentage of cases where stroke symptoms are present are not due to a stroke?
20%
What are the most common stroke mimics?
Seizures
Migraines
Fainting
Infections
Functional Neurological Disorder (FND)
What is functional neurological disorder?
FND is sometimes referred to as a ‘functional stroke’ or a ‘functional stroke mimic’. Caused by a disorder that effects the nervous system rather than the brain resulting in the signals between brain and body being interupted.
What are the symptoms of FND?
Loss of motor control
Sensory symptoms
Speech problems
Seizures
Visual symptoms
Cognitive problems
Bladder and bowel problems.
How much of the brain is involved in a focal seizure?
One localised area of the brain is initially involved – can spread to involve other areas
What are the most common causes of seizures outside of epilepsy?
Provoked (acute symptomatic seizures)
Psychogenic non-epileptic seizures (PNES)
Vasovagal syncope
Cardiogenic events
Eclampsia
Febrile seizures
What is a BTCS?
Bilateral Tonic-Clonic Seizure
What occurs in tonic phases of seizures?
Loss of consciousness
Stiffening of muscles
Can be have a “crying out” effect as air pushes past vocal cords
May bite their tongue
What occurs in the clonic phases of seizure?
Rhythmic jerking of limbs
Loss of control of bladder and/ or bowels
Breathing affected – cyanosis may occur
When do you treat a focal motor seizure as a BTCS?
Where there is impaired consciousness and last longer than 10 minutes
What are focal aware seizures?
The patient is fully aware of surroundings during the seizure but may not be able to move or respond
What are focal impaired awareness seizures?
When awareness is affected at some point during the seizure
What motor or non-motor features may present with focal seizures?
Motor - muscle activity localised jerking, loss of tone or repeated movement
Non Motor – no muscle activity but may affect emotions, thinking and sensations
What are signs of typical absent seizures and who usually has them?
Typical absences – usually last around 10 secs but can be in clusters
Appear as a “switching off” or “day-dreaming”. A sudden and unexpected stop for a few seconds. Can have some slight jerking movements or eye lid flutter especially with longer absences
They do not generally fall but will not know what is happening and can not be brought out of it
Some go unnoticed
Can have hundreds per day or just occasional ones
Most start in childhood or just into adulthood - usually patients with other existing neurological disorders
What are signs of atypical absent seizuresand who usually has them?
Atypical absences – usually last up to about 30 secs
Similar to typical but last longer and have a slower start and finish
May be able to move around but appear clumsy as muscles become limp
Can occur in any age group but usually associated with people who have learning difficulties or brain conditions
What are the features of myoclonic seizures/jerks?
Can be focal or generalised
Mild (twitch) or can be more forceful – enough to throw something they are holding or make them fall over
Does not usually affect level of consciousness
Usually last for less than a second but can be in clusters
What are the features of tonic seizures?
Can be focal or generalised
Muscles tense /stiff
If standing may fall to the floor
Neck extension and eyes open wide and roll upwards
Arms might move upwards
Legs may stretch or contract
May cry out and stop breathing briefly
Usually last three seconds to two minutes
What are the features of atonic seizures?
Muscles become limp
Will fall to floor if standing or may see a drop of the head forward and may “go weak at the knees”
Usually lasts less than a couple of seconds
What are Provoked Acute Symptomatic Seizures?
Seizures not caused by epilepsy but by damage to the brain or metabolic issues
What can cause Provoked Acute Symptomatic Seizures?
May be caused by structural damage to the brain:
TBI
Brain tumour
Stroke
Tuberculous meningitis (TBM)
Neurocysticercosis
May be due to metabolic issues:
Alcohol withdrawal and chronic alcohol over use
Renal failure
Heptatic failure
Blood Glucose – hypoglycaemia
What is the most common cause of TLOC?
Vasovagal syncope
What causes vasovagal syncope?
A temporary disruption of the supply of oxygen and glucose to the brain due to a fall in cerebral blood pressure. Has many causes including:
Standing for long periods.
Excess heat.
Intense emotion, such as fear.
Intense pain.
The sight of blood or a needle.
Prolonged exercise.
Dehydration.
Skipping meals.
and others
What seizure activity can vasovagal syncope exibit?
May have very short muscle jerking (usually less than 20 secs)
Patient may be able to hear but not respond verbally
Once supine recovery is usually quite rapid
What are vasovagal cardiogenic seizures?
Dysrhythmias causing syncope
Don’t usually cause convulsions but may have impairment of consciousness and have decerebrate posturing
What is meningitis?
Infection of the protective membranes surrounding the brain and spinal cord, specifically the leptomeninges
What are pseudopalisades and how are they formed?
In glioblastoma, they are dense cellular arrangements that surround necrotic foci, formed when aggresive malignant cell division leads to not enough blood being able to reach the centre of the tumor, the peripheral cells continue to divide.
Where do menigomas form, what structure do they form?
In parasagittal regions and on the surface of the brain under the dura mater. They form multinuclear synctiums of fused cells, usually arachnoid cap cells
What is the most common brain tumor in adults?
Glioblastomas, a common type of strocytoma - fast growing supratentorial tumors.
What are pituitary adenomas?
Common usually benign tumors formed from the enocrine tissue of the pituiatry, classified by hormones released in tumor form.
What are oligodenrogliomas, what microscopic forms can they take?
Relatively rare supratentorial tumors formed from oligodendrocytes.
More common in frontal and temporal lobes where cells are heavily myelinated
Relatively slow growing - can become malignant
“Fried egg” or “Chicken-wired”
What are haemangioblastomas?
Haemangioblastomas are rare non cancerous (benign) brain tumours. They start in the cells that line the blood vessels in the brain, spinal cord and brain stem. They usually grow slowly over some years.
Most haemangioblastomas start in the back of the brain (cerebellum).
What are coup and contrecoup brain injuries?
Coup - injury on side of impact
Contrecoup - injury on opposite side to impact
Bothh can be present - Coup-contrecoup
What is spina bifida?
Spina bifida is when a baby’s spine and spinal cord does not develop properly in the womb, causing a gap in the spine. Spina bifida is a type of neural tube defect. The neural tube is the structure that eventually develops into the baby’s brain and spinal cord.
How many types of cerebral palsy are there and what defines them?
What is hydrocephalus?
A neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles (cavities) deep within the brain. This excess fluid causes the ventricles to widen, putting harmful pressure on the brain’s tissues.
What are the symptoms of hydrocephalus?
-Bulging of the cranium
-Eyes fixed downward (sunsetting)
-Lethargy
-Irritability
-Seizures
-Nausea and vomiting
-Poor eating
-Problems with muscle tone and strength
What is myasthenia gravis (MG)?
A chronic autoimmune disorder in which antibodies destroy the communication between nerves and muscle, resulting in fluctuating fatigue and weakness of the skeletal muscles.
-The immune system releases antibodies that target and block acetylcholine receptors at the neuromuscular junction.
Myasthenia gravis affects the voluntary muscles of the body, especially those that control the eyes, mouth, throat and limbs.
What is Huntingdons disease?
An incurable adult onset inherited disorder, associated with cell loss in the brain due to a genetic fault causing a loss of a protein called Huntingtin. It is not fully understood why but the protein is important for neuronal function. This disease specifically affects the neurons of the basal ganglia
