chapter 26: neurological disorders Flashcards
Which demographic is at the highest risk of traumatic brain injury (TBI)?
Males ages 15-30.
What are compensatory behaviours?
Behaviours by other mechanisms in the brain that perform the function of an injured/lost function.
Define the terms coup, contrecoup, shearing (in the context of closed-head injuries).
Coup: damage to brain at site of blow caused by brain impacting skull
Contrecoup: damage to brain on side of brain opposite to site of area due rebounding and impacting skull
Shearing: twisting and breaking of nerve fibres caused by rapid movement of brain inside skull
Define hematoma and edema.
Hematoma: mass of blood trapped in the skull
Edema: swelling that can result in pressure on delicate nervous tissue in brain
Which metrics does the Glasgow Coma Scale measure?
Eye opening, motor response, verbal response.
Scores of _ or less on the Glasgow Coma Scale are associated with severe head injury, _ to __ for moderate, __+ for mild injury.
8 (severe), 9 to 12 (moderate), 13+ (mild).
Recovery from TBI can take up to __________, most recovery takes place in first __________.
2 to 3 years, 6 to 9 months.
What is the distinction between symptomatic and idiopathic seizures?
Symptomatic: associated with known cause (e.g. infection, trauma, fever, etc.)
Idiopathic: Spontaneous; no known cause
What is an aura?
Subjective sensation, perception, or motor experience associated with the onset of a seizure.
What are some precipitating factors for seizures in susceptible individuals?
Drugs, emotional distress, fever, hormonal changes, hyperventilation, sensory stimuli, sleep, sleep deprivation, trauma.
What are focal seizures versus generalized seizures?
Focal: begin in one location in brain, electrical activity spreads to involve other regions
Generalized: Seizure activity occurs in both hemispheres, no clear focus
What are the four phases of generalized seizures? Describe their symptoms and associated EEG activity.
Start state: no symptoms, normal EEG activity
Tonic phase: patient detects aura; rapidly increasing EEG activity
Clonic phase: stereotyped convulsions, loss of consciousness and/or breathing; EEG pulses
Coma phase: comatose state; EEG activity of coma patient, less brain activity than resting state
What are akinetic seizures and myoclonic spasms? What do they share in common?
Akinetic seizure: characterized by sudden collapse without warning
Myoclonic spasm: large seizures characterized by flexion or extension of entire body
Both typically only occur in children
What are dissociative seizures and how are they unique?
Seizures that resemble focal seizures but have no EEG changes. Patients report feeling cut off from surroundings (out-of-body experience).
What are some treatments used to end seizures (that have already begun)?
GABA agonists, glutamate antagonists.
What are some drugs used to inhibit seizure development or propogation?
GABA agonists, sodium-channel blockers, anaesthetics, anticonvulsants.
Drugs are __-__% effective in treating seizures. If not, what other interventions are sometimes resorted to?
30-40%; surgery or DBS.
What cells can develop into brain tumours? Why not other kinds of brain cells?
Glial cells or other supporting cells. Neurons do not grow and divide and therefore cannot become tumours.
What is the difference between benign and malignant tumours?
Benign tumours generally do not reoccur after removal, malignant tumours are progressive.
Describe encapsulated tumours, infiltrating tumours, and their respective differences.
Encapsulated tumours: localized in one place, can put pressure on surrounding tissue
Infiltrating tumours: interact with surrounding cells, can destroy or interfere with them
Describe the three types of brain tumours discussed in class (glioma, meningioma, metastatic).
Glioma: arise from glial cells and infiltrate surrounding brain (~45% of brain tumours)
Meningioma: arise in the meninges; benign and encapsulated. Symptoms via compression of adjacent tissue
Metastatic: tumour cells from elsewhere in body start to grow in brain. Prognosis poor and treatment difficult
What causes headaches and where in the head does pain occur?
Factors: stress, neurological disease (e.g. tumours, migraines)
Pain anywhere with vascular tissue: dura mater, blood vessels in brain, cranial and/or cervical nerves
What causes migraines? Describe classic migraines versus common migraines.
Caused by vasoconstriction of cerebral arteries, subsequent blood loss to occipital lobe
Classic: begin with aura, depolarization spreads outwards. Headache associated with blood flow back to areas
Common: not associated with an aura
What are other categories of headaches besides migraines?
Muscle-contraction headaches: result from persistent contraction of muscles in scalp and neck due stress
Non-migrainous vascular headaches: associated with dilation of arteries due all kinds of factors
What is apraxia?
Inability to make or copy voluntary movements (in the absence of paralysis or other impairment). Usually follows damage to neocortex.
What is ataxia?
Failure of muscle coordination or irregularity of muscular action. Commonly follows cerebral damage.
What is athetosis?
Ceaseless slow, sinuous, writhing movements, especially in the hands; due to abnormal function of extrapyramidal system.
What is cataplexy?
Complete loss of movement and posture during which muscle tone is absence but consciousness spared.
What is chorea?
Variety of ceaseless, jerky movements that appear well coordinated but that are performed involuntarily.
What is hemiplegia? How is the Babinski reflex test used to diagnose it?
Complete or partial paralysis to one half of the body. Usually follows damage to contralateral motor cortex.
Babinski reflex test: in intact individuals, toes flex downward after stimulus; those with hemiplegia extend toes.
What is palsy?
Usually refers to persisting movement disorders due brain damage acquired perinatally.
What is paralysis?
Complete loss of movement (more commonly) or sensation in part of body.
Usually permanent damage to motor neurons, temporary after damage to motor cortex (BA 4).
What is spasticity? What is the clasp-knife reflex?
Increased tone in certain muscle groups that maintain posture against force of gravity.
Clasp-knife reflex: if spastic limb is moved against rigidity, resistance will initially increase then tone will suddenly melt.
What is tardive dyskinesia?
Slow, persistent movements, particularly of the mouth and tongue. Usually follows long-term treatment with antipsychotic drugs.
What is myasthenia gravis and what is it caused by?
Severe muscle weakness characterized by muscle fatigue after little activity or exercise; muscles innervated by cranial nerves first to show symptoms.
Caused by acetylcholine receptors at neuromuscular junction destroyed by immune system (autoimmune neuromuscular junction disorder).
What disease involves myelin being attacked and destroyed in the motor and sensory tracts?
Multiple sclerosis (MS).
Describe paraplegia, quadriplegia, Brown-Séquard Syndrome.
Paraplegia: spinal cord damage at level of thoracic through lumbar spine; paralyzes legs and lower torso
Quadriplegia: damage at level of cervical spine; paralyzes all four limbs
Brown-Séquard Syndrome: only one side of spinal cord is damaged, impairing only some of the ascending and descending pathways
What are the discussed examples hyperkinetic-dystonic syndromes, hypokinetic-rigid syndrome, and which brain area are they a result of illness of?
Hyperkinetic: Huntington’s Disease (Chorea), Tourette’s syndrome
Hypokinetic: Parkinson’s Disease
Result from diseases of the basal ganglia.
What causes Huntington’s disease (chorea)?
Mutation in the Huntington gene which results in defective protein accumulating in basal ganglia.
What are the stages of Tourette’s?
Initially: symptoms of tics in face, limbs, body
Second stage: tics accompanied by inarticulate cries
Final stage: echolalia and corprolalia, in addition to tics and cries
What are the positive and negative symptoms of Parkinson’s?
Positive symptoms: tremors at rest, muscular rigidity (due antagonistic contraction), involuntary movements
Negative symptoms: postural disorders, righting disorders, locomotive disorders, speech disturbances, akinesia
Parkinson’s is often idiopathic. What are some potential causes for it?
Damage to substantia nigra following encephalitis (postencephalitic Parkinsonism), drug induced (to treat schizophrenia), damage to dopamine receptors.
Parkinson’s has no direct cure. What are some treatments for it?
L-dopa: crosses BBB to supplement lost dopamine
Monoamine oxidase inhibitors and tricyclic antidepressants: enhance dopamine transmission
Anticholinergenic drugs: block acetylcholine signalling that increases as dopamine decreases
DBS and stem cell transplants
What is an infarct?
Region of brain that is directly impacted by a stroke, is characterized by dead and dying cells.
What as a cerebral ischemia?
Cerebral ischemia: blood vessel is blocked by clot. Thrombosis refers to static clot that remains where it forms, embolism is a clot formed in larger vessel that has clogged smaller one.
What is a migraine stroke?
Blood flow to brain region interrupted by constriction of a blood vessel. Cause of vascular spasm is unknown.
What is a cerebral hemorrhage?
Cerebral blood vessel fails, resulting in bleeding in the brain. Causes can be high blood pressure, trauma, toxic chemicals.
What is an angioma?
Abnormal blood vessel that diverts normal bloodflow. Results in abnormalities in pattern and amount of blood flow.
What is an angioma?
Region of cerebral vascular tissue where elasticity is defective, vessel walls balloon out and weaken structure of vessel.
What are some treatments of cerebral vascular disorders (angioma and aneurysm)?
Restoring blood supply, calcium channel blocking, surgery.
