HLTH 2501: general effects of neurological dysfunction Flashcards
why is diagnosing neurologic damage difficult?
because different causes have many similarities on how they affect the brain
local (focal) effects
are signs related to the specific area of the CNS in which the lesion or trauma is located
example of a local effect
damage to the left frontal lobe results in paralysis of the right arm
supratentorial lesions
occurs in the cerebral hemispheres above the tentorium cerebelli; leads to specific dysfunctions
infratentorial lesion
is located in the brainstem or below the tentorium; leads to widespread impairment because nerves are bundled together in the brainstem when passing through, ex. respiration and circulatory function
left hemisphere damage
may lead to a loss of logical thinking, analytic skills, and communication
right hemisphere damage
impairs the appreciation of music and art and causes behavioural problems
what in the brain determine an individual’s level of consciousness?
the cerebral cortex and the RAS
early change noted in those with acute brain disorders
decreasing level of consciousness or responsiveness
what may cause decreased consciousness levels?
a large supratentorial lesion or a small infratentorial lesion which can affect the RAS
what systemic disorders may interfere with consciousness?
acidosis or hypoglycemia
signs of reduced consciousness
lethargy, confusion, disorientation, memory loss, unresponsive to stimuli, or difficulty is arousal
standard tool in medical assessment for consciousness
the Glasgow Coma Scale
most serious level of loss of consciousness
is a coma when the affected person does not respond to painful or verbal stimuli, the body is motionless, although some reflexes are still present
deep coma
the terminal stage when there is a loss of all reflexes, fixed and dilated pupils, an slow and irregular pulse and respirations
vegetative state
is a loss of awareness and mental capabilities, resulting from diffuse brain damage, although brain stem functions continue (respiration, cardiovascular, and ANS)
in what state is there a sleep-wake cycle?
the vegetative state
locked in syndrome
refers to a condition in which an individual with brain damage is aware and capable of thinking but is paralysed and cannot communicate
criteria for brain dead
cessation of brain function (flat or inactive EEG), absence of brain stem reflexes, absence of spontaneous respirations, and establishment of the certainty of irreversible brain damage
what can temporarily cause loss of brain activity?
drug overdose or hypothermia
what does motor dysfunction result from?
damage to the UMNs in the posterior zone of the frontal lobe, to the corticospinal tracts, or to the LMNs in the anterior horn
what does UMN dysfunction cause?
weakness or paralysis on the opposite side of the body
hyperreflexia
reflexes may be increased due to CNS damage because the spinal cord continues to conduct impulses with no moderating or inhibiting influences from the brain
spastic paralysis
muscle tone may be increased due to CNS damage because the spinal cord continues to conduct impulses with no moderating or inhibiting influences from the brain
what does LMN damage cause?
weakness or paralysis on the same side of the below, at and below the level of damage
what does lower motor dysfunction make muscles appear as>
flaccid (absence of tone)
flaccid paralysis
absence of reflexes
damage to cranial nerves
may result in ipsilateral weakness or flaccid paralysis
two involuntary motor responses that occur in persons with brain damage
decorticate and decerebrate posturing
decorticate responses
rigid flexion in the upper limbs, with adducted arms and internal rotation of the hands; the lower limbs are extended
what individuals often display decroticate responses
those with severe damage in the cerebral hemispheres
decerebrate responses
both the upper and lower limbs are extended, as is the head, and the body is arched
who does decerebrate responses often occur in?
those with brain stem lesions and CNS depression caused by systemic effects
sensory deficits
results from damage to the somatosensory cortex in the parietal lobe (may result in touch, pain, temperature, position, vision, hearing, taste, and smell loss); may also result from damage to the cranial nerves or their nuclei
when is vision lost in both eyes?
when the optic chiasm is totally destroyed
fibres from the medial half of each retina (nasal side)
these crossover
fibres from the lateral half of each retina (temporal side)
do not crossover
homonymous hemianopia
occurs when the optic tract or occipital lobe is damaged and vision is lost from the medial half of one eye and the lateral half of the other eye; it results in loss of the visual field on the opposite side to that of the damage
diplopia
double vision that results in loss of depth perception and hand-eye coordination; may result from partial loss of vision that leads to an inability to coordinate input from right and left visual fields
aphasia
refers to an inability to comprehend or to express language; 3 types and 2 subtypes
main types of aphasia
expressive, receptive, and global; subtypes are fluent and nonfluent
dysphasia
refers to partial impairment and is more common; aphasia is still used often to refer to partial loss though
expressive aphasia
aka motor aphasia; damage to the Broca’s area or left frontal lobe results in an impaired ability to speak or write fluently or appropriately
receptive aphasia
aka sensory aphasia; this results from damage to the Wernicke area and the left temporal lobe results in not being able to understand written or spoken language (does not include hearing)
global aphasia
is a combination of expressive and receptive aphasia from results from major damage to the brain, including the Broca and Wernicke areas; therefore the individual cannot express self or comprehend others language
fluent aphasia
the pace of speech is relatively normal, but the speech itself contains made-up words and sentences that do not make sense; this is associated with damage to the Wernicke area
nonfluent aphasia
is slow and labored speech with short phrases, often small words are omitted; it is associated with damage to the Broca’s area
dysarthria
occurs when words cannot be articulated clearly; it is a motor dysfunction that usually results from cranial nerve damage or muscle impairment
agraphia
is impaired writing ability
alexia
is impaired reading ability
agnosia
is the loss of recognition or association; ex. visual agnosia indicates an inability to recognize objects
another name for seizures
convulsions
what are seizures caused by?
spontaneous excessive discharge of neurons in the brain
precipitating cause of seizures
inflammation, hypoxia, or bleeding in the brain
symptoms of seizures
temporary confusion, a staring spell, uncontrollable jerking of the arms and legs, loss of consciousness or awareness, and cognitive, emotional symptoms like fear and anxiety
tardive dyskinesia
is a neurological disorder caused by longtime use of neuroleptic drugs or antipsychotic drugs
what are neuroleptic drugs used for?
psychiatric disorders as well as some GI disorders
characteristics of tardive dyskinesia
repetitive, involuntary movements such as grimacing, tongue protrusion, lip smacking, puckering, pursuing, and rapid eye blinking
treatment for tardive dyskinesia
minimizing the use of neuroleptic or antipsychotic drugs; the drugs may also be replaced with. options like valbenazine or tetrabenazine
increased intracranial pressure
occurs when any increase in fluid volume (inflammatory exudate or blood) or a mass (tumor) causes an increase in pressure in the brain
result of increased intracranial pressure
less arterial blood can enter the high pressure area and eventually the brain tissue is compressed, and this decreases the functions of the neurons both locally and generally; eventually brain tissue can die
how can changes in intracranial pressure be measured?
by instruments placed in ventricles, by radiologic examinations, and by assessment of consciousness
what neurologic problems are increased intracranial pressure associated with?
brain hemorrhage, trauma, cerebral edema, infection, tumors, or accumulation of excessive amounts of CSF
early signs of increased intracranial pressure
decreasing level of consciousness, headache, vomiting, and papilledema
papilledema
increased pressure of CSF causes swelling around the optic disc
how does the body compensate for increased intracranial pressure?
by shifting more CSF into the spinal cavity, increasing venous return from the brain, and causing arterial vasodilation in the brain
why does headache occur with increased intracranial pressure?
stretching of the dura and walls of large blood vessels
vital signs of increased intracranial pressure
cerebral ischemia, systemic vasoconstriction, slowed heart rate, reduced respiratory rate, and fixed and dilated pupils, or ptosis
cushing reflex
is a response of cerebral ischemia due to the vasomotor centres attempting to increase arterial blood supply to the brain
what can occur if increased intracranial pressure is not relived?
neuronal death will prevent circulatory and respiratory control and BP drops
Cheyne-Stoke respirations
may occur with increased intracranial pressure and are alternating apnea and periods of increasing and decreasing respirations
why do fixed and dilated pupils occur with increased intracranial pressure?
because the pressure on the oculomotor nerve affects the size and response of the pupils; usually one pupil is fixed and dilated and the other is nonfunctional, but can be both is pressure continues to increase
ptosis
droopy eyelid that may occur due to pressure on the oculomotor nerve that may occur with increased intracranial pressure
ngstagmus
excessive eye movements that may occur with increased intracranial pressure
lumbar puncture
can test the CSF by inserting a fine needle between L3 and L4
what is elevated intracranial pressure
> 20 mm Hg
what will CSF from a spinal puncture look like if there is a hemorrhage?
pinkish
what will CSF from a spinal puncture look like if there is an infection?
cloudy and yellowish
what will levels of CSF be from a spinal puncture if there is a neoplasm?
abnormal levels of protein
herniation
occurs when a mass, such as a blood clot or tumor becomes large enough that it may displace brain tissue
transtentorial (central) herniation
occurs when the cerebral hemispheres, diencephalon, and midbrain and displaced downward; the resulting pressure affects the flow of blood and CSF, as well as the RAS and respirations
uncal (uncinate) herniation
occurs when he uncus of the temporal lobe is displaced downward past the tentorium cerebelli, creating pressure on the third cranial nerve, the posterior cerebral artery, and the RAS
cerebellar or tonsillar (infratentorial) herniation
occurs when the cerebellar tonsils are pushed downward through the foramen magnum, which compresses the brain stem and vital centres, causing death
diagnostic tests for brain damage
CT, MRIs, cerebral angiography, doppler ultrasound, EEG, lumbar puncture, and the Glasgow Coma Scale
