300 Coma Flashcards
Defined as deep sleeplike state with eyes closed from which patient cannot be aroused
coma
refers to a higher degree of arousability in which the patient can be transiently awakened by vigorous stimuli accompanied by motor behaviour that leads to avoidance or withdrawal from uncomfortable or aggravating stimuli
stupor
stimulates light sleep and is characterized by easy arousal and the persistence of alertness for brief periods
drowsy
signifies a awake appearing but non responsive state often in a patient who has emerged from coma
vegetative state
most common cause of the vegetative and minimally conscious states
cardiac arrest with cerebral hypoperfusion and head trauma
refers to a partially or fully awake state in which the patient is able to form impressions and think as demonstrated by later recounting of events but remains virtually immobile and mute
akinetic mutism
akinetic mutism results from damage of what
the condition results from damage in the regions of the medial thalamic nucle or the frontal lobes, or from extreme hydrocephalus
describes a milder form of akinetic mutism characterized by mental and physical slowness and diminished ability to initiate activity
abulia
what part of the brain is damaged when patient presents with abulia
medial frontal lobes and their connections
hypomobile and mute syndrome that occurs usually as part of major psychosis typically schizoprenia or major depression
catatonia
How is catatonia different from akinetic mutism
Catatonia and akinetic mutism are superficially similar but in catatonia clinical evidence of cerebral damage such as hyperreflexia and hypertonicity of the limbs is lacking
describes an important type of pseudocoma in which an awake person has no means of producing speech or volitional limb movement but retains voluntary vertical eye movements and lid elevation thus allowing the patient to signal with a clear mind
locked in state
what part of the brain is damaged in patients with locked-in state
usual cause is infarction of the basilar artery, hemorrhage of the ventral pons that transects all descendint motor (corticospinal or corticobulbar) pathways
Damage to what systems leads to coma
widespread damage to the cerebral hemisphere or reduced activity of the reticular activating system (RAS) which is diffusely located in the brainstem
separates the right and left cerebral hemispheres
falx
separates the anterior and posterior fossae
tentorium
refers to the displacement of brain tissue by an overlying or adjacent mass into a contiguous compartment that it normally does not occupy
herniation
most common form of herniation
transtentorial herniation
brain tissue is displaced from the supratentorial to the infratentorial compartment through the tentorial opening
transtentorial herniation
refers specifically to the impaction of the anterior medial temporal gyrus (uncus) into the tentorial opening just anterior to and adjacent to the midbrain
uncal herniation
first sign of uncal hernation
Enlargment of the ipsilateral pupil as the uncus compresses on the third nerved as the nerve transver the subarachnoid space
refers to the hemiparesis contralateral to the hemiparesis and Babinski sign that result the displacement of the cerebral penduncle
Kernohan_ Woltman sign
denotes symmetric downward movement of the thalamic structures through the tentorial opening with compression of the upper midbrain
central transtentorial herniation
heralding signs of central transtentorial herniation
miotic pupils and drowsiness
displacement of the cingulate gyrus under the falx and across the midline
transfascial herniation
downward forcing of the cerebellar tonsils into the foramen magnum
foraminal herniation
why is forminal herniation deadly
it causes early compression of the medulla leading to respiratory arrest
How much horizontal displacement of the pineal gland is associated with drowsiness
3-5 mm displacement
How much horizontal displacement of the pineal gland is associated with stupor
6-8 mm displacement
how much horizontal displacement of the pineal gland is associated with coma
more than 9 mm displacement
True or false. Unlike hypoxia- ischemia which causes neuronal destruction, most metabolic disorders such as hypoglycemia, hyponatremia cause only minor neuropathologic changes.
True.
True or false. Coma and seizures are common accompaniments of large shifts in sodium and water balance in the brain.
True.
When can temperature cause coma
hypothermia itself causes trauma when the temperature is less than 31 degrees Celsius
May be the only sign of seizure in comatose patients
subtle, intermittent twitching movements of foot, finger, or facial muscle may be the only sign of seizure
Sign of metabolic encephalopathy or drug intoxication in a drowsy and confused patient
bilateral asterixis
What is decorticate posturing and what does it suggest?
Decorticate is flexion of the elbows and wrists and supination of the arms which suggests bilateral damage to the rostal to the midbrain
what is decerebrate posturing and what does it indicate
Decerebrate posuturing is the extension of the elbows and wrists with pronation and indicates damage to the motor tracts caudal to the midbrain
posturing in response to noxious stimuli indicates severe damage to what system?
Damaged cortisospinal system
Abduction-avoidance movement of a limb denotes what?
intact corticospinal system
True or false. Given that the nuclei of the cranial nerves and the RAS are both located in the brainstem, assessment of brainstem function is essential to localization of the lesion in coma
True.
Most important brainstem reflexes
pupillary size and reaction to light; spontaneous and elicited eye movements, corneal responses and the respiratory system
Pupillary sign that essentially exclude upper midbrain damage
reactive and round pupils of midsize 2.5-5 mm
Most extreme pupillary signs
bilaterally dilated and unreactive pupils indicated severe midbrain damage from compression by a supratentorial mass
Finding exonerates extensive damage in the midbrain and pons
spotaneous eye movements in coma in a form of conjugate horizontal roving
How does seizure involving the frontal lobe look like
seizures involving the frontal lobe drive the eyes to the opposite side, simulating a pontine destructive lesion
True or false. Eyes look toward a hemispheral lesion and away from a brainstem lesion.
True. Maxim
Eyes may occassionally turn paradoxically away from the side of a deep hemispheral lesion. What do you can this phenomenon
wrong way eyes
What is the eye position in thalamic and upper midbrain lesions
eyes turn downward and inward
described as brisk downward and slow upwards movement of the eyes associated with loss of horizontal eye movements and where is the lesion
ocular bobbing; diagnostic of bilateral pontine damage
described as slower arrythmic downward movement followed by faster upward movement? Where is the lesion
ocular dipping; indicates diffuse cortical anoxic damage
True or false. Doll’s eye is normally suppressed in awake patients
True. It is suppressed in awake person and intact frontal lobe
What does a positive dolls eye mean?
reflects both reduced cortical influence on the brainstem and intact brainstem pathways
provides more intense stimulus for the oculocephalic relfex but provides essentially the same information
thermal or caloric stimulation of the vertibular apparatus
what it the normal result to caloric stimulation
tonic deviation of both eyes to the cold water irrigation
what is the caloric stimulation response in comatose patient?
nystagmus in the opposite direction of the cold water irrigation
what is the normal corneal reflex
brief bilateral lid closure when cornea is touched with wisp of cotton
what does the corneal reflex mean
corneal reflex depend on the integrity of pontine pathways between the fifth (afferent) and seventh (efferent) cranial nerves
True or false, respiratory patterns are less of localizing value in comparison to other brainstem signs
True.
Respiratory pattern. Typically cyclic form , ending with brief apneic period. What does this signify?
Cheyne Stokes respirations signifies bihemispheric damage or metabolic suppression with pontomesencephalic lesions
Respiratory pattern. Rapid deep breathing. What does this signify?
Kussmaul breathing. Implies metabolic acidosis but may also occur with pontomesencephalic lesions
Agonal grasps are due to what
lower brainstem (medullary damage) and recognized as terminal respiratory pattern of severe brain damage
EEG finding. Widespread fast beta activity
coma from sedative drugs
EEG finding. Predominant high voltage slowing (triphasic waves) the frontal region
metabolic encephalopathy
What is alpha coma
widespread variale 8 to 12- hz activity resembling normal alpha rhythm of waking but it is not altered by environmental stimuli
when do you see alpha coma
alpha coma results from pontine or diffuse cortical damage and is associated with poor prognosis
EEG finding. Normal alpha activity suppressed by stimulating the patient.
locked in syndrome, hysteria or catatonia
3 broad categories of coma
coma without focal neurologic signs as in metabolic and toxic encephaties; coma with prominent focal signs as in stroke and cerebral hemorrhage; meningitis syndrome characterized by fever or stiff neck
cerebrovascular disease that can lead to coma
basal ganglia and thalamic hemorrahge (acute but no instantaneous), pontine hemorrhage (sudden onset); cerebellar hemorrhage; basilar artery thrombosis, subarachnoid hemorrhage
True or false. Infarction in the MCA territory leads to instantenous coma.
False. But large infractions causing edema can have mass effect leading to coma
True or false. Children and young adults may have ominous early clinical findings such as brainstem reflexes and yet recover so ultra early prognistication is unwise.
True.
How is the observation prior to declaring a patient is brain dead
observation of 6-24 hour is recommended
refers to ta state of irreversible cessation of all cerebral and brainstem function with preservation of cardiac activity and maintenance of respiratory and somatic function by artificial means
brain death
is the only type of damage recognized as morally, ethically and legally equivalent to death
brain death
