Coma and PVS Flashcards
coma
*severely depressed responsiveness
*defined by Glasgow Coma Scale
acute encephalopathy
*rapidly developing pathobiological process in brain
*within hours, days, less than 4 weeks
delirium
*clinical state characterized by combination of features (DSM-V)
*disturbance in awareness, attention, and cognition, short period, acute change, fluctuates, not explained by neurological disorder, direct consequence of medical condition
brain lesions that cause coma
*diffuse cortical damage; global anoxia
*diencephalon injury; tumor
*caudal diencephalon and upper midbrain paramedian basial stroke
*brainstem lesions involving ARAS
note - brainstem lesions may be very large without causing coma if they don’t involve the ARAS bilaterally
ascending arousal system
*cholinergic system - INPUT into the reticular nucleus, thalamus, and upper brainstem
*cortical activation (glutamate, norepinephrine, etc)
NREM sleep vs coma
*BOTH have EEG patterns (increased high voltage slow waves) and both have lack of activity of ascending arousal system
*sleep = intrinsically regulated inhibition of arousal system
*coma = impairment of the arousal system by damage, diffuse dysfunction of its diencephalon/forebrain targets
approach to patient with coma
- evaluate/treat circulation, airway, breathing, and cervical spine
- exclude/treat hypoglycemia or opioid/benzodiazepine overdose
- serum chemistries, arterial blood gas, urine toxicology screen
- emergent cranial CT (CT angio brain if appropriate) to determine if coma etiology is structural or vascular
“house” approach for etiology of coma
1) structural
2) vascular
3) electric
4) chemisty/metabolic
examples structural etiologies of coma
-subdural hygroma causing midline shift and falcine herniation
-left MCA ischemic stroke, causing malignant cerebral edema and uncal herniation
-right basal ganglia hemorrhage with intraventricular hemorrhage
-obstructive hydrocephalus causing bilateral midbrain compression
example vascular etiologies of coma
-brainstem infarcts caused by acute basilar artery thrombus
metabolic causes of coma/altered mental status
*hypoglycemia
*hypoxemia
*toxin accumulation
*neurotransmitter deficiency or surplus
diagnostic evaluation of altered mental status
*history
*physical exam
*labs
*imaging
important history for altered mental status
*onset
*recent symptoms
*injury
*known medical illness (ex a-fib)
*psych history
*access to drugs (therapeutic or recreational)
important physical exam for altered mental status
*ABC (airway, breathing, circulation)
*vitals - BP, HR, RR, respiratory patterns, O2 sats
*systemic exam (nuchal rigidity, trauma, ingestion/njection/illness)
*neuro exam:
-mental status: GCS, arousal, awareness
-brainstem reflexes (pupil eye mvmts, corneal, oculovestibular, oculocephalic, cough/gag)
-muscle (motor response, reflexes, tone)
-sensory/cerebellar !!
-fundoscopy
Cheynes-Stokes respiratory pattern in coma patient
*characterized by cyclical episodes of apnea and hyperventilation
*INTACT brainstem respiratory reflexes
hyperventilation respiratory pattern in coma patient
indicative of:
-bihemispheric lesions
-midbrain
-pons
apneic respiratory pattern in coma patient
indicative of:
-bilateral pons
-severe metabolic derangement
pupil reflexes in acute uncal herniation
*3rd nerve palsy (dilated pupil, down and out)
3 P’s of acute lesions to PONS
*paralysis
*pinpoint pupils
*pyrexia (fever)
glasgow coma scale
*a numerical scale of 15 that determines a patient’s level of consciousness based on eye opening, verbal response, and motor response
*scored based on best response (not for each limb)
*GCS 8… intubate
GCS - eye opening scale
4 = spontaneously
3 = to speech
2 = to pain
1 = no response
GCS - verbal response scale
5 = oriented to time, person, and place
4 = confused
3 = inappropriate words
2 = incomprehensible
1 = no response
GCS - motor response scale
6 = obeys command
5 = moves to localized pain (actively shoving pain away)
4 = flex to withdraw from pain
3 = abnormal flexion (decorticate posturing)
2 = abnormal extension (decerebrate posturing)
1 = no response
brainstem deficits and limb weakness on same side indicates
cortical/subcortical damage
