Coma and Brain Death

Spontaneous Eye Movements in Coma

-Absence of Cortical Control (voluntary saccades absen, fast phase nystagmus absent, tracking eye movements absent) -If brainstem intact - roving eye movements present -If pontine reticular formation intact - spontaneous blinking present -If superior colliculi intact - Blink to bright light intact

Decerebrate Posturing (extensor)

-Arm extended, leg extended -(arm internally rotated, wrist flexed) -W/o Cerebrum -May occur spontaneously or to painful stimuli -Lesion at MIDBRAIN -"Arms are "E" xtended"

Decorticate (flexor) Posturing

-Arm flexed over chest, leg extended -W/o Cortex -May occurs spontaneously or to painful stimuli -Lesion at thalamus or b/w cortex and thalamus "Arms flexed over heart (cor)"

Cheyne-Strokes Respiration

-Brief period of hyperpnea w/ shorter periods of apnea -usually due Heart failure, uremia, anoxia; CNS lesion from bicerebrum to pons (rare) -Resp drive closely dependent on pCO2 - increase pCO2 --> hyperpnea --> decrease pCO2 --> apnea

Monro-Kellie Doctrine

-Cranium, Vertebral Cana, and dura form rigid container -These are 3 intracranial components: brain, blood, CSF -increase volume in 1 results in decrease in the other 2 -Increase in volume of components causes increase ICP if: 1.) too acute for other components to adjust 2.) total volume overwhelms capacity

Persistent Vegetative State

-Due to severe, irreversible BICEREBRAL injury -BREATHING -AWAKE but unaware, intact brainstem reflexes -Relatives must be involved in decision to withdraw care - "allow to die" "comfort care" etc...

Management of Uncal Herniation

-Elevate head 30 degrees w/ head straight -Intubate and Hyperventilate to pCO2 28-32*** -insert indwelling bladder catheter -Mannitol 100g IV rapidly*** -Dexamethasone (decadron) 10-20 mg IV

Trauma, Disease, and Neck Exam

-Evaluate cervical spine for trauma before moving head or neck -- Xray!!! -After C spine eval --> check for nuchal rigidity (meningitis); perform doll's eye maneuver (see brainstem reflex)

Delirium

-Global cognitive dysfunction -confusion, inattention, chance in consciousness, disorientation, + other neuropsych probs --> agitation and visual hallucinations -Transient, Reversible, and Fluctuating in severity -Aka-Acute Confusional State or Acute Encephalopathy -Neurologists call this! CONFUSION! Think of a DRUNK person!

Eye Movements

-KEY!!! -allows you to distinguish b/w Brainstem or Bicerebral Lesion for COMA -Brainstem contains ARAS + CN nuclei 3,4,and 6 So if you have ABNORMAL eye movements than ---> Brainstem Lesions If you have NORMAL eye movements than --> Bicerebral Lesion

Brainstem Reflex

-Observe Eye movements! (At rest- nystagmus, dysconjugate gaze; doll's eye, caloric testing - irrigate eyes w/ cold water) -Pupillary symmetry and response to light -Corneal reflex -Cough and gag reflex (tells brainstem is still intact) -CN motor response (grimace)

Motor Exam in Comatose Patient

-Observe all 4 limbs for symmetry -Comprehensive formal testing not possible due to decrease consciousness

Sensory Exam in Comatose Patient

-Only test Pain! --> first pin, then deep pain -Nail Bed pressure on all 4 limbs & supraorbital Pressure are preferred deep-pain stimuli -Observe face & limb motor responses to pain

Brain Death

-Profound, IRREVERSIBLE BRAINSTEM injury -NOT BREATHING, on ventilator, no spont resps -COMATOSE - absent brainstem refelxes -Relatives are not involved in decision to withdraw care - brain death determination is a clinical decision by physican, by law UDDA brain death = Death

Locked In Syndrome

-Pt fully conscious*** -Quadriplegia and Bifacial Weakness -Some preservation of eye movements -Most common --> Bilateral ventral pontine lesion (may occur w/ infarction due to basilar artery occlusion)*** -There was that one dude who wrote that one book

Signs of Skull Fracture

-Raccoon Eyes (periorbital hematoma) -Battle Sign (hematoma behind the ear) -CSF Rhinorrhea (CSF out of nose) -CSF Otorrhea (CSF out of ear) -Hemotympanum (blood in ear)

Ataxic Breathing

-complete irregular breathing pattern -Inspiratory gasps of diverse amplitude and length mixed w/ periods of apnea -Present in agonal pts w/ complete resp failure -Cause = lesion in dorsomedial medulla

Ascending Reticular Activating System

-inhibition of this guy leads to DECREASED CONSCIOUSNESS (coma) -located in upper BRAINSTEM -innervate and stimulate thalami and cortex of BOTH CEREBRAL HEMISPHERES (Bicerebral)

Caloric testing

-irrigate eyes w/ cold water -Absence of slow eye mvmts = brainstem dysfucntion -If brainstem in tact eyes move slowly -- TO SIDE OF COLD-WATER IRRIGATION and AWAY FROM SIDE OF WARM-WATER IRRIGATION

Glasgow Coma Scale

-scale used to quantify deficits in pts w/ decreased consciousness -Three categories 1.) Eye opening 2.) Best Motor 3.) Best Verbal Higher the number the better the response -Totally Normal = 15 -Unresponsiveness to all Stimuli = 3 -Poor prognosis < 9

Coma due to Uncal Herniation

1.) depressed consciousness - midbrain/reticular activating system 2.) CN 3 palsy - Upper midbrain (ipsilateral) 3.) Decerebrate Posturing - Contralat upper midbrain 4.) Cheyne-stokes respiration - upper midbrain

Types of Cerebral Herniations

1.)Subfalcine - shift across the midline** 2.) Central - midline transtentorial 3.) Uncal - unilateral transtentorial 4.) Cerebellar - tonsillar

Identify Lesion

1st thing you do when you think someone's in a Coma

Bicerebral or Brainstem

2 places where lesions can occur that produce Sleepiness (comas)

Coma Prognosis

Better if cause = toxic-metabolic Intermediate if cause head injury of hydrocephalus Worse if cause = anoxia or structural -Stoke or uncal herniation = death -Cardiac arrest, no brainstem signs hours later = death -Absent corneal reflexes, absent eye-opening responses, limb atonia after 1-3 days = death or PVS

Cluster Breathing

Irregular clusters of breaths -Caused by low pontine or high medullary lesion

Eye Movements

Key to differentiating bicerebrum and brainstem lesions!

Coma Outcome

Lasts a few weeks at most Evolves into one of three conditions -Normal wakeful state -Persistent vegetative state (PVS) -Death (cardiopulmonary arrest, or brain death)

Apneustic Breathing

Long inspiratory pause, then retention of air, then release -Caused by lesion in lateral tegmentum of lower pons

Hyperventilation w/ Brainstem Injury

Prolonged and rapid hyperpnea -Caused by lesion of midbrain or pons

Most common cause of Brainstem dysfunction

Structural Lesion! -harder to treat -irreversible often

Most common cause of Bicerebral dysfunction

Toxic metabolic problem -OH -high or low Glucose -Sepsis Something you can treat!

Communication With Comatose Patient

Use FIRST NAME! (stronger stimulus) Take into consideration -Tubes and lines, fractures -Aphasia or neglect -Weakness; loss of sensation, vision, hearing -Altered sleep-wake cycles -Sensory overload, pleasure deprivation -Lack of coffee or cigs -Pts native personality If patient can't speak use NON-VERBAL communications (show me 1 finger) -Avoid these while testing, only when communicating

Brain Death

death defined as - irreversible cessation of all functions of the entire brain - including brainstem Three essential clinical findings -Apnea (therefore on ventilator) -Coma (w/ known cause) -Absent brainstem reflexes

Deep tendon reflexes

may give important info regarding localization of sensorimotor deficit in Coma Patient -often difficult to obtain in ICU due to lines or inability to position limbs properly -Can test ankle reflexes w/ leg extended -Plantar testing may be helpful

Consciousness

state of awareness of the self and environment

Coma

total absence of awareness of self and the environment even w/ external stimulation! -Unarousable unresponsiveness in which patient lies w/ eyes closed