Coma And Consciousness

Front 1

What Is Consciousness?

Back 1

(1) Wakefulness (alertness) = upper brainstem and thalamus. ABILITY TO PERCEIVE EXTERNAL STIMULATION; (2) Awareness = cerebral cortex bilaterally. ABILITY TO REGULATE ATTENTION

Front 2

Levels of Consciousness

Back 2

(1) Awake; (2) Confused - unable to maintain a coherent stream of thought or action - distractable and disorganized thinking; (3) Lethargy - drowsiness caused by a condition other than sleep; (4) Obtunded - appears asleep, awakens with stimulation, then immediately returns to sleep; (5) coma - appears asleep, remains unresponsive. No spontaneous eye opening or sleep/wake cycles, but can still have reflex responses to stimuli. If can open eyes, NOT in coma!

Front 3

Coma Arises From

Back 3

(1) Intratentorial lesion disruption the RAS; (2) Supratentorial lesion large enough to affect cerebral cortices bilaterally; (3) Thalamic lesions (bilateral dorsal paramedian/rostral midbrain); (4) Diffuse disturbance that disrupts cortical function and RAS function

Front 4

Reticular Activating System

Back 4

(1) A diffuse array of nuclei and tracts primarily responsible for arousal. (2) Extends from the Pons through the Midbrain to the Thalamus

Front 5

Cerebral Cortex

Back 5

Bilateral involvement of the cerebral cortices will cause depressed awareness. These patients may look awake but are neither aware nor able to respond in any way to stimuli.

Front 6

Differential Diagnosis of coma

Back 6

(1) Vegetative state; (2) Locked-in; (3) Psychiatric mimics - catatonia, dissociative state, conversion/factitious/malingering

Front 7

Vegetative State “Awake but not Aware”

Back 7

Diffuse cortical involvement with preserved subcortical structures. Appears awake, but is neither aware nor able to respond to any stimulus. Sleep/wake cycles are present; Eyes may open spontaneously or after stimulation, but DOES NOT FOLLOW commands nor communicate; May spontaneously smile or weep but are unable to respond appropriately

Front 8

“Locked - In” Syndrome

Back 8

Pt is completely unable to move, despite preserved consciousness. Vertical Eye movements and ability to bilnk are typically preserved. Classically caused by pontine infarcts below or anterior to the RAS.

Front 9

Conversion disorder

Back 9

believes symptoms are real

Front 10

Factitious disorder

Back 10

knows symptoms aren’t real but doesn’t know why they do it

Front 11

Malingering

Back 11

knows symptoms aren't real and knows why they are doing it

Front 12

Pupillary lesions in coma

Back 12

MIDBRAIN = lesion of parasympathetics --> unopposed sympathetic stimulation and dilation. PONTINE = lesions give rise to small, pinpoint pupils 2/2 unopposed parasympathetic. Remember pinpoint/pons/parasympathetic in control

Front 13

Decorticate posturing

Back 13

lesions above the red nucleus(midbrain and pontine junction)

Front 14

Decerebrate posturing

Back 14

lesions below the red nucleus but above the vestibular nucleus (devastating lesions of the pons).

Front 15

Empiric treatment for coma

Back 15

(1) Thiamine 100mg and glucose D-50 IV for Wernicke's encephalopathy; (2) Naloxone; (3) Flumazenil

Front 16

Brain Death Determination

Back 16

1) Coma + (2) Body Temp>35.5 + (3) No spontaneous Respirations + (4) Absence of Brain Stem Function + (5) No reasonable doubt as to an alternative etiology;

Front 17

The Apnea Test

Back 17

The apnea test risks hypoxemia, hypotension, and further ischemic neurologic compromise. Should only be performed as the final aspect of the final (second) brain stem examination. Patient pre-oxygenataed, ventilator disconnected, and pCO2 allowed to rise for 10 minutes. Any respiratory effort is inconsistent with the diagnosis of brain stem death, and the apnea test should be immediately aborted.