11_Coma - Chapter 11: When consciousness is lost Remember:...

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Unformatted text preview: Chapter 11: When consciousness is lost Remember: basic neurobiology Coma Pseudo-coma: Locked in syndrome Locked out” syndrome Akinetic mutism Persistent vegetative state (PVS) Minimally conscious state (MCS) Brain death Consciousness: Arousal + Content (wakefulness + awareness) The Glasgow coma scale Coma • A state of unconsciousness in which both wakefulness and awareness or absent. • The patient can not be aroused and does not display any purposeful reactions to noxious stimuli. • A coma state is really a continuum from light to deep and patients can fall anywhere on the continuum regarding their level of reactions. Coma: 8 or less / 15 1 CORTEX ARAS Coma: Loss of consciousness (arousal + content) PSEUDO-COMA Lesion of • Brainstem and / or • Bilateral thalamus and / or • Bilateral neocortex Locked-in syndrome A clinical condition of quadriplegia and anarthria with preservation of consciousness. • “Locked in” syndrome • “Locked out” syndrome • Akinetic mutism Patients retain vertical eye movement, facilitating non-verbal communication. Time to diagnosis: mean 78 days !!! Ten year survival rate: up to 80% !!! Classic cause: bilateral ventral pontine lesion (stroke, trauma) Other causes: severe Guillian-Barré syndrome severe myasthenia gravis some types of myopathy 2 Locked-in syndrome • • • • De-efferented state Consciousness maintained Vertical willful eye movements, absent horizontal eye movements Altered REM sleep Locked-out syndrome • De-afferented state • Cutting off sensory input to brain • Disconnection from environment Three types: 1. Complete: not any movement possible 2. Incomplete: some rest of movement 3. Classic: only vertical eye movements and blinks are preserved • Bilateral thalamic lesions Akinetic mutism • Eyes open “giving promise of speech” • Patients may not be entirely akinetic or mute • Vigilant / Somnolent type After 1 month Recovery Vigilant type: • More alert and ready to be aroused • Restless, bouts of excitement, agitation or aimless aggressivity • Lesion: subfrontal or cingulate, orbitomedial frontal lobes bilat. Somnolent type: • Inertia, somnolence, lethargy, “abulia” • Paralysis of vertical gaze • Lesion: diencephalo-mesencephalic junction Adapted from Lancet Neurology, 2004, 3, 537-46 3 RECOVERY COMA PVS RECOVERY COMA DEATH PVS DEATH RECOVERY from COMA Non-traumatic: very rare after 3 months. Traumatic: very rare after 1 year RECOVERY COMA PVS DEATH 4 PVS Does a patient with PVS suffer? Controls: activation (red) after painstimulus PVS: activation (red) after painstimulus (brainstem, thalamus, S1) zones without activation (association zones) COMA + TIME => PVS Awake but not aware (Jennett & Plum 1972) “Lights are on, but no one at home” Modified from Laureys at al., Lancet Neurol.2004, 3, 537-46 Formerly termed: “coma vigil” (but no coma) “apallic syndrome”(but zones of pallium (cortex) may be preserved) PVS Audition in PVS Red: A1 Blue: A2 Comments (Crevits): pain perception in vegetative state ??? better: pain sensation Laureys et al., Brain 2000, 123, 1589-601 5 PVS definition • • • • • • • Incompatible with PVS No Awareness of Self or Environment Intact Sleep-Wake Cycles (awake) Preservation of Hypothalamic and Autonomic Function No Sustained Purposeful or Voluntary Behavioral Response No Language Comprehension or Expression Bowel and Bladder Incontinence Full Chew and Swallow not Present • • • • • • Note: this is an official statement of the American Academy of Neurology (AAN) on PVS PVS: types • Severe bilateral cortical injury (“apallic state”) • Permanent damage to brainstem arousal structures Coordinated chewing swallowing Verbal output Sustained visual following Following commands Purposive movements Normal EEG • • • • No pain or suffering (sapience gone) Artificial nutrition and hydration may be discontinued Withdrawing treatment is equivalent to withholding it Diagnosis of permanent unconsciousness can be made with high certainty • Once diagnosed, medical care is of no value to the patient • Patient’s & family wishes (not caregiver) are paramount 6 Minimally conscious state Minimally conscious state limited but clearly discernible evidence of self or environmental awareness demonstrated on a reproducible or sustained basis by one or more of the following behaviors: limited but clearly discernible evidence of self or environmental awareness demonstrated on a reproducible or sustained basis by one or more behaviors… Minimally conscious state limited but clearly discernible evidence of self or environmental awareness demonstrated on a reproducible or sustained basis by one or more of the following behaviors: • Following simple commands • Gestural or verbal yes/no responses (regardless of accuracy) • Intelligible verbalization • Purposeful behavior, including movements or affective behaviors that occur in contingent relation to relevant environmental stimuli and are not due to reflexive activity Minimally conscious state Some examples of qualifying purposeful behavior include: – appropriate smiling or crying in response to the linguistic or visual content of emotional but not to neutral topics or stimuli – vocalizations or gestures that occur in direct response to the linguistic content of questions – reaching for objects that demonstrates a clear relationship between object location and direction of reach – touching or holding objects in a manner that accommodates the size and shape of the object – pursuit eye movement or sustained fixation that occurs in direct response to moving or salient stimuli Pet-scan and cognitive potentials Preserved cerebral processing in the minimally conscious state Laureys et al., Neurology 2004; 63: 916–918 7 Minimally conscious state MCS patients presented a larger P3 to the patient’s own name, in the passive and in the active conditions. Moreover, the P3 to target stimuli was higher in the active than in the passive condition, suggesting voluntary compliance to task instructions like controls. In contrast, no P3 differences between passive and active conditions were observed for VS patients. Evoked-related potentials paradigms may permit detection of voluntary brain function in patients with severe brain damage who present with a disorder of consciousness, even when the patient may present with very limited to questionably any signs of awareness. A patient in a minimally conscious state could be activated by stimulation of the thalamus to name objects. (1 patient, 2007) Neurology, 2008;71:1614–1620 Summary Summary 8 Summary Criteria for brain death in adults (1995) * RECOVERY COMA PVS DEATH *Neurology 45, 1012–1014 (1995) 9 ...
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This note was uploaded on 05/28/2010 for the course GE BIOL020000 taught by Professor Luccrevits during the Spring '10 term at Ghent University.

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