Chapter 16 Alterations in Cognitive Systems Cerebral Hemodynamics

Alterations in Cognitive Systems Consciousness Arousal vs. awareness • State of wakefulness • Mediated by the reticular activating system Ø Awareness • Cognitive functions that embody awareness of self, Ø environment, and affective states (i. e. , moods) • Content of thought Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 2

Alterations in Arousal Coma is produced by either: Bilateral hemisphere damage or suppression Ø Brainstem lesions or metabolic derangement that damages or suppresses the reticular activating system Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 3

Alterations in Arousal Structural Supratentorial Ø Infratentorial Ø Subdural Ø Extracerebral Ø Intracerebral Ø Metabolic Psychogenic Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 4

Alterations in Arousal Clinical manifestations Level of consciousness changes Ø Pattern of breathing • Posthyperventilation apnea (PHVA) • Cheyne-Stokes respirations (CSR) Ø Pupillary changes Ø Oculomotor responses (Doll’s eyes) Ø Motor responses Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 5

Clinical Manifestations Mosby items and derived items © 2010, 2006 by Mosby, Inc. ,

Brain Death (Brainstem Death) Body cannot maintain internal homeostasis Brain death criteria Completion of all appropriate, therapeutic procedures Ø Unresponsive coma (absence of motor and reflex responses) Ø No spontaneous respirations (apnea) Ø No cephalic (ocular or caloric) reflexes Ø Isoelectric EEG Ø Persistence for 1 hour and 6 hours after onset Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 10

Cerebral Death Cerebral death (irreversible coma): death of the cerebral hemispheres exclusive of the brainstem and cerebellum No behavioral or environmental responses The brain can continue to maintain normal respiratory and cardiovascular functions, temperature control, and GI function Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 11

Cerebral Death Survivors of cerebral death Remain in coma Ø Emerge into a vegetative state (“wakeful unconscious state”) Ø Progress into a minimal conscious state • Akinetic mutism (AM) • Locked-in syndrome Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 12

Seizures Disruption in balance of excitation and inhibition Sudden, transient alteration of brain function caused by an abrupt explosive, disorderly discharge of cerebral neurons Motor, sensory, autonomic, or psychic Convulsion Ø Tonic-clonic (jerky, contract-relax) movements associated with some seizures Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 13

Seizures Generalized seizures Partial (focal) seizures Secondary generalization Status epilepticus Ø Experience of a second seizure before the person has fully regained consciousness from the preceding seizure or a single seizure lasting more than 30 minutes Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 14

Seizures Resting potential instability Bursts of action potentials (hypersynchronization) Epileptogenic focus Ø Group of neurons that appear to be hypersensitive to paroxysmal depolarization Tonic phase Clonic phase Postictal state Ø State that follows the seizure Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 15

Seizures: Consequences 250% increase in adenosine triphosphate (ATP) Cerebral oxygen consumption increased by 60% Cerebral blood flow also increases approximately 250% Available glucose and oxygen are depleted With severe seizures the brain tissue may require more ATP than can be produced Ø Lactate accumulates in the brain tissues Ø May produce secondary hypoxia, acidosis, and lactate accumulation Ø May result in progressive brain tissue injury and destruction Ø Cellular exhaustion and destruction Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 16

Seizure Syndromes Epilepsy “To be seized by a force from without” Ø Types • Idiopathic • Symptomatic • Cryptogenic Ø Aura Prodroma Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 17

Alterations in Awareness Selective attention Ability to select from available competing environmental and internal stimuli Ø Sensory inattentiveness • Extinction • Neglect syndrome Ø Selective attention deficit Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 18

Alterations in Awareness Declarative memory Nondeclarative memory Dysmnesia Retrograde amnesia Ø Anterograde amnesia Ø Vigilance, detection, and working memory deficits Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 19

Data Processing Deficits Agnosia Ø Tactile, visual, auditory, etc. Aphasia Dysphasia Expressive dysphasia Ø Transcortical dysphasia Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 20

Acute Confusional States Acquired mental disorder with deficits in attention and coherence of thoughts and action Secondary to drug intoxication, metabolic disorder, or nervous system disease Ø Disruption of reticular activating system of upper brainstem and its projections to thalamus, basal ganglion, and specific areas of the cortex and limbic areas Ø Abrupt onset Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 21

Dementia Progressive failure of cerebral functions not caused by an impaired level of consciousness Classifications Cortical • Alzheimer and Pick diseases Ø Subcortical • Parkinson and Huntington diseases Ø Cortical and subcortical • Infectious and Creutzfeldt-Jakob diseases Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 22

Alzheimer Disease Familial, early and late onset Nonhereditary (sporadic, late onset) Theories Mutation for encoding amyloid precursor protein Ø Alteration in apolipoprotein E Ø Pathologic activation of N-methyl-D-aspartate (NMDA) Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 23

Alzheimer Disease Neurofibrillary tangles Senile plaques Clinical manifestations Forgetfulness, emotional upset, disorientation, confusion, lack of concentration, decline in abstraction, problem solving, and judgment Ø Insidious onset Ø Diagnosis made by ruling out other causes of dementia Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 24

Increased Intracranial Pressure Normal 5 to 15 mm. Hg Caused by increased intracranial content Ø Tumor growth, edema, excessive CSF, or hemorrhage Stage one Stage two Stage three Stage four Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 25

Herniation Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an

Herniation Syndromes Supratentorial herniation Ø Uncal • Uncus or hippocampal gyrus (or both) shifts from the middle fossa through the tentorial notch into the posterior fossa Ø Central • Downward shift of the diencephalon through the tentorial notch Ø Cingulate • Cingulate gyrus shifts under the falx cerebri Infratentorial herniation Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 27

Cerebral Edema Increase in the fluid (intracellular or extracellular) within the brain Types Vasogenic Ø Cytotoxic Ø Ischemic Ø Interstitial Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 28

Hydrocephalus Variety of conditions Excess fluid within the cranial vault, subarachnoid space, or both Caused by interference in CSF flow Decreased reabsorption Ø Increased fluid production Ø Obstruction within the ventricular system Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 29

Hydrocephalus Noncommunicating hydrocephalus Communicating (extraventricular) hydrocephalus Hydrocephalus ex vacuo Ø Normal-pressure hydrocephalus Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 30

Alterations in Motor Function Hypotonia Hypertonia Spasticity Gegenhalten (paratonia) Rigidity Mosby items and derived

Alterations in Movement Paresis and paralysis Pyramidal motor syndromes Ø Upper motor neuron syndromes • Hemiparesis or hemiplegia • Diplegia • Paraparesis or paraplegia • Quadriparesis or quadriplegia • Spinal shock Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 32

Alterations in Movement Mosby items and derived items © 2010, 2006 by Mosby, Inc.

Alterations in Movement Lower motor neuron syndromes Flaccid paresis or flaccid paralysis Ø Hyporeflexia or areflexia Ø Gamma neuropathies Ø Fibrillation Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 35

Lower Motor Neuron Syndromes Mosby items and derived items © 2010, 2006 by Mosby,

Lower Motor Neuron Syndromes Amyotrophies Paralytic poliomyelitis Ø Nuclear palsies Ø Progressive spinal muscular atrophy Ø Progressive bulbar palsy Ø Bulbar palsy Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 37

Alterations in Movement Hyperkinesia Excessive movement Ø Chorea, wandering, tremor at rest, postural tremor, etc. Ø Paroxysmal dyskinesias Tardive dyskinesia Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 38

Alterations in Movement Huntington disease Also known as chorea Ø Autosomal dominant hereditary-degenerative disorder Ø Severe degeneration of the basal ganglia (caudate and putamen nuclei) and frontal cerebral cortex • Depletion of gamma-aminobutyric acid (GABA) Ø Choreiform movemets Ø Disrupted thought processes Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 39

Alterations in Movement Hypokinesia Decreased movement Ø Akinesia Ø Bradykinesia Ø Loss of associated movement Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 40

Parkinson Disease Severe degeneration of the basal ganglia (corpus striatum) involving the dopaminergic nigrostriatal pathway Parkinsonian rigidity Ø Parkinsonian bradykinesia Ø Parkinsonian tremor Ø Postural abnormalities Ø Autonomic and neuroendocrine symptoms Ø Cognitive-affective symptoms Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 41

Parkinson and Dementia 50% of persons have depression, an inherent part of the pathologic state and not a situational response 30% treated on outpatient basis have dementia; 80% of persons requiring institutional care have dementia Disorientation, confusion, memory loss, distractibility, and difficulty with concept formation, abstraction, calculations, thinking, and judgment Symptoms fluctuate, but they progressively worsen Anxiety disorders; impulse-control disorders; and punding, a disorder of stereotypic motor behavior in which there is intense fascination with repetitive handling and examining of mechanical objects Excessive daytime sleepiness is experienced in more than 50% of persons Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 42

Disorders of Posture (Stance) Dystonia Dystonic postures and movements Ø Decorticate posture Ø Decerebrate posture Ø Basal ganglion posture Ø Senile posture Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 43

Disorders of Posture (Stance) Mosby items and derived items © 2010, 2006 by Mosby,

Disorders of Gait Spastic gait Scissors gait Cerebellar gait Basal ganglion gait Senile gait

Disorders of Expression Hypermimesis Hypomimesis Dyspraxias and apraxias Mosby items and derived items ©

Disorders of Expression Mosby items and derived items © 2010, 2006 by Mosby, Inc.

Extrapyramidal Motor Syndromes Basal ganglia motor syndromes Cerebellar motor syndromes Rostral vermis Ø Caudal vermis Ø Neocerebellar syndrome Ø Mosby items and derived items © 2010, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 48