Concepts of Neurologic
Dysfunction
Chapter 16
1
Alterations in Cognitive Systems

Consciousness


State of awareness of oneself and the
environment
Arousal


State of awakeness
Awareness

Content of thought
2
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Alterations in Arousal

Structural







Supratentorial
Infratentorial
Subdural
Extracerebral
Intracerebral
Metabolic
Psychogenic
3
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Alterations in Arousal

Coma is produced by either:


Bilateral hemisphere damage or suppression
Brain stem lesions or metabolic derangement that
damages or suppresses the reticular activating
system
4
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Alterations in Arousal

Clinical manifestations


Level of consciousness changes
Pattern of breathing





Posthyperventilation apnea (PHVA)
Cheyne-Stokes respirations (CSR)
Pupillary changes
Oculomotor responses
Motor responses
5
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Clinical Manifestations
6
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Clinical Manifestations
7
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Clinical Manifestations
8
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Clinical Manifestations
9
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Brain Death (Brainstem Death)


Body can no longer maintain internal homeostasis
Brain death criteria






Completion of all appropriate and therapeutic procedures
Unresponsive coma (absence of motor and reflex
responses)
No spontaneous respirations (apnea)
No cephalic (ocular or caloric) reflexes
Isoelectric EEG
Persistence for 1 hour and 6 hours after onset
10
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Cerebral Death



Cerebral death (irreversible coma) is 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
11
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Cerebral Death

Survivors of cerebral death



Remain in coma
Emerge into a vegetative state (“wakeful
unconscious state”)
Progress into a minimal conscious state


Akinetic mutism (AM)
Locked-in syndrome
12
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Seizures



Sudden, transient alteration of brain function
caused by an abrupt explosive, disorderly
discharge of cerebral neurons
Motor, sensory, autonomic, or psychic
Convulsion

Clonic-tonic (jerky, contract-relax) movements
associated with some seizures
13
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Seizures




Generalized seizures
Partial (focal) seizures
Secondary generalization
Status epilepticus

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
14
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Seizures

Postictal state


Epileptogenic focus



State that follows the seizure
Group of neurons that appear to be hypersensitive
to paroxysmal depolarization
Tonic phase
Clonic phase
15
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Seizure Syndromes

Epilepsy


“To be seized by a force from without”
Types



Idiopathic
Symptomatic
Cryptogenic
16
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Alterations in Awareness

Selective attention


Ability to select from available, competing
environmental and internal stimuli
Sensory inattentiveness



Extinction
Neglect syndrome
Selective attention deficit
17
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Alterations in Awareness



Declarative memory
Nondeclarative memory
Dysmnesia



Retrograde amnesia
Anterograde amnesia
Vigilance, detection, and working memory
deficits
18
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Data Processing Deficits

Agnosia



Tactile, visual, auditory, etc.
Aphasia
Dysphasia


Expressive dysphasia
Transcortical dysphasia
19
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Acute Confusional States

Acquired mental disorder characterized by
deficits in attention and coherence of thoughts
and action

Secondary to drug intoxication, metabolic
disorder, or nervous system disease
20
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Dementia


Progressive failure of cerebral functions that is not
caused by an impaired level of consciousness
Classifications

Cortical


Subcortical


Alzheimer and Pick diseases
Parkinson and Huntington diseases
Cortical and subcortical

Infectious and Creutzfeldt-Jakob diseases
21
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Alzheimer Disease



Familial, early and late onset
Nonhereditary (sporadic, late onset)
Theories



Mutation for encoding amyloid precursor protein
Alteration in apolipoprotein E
Pathologic activation of N-methyl-D-aspartate
(NMDA)
22
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Alzheimer Disease



Neurofibrillary tangles
Senile plaques
Clinical manifestations


Forgetfulness, emotional upset, disorientation,
confusion, lack of concentration, decline in
abstraction, problem solving, and judgment
Diagnosis is made by ruling out other causes
of dementia
23
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Increased Intracranial Pressure


Normal 5 to 15 mm Hg
Caused by an increase in intracranial content





Tumor growth, edema, excessive CSF, or
hemorrhage
Stage one
Stage two
Stage three
Stage four
24
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Herniation
25
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Herniation Syndromes

Supratentorial herniation

Uncal


Central


Downward shift of the diencephalon through the
tentorial notch
Cingulate


Uncus or hippocampal gyrus (or both) shifts from the
middle fossa through the tentorial notch into the
posterior fossa
Cingulate gyrus shifts under the falx cerebri
Infratentorial herniation
26
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Cerebral Edema


Increase in the fluid (intracellular or
extracellular) within the brain
Types




Vasogenic
Cytotoxic
Ischemic
Interstitial
27
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Hydrocephalus



Variety of conditions
Excess fluid within the cranial vault,
subarachnoid space, or both
Caused by interference in CSF flow



Decreased reabsorption
Increased fluid production
Obstruction within the ventricular system
28
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Hydrocephalus


Noncommunicating hydrocephalus
Communicating (extraventricular)
hydrocephalus


Hydrocephalus ex vacuo
Normal-pressure hydrocephalus
29
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Alterations in Emotions and Moods


Anger, hostility, envy, fear, and love all guide
behavior and are mediated largely by the
limbic system
Limbic system dysfunction results in emotion
and mood alterations
30
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Alterations in Motor Function





Hypotonia
Hypertonia
Spasticity
Gegenhalten (paratonia)
Rigidity
31
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Alterations in Movement

Paresis and paralysis


Pyramidal motor syndromes
Upper motor neuron syndromes





Hemiparesis or hemiplegia
Diplegia
Paraparesis or paraplegia
Quadriparesis or quadriplegia
Spinal shock
32
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Alterations in Movement
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Alterations in Movement
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Alterations in Movement

Lower motor neuron syndromes




Flaccid paresis or flaccid paralysis
Hyporeflexia or areflexia
Gamma neuropathies
Fibrillation
35
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Lower Motor Neuron Syndromes
36
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Lower Motor Neuron Syndromes

Amyotrophies





Paralytic poliomyelitis
Nuclear palsies
Progressive spinal muscular atrophy
Progressive bulbar palsy
Bulbar palsy
37
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Alterations in Movement

Hyperkinesia




Excessive movement
Chorea, wandering, tremor at rest, postural
tremor, etc.
Paroxysmal dyskinesias
Tardive dyskinesia
38
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Alterations in Movement

Huntington disease



Also known as “chorea”
Autosomal dominant hereditary-degenerative
disorder
Severe degeneration of the basal ganglia (caudate
and putamen nuclei) and frontal cerebral cortex

Depletion of γ-aminobutyric acid (GABA)
39
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Alterations in Movement

Hypokinesia




Decreased movement
Akinesia
Bradykinesia
Loss of associated movement
40
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Parkinson Disease

Severe degeneration of the basal ganglia
(corpus striatum) involving the dopaminergic
nigrostriatal pathway





Parkinsonian rigidity
Parkinsonian bradykinesia
Postural abnormalities
Autonomic and neuroendocrine symptoms
Cognitive-affective symptoms
41
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Parkinson Disease
42
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Disorders of Posture (Stance)

Dystonia





Dystonic postures and movements
Decorticate posture
Decerebrate posture
Basal ganglion posture
Senile posture
43
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Disorders of Posture (Stance)
44
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Disorders of Gait





Spastic gait
Scissors gait
Cerebellar gait
Basal ganglion gait
Senile gait
45
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Disorders of Expression



Hypermimesis
Hypomimesis
Dyspraxias and apraxias
46
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Disorders of Expression
47
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Extrapyramidal Motor Syndromes


Basal ganglia motor syndromes
Cerebellar motor syndromes



Rostral vermis
Caudal vermis
Neocerebellar syndrome
48
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