Concepts of Neurologic Dysfunction

1. Concepts of Neurologic Dysfunction Chapter 16

2. Alterations in Cognitive Systems • Consciousness • State of awareness of oneself and the environment • Arousal • State of awakeness • Awareness • Content of thought

3. Alterations in Arousal • Structural • Supratentorial • Infratentorial • Subdural • Extracerebral • Intracerebral • Metabolic • Psychogenic

4. 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

5. 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

6. Clinical Manifestations

7. Clinical Manifestations

8. Clinical Manifestations

9. Clinical Manifestations

10. 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

11. 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

12. 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

13. 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

14. 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

15. Seizures • Postictal state • State that follows the seizure • Epileptogenic focus • Group of neurons that appear to be hypersensitive to paroxysmal depolarization • Tonic phase • Clonic phase

16. Seizure Syndromes • Epilepsy • “To be seized by a force from without” • Types • Idiopathic • Symptomatic • Cryptogenic

17. Alterations in Awareness • Selective attention • Ability to select from available, competing environmental and internal stimuli • Sensory inattentiveness • Extinction • Neglect syndrome • Selective attention deficit

18. Alterations in Awareness • Declarative memory • Nondeclarative memory • Dysmnesia • Retrograde amnesia • Anterograde amnesia • Vigilance, detection, and working memory deficits

19. Data Processing Deficits • Agnosia • Tactile, visual, auditory, etc. • Aphasia • Dysphasia • Expressive dysphasia • Transcortical dysphasia

20. 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

21. Dementia • Progressive failure of cerebral functions that is not caused by an impaired level of consciousness • Classifications • Cortical • Alzheimer and Pick diseases • Subcortical • Parkinson and Huntington diseases • Cortical and subcortical • Infectious and Creutzfeldt-Jakob diseases

22. 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)

23. 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

24. 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

25. Herniation

26. Herniation Syndromes • Supratentorial herniation • Uncal • Uncus or hippocampal gyrus (or both) shifts from the middle fossa through the tentorial notch into the posterior fossa • Central • Downward shift of the diencephalon through the tentorial notch • Cingulate • Cingulate gyrus shifts under the falx cerebri • Infratentorial herniation

27. Cerebral Edema • Increase in the fluid (intracellular or extracellular) within the brain • Types • Vasogenic • Cytotoxic • Ischemic • Interstitial

28. 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

29. Hydrocephalus • Noncommunicating hydrocephalus • Communicating (extraventricular) hydrocephalus • Hydrocephalus ex vacuo • Normal-pressure hydrocephalus

30. 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

31. Alterations in Motor Function • Hypotonia • Hypertonia • Spasticity • Gegenhalten (paratonia) • Rigidity

32. 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

33. Alterations in Movement

34. Alterations in Movement

35. Alterations in Movement • Lower motor neuron syndromes • Flaccid paresis or flaccid paralysis • Hyporeflexia or areflexia • Gamma neuropathies • Fibrillation

36. Lower Motor Neuron Syndromes

37. Lower Motor Neuron Syndromes • Amyotrophies • Paralytic poliomyelitis • Nuclear palsies • Progressive spinal muscular atrophy • Progressive bulbar palsy • Bulbar palsy

38. Alterations in Movement • Hyperkinesia • Excessive movement • Chorea, wandering, tremor at rest, postural tremor, etc. • Paroxysmal dyskinesias • Tardive dyskinesia

39. 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)

40. Alterations in Movement • Hypokinesia • Decreased movement • Akinesia • Bradykinesia • Loss of associated movement

41. 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

42. Parkinson Disease

43. Disorders of Posture (Stance) • Dystonia • Dystonic postures and movements • Decorticate posture • Decerebrate posture • Basal ganglion posture • Senile posture

44. Disorders of Posture (Stance)

45. Disorders of Gait • Spastic gait • Scissors gait • Cerebellar gait • Basal ganglion gait • Senile gait

46. Disorders of Expression • Hypermimesis • Hypomimesis • Dyspraxias and apraxias

47. Disorders of Expression

48. Extrapyramidal Motor Syndromes • Basal ganglia motor syndromes • Cerebellar motor syndromes • Rostral vermis • Caudal vermis • Neocerebellar syndrome