Transcript ppt
Tests Rarely Assess a Single Cognitive Domain or Function Trail Making A Trail Making B etc. etc. Tests and the Processes they Assess COGNITIVE PROCESS TEST Trail Making A Trail Making B Arithmetic Symbol Search Vocabulary Verbal Fluency Cognitive Flexibility Working Memory Visual Scanning Verbal Retrieval Processing Speed + + + + + + + + - + + + + + + + + Focal vs. Diffuse Test Patterns • Focal – 1-2 domains significantly affected – Other domains typically WNL – Seen in focal neurologic process involving area critical to affected domains • Diffuse – milder deficits in attention, concentration, memory, processing speed, executive function – Seen in diffuse neurologic process affecting information processing speed and integration History and Deficit Pattern of Common Conditions Deficit Pattern Age at Onset Symptom Onset Time Course Stroke (cortical) Focal Late Acute Decline w/ recovery Encephalitis (HSV) Focal Any Acute Decline w/ recovery Traumatic Brain Injury Focal Any Acute Decline w/ recovery Tumor Focal Any Acute/Gradual Variable decline Dementia (early) Focal Late Gradual Slow decline Epilepsy Mixed Early/Late Gradual Slow decline Stroke (sub-cortical) Mixed Mid-Late Acute/Gradual Step-wise decline Dementia (late) Diffuse Late Gradual Slow decline Alcohol Diffuse Mid-Late Gradual Slow Decline Multiple Sclerosis Diffuse Early-Mid Gradual Decline/Fluctuating Depression Diffuse Any Gradual Fluctuating Integrating Test Data with other Clinical Information • Three Important Principles – Avoid the Fallacy of Affirming the Consequent • because B often follows A, occurrence of B proves that A has occurred – Be Open Minded • generate as many reasonable explanations for what you see – Apply Occam’s Razor • “the most likely explanation for a pattern is the one that requires the least number of unlikely events to account for it “ Errors in Formulation Affirming the Consequent • Complains of memory change after MVA • Testing - diffuse pattern (moderate-severe deficits in attention, executive function, processing speed c/w traumatic brain injury) • MRI – subtle, diffuse changes in deep white matter Additional History • No loss of consciousness in MVA • History of functional declines, sensory and motor changes in year prior to MVA • Testing 1 year later shows further declines • Neurologic examination shows abnormal nerve conduction consistent with multiple sclerosis Errors in Formulation Keeping an Open Mind • • • • Acute onset word-finding deficits – no recent events History of worsening depression Neurologic exam normal Neuropsychological testing is normal except for severe impairment in confrontation naming with paraphasias • Imaging shows multiple lesions, one in right temporal lobe with fresh blood Additional History • Left-handed • Strong family history of – left-handedness – early strokes • Findings consistent with hemorrhage of genetically-based, cavernous angioma (small tumor of vessel wall) in right, language dominant hemisphere • Depression is irrelevant in this context Errors in Formulation ‘Occam’s Razor’ • • • • 54 yo. M with recent memory complaints Neurologic exam normal Normal neuroimaging Family is concerned about ‘early Alzheimer’s’ Additional History • Long-standing history of major depressive disorder • No family history of dementia • Trouble caring for home and finances after partner died 4 years ago • Recently ‘got lost’ standing in front of his house, recovered quickly • Continues to perform at high level at cognitively demanding job Behavioral Geography of the Brain • The human brain has – ~ 100 billion neurons in the human brain – ~100 trillion synaptic connections – ~3 million miles of axons in the human brain Brain Orientation Anterior Posterior Superior Inferior Rostral Caudal Dorsal Ventral Brain Orientation Other definitions • • • • Lateral – to the side Medial (mesial) – toward the middle Proximal – areas of brain near to one another Distal – areas of the brain far from one another • Ipsilateral – structures on same side of the body • Contralateral – structures on opposite sides of body Divisions of the Brain Major Division Subdivision Principal Structure Forebrain Telencephalon Cerebral Cortex Basal Ganglia Limbic System Diencephalon Thalamus Hypothalamus Midbrain Mesencephalon Tectum Tegmentum Hindbrain Metencephalon Cerebellum Pons Myelencephalon Medulla Oblongata Hindbrain • Metencephalon – Cerebellum • Involved in aspects of learning and coordination of skilled or smooth movement • Posture, walking, equilibrium – Pons • Links cerebellum to cerebrum, relays information from cerebral hemispheres to cerebellum • Role in vision, balance, auditory processing • Mylelencephalon – Medulla • Regulates bp, heart rate, respiration, controls breathing, basic muscle tone Midbrain • Mesencephalon – Tectum (roof) – Tegmentum (floor) • Controls responses to sight • Relay station of auditory and visual information • Motor control of some muscles Forebrain • Diencephalon – Thalamus – hypothalamus • Telencephalon – Limbic System – Basal Ganglia – Cerebral Cortex Diencephalon • Hypothalamus – Controls aspects of motivated (pleasure and pain) and regulatory bx • bodily functions, body temp, thirst, hunger • circadian rhythms • “master gland” – regulation and secretion of hormones • Thalamus – Gateway to cortex – Relay center for sensory information – Links nervous and endocrine system Limbic system • Groups of structures in center of brain above brainstem – – – – – – – amygdala hippocampus parahippocampal gyrus cingulate gyrus fornix septum olfactory bulbs • Maintains homeostasis • Emotional reactions needed for survival Basal Ganglia • Collection of subcortical nuclei in forebrain – Caudate nucleus – Putamen – Globus pallidus • Structures involved in voluntary control of movement • Motor planning and programming for speech • Attention and alerting before a motor response Cerebral Cortex Blumenfeld, 2002 Brain anatomy Brain anatomy