Introduction to Neuropsychological Assessment

Transcription

1 Definitions and Learning Objectives Introduction to Neuropsychological Assessment Alan Sunderland Reader in Clinical Neuropsychology Neuropsychological assessment seeks to define cognitive disability in the person with acquired brain damage. What is a Clinical Neuropsychologist? What are the common causes of brain damage? What problems are dealt with by the clinical neuropsychologist? What are the goals of assessment? What methods are used? General References Kolb, B. & Whishaw I.Q. Fundamentals of human neuropsychology. Fifth Edition.. Worth Publishers Chapter 28. Wilson, Barbara A. Case studies in neuropsychological rehabilitation.. Oxford University Press Short loan What is a Clinical Neuropsychologist? Career paths in neuropsychology. Academic research in cognitive neuropsychology. What can brain damage tell us about normal cognition? Psychology degree. MSc/PhD Clinical research What are the most useful methods of assessment & therapy? General clinical training (DClinPsy) Specialist training Clinical Practice Division of Neuropsychology Membership (MSc + clinical log) Common causes of acquired brain damage Traumatic head injury (road accidents etc.) Stroke (cerebrovascular( accident = CVA) Alzheimer s s Disease Brain tumour Viral infections (encephalitis etc.) Common types of problem Motor and sensory losses e.g. hemiplegia Emotional problems. hemiplegia; hemianopia Anxiety and depression are common. 3 factors may be involved (Gainotti( Gainotti,, 1993) - Neurological factors e.g. impaired emotional control. Attitudinal factors - reaction to disability. Psychosocial factors isolation due to disability. Interventions similar to other areas clinical psychology. Cognitive disability impaired on everyday tasks e.g. memory deficit impaired interpersonal skills e.g. conversation control Severe damage affects many domains. Milder damage may have very selective effects. 1

2 Head injury = traumatic brain injury Causes of serious head injury: 50% road accidents, 30% falls, 10% assaults But falls are the most common cause for children. The vast majority are closed injuries, not open penetrating injuries Huge numbers of minor injuries (often seen in A&E departments) In UK per year : 100,000 admitted to hospital: 10,000 transferred to neurosurgical units. Highest incidence for year old males. Head injury brain damage in closed injuries. Primary damage Major damage often due to acceleration/deceleration DAI diffuse axonal injury (may only be visible microscopically). Damage especially to deep white matter e.g brainstem, corpus callosum. Bruising (contusion( contusion) ) under the blow and where brain hits/scrapes against skull (especially frontal & temporal poles and contrecoup). Definition of severity as a key issue. DAI (axonal spheroids) Cortical contusions Head injury brain damage in closed injuries. Secondary damage Due to bleeding (haematoma( haematoma) Or increased pressure due to subdural haematoma and/or brain swelling (oedema). Progression of subdural haematoma Head injury brain damage in closed injuries. Implications acute head injury is a medical emergency discrete, focal damage is unusual preferred sites for damage, but very variable and not always visible limited value of brain scans for predicting functional outcome. therefore importance of behavioural/cognitive assessment Head injury sequence of events. Head injury defining severity Post-traumatic Amnesia (PTA). Post-traumatic amnesia is the period from injury to the return of continuous memory (and therefore includes coma and memory islands). Injury Coma PTA Recovery period Permanent deficits Minutes weeks 6 months Several years May include a lengthy period of confusion & confabulation. A better predictor of cognitive outcome than coma duration. Can be estimated retrospectively by interview (McMillan et al, 1996 What is the first thing you remember after your head injury?...etc.). PTA < 24 hours = mild. Most cases have no longer term problems. PTA >24 hours = severe. Most cases have some long-term cognitive deficits. 2

3 Head injury patterns of long-term impairment Stroke. A neurologic deficit with sudden onset due to failure of blood supply to the brain. Reports by the patient or their relatives. Most common long-term problems reported by relatives slowness; forgetfulness; irritability; personality change Deficits apparent on tests Slowing (RT), impaired episodic memory, dysexecutive problems, plus variable selective deficits in individual cases e.g. word-finding problems (anomia). A characteristic of acquired brain damage is that cognitive functioning tends to be patchy normal performance in some areas, impaired in others. A consequence of damage to the developed brain. Middle cerebral artery the most common site of stroke. Contralateral weakness (hemiplegia). Posterior cerebral artery Supplies the temporal and occipital lobes. Dysphasia after dominant (left) hemisphere lesions. Occlusion often leads to hemianopia, visual processing deficits and dyslexia. Visuospatial problems after non-dominant (right) hemisphere lesions. Stroke. Common Selective Cognitive Impairments Domain Impairments Language Dysphasias Dyslexias Attention & Perception Neglect Spatial confusion Memory Working memory deficits Episodic memory deficits Apraxias Action Language & apraxic problems most evident after left hemisphere stroke. Perceptual problems most evident after right hemisphere stroke. What are the goals of neuropsychological assessment? Contributing to Diagnosis Major brain damage is now diagnosed by neuroimaging. But diffuse or early cortical damage may only be evident from cognitive dysfunction (e.g. AD, head injury). Guiding management or rehabilitation. Impossible to predict functional problems directly from brain scans. Neuropsychological assessment is crucial in identifying deficits and spared functions. Monitoring recovery or deterioration. A significant degree of recovery occurs over the months after non-degenerative damage (head injury, stroke). Deterioration in degenerative conditions may be slowed by medical treatments (e.g. drugs in AD). Need for serial neuropsychological assessments. 3

4 Methods of Assessment Interviews and behavioural observation. Normal psychometric tests e.g. IQ scales. Standardised neuropsychological tests. Unstandardised clinical tests. Strengths Allows a comparison with normal. Huge standardisation sample. Different sub-tests allow a profile across different abilities. Different profiles with different sites of brain damage e.g left vs right. Observation of performance provides qualtitative information. Weaknesses Not designed to detect effects of brain injury. No basis in cognitive theory. Poor specificity for localised damage (Warrington, 1986). Implications of deficit for everyday functioning are unclear. Standardised Neuropsychological Tests e.g. Recognition Memory Tests (Warrington, 1986) Shown 50 strangers faces & 50 words. 2-alternative forced choice tests:- Strengths Validated as measures of selective cognitive impairment. Unstandardised Clinical Tests e.g. Drawing objects from memory in cases of unilateral neglect. Weaknesses Limited standardisation sample for most neuropsychological tests. Limits on sensitivity & specificity of any single test. Which of these have you seen before? Aid Bake Mean score Words Faces Controls Left temporal Right temporal Worst control Strengths Designed to probe individual problems (can be extended into a single case experiment). Weaknesses Absence of extensive standardisation data from age-matched controls. Assumption of abnormality can be wrong (wide normal range). Difficulty level of different conditions may not be matched. Methods of Assessment Best Practice A convergent approach using all methods. Use of a test battery rather than reliance on any single score. A hypothesis-driven approach:- Seeking profiles of impairment based on knowledge of neuropsychology. Using an experimental approach with each case (If time allows!) Case Example from Wilson (1999) A 62 year old lady who had suffered a right posterior stroke 5 months previously. Had been a church warden & active in the WRVS. Left hemiplegia and left unilateral neglect. Seemed to have limited insight or concern about her problems. Goal of neuropsychological assessment was to assist in rehabilitation planning. 4

5 Unilateral Neglect Difficulty in attending to (or even thinking about) one side of space. Common after right temporo- parietal damage. Cancellation tests Line Bisection Tests Case Example from Wilson (1999) Wechsler Adult Intelligence Scale Verbal IQ 99 ( Average ) Performance IQ 62 ( Retarded ) Age-scaled scores (average= 10+/-3) Information 10 Digit symbol 3 Comprehension 11 Picture completion 6 Arithmetic 6 Block design 3 Digit Span 10 Picture arrangement 6 Vocabulary 12 Object assembly 1 National Adult Reading Test (Reading irregular words e.g. chord ). Estimated premorbid IQ = 116 The huge verbal-performance discrepancy is almost certainly due to the stroke. Premorbidly Dolly was probably functioning in the average to bright average range Her impaired performance IQ may be partly due to unilateral neglect and partly due to more widespread visuoperceptual difficulties. Case Example from Wilson (1999) Unilateral Negect Cancellation test. Many omissions. 9 th percentile for right CVA patients. Line bisection. 6.5mm error. 30 th percentile for right CVA patients. Drawing from memory. Severe left inattention. Wechsler Memory Scale, Prose recall. Immediate = 13.5 (above average) Delayed = 10 (average) Warrington Recogntion Memory Tests Words = 6 (low average) Faces = 3 (impaired). her memory does not seem particularly impaired The faces test was compromised by her visuospatial difficulties. Assessment demonstrates patchy impairment severe neglect in presence of preserved verbal skills and normal performance on some memory tasks. Indicates resources available for rehabilitation training. Summary. 1 Stroke and head injury are two common forms of acquired brain damage. Cognitive problems tend to be patchy and neuropsychological assessment can define problems and resources for rehabilitation. Normal psychometric tests, standardised neuropsychological tests, and unstandardised clinical tests are all useful. The best approach to assessment combines these methods within a hypothesis-testing framework. Summary. 2 Unilateral neglect is common after right posterior stroke. Cancellation tests, line bisection and drawing from memory are useful assessments. In closed head injury, PTA is a marker of severity. Slowed information processing and impaired episodic memory are common problems in severe cases. Reaction time and episodic memory can be serially assessed to monitor recovery. 5

6 6