Neuropsychology Flashcards
Neuropsychology
Neuropsychology is the study of learning and behavior in relationship to the brain. It is a framework that draws from neurology, neu- roanatomy, cognitive sciences, and clinical, social, developmental, and biological psychol- ogy. It is critical that with pediatric evaluation, the brain is understood in the context of devel- opmental change. A neuropsychologist has earned a PhD in clinical psychology and com- pleted 2 years of specialized postdoctoral training.
Purpose of a Neuropsychological Evaluation
There are several appropriate reasons for referral to people with epilepsy to undergo neuropsy- chological evaluation:
* Obtain profile of strengths and weaknesses
– Measure the presence and degree of
behavioral and cognitive difficulties
– Identify strengths to inform treatment planning
* Profile provides evidence for the localization of dysfunction/function
* Measure the cognitive or behavioral impact/risk of rehabilitation, pharmacologi- cal, surgical, or therapeutic interventions
– Establish the baseline of functioning for
systematic comparisons across time
* Increase patient preparedness and inform items selection/protocol adjustments on an individual basis for cognitive mapping pro- cedures: Intracarotid Amytal Test (IAT)/ WADA, functional MRI (fMRI), Electrocor-
tical Stimulation (ECS)
* Help formulate appropriate treatment plans
(educational/vocational and medical)
* Predict individual’s ability to achieve success
in particular settings
Neuropsychologists vs psychologists
Different from general psychological practice, a neuropsychologist:
* Does not necessarily diagnose psychiatric conditions or provide therapy/treatment
* May not assess specific vocational skills (driving, interest inventory, etc.).
Components of a Neuropsychological Evaluation
Through history, testing, and behavioral obser- vations, there is an examination of external behavior to make inferences about brain function and structure. The history is similar to other providers where information is systematically gathered through interview with the patient and their caregivers/spouses, and record review. Formal testing of abilities and behavioral obser- vations are conducted over the course of one or more office visits or, less ideally, on an inpatient basis. There are numerous neuropsychological measures available. Table 22.1 is not an exhaustive list; however, the measures listed are commonly used both clinically and in research in epilepsy populations. Formal testing refers to a standardized method of administration and scor- ing of responses. A profile of strengths and weaknesses is derived by comparing a person’s test scores to a normative population of a similar age across domains. Domains of functioning include the following:
* General Cognitive Functioning/Intelligence Quotient (IQ)
* Language
* Memory and Learning
* Attention
* Executive-Regulatory Function
* Visual/Spatial/Nonverbal processing
* Motor
* Academic Achievement
* Adaptive Functioning
* Social/Emotional
* Personality
Cognitive profiles in epilepsy
It is long recognized that persons with epilepsy have greater incidence of cognitive and psychi- atric comorbidities (Gowers 1881). Consistent with the heterogeneity of seizure disorders, but even often within a single type of epilepsy, no single cognitive profile exists for epilepsy. Other general considerations are as follows Although there are some findings that focal epilepsy is associated with focal deficits, this is true for adults more than children likely due to the plasticity of children’s brains. There- fore, children do not follow adult profiles. Moreover, even though focal epilepsy may result in a deficit related to the location of the epilepsy, this is not the only deficit that the person is contending with. For example, a person with left temporal lob epilepsy may have verbal memory difficulties, but also has inattention and slow processing speed. Seizures (focal or generalized) may impact functioning across any or all domains. Cognitive difficulties may predate and/or persist beyond onset, which may indicate that cognitive difficulties may share a com- mon underlying neuroanatomic substrate with what is generating the seizures.
Progressive deterioration of cognitive skills is observed in a minority of individuals. As such, a plateau and/or regression of skills is a strong impetus for surgery, in particular for hemispherectomy, but any other resection as well. Please see below within specific domain areas for further discussion.
Factors that combine to determine neuropsychological outcome
There are multiple factors that combine to determine neuropsychological outcome:
– Age of onset
– Seizure type
– Underlying pathology
– Neuronal discharges (ictal and interictal)
– Episodes of status
– Antiseizure medications (ASMs)
– Psychosocial
– Public attitudes/stigma
– Individual attitude (e.g., self-worth; depression)
Neuropsychological domains testing
Some general cognitive out- comes include the following:
– Generalized seizures are worse than focal, and tonic–clonic seizures are worse than absence
– Earlier onset is associated with more difficulties
– Interictal subclinical discharges are associated with transient cognitive impairment (TCI). This has mixed evidence, but fewer studies.
ID in epilepsy
Approximately one-third of people with epilepsy have IQ scores below 70, which falls in the Intellectually Deficient (ID—formally MR) range. The majority (≈ 2/3) of people with epi- lepsy have average range (or higher) intelligence.
Nonetheless, even taking this cohort—excluding the one-third with IQ < 70)—there is a down- ward shift of IQ with a Mean IQ (≈ 90) which falls in the low average range compared to the normal population where Mean IQ = 100.
Risk factors for ID in epilepsy:
* Primary generalized epilepsy, West syndrome, Lennox–Gastaut syndrome, localization- related epilepsy, but seizure focus difficult to isolate
* Severe volumetric abnormalities
* Early onset of epilepsy
* Frequent seizures, more episodes of status
epilepticus
* Polytherapy
* Comorbid diagnoses (e.g., autism)
As such, IQ is considered a proxy for out- come, disease severity, and extent of underlying pathology.
Language
Along with memory, language is probably one of the most studied domains in people with epilepsy given that focal epilepsy is most often in the temporal, followed by frontal lobes.
* Language representation: There is a higher incidence (25–30%) of atypical dominance (right or bilateral) than the normal right-handed population (5%).
– Atypical language dominance is more likely with large, early in development insults (e.g., perinatal stroke), with earlier onset and with left-handedness.
– If language remains ipsilateral to focus, a left hemispheric focus may have impact on language functions (speeded naming).
* Appropriate simple, single-word knowledge, untimed language skills.
* Adults with TLE frequently have word-finding problems, which is found by confrontation naming tasks (e.g., Boston Naming Test), which may be related to the hippocampal role in word retrieval.
* Progressive language impairment is associ- ated with Rasmussen’s encephalitis and Lan- dau–Kleffner syndrome, both of which have a period of normal language development.
Memory
Similar to language findings, memory difficulties are commonly associated with TLE.
* The presence of mesial temporal pathology and degree of hippocampal atrophy is asso- ciated with greater impairment.
* “Material specificity” of memory problems is true more so in adults such that left TLE is associated with verbal memory problems. Similarly, right TLE is associated (but not as strongly) with visual memory problems. This finding is the basis of the utility of presurgical evaluation by providing evidence for location of seizure focus and determining the risk of postsurgical cognitive deficits. List learning measures tend to be the most predictive of hippocampal dysfunction.
Unlike for other areas of functioning, there is evidence for progressive loss with continued seizures which is consistent with the changes seen on MRI.
One hypothesis of why memory deficits are not specific to TLE is that memory perfor- mance may also be disrupted due to other skills such as poor organization or attention that rely on frontal lobe functions.
Attention/Executive Functions
Beyond the effects of IQ, attention problems are commonly observed.
* Prevalence of ADHD is 20–40%.
* ADHD Inattentive Presentation is more common, and the boys and girls are equally represented, which is different from devel-
opmental ADHD with no seizures.
* There may be higher rates of attention prob-
lems with FLE and CAE.
* Associated issues such as nocturnal seizures
or medication side effects may be the primary
cause of inattention.
* Myth that stimulants used for ADHD symp-
toms would lower seizure threshold; however, many studies have shown this to be untrue.
Executive functioning (EF), a set of skills that is necessary for efficient and goal-directed behavior is less well studied, but is a common difficulty. Aspects of EF that are shown to be impaired in people with epilepsy include shifting, cognitive flexibility, working memory, and organization.
Parent questionnaire of EF was a significant predictor of performance and helpful in identifying an “at-risk” group of children with new-onset epilepsy.
Visual/Spatial
Findings are less consistent for visuospatial skills such as object recognition, drawing objects, and visual closure. While some studies have found these to be lower in right-hemispheric seizure foci, others have noted that language dominance may be an important factor. If language function has reorganized to the right related to a left hemispheric focus, a deficit in visuospatial pro- cessing may develop because the transfer of language to the right hemisphere is displacing visuospatial function to preserve language. This is referred to as the “crowding hypothesis.”
Psychomotor/Reaction Time
Slow processing speed is a common finding in people with epilepsy and may be due to neu- roanatomic anomalies or treatment effects.
* Processing speed deficits are the most com- mon side effect of ASMs. Slower speed is associated with polytherapy (defined by load or toxicity as well as number) and type of ASM (topiramate; phenobarbital; GABA-ergic inhibition).
* Seizure type has been implicated, particularly FLE and benign rolandic epilepsy.
Academic Functioning
Poor academic achievement is associated with all epilepsy types. Outcome is moderated by psy- chosocial variables. As with other cognitive skills, problems may predate seizure onset; however, should seizure control disrupts school attendance, there may be a larger gap following seizure onset.
