L8 Cognitive Deficits following Stroke & Treatments

Question 1

Which cognitive domains can be affected by stroke?

Answer 1

Attention - focus attention, stained attention, selected attention and divided attention

Memory - semantic, episodic, working memory

Language - broccas and wernicas aphasia

Executive function - planning, judgment, processing, problem-solving

Perception - hemispatial neglect, agnosia, prosopagnosisa, dypraxia/apraxia

Question 2

Describe the Mini-Mental State Examination (MMSE) and evaluate it.

Answer 2

The MMSE is a 30 item standardised measure used in assessing cognitive impairments in a variety of neurological conditions such as stroke, brain trauma and dementia. uses multiple tasks to gain insight into the functioning of multiple cognitive domains;

Orientation - measured by asking questions about the time, day of the week, month, year etc

STM - the patient asked to generate 3 objects from their head and asked to repeat the three objects again to see if they remember

LTM - asked to recall the objects again later

Attention + calculation - asked to count backwards from 657 in 3’s, firstly to check if their mathematical ability is affected, and to see whether they can remain focused for long

Comprehension - asked to explain what certain words/things are

Copying - asked to draw pictures etc, copy text, useful for finding hemispatial neglect

The patient ends up with a final score /30;
24+/30 = normal
18-24/30 = mild cognitive impairment
<18/30 = servere cognitive impairment

Strengths:

• widely used
• general assessment applicable to virtually any condition with cognitive impairment
• easy and quick to administer
• doesn’t require a professional
• inexpensive

Limitations:

• lacks sensitivity, a more general rule of thumb warranting further examination
• includes no measure for Executive function
• confounded by age; education, culture
• not free to use, less readily available than some measures

Improvements

• other versions have included tasks to asses EF,
• can be completed in a more thorough version with greater sensitivity

Question 3

Describe the Montreal Cognitive Assessment (MCA) and evaluate it.

Answer 3

Very similar to MMSE however also assesses Visuospatial awareness and EF. some of the additional tasks include;

Clock drawing - useful for detecting hemispatial neglect

EF task - asked to solve simple and more complicated puzzles

Naming task - asked to identify items etc assess semantic memory

Attentional task - shown a sequence and asked to tap whenever they see or hear a certain letter, eg “tap when you see the letter A” - AHHDKFSLAJDLGPGPLDAJSJAAJDOFKSA

Abstract thinking - asked to link certain objects together in some meaningful way

production - see how many objects you can think of which start with the letter p

Strengths:

• more sensitive for mild cognitive impairment
• translated into more languages than the MMSE
• free to use

Limitations:

• not useful for severe cognitive impairments
• relatively new and less widely used than established MMSE

Question 4

Describe the Neuropsychological Battery Test (NBT) and evaluate it.

Answer 4

This isn’t a test but rather an approach of cognitive assessment which involves an in-depth evaluation using multiple complete measures for various cognitive domains.

Strengths:

• offers a detailed assessment with high sensitivity of cognitive deficits
• used extensively in research to further understanding about brain damages effects on cognition

Limitations:

• time-consuming
• costly
• only done in small samples due to time limitation
• difficult to complete and thus open to drop out and fatigue effects
• useless for those with severe impairment

Question 5

What is Hemi-spatial neglect?

Answer 5

Hemispatial neglect is when a person struggles to perceive things in one side of their visual field (side contralateral to damage from the stroke). This is a deficit in sensory perception (not a visual deficit), the eyes work as they did before. Occurs in roughly 26% of stroke survivors, and is due to damage to areas on the parietal lobe

Question 6

describe and evaluate 3 tests used to assess Hemi-spatial neglect.

Answer 6

1. Line Bisection Task - involves bisecting the middle section of many lines in various orientations across a sheet. If someone has severe hemispatial neglect, typically they may not bisect many of the lines on one half of the page, and consistently bisect the line in the wrong place

Evaluation:

• inexpensive, quick and easy
• easy to interpret
• no training needed
• not very controlled, quantifiable or sensitive in assessment of hemispatial neglect, more of an initial indicator
• confounded by motor disability

2. Clock Drawing Task - person told to draw a traditional analogue clock face. this is a pretty similar measure to line bisection

Evaluation:

• tests higher-level function and memory
• reliable measure
• slightly better sensitivity than the line bisection task
• confounded by age and education
• confounded by motor disability

3. Behavioural Inattention Test (BIT) - is a more thorough measure of hemispatial neglect includes two parts;
   1st - Conventional section - includes standard tests eg line bisect and clock face task
   2nd - Behavioural section - includes observation of multiple daily activities such as eating a plate of food, tieing shoelaces, writing a letter, calling a friend

Evaluation:

• gives a comprehensive view of hemispatial neglect
• uses real-life tasks, so ecologically valid
• high sensitivity
• time-consuming
• expensive
• useless for severe strokes
• confounded by motor ability
• needs trained professional

Question 7

Discuss 3 treatments/ therapies used in treating Hemi-spatial neglect.

Answer 7

1. rTMS - Post-stroke hemispatial neglect can be the result of direct damage but also intrahemispheric rivalry, in which the stronger hemisphere overcompensates for weakness in the other, which leads to atrophy of the weaker side and less activity over time. rTMS has been proposed as a suitable treatment for the rebalancing of hemispheric activity in stroke patients with hemispatial neglect.

(Müri et al (2013) has provided evidence for rTMS as an effective therapy which can rebalance activity between hemispheres. did a literature review, found 12 papers with 170 patients who did rTMS. found all had therapeutic benefits over sham and non-treatment- didn’t matter if they received fast or slow-wave rTMS. found long term benefits for neglect

2. Visual Scanning Method (VSM) - Remedial treatment in which a patient is encouraged to constantly attend to the weaker side. Done gradually over 30 sessions over 6 weeks, in which patient completes attentional type takes which need weaker side eg copying images or texts. helps shift attentional focus onto the weaker side which can encourage neuroplasticity and the reconnection of damaged or weakened areas. can be done in real life, on a computer or through virtual reality.
3. Compensatory treatments - helps a person compensate for the neglect. multiple versions;
   a) Prism glasses - enlarge neglected side
   b) limb movement attention - get patient to move weaker side and attent to the feeling of movement in the weaker side
   c) eye patching - forces use of weakened side, helps rebalance hemispherical activity

Question 8

What is Apraxia?

Answer 8

Apraxia is a reduced ability to carry out motor actions like movement or speech. Involves damage in both frontal and parietal regions, specifically the motor cortex.

Diagnosis for Apraxia is difficult because the doctor needs to rule out the possibility of it being due to muscle weakness, sensory impairment or lack of comprehension.

Question 9

Discuss treatments and therapies used in treating Apraxia

Answer 9

1. rTMS - Apraxia can follow damage to the motor cortex because the damage prevents the motor cortex from functioning appropriately. high-frequency rTMS has been suggested as a therapeutic tool which can aid the recovery of motor function in stroke patients.

(Emara at al,. (2016) 60 patients who had suffered an ischaemic stroke at least 1 month prior, 20 received high-frequency rTMS on weaker stroke hemisphere, 20 received low-frequency rTMS on healthy hemisphere, 20 received ‘sham’ rTMS; all alongside standard physiotherapy, measures of motor function taken with Finger Tapping (FT) thumb test, which mapped how connected the motor cortex is to thumb through single TMS shocks- being able to generate thumb twitch by zapping large area of cortex indicated good cortical motor connectivity, also did multiple (5) motor function tests and cognitive test using Activity Index (AI), found both active treatment tests showed significantly better improvements in FT and AI test over sham)

Question 10

What are Aphasias?

Answer 10

Aphasias come in various forms and involve loss of ability to communicate.

Question 11

Discuss some treatments and therapies used for treating Aphasias.

Answer 11

1. Speech and Language Therapy - delivered by a trained professional. involves a large number of word and speech-related tasks. can be completed on a computer or in person, benefits from greater engagement ie the more a patient engages, the better the outcomes. reconnects person to language. can be done in many languages however sometimes difficult to find a therapist to deliver it in said language- computerised version is more versatile.
2. rTMS - Ren et al (2014) did a literature review on rTMS as a therapy for aphasias. Found 7 RCT’s including 160 stroke patients with aphasias (broccas + wernicas) who had received slow-wave rTMS on area controlateral to stroke. Found an overall significant effect size of 1.26 in the recovery of speech and comprehension abilities. Also found no adverse outcomes for patients in any study due to rTMS treatment.
3. Constraint therapy - prevent other modes of communication such as body language or writing, make them try as hard as they can to use speech.
4. Aphasic Group Meetings - meet to practice conversation, helps with both production and comprehension, useful because many can receive therapy at the same time, plus patients find it helpful to talk to someone with some understanding of their condition, makes them less stressed and helps with recovery.

Question 12

Describe the Sun et al (2014) paper

Answer 12

Review of literature; summarises the prevalence, risk factors, mechanisms and management of CI following stroke.

Prevalence

• found reviews from 22+ countries
• found prevalence of post-stroke CI was roughly 30%
• varied widely based on country, ethnicity and diagnostic criteria
• eg using neuropsychological test batteries gave 96% CI figure; because they are far more sensitive for mild CI

Risk factors for post-stroke CI

• Low education, higher age linked to frequency of post-stroke CI
• education complicated tho because may be protective however gives more for a person to lose so it unclear what kind of role it plays
• other risk factors linked are hypertension, smoking, diabetes

Mechanisms for PSCI

• studies have correlated volume of infarcts (a small area of dead tissue resulting from lack of blood supply) with PSCI
• however, doesn’t explain variability in CI’s well
• a better explanation is to look at both the volume and location of infarcts
• EG Szabo et al 2009 did MRIs on individuals who had posterior cerebral artery ischaemia and found that infarcts on left hippocampus = deficits in verbal LTM, whereas infarcts on right hippocampus = deficits in non-verbal LTM

Management

• so far no effective global treatments for CI
• AD drugs like Cholinesterase inhibitors have been used, work by increasing acetylcholine (neurotransmitter). studies have shown it increases EF in PSCI but fail to have global effects
• Memantine is a receptor agonist which reduces neurotoxicity