MS as a disconnection syndrome

Dineen RA et al.  Disconnection as a mechanism for cognitive dysfunction in multiple sclerosis.  Brain 2009;132: 239-249

Authors use DTI MRI and neuropsychology to try to correlate white matter specific disconnections with cognitive disorders in MS.Without delving into methodology, PASAT scores correlated with splenium and body of corpus callosum, parieto-occipital radiations of the forceps major, left cingulum, the right inferior longitudinal fasciculus running into the left temporal lobe, parietal tracts and portions of the left superior longitudinal fasciculus, and the parietal arcs of the arcuate fasciculi bilaterally.

The Benton Visual Retention Test correlated with lesions in splenium and body of the corpus callosum, the parietal and occipital projections of the forceps major bilaterally, the left inferior longitudinal fasciculus running into the temporal lobe, the left arcuate fasciculus, the left cingulum, the anterior portion and tail of the fornix, the white matter of the right parietal and medial occipital lobes.  Te right temporal lobe figured prominently with adjustment for IQ. 

CVLT II-- correlations with the body and splenium of the corpus callosum, the parietal and occipital projections of the forceps major bilaterally, the parietal portion of the left superior longitudinal fasciculus, the left inferior longitudinal fasciculus and arcuate fasciculus, the left posterior fornix and cingulum running from the temporal lobe. 

No correlations found for the following tests: JLO, COWAT, DST CS.

Localizaiton of tests within frontal lobes

Stuss DT. Levine B.  Adult clinical neuropsychology: lessons from studies of frontal lobes.  Ann Rev Psychol 2002; 53: 401-433.

Long article, a few (random) points distilled out, heavily tilted towards localization of neuropsych tests within frontal lobes.

Anatomically, the ventral prefrontal cortex is dissociated from the dorsolateral prefrontal cortex (DLPFC).  The former, is associated with emotional regulation, evolutionarily emerged from orbitofrontal and olfactory cortex and limbic nuclei.  It also is important for inhibition, emotion and reward processing.  By contrast, the DLPFC evolutionarily comes from archicortical trend of hippocampus, and is involved in spatial and conceptual processing, including executive functioning.  The frontal poles are more recently evolved and are involved in self awareness, autonoetic consciousness, and humor.

By function:

Frontal lobe language (key reference is Alexander MP et al., 1989 Brain Lang. )  excluding articulation and Broca's aphasia, frontal language function and dysfunction is grouped under activation and formulation (paralinguistics).  Dynamic aphasia, or trouble activating language, occurs after damage to SMA or ACC. TMA, with truncated language, occurs after damage to left DLPFC.  (in other publications, Alexander refers to 'subbcallosal fasciculus').   Usually this is tested using letter fluency.  In Stuss 1998 (JINS) rview of 74 local lesion patients, left DLPFC patients were most impaired, right DLPFC and VPFC patients were not impaired.  However left parietal lesioned patients also were impaired and could not be differentiated from left DLPFC patients.  Superior medial damage on either side (SMA) was associated with poor productions, and posterior superior lateral temporal lesions were implicated .  The latter could be teased out  by switching between letter and semantic fluency tasks.  All above are left sided lesions (except SMA).  Discourse lesions that are left sided include simplification, perseveration and omissions. Right sided lesions may cause amplification of details, wandering from topic, insertion of irrelevancies, and dysprosody, leading to incoherence.

Control of Memory:

Its important to differentiate between basic associative cue-engram processes (medial temporal lobe/hippocampal structures) and strategic processes that may be more top down such as coordination, elaboration and interpretation of these processes.  Wechsler Memory Scale and many others tap both processes but make no effort to dissociate them.  Author cites CVLT as an example of the "Boston approach" that includes efforts to measure serial position learning, semantic organization, interference effects, cued recall, recognition and response bias. Most recent WMS revision has semantically unrelated words, precenting analysis of semantic clustering.  Stuss et al. 1994 Psychology showed right DLPFC lesion patients had more intralist repetitions due to response monitoring defect.  Left frontal caused problems with encoding, retrieval and recognition.  Frontal lobes are important to retrieval involving monitoring, verification, & placement of information especially in spatial and temporal contexts, with lesions causing reduplication, confabulation and retrograde amnesia.  There is a right hemispheric bias in retrieval, but also a DLPFC/VPFC wherein latter is involved in retrieval cue specification and former in higher level postretrieval monitoring (see Fletcher, 1998 Brain, also Petrides). 

Working Memory:
Original idea jacobsen 1936 monkeys with frontal lesions could not make decisions once stimulus was removed from view.  Frontal lobe involvement keeps information online while other areas (slave systems) perform operations.  Frontal involvement increases with interference .  DLPFC monitors and manipulates, whereas VPFC maintains, controls interference and inhibition.  Digit span/spatial span give information about working memory storage capacity but not rehearsal or executive control.  Frontal lesions in one study did not affect digit span.  Reverse digit span measures manipulation of above.  Brown-Peterson technique taps interference.  Supraspan tests measure processing when capacity is exceeded.  Not standard.

Anterior attention processes
Attentional switching:  WCST and TMT, part B.  WCST originally shown by Milner to be response to frontal damage.  New problem solving Dias et al. (J Neurosci 1997).  .  WCST shifts are extradimensional eg. color to form, on basis of feedback, or intradimensional, eg within a color red to blue.  Extradimensional shifts are due to DLPFC in healthy adults.  VPFC damage does not affect extradimensional shifting.  However, VPFC lesions could contribute to the relatively rare error of loss of set due to susceptibility to interference.  DLPFC patients also had loss of set due to loss of sustained attention.Posterior damage also can affect WCST. 

TMT Part B ostensibly uses Part A as an internal control for factors other than switching, but has been criticized as not well matched to Part B in other respects.  Stuss et al. found time correlated with frontal pathology, but effect was eliminated when score was corrected for TMT Part A.  DLPFC patients were distinguished from Part A based on errors but not time.

Selective attention: Stroop test
Stuss found deficit in left sided lesions was due to problems in color naming, not interference.  (Stuss et al., Neuropsychologia 2001).  Patients with superior medial lesions showed errors due to importance of area in maintaining an activated intention.  Inferior medial patients were normal.

Sustained attention:
Continuous performance tests are sensitive to frontal damage especially with increased complexity (eg. respond to "O" after "x".  The Sustained Attention to Response Tast (SART, Robertson 1997 Neuropsychologia) and the Elevator Counting Test (Robertson 1991  the Test of Everyday Attention)

VPFC important in acquiring and reversing stimulus/reward.  The Iowa Gambling Test (Bechara et al.) is based on Somatic Marker Hypothesis, that reasoning is constrained based on previous conditioning, mediated by ventromedial frontal lobes.  VPFC lesions cause "self regulatory disorder" or "SRD."  Another test is the Strategy Application Test, based on the Six Element Test of Shallice and Burgess.  Every patient with focal VPFC damage, especially on right was impaired.  It correlated with outcome questionnaires.

Frontal Pole:  Autobiographical Memory Test.  (Kopelman, 1989J Clin Exper Neuropsychol).  Also, Dysexecutive Questionnaire (Burgess et al, 1996

NPH questionnaires for initial evaluation

from The Neurologist 2010 Wilson et al.

Gait

1. Do you have a problem getting in or out of a seat, walking, or maintaining your balance?
2. How long has it been since you first had this problem?
3. Do you have a problem getting in and out of a car?
4. Do you have a problem starting to walk, as though your feet are stuck to the floor?
5. Do you shuffle or scuff your feet as you walk?
6. Do you have trouble turning?
7. Do you have trouble stepping over a curb or walking on an uneven surface such as grass?
8. Do you touch walls, surfaces or countertops when you walk?
9. In the past month, how often have you fallen?
10. Do you use a cane, walker or wheelchair?

Bladder

1. Do you urinate more frequently than you used to?
2. Do you lose a little urine before reaching the toilet?
3. Do you lose control of your bladder (incontinence)?
4. Do you wear a pad, undergarment or Depends for protection?

Cognition

1. Do you have trouble with your thinking or memory?
2. How long have you had the trouble?
3. Do you have trouble with forgetfulness (repeating questions, difficulty learning, short term memory loss)
4. Do you have trouble with orientation  ( getting lost, disoriented, losing track of time, not recognizing familiar places or persons)
5. Do yo have problems with judgment or solving everyday problems at home such as managing medications, money, cooking, or understanding explanations?
6. Do yo have trouble caring for yourself, for example, bathing, using the toilet,  dressing or eating?
7. Do you have trouble organizing your schedule or routine?

Uniform Data Set for Neuropsychological Battery and Select Informant Measures

Neuropsychological Assessment for possible Alzheimer's disease

Domain assessed                              Assessment Tools                     Substitute Tool/additional tool

Multidomain screening tool               MMSE                                     MoCa

Verbal episodic memory                   WMS R, Log mem IA imm

Delayed verbal episodic memory       WMS R, Log mem IIA delayed

Attention                                           Digit Span forward and backward

Executive function                              Trailmaking Test Part B          additional: COWAT, category fluency

Psychomotor speed                            Trailmaking Test Part A
                                                          WAIS R digit symbol                 SDMT

Language                                            Boston Naming Test (30 item)   additional: BNT (60 item)
                                                                                                           Token Test, finger naming, color
                                                                                                           naming, right-left orientation, reading
                                                                                                           writing, spelling

Functional Status                                 Clinical Dementia Rating
                                                           Functional Assessment Questionnaire

Behavioral Assessment                        Geriatric Depression Scale        Zung Depression/Anxiety Scales
                                                           Neuropsychiatric Inventory Questionnaire

Source Morris JC, Weintraub S, Chui HC et al.  The Uniform Data Set (UDS) clinical and cognitive variables and descriptive data from Alzheimer's disease centers. Alz Dis Assoc Disord 2006; 20: 210-216.
Third column represents solely my own substitutions and additions

Other useful standard tests
                                                           Caregiver Burden Index (Zarit)
                                                           Praxis: test limb and oral praxis from Behavioral Neurology Index
                                                           Nonverbal memory:  Rey O CFT, copy, immediate and delayed

Localization of JLO and FRT

FRT (facial recognition test) of Benton localizes most strongly to the right posterior inferior parietal and right ventral occipital temporal (fusiform areas)

Judgment of Line Orientation localizes best to right posterior parietal area. 

references
1)  Tranel and Levin, in press JCEN

Validity of MOCA and MMSE in Parkinsons disease

Hoops S et al.  Validity of the MoCA and MMSE in the detection of MCI and dementia in Parkinson disease.  Neurology 2009; 73:1738-1745. 

MoCA is better than MMSE in MCI and AD in general population.  Using a cutoff score of less than or equal to 25 on the MoCA in PD found that 52 % of patients with normal MMSE had impairment using this point.  MoCA has good test-retest reliability, interrater reliability, and convergent validity with a neuropsychological battery ina small sample of patients with PD.   This study looked at discriminant validity using 132 subjects (NC 92, mci 23, pdd 17).  MoCA and MMSE performance for subjects with cognitive deficits on neuropsych testing  without self report of cognitive decline showed no differences between the 2 tests.  HOWEVER, EXAMINING MoCA SUBSCORE, PATIENTS WITH MCI OR PDD HAD SIGNIFICANTLY LOWER VISUOSPATIA/EXECUTIVE, ATTENTION, LANGUAGE, DELAYED RECALL, AND ORIENTATION SUBSCORES. 

Discussion-- MoCA has good discriminant validity and performs similarly to MMSE overall, but is superior as a screening instrument.  The optimal screening point cutoff for detection of any cognitive disorder for MoCA had greater specificity (.53)

Concerns about the WAIS 4 and WMS 4

Loring DW, Bauer RM.  Cautions and concerns regarding the newWechsler IQ and Memory Scales.  Neurology 74: 685-690 2010.

The new tests have fundamental changes from the old versions and are not established in various populations that they intend to serve.  Although the guidelines require neuropsychologists to use the "most current" tests, Bauer and Loring argue that the old tests are better validated and should be used preferentially in many cases.They compare the new versions of the WMS and WAIS to Windows Vista software release-- those who wish to run Windows XP should not be prevented from doing so.

Authors note the WAIS traditional scores of VIQ and PIQ are not truly measures of verbal and nonverbal intelligence as originally conceived, but cluster into 4 domains of verbal comprehension, perceptual reasoning, working memory, and processing speed. VIQ contains measures of verbal abstraction (Similarities) and knowledge (Information), also attention and working memory (Digit Span).  PIQ shows visuospatial problem solving (Block Design) and processing speed (Digit Symbol).  In WAIS III, 4 factor composites could be calculated, along with PIQ and VIQ. 

In WAIS 4, only FSIQ can be calculated, with VIQ and PIQ eliminated.  VCI and PCI are "substituted" for VIQ and PIQ for "decision making."  VCI and PCI exclude working memory and processing speed, which account for 40 % of the variance of FSIQ.  The General Abilities Index (GAI) is introduced, which also excludes working memory and processing speed.  GAI does not replace FSIQ, and VCI and PCI do not measure the same things as VIQ and PIQ.

The WAIS subsets have been changed to decrease emphasis on speeded tests, so that they are less sensitive to diseases that show psychomotor slowing (such as Parkinson's disease) and slowed information processing (such as multiple sclerosis).  The new WAIS will most likely have less patients with FSIQ under 70, leading to epidemiologic mismatches and skews in historical studies and less people qualifying for disabilities.  This is because many diseases with disability depend on the measurement of psychomotor slowing. The ostensible reason for the new version, to recalibrate the average IQ to 100, may not be met since the amount of change in the FSIQ mean is less than the variance of the test.

The WMS-4 incorporates changes, but many previous changes have fallen flat and then been eliminated in the "next" edition of the test.  The most important change since 1945 is the inclusion of the 30 minute delayed recall of the Logical Memory and Visual Reproduction subtests. In the WMS 3, previous concerns that were addressed failed to hold up under clinical experience and subsequently had to be dropped, analagous to a new software release.  In the WMS-4, the second trial for repetition of one of the to Logical Memory stories is inexplicably dropped, even though one of the reasons for the failure to find material specific memory impairments is the use of single trial memory tasks instead of learning over trials.  New nonverbal memory test within a grid may prove beneficial, because it requires remembering both visual and spatail information, but that has yet to be determined empirically.  Moreover, validity of the tests to specific diseases and prediction of clinical outcome is absent with the new tests.  For example, only 8 patients who had undergone temporal lobectomy were in the sample.  In some clinical trials, the HVLT or RVLT have been chosen because they are unlikely to be revised.  Test retest data also does not exist, and will not for many years, with the new forms of the tests, because data was not obtained prior to publication. 

Authors conclude that the old tests are not outdated, but proven useful, and that the new versions of the old tests do not deserve to be considered automatically current without further validation.