An Evaluation of the Emerging Techniques in Sports-Related Concussion.

SUMMARY: Sports-related concussion is now in public awareness more than ever before. Investigations into underlying pathophysiology and methods of assessment have correspondingly increased at an exponential rate. In this review, we aim to highlight some of the evidence supporting emerging techniques in the fields of neurophysiology, neuroimaging, vestibular, oculomotor, autonomics, head sensor, and accelerometer technology in the setting of the current standard: clinical diagnosis and management. In summary, the evidence we reviewed suggests that (1) head impact sensors and accelerometers may detect possible concussions that would not otherwise receive evaluation; (2) clinical diagnosis may be aided by sideline vestibular, oculomotor, and portable EEG techniques; (3) clinical decisions on return-to-play eligibility are currently not sensitive at capturing the neurometabolic, cerebrovascular, neurophysiologic, and microstructural changes that biomarkers have consistently detected days and weeks after clinical clearance. Such biomarkers include heart rate variability, quantitative electroencephalography, as well as functional, metabolic, and microstructural neuroimaging. The current challenge is overcoming the lack of consistency and replicability of any one particular technique to reach consensus.

Brain Reserve in a Case of Cognitive Resilience to Severe Leukoaraiosis.

OBJECTIVE: Leukoaraiosis, or white matter rarefaction, is a common imaging finding in aging and is presumed to reflect vascular disease. When severe in presentation, potential congenital or acquired etiologies are investigated, prompting referral for neuropsychological evaluation in addition to neuroimaging. T2-weighted imaging is the most common magnetic resonance imaging (MRI) approach to identifying white matter disease. However, more advanced diffusion MRI techniques may provide additional insight into mechanisms that influence the abnormal T2 signal, especially when clinical presentations are discrepant with imaging findings. METHOD: We present a case of a 74-year-old woman with severe leukoaraoisis. She was examined by a neurologist, neuropsychologist, and rheumatologist, and completed conventional (T1, T2-FLAIR) MRI, diffusion tensor imaging (DTI), and advanced single-shell, high b-value diffusion MRI (i.e., fiber ball imaging [FBI]). RESULTS: The patient was found to have few neurological signs, no significant cognitive impairment, a negative workup for leukoencephalopathy, and a positive antibody for Sjogren's disease for which her degree of leukoaraiosis would be highly atypical. Tractography results indicate intact axonal architecture that was better resolved using FBI rather than DTI. CONCLUSIONS: This case illustrates exceptional cognitive resilience in the face of severe leukoaraiosis and the potential for advanced diffusion MRI to identify brain reserve.

Dual-Task Gait Assessment in a Clinical Sample: Implications for Improved Detection of Mild Cognitive Impairment.

OBJECTIVES: Research has longitudinally linked dual-task gait dysfunction to mild cognitive impairment (MCI) and dementia risk. Our group previously demonstrated that dual-task gait speed assessment distinguished between subjective cognitive complaints (SCC) and MCI in a memory clinic setting, and also found that differences in dual-task gait speed were largely attributable to executive attention processes. This study aimed to reproduce these findings in a larger diverse sample and to extend them by examining whether there were group differences in single- versus dual-task cognitive performance (number of letters correctly sequenced backward). METHOD: Two-hundred fifty-two patients (M age = 66.01 years, SD = 10.46; 119 MCI, 133 SCC) presenting with cognitive complaints in an academic medical setting underwent comprehensive neuropsychological and gait assessment (single- and dual-task conditions). RESULTS: Patients with MCI walked slower and showed greater decrement in cognitive performance than those with SCC during dual-task conditions. Neuropsychological measures of executive attention accounted for significant variance in dual-task gait performance across diagnostic groups beyond demographic and health risk factors. DISCUSSION: Reproduction of our results within a sample over four times the previous size provides support for the use of dual-task gait assessment as a marker of MCI risk in clinical settings.

Five-factor structure of the RBANS is supported in an Alzheimer's disease sample: Implications for validation of neuropsychological assessment instruments.

Development of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was theoretically driven, with the goal of providing an assessment of abilities across five cognitive domains. Since its development, numerous factor analytic studies have failed to provide empirical support for the proposed five-factor structure and, furthermore, have lacked consensus on the internal structure of this instrument. A key limitation of these prior studies is the use of normal or mixed clinical samples, a practice that can obscure distinctions that may be evident in specific homogeneous clinical samples. The current study examined the factor structure of the RBANS in a sample of 107 male Veterans diagnosed with probable Alzheimer's disease (AD). Confirmatory factor analysis of a model reflecting the five Index Scores (Immediate Memory, Visuospatial/Constructional, Language, Attention, and Delayed Memory) found that the proposed five-factor structure fit the data well. These findings suggest that the RBANS does measure five distinct constructs and use of Index Scores is appropriate. Furthermore, the current findings highlight the importance of testing construct validity of neuropsychological assessment instruments in specific homogeneous samples.

Improving Sensitivity to Detect Mild Cognitive Impairment: Cognitive Load Dual-Task Gait Speed Assessment.

OBJECTIVES: Longitudinal research indicates that cognitive load dual-task gait assessment is predictive of cognitive decline and thus might provide a sensitive measure to screen for mild cognitive impairment (MCI). However, research among older adults being clinically evaluated for cognitive concerns, a defining feature of MCI, is lacking. The present study investigated the effect of performing a cognitive task on normal walking speed in patients presenting to a memory clinic with cognitive complaints. METHODS: Sixty-one patients with a mean age of 68 years underwent comprehensive neuropsychological testing, clinical interview, and gait speed (simple- and dual-task conditions) assessments. Thirty-four of the 61 patients met criteria for MCI. RESULTS: Repeated measure analyses of covariance revealed that greater age and MCI both significantly associated with slower gait speed, ps<.05. Follow-up analysis indicated that the MCI group had significantly slower dual-task gait speed but did not differ in simple-gait speed. Multivariate linear regression across groups found that executive attention performance accounted for 27.4% of the variance in dual-task gait speed beyond relevant demographic and health risk factors. CONCLUSIONS: The present study increases the external validity of dual-task gait assessment of MCI. Differences in dual-task gait speed appears to be largely attributable to executive attention processes. These findings have clinical implications as they demonstrate expected patterns of gait-brain behavior relationships in response to a cognitive dual task within a clinically representative population. Cognitive load dual-task gait assessment may provide a cost efficient and sensitive measure to detect older adults at high risk of a dementia disorder. (JINS, 2017, 23, 493-501).

Primary Progressive Speech Abulia.

BACKGROUND AND OBJECTIVE: Primary progressive aphasia (PPA) is a neurodegenerative disorder characterized by progressive language impairment. The three variants of PPA include the nonfluent/agrammatic, semantic, and logopenic types. The goal of this report is to describe two patients with a loss of speech initiation that was associated with bilateral medial frontal atrophy. METHODS AND RESULTS: Two patients with progressive speech deficits were evaluated and their examinations revealed a paucity of spontaneous speech; however their naming, repetition, reading, and writing were all normal. The patients had no evidence of agrammatism or apraxia of speech but did have impaired speech fluency. In addition to impaired production of propositional spontaneous speech, these patients had impaired production of automatic speech (e.g., reciting the Lord's Prayer) and singing. Structural brain imaging revealed bilateral medial frontal atrophy in both patients. CONCLUSION: These patients' language deficits are consistent with a PPA, but they are in the pattern of a dynamic aphasia. Whereas the signs-symptoms of dynamic aphasia have been previously described, to our knowledge these are the first cases associated with predominantly bilateral medial frontal atrophy that impaired both propositional and automatic speech. Thus, this profile may represent a new variant of PPA.

Improved verbal learning in the semantic variant of primary progressive aphasia when using semantic cues.

The semantic variant of primary progressive aphasia (PPA-S) is characterized by impairments in confrontation naming and single word comprehension. Although episodic memory may be relatively spared, there can be impairment in verbal learning tasks. We report a patient with PPA-S and impaired verbal learning who was tested to learn if when provided with semantic categories, her learning would improve. A 70-year-old right-handed woman with a 2-year history of progressive difficulties with word finding, naming, and memory was tested for language and memory deficits using the Hopkins Verbal Learning Test-Revised (HVLT-R). She was then retested with the HVLT-R after being provided with the three semantic categories to which these words belonged. Confrontation naming was impaired on the Boston Naming Test. Sentence repetition was normal. Comprehension testing with word picture matching and sentence comprehension was normal. On a test of semantic associations, Pyramids and Palm Trees, she was impaired. She was also impaired on tests of verbal learning (HVLT-R) (total: 13) but not recall. When a different version of the HVLT-R was given with the semantic categories of the words given beforehand, her scores improved (total: 26). This patient with PPA-S had an impairment of verbal learning, but not delayed recall. When given a semantic category cue beforehand, her verbal learning performance improved. This observation suggests that this patient did not spontaneously use semantic encoding. Using a semantic cueing strategy may help other patients with PPA-S improve their capacity for verbal learning.

Cerebellar allocentric and action-intentional spatial neglect.

Contralesional hemispatial neglect most often results from lesions in the right posterior temporoparietal cortex. Less commonly, contralesional and ipsilesional neglect are caused by lesions in the frontal lobe. Although unilateral left cerebellar lesions have been reported to cause body-centered (egocentric) ipsilesional neglect, they have not been reported to cause left-side object-centered (allocentric) neglect together with a leftward action-intentional bias. We describe a patient who had these signs of neglect 7 months after a left cerebellar hemorrhage. This 61-year-old right-handed woman reported emotional lability and difficulty walking, frequently bumping into things on her left side. Neurologic examination revealed ocular dysmetria and left-side limb ataxia. Neuropsychological tests showed evidence of neglect. On a clock-drawing test, the patient accurately drew a circle but her number placement deviated to the left side. She showed the same leftward deviation when she tried to draw a circle composed of small triangles. Although her line bisection was normal, on an allocentric task of open-triangle cancellation she was most likely to neglect triangles with a left-side opening. Her performance on this task indicated left allocentric neglect. Her leftward deviation on the clock and figure drawing tasks seems to be a form of an action-intentional grasp, which may have been induced by right frontal dysfunction superimposed on a deficit of global attention.