Sensory and cognitive impairments in subjects with Post-stroke Hemiparesis Dr. Deborah Larsen, PT, PhD Alexandra Borstad, PT, PhD Parminder Kaur, PT, MPT Petra Schmalbrock, PhD

Sensory and Cognitive Deficits Post-Stroke Sensory (SD) and mild cognitive deficits (MCD) often go undiagnosed post-stroke. Post stroke cognitive impairments are progressive and persistent in nature, reaching dementia by 5 yrs in 20- 25% of patients with non-severe ischemic stroke. Somatosensory impairments are reported in 53-60% of stroke survivors and include both proprioceptive and cutaneous input. Almost 90% of stroke survivors demonstrate either SD or MCD and no study has looked at the relationship between these deficits.

Post stroke Impairments Sensory Impairments Motor impairments Cognitive impairments

Hypotheses Post-stroke subjects will perform worse on measures of sensory discrimination and cognition than age- matched peers. Deficits in sensory and cognitive function will relate to poorer motor function. Functional MRI analyses will differentiate activation patterns between controls and post-stroke participants.

Subjects 14 controls,12 chronic post-stroke subjects were tested in a single behavioral and imaging session. Inclusion criteria - 1) single hemiparetic documented stroke; 2) aged 21-85; 3) hand movement sufficient to grasp and release objects; 4) ability to understand test instructions Exclusion criteria -1) prior diagnosis of cognitive (eg. dementia), sensory (eg. neuropathy) or neurologic (eg. Parkinsons) disorders; 2) metal device or other incompatibility with MRI testing; 3) Mini Mental Exam <24.

Materials and methods Motor Sensory Functional MRI Cognition Hand Active Sensation Test (HASTe), Brief Kinesthesia Test (BKT), Form Perception Test (FPT); Cognition N-back (1 back & 2 back) Paced Auditory Serial Addition Test (PASAT; 2 & 3 sec), Choice Reaction Test (CRT) Motor Box and Blocks (BBT), 9 Hole Peg (9NP) Functional MRI Sensory (brush discrimination) Paced Visual Serial Addition Test (PSVAT)

Results

Functional MRI Data Stroke subjects performed worse than their matched controls on both sensory & cognitive tests Sensory & cognitive scores correlated strongly with each other and with motor scores (BBT) Networks supporting sensory discrimination and working memory overlap with the parietal lobe and dorsal frontal cortex playing a key role in both tasks. Post stroke subjects demonstrated disruption of both networks (cognitive and sensory tracts) compared to controls.

Sensory Group Differences Task Affected Unaffected Brief Kinesthesia Prob > t 0.0056 Prob > t 0.0452 Form Perception Test Prob > t 0.0057, Prob < t 0.0059 Brush discrimination Prob >t 0.0194 Not significant Monofilament (pinky) Monofilament (index)

Cognitive Testing: Group Comparisons Task Reaction time Prob > t 0.0476 PASAT – 2 seconds Prob < t 0.0174 PASAT – 3 seconds Prob < t 0.0037 2 – back (accuracy) Prob < t 0.0012 1 – back (accuracy) Prob < t 0.0462

Sensory task -Right Brush discrimination (Z> 3.0, p<.01) Post stroke group L – postcentral gyrus R – Supramarginal gyrus L – Precentral gyrus Control group L – Parietal operculum R – Inferior frontal gyrus R – Cerebellum R – paracingulate cortex L – Middle Frontal gyrus

Cognitive task – PVSAT Post stroke group Control group L – Middle Frontal Gyrus L – Frontal Orbital Cortex Control group L – Supramarginal Gyrus Cerebellum L – Inferior Temporal gyrus R – Occipital Pole R - Middle Frontal Gyrus L – Thalamus L – Middle Temporal gyrus L - Precuneus

Areas of overlap for cognitive and right brush discrimination tasks Rt supplementary motor area Lt angular gyrus Lt supramarginal gyrus Rt angular gyrus Middle frontal gyrus Lt precentral gyrus Lt & Rt frontal operculum cortex

Areas of overlap for cognitive & sensory tasks R – Supplementary Motor area L – Angular Gyrus R – Middle frontal gyrus R – Angular Gyrus L – Supramarginal gyrus L & R frontal operculum L – Precentral gyrus Blue = sensory Orange = cognitive

Correlations between Sensory, Cognitive & Motor Measures HASTe strongly correlated with PASAT (r=.722, p<.0001). PASAT strongly correlated with BBT (r=.685, p<.001) HASTe moderately correlated with BBT (r=.431, p<.05).

Summary of Results Post-stroke subjects demonstrated disruption of both networks. Sensory and working memory deficits are common after stroke and may be related to disruption of common neural networks. These overlooked deficits impact motor recovery. Stroke rehabilitation protocols continue to focus on motor impairments, ignoring the contributions of concomitant sensory deficits.

Clinical significance Therapists need to include measures of sensory discrimination and cognition within their standard assessment procedures for stroke survivors.