Prefrontal activation during dual-task seated stepping and walking performed by subacute stroke patients with hemiplegia.

Objectives: This study examined prefrontal cortex (PFC) activation during dual-task seated stepping and walking performed by subacute stroke patients with hemiplegia and evaluated the relationship between PFC activation, frontal lobe functions, and dual-task interference. Methods: Patients with functional ambulation category (FAC) scores ≤ 2 comprised the seated stepping task group. Those with FAC scores > 2 comprised the walking task group. There were 11 patients in the seated stepping task group (mean age, 65.3±12.2 years; age range, 55-73.5 years; 7 male and 4 female patients; time since stroke onset, 45.7±9.9 days) and 11 patients in the walking task group (mean age, 65.6±15.2 years; age range, 49.5-74.5 years; 7 male and 4 female patients; time since stroke onset, 57.5±18.3 days). Both groups completed the Frontal Assessment Battery (FAB). The seated stepping task group performed the following three tasks: cognitive task (CT), normal seated stepping (NSS), and dual-task seated stepping (DTSS). The walking task group completed the following tasks: CT, normal walking (NW), and dual-task walking (DTW). The CT was a letter fluency task; this letter fluency task was simultaneously performed during seated stepping (DTSS) and walking (DTW). Changes in the oxygenated hemoglobin (O2Hb) concentration and deoxygenated hemoglobin concentration during the tasks were measured using near-infrared spectroscopy (Pocket NIRS HM; Dynasense Inc., Japan). The number of steps, walking speed, and percentage of correct responses to the CT were recorded. Results: The results showed that DTSS activated the PFC significantly more than performing a single task and that NSS was associated with a significantly higher difference in the hemoglobin concentration when compared to that associated with the CT, which was a single task. In the walking task group, PFC activation was significantly higher during DTW, NW, and CT (in that order), and O2Hb concentrations were significantly higher in the contralesional hemisphere than in the ipsilesional hemisphere during all tasks. Associations between PFC activation, FAB scores, and dual-task interference in the seated task group indicated significant positive correlations between FAB scores and cognitive performance with dual-task interference. Conclusion: DTSS may be an effective means of activating the PFC of patients with difficulty walking.

Effects of Cognitive Dysfunction and Dual Task on Gait Speed and Prefrontal Cortex Activation in Community-Dwelling Older Adults.

We aimed to determine how prefrontal cortex activation and gait speed during walking is affected by cognitive dysfunction and dual-tasking. Eleven and 14 participants were included in the MOCA-J (Japanese version of the Montreal Cognitive Assessment score) < 26  (age, 76.0 ± 5.7 years; sex, six men and five women) and the MOCA-J ≥ 26 groups (age 73.9 ± 4.3 years; sex, seven men and seven women), respectively. We measured prefrontal cortex oxygenated hemoglobin (oxy-Hb) levels (using Pocket NIRS HM), and gait speed during normal and dual-task walking (a letter fluency task was added). The oxy-Hb levels were significantly lower in the MOCA-J < 26 group than in the MOCA-J ≥ 26 group during dual-task walking. The gait speed was significantly lower during dual-task walking, compared with normal walking, in the MOCA-J < 26group.These results may have been influenced by the compensatory mechanisms in the frontal lobe.

Quadriceps Thickness and Echo Intensity Predict Gait Independence in Individuals with Severe and Mild Hemiparetic Stroke.

INTRODUCTION: Smaller muscle size and higher adipose tissue ratio of the quadriceps femoris are often observed after stroke. However, it is unclear whether muscle size and the intramuscular fat ratio of the quadriceps measured with ultrasonography (US) reflect gait independence in individuals with mild or severe hemiparetic stroke. OBJECTIVE: The present study was performed to examine the relationships of gait independence with muscle thickness (MT) and echo intensity (EI) of the quadriceps femoris in individuals with hemiparesis after stroke. METHODS: We examined 43 individuals with hemiparetic stroke. We assessed functional independence measure (FIM) gait scores and measured thickness and EI of the quadriceps using US. The relationships of FIM gait scores with MT and EI were examined using Spearman's correlation coefficients in mild (n = 21) and severe (n = 22) hemiparetic stroke groups. RESULTS: In the mild hemiparetic group, FIM gait scores were correlated with paretic limb MT (rho = 0.60, p < 0.01) and EI (rho = -0.57, p < 0.01). In the severe hemiparetic group, FIM gait scores were correlated with paretic limb MT (rho = 0.67, p < 0.01) and EI (rho = -0.43, p < 0.05), as well as non-paretic limb MT (rho = 0.86, p < 0.01) and EI (rho = -0.56, p < 0.01). CONCLUSIONS: Quadriceps thickness and EI were associated with the degree of gait independence. Atrophy and increased intramuscular fat of the quadriceps may be limiting factors for achieving gait independence.

Relationship of Quadriceps Muscle Thickness with Motor Paralysis and Muscle Echo Intensity in Post-Stroke Patients.

INTRODUCTION: Quadriceps muscle atrophy and quality loss, defined as an increased ratio of intramuscular fat and/or connective tissue, are often observed especially in the paretic limb of post-stroke patients. This study was performed to examine the relationship of quadriceps muscle thickness (MT) with muscle echo intensity (EI) and the severity of motor paralysis after stroke. METHODS: Thirty-six hemiparetic subacute post-stroke patients were enrolled. We examined the MT (index of muscle quantity) and the EI (index of muscle quality) at the anterior mid-thigh in both limbs. We also assessed the Brunnstrom stage (BR stage), subcutaneous adipose tissue thickness, time since stroke, age, body weight, sex, number of medications, and nutritional and inflammation status. RESULTS: The MT in the paretic limb was explained by the BR stage (ß = -0.26, p < 0.01), body weight (ß = 0.68, p < 0.01), and serum albumin (ß = 0.34, p < 0.01), with an adjusted R2 of 0.81. The MT in the non-paretic limb was explained by the muscle EI (ß = -0.55, p < 0.01) and age (ß = -0.40, p < 0.01), with an adjusted R2 of 0.69. The muscle EI was explained by the MT in the paretic limb (ß = -0.34, p < 0.01) and non-paretic limb (ß = -0.69, p < 0.01). CONCLUSIONS: Our results suggest that motor paralysis, aging, and malnutrition contribute to quadriceps atrophy in post-stroke patients. Moreover, a potential countermeasure to diminish muscle quality loss is maintenance of muscle quantity.