Ipsilesional spatial bias after a focal cerebral infarction in the medial agranular cortex: A mouse model of unilateral spatial neglect.

Unilateral spatial neglect is a disorder of higher brain function that occurs after a brain injury, such as stroke, traumatic brain injury, brain tumor, and surgical procedures etc., and leads to failure to attend or respond to stimuli presented to the side contralateral to the lesioned cerebral hemisphere. Because patients with this condition often have other symptoms due to the presence of several brain lesions, it is difficult to evaluate the recovery mechanisms and effect of training on unilateral spatial neglect. In this study, a mouse model of unilateral spatial neglect was created to investigate whether the size of the lesion is related to the severity of ipsilesional spatial bias and the recovery process. Focal infarction was induced in the right medial agranular cortex (AGm) of mice via photothrombosis. After induction of cerebral infarction, ipsilesional spatial bias was evaluated for 9 consecutive days. The major findings were as follows: (1) unilateral local infarction of the AGm resulted in ipsilateral bias during internally guided decision-making; (2) the lesion size was correlated with the degree of impairment rather than slight differences in the lesion site; and (3) mice with anterior AGm lesions experienced lower recovery rates. These findings suggest that recovery from ipsilesional spatial bias requires neural plasticity within the anterior AGm. This conditional mouse model of ipsilesional spatial bias may be used to develop effective treatments for unilateral spatial neglect in humans.

Gait Training Using a Wearable Robotic Device for Non-Traumatic Spinal Cord Injury: A Case Report.

INTRODUCTION: We aimed to report the clinical evaluation results of gait training with the Honda Walking Assist Device® (HWAT) in a patient with spinal cord injury (SCI). PATIENTS AND METHODS: A 63-year-old male with SCI (grade D on the American Spinal Injury Association Impairment Scale) underwent 20 HWAT sessions over 4 weeks. The self-selected walking speed (SWS), mean step length, cadence, 6-minute walking test (6MWT), Walking Index for SCI score, SCI Functional Ambulation Inventory gait score, American Spinal Injury Association Impairment Scale grade, neurological level, upper and lower extremity motor scores, modified Ashworth Scale, Penn Spasm Frequency Scale, and Spinal Cord Independence Measure version III were measured on admission, at the start of HWAT, at 2 and 4 weeks post-HWAT, and at discharge. Three-dimensional kinematic gait analysis and electromyographic assessments were performed before and after HWAT. RESULTS: The patient safely completed 20 HWAT sessions. We found improvements above the clinically meaningful difference in SWS and 6MWT as well as increased hip extension, ankle plantar- and dorsi-flexion range of motion and increased hip extensor, abductor, adductor, and ankle plantar flexor muscle activity. DISCUSSION: The SWS improved more markedly during the HWAT intervention, exceeding the minimal clinically important difference (0.10 to 0.15 m/s) in walking speed for people with SCI until discharge. Moreover, the 6MWT results at 2 weeks after the start of HWAT exceeded the cutoff value (472.5 m) for community ambulation and remained at a similar value at discharge. CONCLUSION: The walking distance (6MWT) and the walking speed (SWS) both demonstrated clinically important improvements following 20 treatment sessions which included HWAT.

Adjusting Assistance Commensurates with Patient Effort During Robot-Assisted Upper Limb Training for a Patient with Spasticity After Cervical Spinal Cord Injury: A Case Report.

Limited evidence is available on optimal patient effort and degree of assistance to achieve preferable changes during robot-assisted training (RAT) for spinal cord injury (SCI) patients with spasticity. To investigate the relationship between patient effort and robotic assistance, we performed training using an electromyography-based robotic assistance device (HAL-SJ) in an SCI patient at multiple settings adjusted to patient effort. In this exploratory study, we report immediate change in muscle contraction patterns, patient effort, and spasticity in a 64-year-old man, diagnosed with cervical SCI and with American Spinal Injury Association Impairment Scale C level and C4 neurological level, who underwent RAT using HAL-SJ from post-injury day 403. Three patient effort conditions (comfortable, somewhat hard, and no-effort) by adjusting HAL-SJ's assists were set for each training session. Degree of effort during flexion and extension exercise was assessed by visual analog scale, muscle contraction pattern by electromyography, modified Ashworth scale, and maximum elbow extension and flexion torques, immediately before and after each training session, without HAL-SJ. The amount of effort during training with the HAL-SJ at each session was evaluated. The degree of effort during training can be set to three effort conditions as we intended by adjusting HAL-SJ. In sessions other than the no-effort setting, spasticity improved, and the level of effort was reduced immediately after training. Spasticity did not decrease in the training session using HAL-SJ with the no-effort setting, but co-contraction further increased during extension after training. Extension torque was unchanged in all sessions, and flexion torque decreased in all sessions. When performing upper-limb training with HAL-SJ in this SCI patient, the level of assistance with some effort may reduce spasticity and too strong assistance may increase co-contraction. Sometimes, a patient's effort may be seemingly unmeasurable; hence, the degree of patient effort should be further measured.

Internally-represented space and its mirror-reversed image of the visuospatial representation: A possible association.

The cognitive capacity for number representation is thought to be a functional isomorphism of space representation. Numbers are represented in a left-to-right-oriented mental number line and hemispatial neglect patients consistently demonstrate rightward midline shift of visuospace, the internal space and number representation. However, patients with pathologic pain in one limb showed a negative correlation between midline shift of the visuospace and number representation. The purpose of the present study is to ascertain whether such dissociation in accessing space and number representation is observed in another neuropathic pain condition, and then to propose a theoretical model regarding an intimate relationship between visuospace and internal space representations. Using patients with deafferentation pain caused by a nerve lesion in a limb, we investigated whether number representation is closely linked to space representation by evaluating visual subjective body-midline judgments in dark and light conditions (egocentric- and allocentric-spaces, respectively). We also used a number-interval-bisection task to analyze this question. All of the patients perceived allocentric-space accurately. Respective patients showed perceptual shifts in egocentric-space and number representation, however they did not demonstrate any trend of the shifted-direction. Direct comparison revealed that number representation is negatively correlated with not allocentric-space but egocentric-space: a leftward midline-shift of egocentric-space was linked with a rightward midline-shift of number bisection, and vice-versa. Internally-represented space demonstrated a mirror-reversed image of the visuospatial representation, similar to our previous finding. To explain the inverted representation, we can propose a theoretical model that spacing between mentally-aligned numbers in a left-to-right sequential line is anisometric.