Interactions between arm and leg neuronal circuits following paired cervical and lumbosacral transspinal stimulation in healthy humans.

Transspinal (or transcutaneous spinal cord) stimulation is a promising noninvasive method that may strengthen the intrinsic spinal neural connectivity in neurological disorders. In this study we assessed the effects of cervical transspinal stimulation on the amplitude of leg transspinal evoked potentials (TEPs), and the effects of lumbosacral transspinal stimulation on the amplitude of arm TEPs. Control TEPs were recorded following transspinal stimulation with one cathode electrode placed either on Cervical 3 (21.3 ± 1.7 mA) or Thoracic 10 (23.6 ± 16.5 mA) vertebrae levels. Associated anodes were placed bilaterally on clavicles or iliac crests. Cervical transspinal conditioning stimulation produced short latency inhibition of TEPs recorded from left soleus (ranging from - 6.11 to -3.87% of control TEP at C-T intervals of -50, -25, -20, -15, -10, 15 ms), right semitendinosus (ranging from - 11.1 to -4.55% of control TEP at C-T intervals of -20, -15, 15 ms), and right vastus lateralis (ranging from - 13.3 to -8.44% of control TEP at C-T intervals of -20 and - 15 ms) (p < 0.05). Lumbosacral transspinal conditioning stimulation produced no significant effects on arm TEPs. We conclude that in the resting state, cervical transspinal stimulation affects the net motor output of leg motoneurons under the experimental conditions used in this study. Further investigations are warranted to determine whether this protocol may reactivate local spinal circuitry after stroke or spinal cord injury and may have a significant effect in synchronization of upper and lower limb muscle synergies during rhythmic activities like locomotion or cycling.

Soleus H-reflex amplitude modulation during walking remains physiological during transspinal stimulation in humans.

The soleus H-reflex modulation pattern was investigated during stepping following transspinal stimulation over the thoracolumbar region at 15, 30, and 50 Hz with 10 kHz carry-over frequency above and below the paresthesia threshold. The soleus H-reflex was elicited by posterior tibial nerve stimulation with a single 1 ms pulse at an intensity that the M-wave amplitudes ranged from 0 to 15% of the maximal M-wave evoked 80 ms after the test stimulus, and the soleus H-reflex was half the size of the maximal H-reflex evoked on the ascending portion of the recruitment curve. During treadmill walking, the soleus H-reflex was elicited every 2 or 3 steps, and stimuli were randomly dispersed across the step cycle which was divided in 16 equal bins. For each subject and condition, the soleus M-wave and H-reflex were normalized to the maximal M-wave. The soleus background electromyographic (EMG) activity was estimated as the linear envelope for 50 ms duration starting at 100 ms before posterior tibial nerve stimulation for each bin. The gain was determined as the slope of the relationship between the soleus H-reflex and the soleus background EMG activity. The soleus H-reflex phase-dependent amplitude modulation remained unaltered during transspinal stimulation, regardless frequency, or intensity. Similarly, the H-reflex slope and intercept remained the same for all transspinal stimulation conditions tested. Locomotor EMG activity was increased in knee extensor muscles during transspinal stimulation at 30 and 50 Hz throughout the step cycle while no effects were observed in flexor muscles. These findings suggest that transspinal stimulation above and below the paresthesia threshold at 15, 30, and 50 Hz does not block or impair spinal integration of proprioceptive inputs and increases activity of thigh muscles that affect both hip and knee joint movement. Transspinal stimulation may serve as a neurorecovery strategy to augment standing or walking ability in upper motoneuron lesions.

Frequency, Risk Factors, and Outcomes of Intracranial Atherosclerotic Stenosis in Stroke Patients From the Southern Region of Saudi Arabia.

Background Intracranial Atherosclerotic Stenosis (ICAS) represents a noteworthy cerebrovascular pathology linked to ischemic stroke, contributing to a considerable burden of morbidity and mortality on a global scale. The present study was undertaken with the primary objective of investigating the frequency, risk factors, and outcomes of ICAS in stroke patients within the Southern Region of Saudi Arabia. Methods This was a descriptive cross-sectional study conducted at a tertiary care hospital located in the southern region of Saudi Arabia, from June 2022 to December 2022. The study population consisted of patients aged 18 years and above who were diagnosed with acute ischemic stroke during the designated research period. Patients with hemorrhagic stroke, transient ischemic attack (TIA), or incomplete medical records were excluded from the analysis. Data pertaining to the patients were retrieved from their respective medical records. Results Out of 201 patients admitted with stroke, 92 (45.77%) were found to have intracranial stenosis. The majority of patients were female (52.2%) and aged over 55 years (60.9%). The presence of hypertension exhibited a statistically significant correlation with varying degrees of stenosis (p=0.02), as did ischemic heart disease and obesity (p=0.04) and active smoking (p=0.01). Hypertension displayed a marginal association with intracranial stenosis, with an odds ratio of 1.01 (95% CI: 0.25, 4.11) and a p-value of 0.02. Similarly, dyslipidemia showed a potential correlation, with an odds ratio of 1.16 (95% CI: 0.44, 3.03) and a p-value of 0.014. On the other hand, obesity showed a stronger association, with an odds ratio of 4.53 (95% CI: 1.05, 19.51) and a p-value of 0.04. Among the patients, 25 (27.17%) underwent revascularization procedures, while 44 (47.83%) were not eligible for such intervention. During the three-month follow-up, 4 (16%) experienced an ipsilateral stroke, and 3 (12%) suffered from a contralateral transient ischemic attack (TIA). Encouragingly, 18 (72%) of the treated patients showed no recurrence during the follow-up period. Conclusion This study concludes that approximately half (45.77%) of stroke patients had intracranial stenosis, and significant associations were found between varying degrees of stenosis and hypertension, ischemic heart disease, obesity, and active smoking. Hypertension demonstrated a marginal correlation, while obesity exhibited a stronger association with intracranial stenosis.