The effects of paired associative stimulation of tibial nerve-M1 cortex on forelimb dysfunction in rats with cerebral ischemic stroke and the underlying mechanisms / 中华物理医学与康复杂志

Objective To explore the effects and the underlying mechanisms by which paired associative stimulation ( PAS) of tibial nerve electrostimulation and M1 cortex transcranial magnetic stimulation ( TMS) in pro-moting the recovery of forelimb dysfunction in rats with cerebral ischemic stroke. Methods Resting motor thresholds of left extensor carpi radialis muscle ( ECR) were determined 5 min before and 5 min, 30 min, 60 min after PAS,respectively, in 8 male Sprague-Dawley ( SD) rats. Then 48 male SD rats were divided into a sham group ( n=16) subject to sham surgery, an experimental group (n=32) which was further divided into a MCAO group (n=16) and a PAS group (n=16) after cerebral ischemic stroke model was established successfully by occluding the right middle cerebral artery. 24 hours after surgery, PAS consisting of left tibial nerve stimulation and right M1 cortex area TMS was applied to PAS group once daily for 7 consecutive days. The corner tests and grip strength tests were per-formed before and after 7 days of PAS treatment in each group. The RMTs of left ECR were determined, metabolites of the left area tissue of cervical spinal cord were measured by nuclear magnetic resonance spectrum, and expressions of Bcl-2 and Bax of left and right area tissue of cervical spinal cord enlargement were detected by Western Blot tech-nique after 7 days of intervention. Results The average RMTs of left ECR at 5 min, 30 min, 60 min after PAS were significantly lower than those at 5 min before PAS ( P<0.05) . All rats in experimental group showed significant higher turning scores and lower grip strength when compared with sham group (P<0.001 or P<0.01). After PAS interven-tion, PAS group demonstrated lower turning scores, higher grip strength and lower RMT of left ECR as compared with MCAO group ( P<0.05 or P<0.01) . The expression of GABA of left cervical enlargment was significantly decreased in MCAO group when compared with the sham group ( P<0.05) , and there was no significant difference between MCAO group and PAS group. Meanwhile, other metabolites showed no significant difference among the three groups. The av-erage expression level of Bcl-2 and Bax proteins in both sides of cervical spinal cord enlargment showed no significant difference among three groups either. Conclusions Tibial nerve-M1 cortex area PAS may increase the excitability of motor cortical representation of forelimbs in rats, by which PAS promotes the recovery of forelimb dysfunction in rats with cerebral ischemic stroke.

Comparison of Diffusion Tensor Tractography and Motor Evoked Potentials for the Estimation of Clinical Status in Subacute Stroke

OBJECTIVE: To compare diffusion tensor tractography (DTT) and motor evoked potentials (MEPs) for estimation of clinical status in patients in the subacute stage of stroke. METHODS: Patients with hemiplegia due to stroke who were evaluated using both DTT and MEPs between May 2012 and April 2015 were recruited. Clinical assessments investigated upper extremity motor and functional status. Motor status was evaluated using Medical Research Council grading and the Fugl-Meyer Assessment of upper limb and hand (FMA-U and FMA-H). Functional status was measured using the Modified Barthel Index (MBI). Patients were classified into subgroups according to DTT findings, MEP presence, fractional anisotropy (FA) value, FA ratio (rFA), and central motor conduction time (CMCT). Correlations of clinical assessments with DTT parameters and MEPs were estimated. RESULTS: Fifty-five patients with hemiplegia were recruited. In motor assessments (FMA-U), MEPs had the highest sensitivity and negative predictive value (NPV) as well as the second highest specificity and positive predictive value (PPV). CMCT showed the highest specificity and PPV. Regarding functional status (MBI), FA showed the highest sensitivity and NPV, whereas CMCT had the highest specificity and PPV. Correlation analysis showed that the resting motor threshold (RMT) ratio was strongly associated with motor status of the upper limb, and MEP parameters were not associated with MBI. CONCLUSION: DTT and MEPs could be suitable complementary modalities for analyzing the motor and functional status of patients in the subacute stage of stroke. The RMT ratio was strongly correlated with motor status.

Evaluation of the neuromuscular compartments in the peroneus longus muscle through electrical stimulation and accelerometry

BACKGROUND: Muscles are innervated exclusively by a nerve branch and possess definite actions. However, mammalian skeletal muscles, such as the trapezius, the medial gastrocnemius, and the peroneus longus, are compartmentalized. In the peroneus longus muscle, multiple motor points, which innervate individual neuromuscular compartments (NMC), the superior (S-NMC), anteroinferior (AI-NMC), and posteroinferior (PI-NMC), have been described. The contribution of each neuromuscular compartment to the final action of the muscle is fundamental for the rehabilitation of patients afflicted by neurological and muscle dysfunctions. Interventions are often based on electrical principles that take advantage of the physiological characteristics of muscles and nerves to generate therapeutic effects. OBJECTIVE: To compare the effects of stimulating the different neuromuscular compartments (NMCs) of the peroneus longus muscle on the motor threshold (MT) and acceleration of the foot. METHOD: This is a cross-sectional study comprising 37 subjects. The three NMCs of the peroneus longus muscle were stimulated, and the acceleration of the foot and the motor threshold of each NMC were evaluated. A repeated measures analysis of variance with Bonferroni corrections of two intra-subjects factors was performed. RESULTS: The stimulation of the different NMCs did not result in any differences in MT (F=2.635, P=0.079). There were significant differences between the axes of acceleration caused by the stimulation of the different NMCs (F=56,233; P=0.000). The stimulation of the posteroinferior compartment resulted in the greatest acceleration in the X-axis (mean 0.614; standard deviation 0.253). CONCLUSIONS: The posteroinferior compartment primarily contributes to the eversion movement of the foot. NMCs have specific functional roles that contribute to the actions of the muscles to which they belong. .

Effects of 1 Hz Repetitive Transcranial Magnetic Stimulation on Cortical Excitability and Seizure Reduction in Intractable Neocortical Epilepsy / 대한간질학회지

BACKGROUND & OBJECTIVES: Repetitive transcranial magnetic stimulation (rTMS) can modulate the excitability of cortical networks, possibly reduce the excitability by low frequency stimulation. In this study, we are conducting a study using 1 Hz rTMS in patients with intractable neocortical epilepsy. We wish to see whether 1Hz rTMS induces considerable changes in the cortical excitability and whether it leads to a significant reduction in seizure frequency in individual patients. METHODS: Patients with intractable neocortical epilepsy were recruited, and 1 Hz rTMS (110% of resting motor threshold, 1800 stimuli twice a day) was delivered to the seizure focus for 5 consecutive days. Resting motor threshold (r-MT), MEP amplitudes at different intensities, intracortical inhibition (ICI) and intracortical facilitation (ICF) were measured as TMS indices for motor cortical excitability. TMS measures were repeated before and after daily rTMS session, and again after 2 weeks. RESULTS: Four patients (aged 15 to 53, 3 females and 1 male, 2 TLE and 2 FLE) were described here:cortical excitability in 2 neocortical TLE patients showed lower r-MT and reduced ICF in ipsilateral hemisphere to epileptic focus. One of them with cortical dysplasia showed increased r-MT and ICI, and decreased ICF after daily rTMS session. This patient was seizure-free for 10 weeks, after which the seizure frequency returned to the baseline. CONCLUSIONS: Our preliminary data shows that 1 Hz rTMS may decrease cortical excitability and/or intracortical facilitation, and increase intracortical inhibition after daily rTMS. These findings suggest possible therapeutic effects of low frequency rTMS for patients with intractable neocortical epilepsy.