The effects of anodal transcranial direct current stimulation and patterned electrical stimulation on spinal inhibitory interneurons and motor function in patients with spinal cord injury.

Supraspinal excitability and sensory input may play an important role for the modulation of spinal inhibitory interneurons and functional recovery among patients with incomplete spinal cord injury (SCI). Here, we investigated the effects of anodal transcranial direct current stimulation (tDCS) combined with patterned electrical stimulation (PES) on spinal inhibitory interneurons in patients with chronic incomplete SCI and in healthy individuals. Eleven patients with incomplete SCI and ten healthy adults participated in a single-masked, sham-controlled crossover study. PES involved stimulating the common peroneal nerve with a train of ten 100 Hz pulses every 2 s for 20 min. Anodal tDCS (1 mA) was simultaneously applied to the primary motor cortex that controls the tibialis anterior muscle. We measured reciprocal inhibition and presynaptic inhibition of a soleus H-reflex by stimulating the common peroneal nerve prior to tibial nerve stimulation, which elicits the H-reflex. The inhibition was assessed before, immediately after, 10 min after and 20 min after the stimulation. Compared with baseline, simultaneous application of anodal tDCS with PES significantly increased changes in disynaptic reciprocal inhibition and long-latency presynaptic inhibition in both healthy and SCI groups for at least 20 min after the stimulation (all, p < 0.001). In patients with incomplete SCI, anodal tDCS with PES significantly increased the number of ankle movements in 10 s at 20 min after the stimulation (p = 0.004). In conclusion, anodal tDCS combined with PES could induce spinal plasticity and improve ankle movement in patients with incomplete SCI.

Premotor potential study in carpal tunnel syndrome.

INTRODUCTION: Premotor potentials (PMPs) precede compound muscle action potentials evoked from the second lumbrical muscle after median nerve stimulation. Although PMP has been identified as a median sensory nerve action potential, few reports have documented the significance of PMP parameters for diagnosing carpal tunnel syndrome (CTS). METHODS: We investigated the relationships between PMP parameters and results of 6 standard median nerve conduction studies in 74 CTS hands. RESULTS: Significant correlations were noted in all comparisons. PMP conduction velocity was strongly correlated with the sensory conduction velocity between wrist and digit 2 (r(2) = 0.91). Moreover, PMP parameters were significantly correlated with neurophysiological severity of CTS. CONCLUSION: Measuring PMP parameters with a second lumbrical-interosseous study may be useful for diagnosing CTS.

Compression of the Median Nerve and Ulnar Nerve's Deep Palmar Branch by a Ganglion Cyst in the Carpal Tunnel: A Case Report.

CASE: A 39-year-old woman presented with a ganglion cyst in the carpal tunnel simultaneously compressing the right median nerve and the deep palmar branch of the ulnar nerve. During surgery, the soft tissue was exposed under the median nerve and on the deep palmar branch of the ulnar nerve running transversely in the deep area of the carpal tunnel. CONCLUSION: Simultaneous compression of the median nerve and deep palmar branch of the ulnar nerve is extremely rare; however, such a pathoanatomical relationship must be considered while examining a patient because these nerves are located close to each other.

Two Cases of Doppler Sonography for Intraneural Vascularity of Ulnar Neuropathy at the Elbow: Before and After Surgery.

The finding of an intraneural blood flow (IBF) signal on Doppler sonography (DS) in non-surgical cases is interpreted in several ways and usually represents a pathologic condition with entrapment neuropathy. There have been no reports of the IBF signal on DS after surgery for ulnar neuropathy at the elbow (UNE). IBF was investigated before and after surgery in two cases diagnosed with UNE before surgery and confirmed after surgery. Both underwent electrodiagnostic (EDX) studies, grey scale sonography (GS), and DS before and after surgery and were diagnosed as having UNE by EDX study and GS. On DS, an IBF signal was not detected in both cases before surgery. After surgery, both cases improved their clinical and EDX findings, and an IBF signal and pulsatility were detected on DS. With respect to vascular problems, recovering venous and arterial blood supplies and dilated vessels would show much more blood flow during recovery of the affected ulnar nerve site following decompression surgery. The IBF signal would not always implicate pathology. When assessing recovery from UNE after surgery, it may be useful to evaluate intraneural vascularity at the affected site with DS.

Selective motor fascicle transfer and neural-machine interface: case report.

An amputated nerve transferred to a nearby muscle produces a transcutaneously detectable electromyographic signal corresponding to the transferred nerve; this technique is known as targeted muscle reinnervation (TMR). There are 2 issues to overcome to improve this technique: the caliber and the selectivity of the transferred nerve. It is optimal to select and transfer each motor fascicle to achieve highly developed myoelectric arms with multiple degrees-of-freedom motion. The authors report on a case in which they first identified the remnant stumps of the amputated median and radial nerves and then identified the sensory fascicles using somatosensory evoked potentials. Each median nerve fascicle was transferred to the long head branch of the biceps or the brachialis branch, while the short head branch of the biceps was retained for elbow flexion. Each radial nerve fascicle was transferred to the medial or lateral head branch of the triceps, while the long head branch of the triceps was retained for elbow extension. Electrophysiological and functional tests were conducted in the reinnervated muscles. Functional and electrophysiological improvement was noted, with marked improvement in the identification rate for each digit, forearm, and elbow motion after the selective nerve transfers. The authors note that more selective nerve transfers may be required for the development of prostheses with multiple degrees of freedom.

Quantitative evaluation of age-related decline in control of preprogramed movement.

In this paper, we examined the age-related changes in control of preprogramed movement, with emphasis on its accuracy. Forty-nine healthy subjects participated in this study, and were divided into three groups depending on their ages: the young group (20-39 years) (n = 16), the middle-age group (40-59 years) (n = 16), and the elderly group (60-79 years) (n = 17). We asked the subjects to perform step-tracking movements of the wrist joint with a manipulandum, and recorded the movements. We evaluated the accuracy of control of preprogramed movement in the three groups in terms of the primary submovement, which was identified as the first segment of the step-tracking movement based on the bell-shaped velocity profile, and calculated the distance between the end position of the primary submovement and the target (i.e. error). The error in the young group was found to be significantly smaller than that in the middle-age and elderly groups, i.e., the error was larger for the higher age groups. These results suggest that young subjects have better control of preprogramed movement than middle-age or elderly subjects. Finally, we examined the temporal property of the primary submovement and its age-related changes. The duration of the primary submovement tended to be longer for the aged groups, although significance was reached only for the elderly group. In particular, the ratio of the duration of the primary submovement to total movement time tended to be lower for the aged groups, suggesting that the proportion of additional movements that are required to compensate for the incomplete control in the preprogramed movement, which are under feedback control, was higher for the aged groups. Consequently, our results indicate that the distance between the end point of the primary submovement and the target center (i.e. error) in the step-tracking movement is a useful parameter to evaluate the age-related changes in control of preprogramed movement.

Premotor Potential Study for Diagnosis of Carpal Tunnel Syndrome.

INTRODUCTION: The second lumbrical-interossei latency difference test (2LINT) is used frequently for electrodiagnosis of carpal tunnel syndrome (CTS). A premotor potential observed with 2LINT has been identified as a median-nerve sensory nerve action potential. We evaluated the utility of the premotor potential latency analysis (i.e., premotor potential study; PPS) for CTS electrodiagnosis. METHODS: Sensitivity, specificity, and percentage "no evoked response" (%NER) values were compared prospectively among PPS, median-nerve sensory nerve-conduction studies (NCSs) for digits 1, 2, and 4, and palmar mixed NCS. RESULTS: Sixty-four healthy control hands and 104 hands with CTS were enrolled in this study. PPS sensitivity was superior to other sensory/mixed NCSs (75% vs. 42%-62%). All NCS specificities were acceptable (95%-97%). The %NER of PPS was lower than that of other NCSs (13% vs. 25%-44%). CONCLUSION: Premotor potential could be evoked in more CTS hands and was the most sensitive among median-nerve sensory and mixed NCSs. Therefore, we could use the 2LINT with PPS as median and ulnar motor NCS as well as median sensory NCS.

A new therapeutic application of brain-machine interface (BMI) training followed by hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy for patients with severe hemiparetic stroke: A proof of concept study.

BACKGROUND: Hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy improved paretic upper extremity motor function in patients with severe to moderate hemiparesis. We hypothesized that brain machine interface (BMI) training would be able to increase paretic finger muscle activity enough to apply HANDS therapy in patients with severe hemiparesis, whose finger extensor was absent. OBJECTIVE: The aim of this study was to assess the efficacy of BMI training followed by HANDS therapy in patients with severe hemiparesis. METHODS: Twenty-nine patients with chronic stroke who could not extend their paretic fingers were participated this study. We applied BMI training for 10 days at 40 min per day. The BMI detected the patients' motor imagery of paretic finger extension with event-related desynchronization (ERD) over the affected primary sensorimotor cortex, recorded with electroencephalography. Patients wore a motor-driven orthosis, which extended their paretic fingers and was triggered with ERD. When muscle activity in their paretic fingers was detected with surface electrodes after 10 days of BMI training, we applied HANDS therapy for the following 3 weeks. In HANDS therapy, participants received closed-loop, electromyogram-controlled, neuromuscular electrical stimulation (NMES) combined with a wrist-hand splint for 3 weeks at 8 hours a day. Before BMI training, after BMI training, after HANDS therapy and 3month after HANDS therapy, we assessed Fugl-Meyer Assessment upper extremity motor score (FMA) and the Motor Activity Log14-Amount of Use (MAL-AOU) score. RESULTS: After 10 days of BMI training, finger extensor activity had appeared in 21 patients. Eighteen of 21 patients then participated in 3 weeks of HANDS therapy. We found a statistically significant improvement in the FMA and the MAL-AOU scores after the BMI training, and further improvement was seen after the HANDS therapy. CONCLUSION: Combining BMI training with HANDS therapy could be an effective therapeutic strategy for severe UE paralysis after stroke.

Modulation of cortical and spinal inhibition with functional recovery of upper extremity motor function among patients with chronic stroke.

PURPOSE: We hypothesized that recovery of upper extremity motor function is associated with reduction of intracortical inhibition and improved reciprocal inhibition. This study examines the relationships of functional recovery in chronic stroke with the intracortical inhibition and spinal reciprocal inhibition. METHODS: Participants were 61 patients with chronic hemiparetic stroke. The participants were applied hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy for 3 weeks. The Fugl-Meyer test upper extremity motor score (FM) and modified Ashworth scale (MAS) were assessed before (T0), immediately after (T1) and 3 months after (T2) the end of HANDS therapy. A paired pulse TMS paradigm was applied to assess short intracortical inhibition (SICI). Reciprocal inhibition (RI) was assessed with H reflex conditioning-test paradigm. RESULTS: FM and MAS were improved until T2. The change of FM from T0 to T2 was positively correlated with the change in affected SICI from T0 toT1. The change of wrist MAS from T0 to T1 was positively correlated with the change of RI. CONCLUSIONS: In chronic stroke patients with moderate or severe hemiparesis, well-recovered patients showed disinhibition of ipsilesional hemisphere and increased resiprocal inhibition of forearm.

Swallowing appliance: intraoral reshaping prosthesis for dysphagia secondary to oral floor cancer: a pilot study.

Patients with oral floor cancer often have difficulty swallowing solid foods. The aim of this study was to improve the propulsion of solid foods using a swallowing appliance (SW-A). Subjects comprised three patients with oral floor cancer who had undergone curative surgery. Each participant was asked to swallow gelatin under three conditions: without an SW-A, with a maxillary SW-A, and with both maxillary and mandibular SW-As. This procedure was repeated thrice with three volumes of gelatin (2.5, 5, and 7.5 ml), with videofluorographic swallowing study. Swallowing was assessed on the basis of whether the participant could propel the gelatin from the oral cavity to the pharynx. No subject could propel 2.5 ml of gelatin to the pharynx without an SW-A or with only a maxillary SW-A in place. When both SW-As were used, all subjects could propel all three volumes of gelatin. The mandibular SW-A complemented the compensatory effects of the maxillary SW-A.

What is the most sensitive test for diagnosing carpal tunnel syndrome?

OBJECTIVE: To compare sensitivities between 7 principal nerve conduction studies (NCS) for diagnosing carpal tunnel syndrome (CTS). METHOD: In 104 CTS and 64 control hands, following "Standard" NCSs were examined simultaneously: (1) Median sensory NCS; (2) segmental wrist-palm sensory NCS; (3) 4th digit latency difference; (4) 1st digit latency difference and (5) palmar mixed nerve latency difference. As "Guideline" and "Option" NCSs, we also examined: (6) Median motor distal latency and (7) second lumbrical-interossei latency difference (2LILD). Forty-nine CTS hands were divided into a milder subgroup only if action potentials could be recorded using all tests applied; that is, those with any absent potentials were excluded from the subgroup. Sensitivities and specificities were compared to each other. RESULTS: In all CTS hands, the sensitivity of test (1), (2), (3), (4), (5), (6) and (7) was 83, 87, 92, 90, 90, 70 and 92%, respectively. In the milder subgroup, it was 67, 78, 84, 82, 84, 43, and 84% in the same order. There was no statistical difference between Standard tests and 2LILD. Specificities of all tests were over 95%. CONCLUSIONS: All "Standard" tests and 2LILD have high comparable sensitivities. Therefore, 2LILD should be recommended as "Standard" NCS detecting CTS.

Changes in cortical excitability during and just before motor imagery.

OBJECTIVE: Changes in cortical excitability during motor imagery were investigated in order to reveal the effect of hand dominance. During motor imagery, motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) muscle of the dominant hand using transcranial magnetic stimulation (TMS). METHODS: Twelve healthy right-handed subjects participated. Three motor imagery tasks (MITs) were provided; dominant hand grasping, non-dominant hand grasping, and ankle dorsiflexion ipsilateral to the dominant hand. MEPs were also recorded from the FDI muscle of the non-dominant hand during the same tasks. RESULT: MEPs increased significantly in the dominant hand during MIT, just before MIT of the dominant hand, and prior to ankle dorsiflexion ipsilateral to the dominant hand. MEPs obtained from the FDI muscle of the dominant hand during MITs were greater than that obtained from the FDI muscle of the non-dominant hand. However, this difference was not significant. CONCLUSION: The left primary motor cortex (M1) was more excited than M1 during MITs of the hand muscles. Cortical excitability increased just before MIT of the contralateral hand and leg muscles.

Relationship between event-related desynchronization and cortical excitability in healthy subjects and stroke patients.

OBJECTIVE: Relation between cortical excitability and magnitudes of event-related dysynchronizaton (ERD) has not been clarified. This study was investigated that relationshp between cortical excitability and ERD magnitudes in healthy subjects and stroke patients. METHODS: Ten healthy subjects and four patients with stroke participated in this study. EEGs were recorded over the sensorimotor cortex (left hemisphere in healthy subjects; damaged hemisphere in stroke subjects) to calculate ERD during motor imagery,. Motor-evoked potential (MEP) induced by single-pulse transcranial magnetic stimulation over the primary motor cortex was recorded from the first dorsal interosseus (FDI) muscle at ERD magnitudes of 10% and 30%. RESULTS: MEP significantly increased at 10% and 30% ERD (p<0.01) than that during rest in healthy subjects. The 30% ERD condition showed significantly higher MEP than that at 10% ERD (p<0.05). In stroke patients, MEP increased with ERD induced by motor imagery, but the change of MEP to ERD amplitude was critically different among the subject. CONCLUSION: ERD magnitude corresponds to corticospinal excitability increases in healthy subjects and patients with hemiplegic stroke. BCI based on motor imagery-induced ERD may be a potential rehabilitation strategy for patients with hemiplegic stroke.

Effect of low-frequency repetitive transcranial magnetic stimulation combined with physical therapy on L-dopa-induced painful off-period dystonia in Parkinson's disease.

Previous research has shown that low-frequency repetitive transcranial magnetic stimulation over the primary motor area and supplementary motor area can reduce L-dopa-induced dyskinesias in Parkinson's disease; however, it involved only patients with peak-dose or diphasic dyskinesia. We report a case of a patient with severely painful off-period dystonia in the unilateral lower limb who underwent 0.9-Hz subthreshold repetitive transcranial magnetic stimulation over contralateral primary motor area and supplementary motor area. Repetitive transcranial magnetic stimulation over the primary motor area significantly reduced the painful dystonia and walking disturbances but repetitive transcranial magnetic stimulation over the supplementary motor area did not. The cortical silent period also prolonged after repetitive transcranial magnetic stimulation over the primary motor area. At 5 mos of approximately once a week repetitive transcranial magnetic stimulation over the primary motor area, the Unified Parkinson's Disease Rating Scale motor score also improved. This report shows that repetitive transcranial magnetic stimulation over the inhibitory primary motor area can be useful for rehabilitating patients with Parkinson's disease with off-period dystonia and suggests that this treatment should be further verified in such patients.

The origin of the premotor potential recorded from the second lumbrical muscle in normal man.

OBJECTIVE: When recording with a palm electrode, a premotor potential precedes the compound muscle action potential (CMAP), evoked from the second lumbrical (2L) muscle following median nerve stimulation. The purpose of this study was to determine the origin of the premotor potential from the 2L. METHODS: We recorded potentials with multi-channel electrodes in the palm and finger in a bipolar or referential manner, stimulating the second digit or median nerve at the wrist. RESULTS: We recorded the traveling nearfield sensory nerve action potential (SNAP) and stationary negative potential in the palm. The peak latency of the stationary negative potential was the same as the one of the near-field potential of the digital sensory fibers at the base of the second finger. The onset of the premotor potential from the 2L muscle is aligned to the palmar SNAP in a bipolar manner by antidromic stimulation. CONCLUSIONS: We conclude that the premotor potential from the 2L muscle is composed of a SNAP arising from antidromically activated palm sensory branches and a far-field potential generated by the median digital nerve fibers as they pass from the palm into the second finger. SIGNIFICANCE: Our results might be useful for evaluating the 2L-interossei test for diagnosing carpal tunnel syndrome.

Suprahyoid muscles motor evoked potentials in response to transcranial magnetic stimulation.

OBJECTIVE: The objective of this study was to reveal whether corticobulbar projection to the suprahyoid muscles (SHM) is contralateral or bilateral. METHODS: Thirty-nine healthy subjects between 27 and 77 years of age participated. All subjects underwent transcranial magnetic stimulation (TMS) in both cerebral hemispheres using surface EMG recording in bilateral SHM. One subject underwent TMS in cerebral hemisphere at the same time using needle and surface EMG recording in the contralateral and ipsilateral SHM. Eight subjects underwent TMS in both cerebral hemispheres using surface EMG recording in bilateral SHM, within 6 months of the first day. RESULTS: We obtained larger response in contralateral SHM than in ipsilateral SHM in the surface EMG recording. However, in the needle EMG recording, only contralateral SHM responses were evoked. TMS of either hemisphere evoked contralateral SHM motor-evoked potentials (MEPs) in all subjects [SHM latency: (left) 8.5 ± 0.9 ms, (right) 8.6 ± 1.1 ms]. There was no significant difference in latency between the first and second tests. In a case of right medullary infarction with left cortical stimulation, MEPs of right SMH were absent. CONCLUSION: Corticobulbar projections to the SHM appear to be dominated by contralateral projections in healthy adults.

Changes in sensory functions after low-frequency repetitive transcranial magnetic stimulation over the motor cortex.

OBJECTIVE: To investigate changes in various sensory functions after low-frequency repetitive transcranial magnetic stimulation (rTMS) in healthy subjects. METHODS: A Neurometer® CPT/C was used to measure current perception threshold (CPT) values at frequencies of 2000, 250, and 5 Hz in the left index finger to assess the tactile sense, fast pain, and slow pain, respectively. Somatosensory evoked potentials (SEPs) elicited by left median nerve stimulation at the wrist were used to assess excitability in the primary sensory cortex (S1). These were investigated before and after rTMS (0.9 Hz, 0.9 ÁEresting motor threshold, 500 pulses) or sham rTMS over the right primary motor cortex (M1). RESULTS: All CPT values increased significantly and the P25-N33 of SEP amplitude decreased significantly after real rTMS, but not after sham rTMS; however, no correlations between the changes were observed. CONCLUSIONS: Low-frequency rTMS over the M1 provides global anesthetic effects and inhibits excitability in S1. The lack of correlation between these changes suggests that the anesthetic effects may not always relate to the excitability of S1; thus, the mechanisms responsible for the changes remain unclear. Nevertheless, these findings suggest that rTMS may be a useful strategy for treating intractable pain in rehabilitation medicine.

The efficacy of supraglottic swallow as an indirect swallowing exercise by analysis of hyoid bone movement.

Supraglottic swallow (SGS) is one of the swallowing maneuvers used to enhance safe bolus passage into the esophagus and to avoid aspiration into the trachea. We examined the efficacy of SGS as an indirect swallowing exercise by quantifying hyoid bone movements during SGS. Videofluorography was used to analyze SGS in 10 healthy volunteers. SGS increased the hyoid bone posterior and superior excursion, and maintained these displacements longer, suggesting the effectiveness of the SGS as an indirect swallowing exercise. Thus SGS could be used not only as air way protection but also as an indirect swallowing exercise to strengthen the muscles adhering to the hyoid bone, and to expand the range of motion of the hyoid bone.