Effects of pudendal neuromodulation on bladder function in chronic spinal cord-injured rats.

BACKGROUND/PURPOSE: Few studies have investigated the feasibility of using pudendal neuromodulation to regulate bladder function in spinal cord-injured (SCI) animals. The present study aimed to determine the effects of electrical activation of the pudendal sensory branch on improving voiding functions in rats 6 weeks after a spinal cord injury and to explore the underlying neuromodulatory mechanisms. METHODS: Two urodynamic measurements were used to assess the effects of electrical stimulation (ES) on bladder and urethral functions: simultaneous recordings of the intravesical pressure (IVP) during continuous isotonic transvesical infusion (i.e., isotonic IVP) and external urethral sphincter (EUS) electromyography (EUS-EMG), and simultaneous recordings of transvesical pressure under isovolumetric conditions (i.e., isovolumetric IVP) and urethral perfusion pressure (UPP). RESULTS: Six weeks after the SCI, the rats showed voiding dysfunction, as indicated by abnormal cystometric measurements (e.g., increased volume threshold, increased contraction amplitude, and increased residual volume, and decreased voided volume). The voiding efficiency (VE) decreased to 13% after the SCI, but increased to 22-34% after applying pudendal afferent stimulation. In addition, pudendal stimulation significantly increased the EUS burst period and increased the difference between the UPP and the high-frequency oscillation (HFO) baselines, and changed the time offset between bladder and EUS activities. These findings suggest that pudendal afferent stimulation improved the VE by prolonging the micturition interval, decreased the urethral resistance, and recovered detrusor-sphincter dyssynergia during the voiding phase. CONCLUSION: This study demonstrates the feasibility of using pudendal neuromodulation in chronic SCI rats. These results could aid in developing an advanced neural prosthesis to restore bladder function in clinical settings.

Low-cost tele-assessment system for home-based evaluation of reaching ability following stroke.

OBJECTIVE: Tele-assessment techniques can provide healthcare professionals with easily accessible information regarding patients' clinical progress. Recently, kinematic analysis systems have been used to assess rehabilitative outcomes in stroke patients. Kinematic systems, however, are not compatible with tele-assessment. The objective of our study was to develop a tele-assessment system for acquiring kinematic data of forward reaching movements in stroke patients, with an emphasis on cost-effectiveness, portability, and ease of use. MATERIALS AND METHODS: We selected four healthy control participants and eight hemiplegic stroke patients for our study. The stroke patients were classified as Brunnstrom stage III, stage IV, or stage V. Our tele-assessment system used two three-axes accelerometers, a potentiometer, a multifunctional data acquisition card, and two computers. A standardized kinematic system was applied simultaneously to validate the measurements recorded by our tele-assessment system during five repetitions of forward reaching movements. RESULTS: The correlation coefficients of the reaching displacement, velocity, and acceleration measurements obtained using our tele-assessment system and the standardized kinematic system were 0.956, 0.896, and 0.727, respectively. Differences in the maximum reaching distance and the maximum reaching velocity of forward reaching movements were observed among the study groups. There were no significant differences in the time required to complete the testing session among the study groups. CONCLUSIONS: Our tele-assessment system is valid for the evaluation of upper-extremity reaching ability in stroke patients. Further research is needed to investigate the feasibility of the use of the tele-assessment system in patients' homes.

Quantification and recognition of parkinsonian gait from monocular video imaging using kernel-based principal component analysis.

BACKGROUND: The computer-aided identification of specific gait patterns is an important issue in the assessment of Parkinson's disease (PD). In this study, a computer vision-based gait analysis approach is developed to assist the clinical assessments of PD with kernel-based principal component analysis (KPCA). METHOD: Twelve PD patients and twelve healthy adults with no neurological history or motor disorders within the past six months were recruited and separated according to their "Non-PD", "Drug-On", and "Drug-Off" states. The participants were asked to wear light-colored clothing and perform three walking trials through a corridor decorated with a navy curtain at their natural pace. The participants' gait performance during the steady-state walking period was captured by a digital camera for gait analysis. The collected walking image frames were then transformed into binary silhouettes for noise reduction and compression. Using the developed KPCA-based method, the features within the binary silhouettes can be extracted to quantitatively determine the gait cycle time, stride length, walking velocity, and cadence. RESULTS AND DISCUSSION: The KPCA-based method uses a feature-extraction approach, which was verified to be more effective than traditional image area and principal component analysis (PCA) approaches in classifying "Non-PD" controls and "Drug-Off/On" PD patients. Encouragingly, this method has a high accuracy rate, 80.51%, for recognizing different gaits. Quantitative gait parameters are obtained, and the power spectrums of the patients' gaits are analyzed. We show that that the slow and irregular actions of PD patients during walking tend to transfer some of the power from the main lobe frequency to a lower frequency band. Our results indicate the feasibility of using gait performance to evaluate the motor function of patients with PD. CONCLUSION: This KPCA-based method requires only a digital camera and a decorated corridor setup. The ease of use and installation of the current method provides clinicians and researchers a low cost solution to monitor the progression of and the treatment to PD. In summary, the proposed method provides an alternative to perform gait analysis for patients with PD.

Patient-driven loop control for hand function restoration in a non-invasive functional electrical stimulation system.

PURPOSE: In this study, a patient-driven loop control in a non-invasive functional electrical stimulation (FES) system was designed to restore hand function of stroke patients with their residual capabilities. METHOD: With this patient-driven loop control, patients use the electromyographic (EMG) signals from their voluntary controlled muscles in affected limbs to adjust stimulus parameters of the system. A special designed FES system generated electrical stimuli to excite the paralyzed muscles through surface electrodes on the basis of the control command from the residual myoelectric signals. EMG signals were also served as the trigger and the adjustment of stimulus parameters and thereby adding versatility of the FES system. Four stroke patients were recruited in the experiment to validate our system. RESULTS: The experimental results showed that hemiplegics could successfully control the system to restore their lost hand functions with the strategy of patient-driven loop control (the average estimated success rate was 77.5% with the tasks of cylindrical grasp and lateral pinch); and further, they would benefit by using the residual capabilities to regain their hand functions from the viewpoints of rehabilitation and psychology. CONCLUSION: According to the experiment results, this patient-driven loop control can be beneficial for hemiplegics to restore their hand functions such as cylindrical grasp and lateral pinch. The control strategy of this study has the potential to be employed not only in the FES system but also in other assistive devices.

A remote data access architecture for home-monitoring health-care applications.

With the aging of the population and the increasing patient preference for receiving care in their own homes, remote home care is one of the fastest growing areas of health care in Taiwan and many other countries. Many remote home-monitoring applications have been developed and implemented to enable both formal and informal caregivers to have remote access to patient data so that they can respond instantly to any abnormalities of in-home patients. The aim of this technology is to give both patients and relatives better control of the health care, reduce the burden on informal caregivers and reduce visits to hospitals and thus result in a better quality of life for both the patient and his/her family. To facilitate their widespread adoption, remote home-monitoring systems take advantage of the low-cost features and popularity of the Internet and PCs, but are inherently exposed to several security risks, such as virus and denial-of-service (DoS) attacks. These security threats exist as long as the in-home PC is directly accessible by remote-monitoring users over the Internet. The purpose of the study reported in this paper was to improve the security of such systems, with the proposed architecture aimed at increasing the system availability and confidentiality of patient information. A broker server is introduced between the remote-monitoring devices and the in-home PCs. This topology removes direct access to the in-home PC, and a firewall can be configured to deny all inbound connections while the remote home-monitoring application is operating. This architecture helps to transfer the security risks from the in-home PC to the managed broker server, on which more advanced security measures can be implemented. The pros and cons of this novel architecture design are also discussed and summarized.

An effective and efficient compression algorithm for ECG signals with irregular periods.

This paper presents an effective and efficient preprocessing algorithm for two-dimensional (2-D) electrocardiogram (ECG) compression to better compress irregular ECG signals by exploiting their inter- and intra-beat correlations. To better reveal the correlation structure, we first convert the ECG signal into a proper 2-D representation, or image. This involves a few steps including QRS detection and alignment, period sorting, and length equalization. The resulting 2-D ECG representation is then ready to be compressed by an appropriate image compression algorithm. We choose the state-of-the-art JPEG2000 for its high efficiency and flexibility. In this way, the proposed algorithm is shown to outperform some existing arts in the literature by simultaneously achieving high compression ratio (CR), low percent root mean squared difference (PRD), low maximum error (MaxErr), and low standard derivation of errors (StdErr). In particular, because the proposed period sorting method rearranges the detected heartbeats into a smoother image that is easier to compress, this algorithm is insensitive to irregular ECG periods. Thus either the irregular ECG signals or the QRS false-detection cases can be better compressed. This is a significant improvement over existing 2-D ECG compression methods. Moreover, this algorithm is not tied exclusively to JPEG2000. It can also be combined with other 2-D preprocessing methods or appropriate codecs to enhance the compression performance in irregular ECG cases.

The M3S-based electric wheelchair for the people with disabilities in Taiwan.

PURPOSE: This study aims to establish an electronic wheelchair system in Taiwan that conforms to multiple master-multiple slave (M3S) standards. The proposed system could enhance the safety and convenience of people with disabilities. MATERIAL AND METHOD: The M3S-based head-controlled electric wheelchair consists of three parts: (A) the input device, (B) the output device, and (C) the safety device. Head movement can be used as the input control to cause the tilting device to produce a corresponding level of analog voltage (backward & forward/left & right) which is then transmitted to the analogy/digital conversion module to control the output device (wheelchair's motor). Ten subjects with C5 incompleted spinal cord injury were recruited in the clinical assessment. They were randomly assigned into groups A and B. In the group A, the subjects were assigned to operate the head-controlled wheelchair system with M3S standard before operating the head-controlled wheelchair system without M3S standard. In the group B, the subjects were assigned to operate the head-controlled wheelchair system without M3S standard before operating the head-controlled wheelchair system with M3S standard. Two subjects in the group B drop off due to their personal reasons. RESULTS: The time cost for group A in completing tasks 1, 2, and 3 with the M3S and without the M3S were insignificant (p>0.05). The time cost for completing in group B was insignificant (p>0.05). Thus, the wheelchair operating time is depended on the proficiency of the subjects, not the M3S standard added. DISCUSSIONS AND CONCLUSIONS: The time cost for subjects to operate the wheelchair was determined by their proficiency, not the M3S standard control added to the system. However, the M3S-based system did realize the safety mechanism and complex auxiliary tools with and without the plug-in and play function.

A laser micromachined probe for recording multiple field potentials in the thalamus.

Multichannel recording provides integral information about electrical brain activities at one instant in time. In this study, multielectrode probes were fabricated to record the thalamic field potentials (FPs) responding to the electrical stimulation of nerve at the rat tail. At first, the number of sweeps used to form the evoked FP average and the spatial sampling density were determined by using cross-correlation functions, which were then statistically analyzed. The difference was significant at P < 0.05, if the number of sweeps for averaging was more than 50 and the spatial interval between two consecutive recording sites was less than 50 microm in the anteroposterior, mediolateral and ventrodorsal directions. The responsive area was distributed vertically in the thalamus (ventral posterior lateral (VPL) nucleus); therefore, the recording sites were arranged in one linear array. Sixteen recording sites, which were 50 microm apart from each other, were distributed in the ventrodorsal direction. A 16-channel silicon probe was fabricated by using a standard photolithography process and laser micromachining techniques. The probe provides capabilities to record multiple thalamic evoked FPs and multiunit activities simultaneously.

One-dimensional phased array with mechanical motion for conformal ultrasound hyperthermia.

This paper investigates the feasibility of conformal heating for external ultrasound hyperthermia by using a phased array transducer with mechanical motion. In this system, a one-dimensional phased array is arranged on a shaft and moves along the shaft, while dynamically focusing on the planning target volume (PTV) with numerous focal spots. To prevent overheating in the intervening tissue between the skin and the PTV, the shaft and the phased array are rotated together to enlarge the acoustical window. With the purpose of conformal heating, the power deposition of the PTV is constructed by combinations of the focal spots and an iterative gradient descent method is then used to determine an optimal set of power weightings for the focal spots. Different tumour shapes are evaluated and the simulation results demonstrate that the volume percentage of the PTV with temperatures higher than 43 degrees C is over 95%. The overheating volume outside the PTV is less than 25% of the PTV. This method provides good conformal heating for external ultrasound hyperthermia. The concept of combining electrical focusing and mechanical motion has the advantages of both enlarging the acoustic window and providing dynamic focusing ability, which is essential for successful conformal heating.

The comparison of electromyographic pattern classifications with active and passive electrodes.

Electromyographic (EMG) signals are usually acquired using surface electrodes, and they commonly serve as the control sources of myoelectric prosthetic limbs. The use of passive electrodes and amplifiers with adjustable gain is very popular in laboratories for the development of new control strategies. However, active electrodes without conductive jelly are used in most clinical applications of myoelectric hand control. There remains an important question: Are there any differences between using active and passive electrodes in EMG pattern classifications? Autoregressive and cepstral coefficients were used to evaluate recognition rates via both types of electrodes. The results showed that the estimated recognition rates in the passive electrodes were comparable to those in the active ones (averaged recognition rate, 88.5 vs. 85.84% in the autoregressive coefficients, and 84.84 vs. 83.5%, in the cepstral coefficients, respectively). Aside from the lack of significant statistical differences between them, the results imply that the differences between the recognition rates via these electrodes could be negligible. This would be helpful for the myoelectric control of assistive devices.

A head movement image (HMI)-controlled computer mouse for people with disabilities.

PURPOSE: This study proposes image processing and microprocessor technology for use in developing a head movement image (HMI)-controlled computer mouse system for the spinal cord injured (SCI). METHOD: The system controls the movement and direction of the mouse cursor by capturing head movement images using a marker installed on the user's headset. In the clinical trial, this new mouse system was compared with an infrared-controlled mouse system on various tasks with nine subjects with SCI. RESULTS: The results were favourable to the new mouse system. The differences between the new mouse system and the infrared-controlled mouse were reaching statistical significance in each of the test situations (p<0.05). CONCLUSIONS: The HMI-controlled computer mouse improves the input speed. People with disabilities need only wear the headset and move their heads to freely control the movement of the mouse cursor.

Infrared-based communication augmentation system for people with multiple disabilities.

PURPOSE: This study describes an eyeglass-type infrared-based communication board for the nonspeaking with quadriplegia. METHOD: This system is composed of four major components: a headset, an infrared transmitting module, an infrared receiving/signal-processing module, and a main controller, the Intel-8951 microprocessor. This design concept was based on the use of an infrared remote module fastened to the eyeglasses which could allow the convenient control of the input motion on the keys of a communication board, which are all modified with infrared receiving/signal-processing modules. For system evaluation, 12 subjects (all men, 21-45 years old, six normal subjects as the control group and six nonspeaking with quadriplegia as the experimental group) were recruited. RESULTS: The average accuracy of the control group and the experimental group were 93.1 +/- 4.3% and 89.7 +/- 5.5%, respectively. The average time cost of the control group and the experimental group were 78.3 +/- 8.7 s and 89.9 +/- 10.2 s, respectively. An independent t-test revealed that the differences in the average accuracy and the average time cost of the control group and the experimental group were not significant (p>0.05). CONCLUSIONS: The increase of opportunity to communicate using the infrared-based communication board would help people with multiple disabilities to socialize actively.

SEMG-controlled telephone interface for people with disabilities.

This paper proposes the development of a surface electromyographic (SEMG)-controlled telephone interface for the disabled. The system is composed of three major components: (1) a SEMG receiving/signal-processing module; (2) a row-column scanning interface for the telephone dialling pad; and (3) a main controller, the Intel-8951 microprocessor. The design concept was based on the idea of using a SEMG generated by the disabled and converting it into a trigger pulse. This could allow convenient control of the dialing motion in the row-column scanning keys of a telephone dialling pad. People with disabilities are competent for certain kinds of work such as being a telephone operator. The increase of opportunities to perform a job for the disabled would help them live independently.

Neural network and fuzzy control in FES-assisted locomotion for the hemiplegic.

This study is aimed at establishing a neural network and fuzzy feedback control FES system used for adjusting the optimum electrical stimulating current to control the motion of an ankle joint. The proposed method further improves the drop-foot problem existing in hemiplegia patients. The proposed system includes both hardware and software. The hardware system determines the patient's ankle joint angle using a position sensor located in the patient's affected side. This sensor stimulates the tibialis anterior with an electrical stimulator that induces the dorsiflexion action and achieves the ideal ankle joint trace motion. The software system estimates the stimulating current using a neural network. The fuzzy controller solves the nonlinear problem by compensating the motion trace errors between the neural network control and actual system. The control qualities of various controllers for four subjects were compared in the clinical test. It was found that both the root mean square error and the mean error were minimal when using the neural network and fuzzy controller. The drop-foot problem in hemiplegic's locomotion was effectively improved by incorporating the neural network and fuzzy controller with the functional electrical simulator.

Pudendal neuromodulation with a closed-loop control strategy to improve bladder functions in the animal study.

The aim of this study was to develop a new closed-loop control strategy for improving bladder emptying and verify its performance in animal experiments. Two channel outputs of electrical currents triggered by intravesical pressure (IVP)-feedback signals were set to automatically regulate the rat's pudendal nerve for selective nerve stimulation and blocking. Under this experimental design, a series of in-vivo animal experiments were conducted on anesthetized rats. Our results showed that the IVP-feedback control strategy for dual-channel pudendal neuromodulation performed well in animal experiments and could be utilized to selectively stimulate and block the pudendal nerve to augment bladder contraction and restore external urethral sphincter (EUS) bursting activity to simultaneously improve bladder emptying. This study demonstrates the feasibility of the IVP-based feedback-control strategy with animal experiments, and the results could provide a basis for developing a sophisticated neural prosthesis for restoring bladder function in clinical use or the relative neurophysiological study.

Reducing anterior tibial translation by applying functional electrical stimulation in dynamic knee extension exercises: quantitative results acquired via marker tracking.

BACKGROUND: Pain that accompanies anterior cruciate ligament deficiency during dynamic knee extension exercises is usually caused by excessive anterior tibial translation, which can be restricted if the anterior cruciate ligament was intact. METHODS: A functional electrical stimulator is incorporated with a training device to induce hamstring contractions during certain degrees of knee extension to replicate effects similar to those generated by an intact anterior cruciate ligament and to reduce anterior tibial translation. By using a camera that tracks markers placed on bony prominences of the femur and tibia, the anterior tibial translations corresponding to various settings were determined by customized image processing procedures. FINDINGS: In the electrical stimulation sessions, the knee extensions with electrical stimulation feedback induced significantly (n=6, P<.05) less anterior tibial translation over the range of 20 to 50° when compared to those using the standard isokinetic shank restraint. Likewise, the knee extensions with an anti-shear device that blocks tibia displacement mechanically also induced significantly (n=6, P<.05) less anterior tibial translation, but over a different range of knee extension (30 to 70°). INTERPRETATION: Despite the fact that both the electrical stimulator and the anti-shear device assisted in reducing anterior tibial translation, the tendency of the curves generated with the functional electrical stimulation was generally more similar to those generated when using the standard isokinetic shank restraint.

Pulse energy as a reliable reference for twitch forces induced by transcutaneous neuromuscular electrical stimulation.

Voltage-controlled neuromuscular electrical stimulation has been considered to be safer in noninvasive applications notwithstanding the fact that voltage-controlled devices purportedly generate forces less predictable than their current-controlled equivalents. This prompted us to evaluate relevant electrical parameters to determine whether forces induced by voltage-controlled stimuli were able to match to those induced by current-controlled ones, which tend to evoke forces that were more predictable. Force magnitudes corresponding to current- and voltage-controlled stimuli were aligned with respect to electric charge (equivalent to average current intensity) and electrical energy (equivalent to average power) of the same stimulation pulse to determine which provided a better coherence. Consistency of forces evaluated with energy was significantly (p < 0.001) better than that evaluated with electric charges, suggesting that electrically stimulated forces can be reliably predicted by monitoring the energy parameter of stimulation pulses. The above results appear to show that electrode-tissue impedance, a factor that makes charge and energy evaluations different, redefined the actual effects of current intensities in generating favorable results. Accordingly, novel schemes that track the energy (or average power) of a stimulation pulse may be used as a reliable benchmark to associate mechanical (force) and electrical (stimulation pulse) characteristics in transcutaneous applications of electrical stimulation.

Clinical effects of combined bilateral arm training with functional electrical stimulation in patients with stroke.

Cerebral vascular disease (or stroke) is the main cause of disabilities in adults. Upper-limb dysfunction after stroke usually exists, leading to severe limits of motor capabilities as well as daily activities. Therefore, effective treatment interventions for upper-limb rehabilitation after stroke are needed. Based on the neurophysiological evidence and clinical measures, combined bilateral arm training (BAT) with functional electric stimulation (FES) could improve hand function in stroke patients. In this study, we attempt to combine BAT with FES applying to the post-stroke paretic arm. A linear guide platform with FES feedback control was developed to execute the training of bilateral reaching movements. 35 stroke subjects were recruited and divided into two groups (BAT with FES and BAT alone). 23 participants completed this experiment with 3-week intervention. According to our preliminary results, a favorable trend toward improvement in experimental group (BAT with FES) existed after treatment and at follow-up. Further analysis would be conducted to investigate the kinematic change on motor performance. Moreover, various treatment doses as well as more functional approaches would also be considered for better effects of upper limb rehabilitation after stroke.

Electric compass aided global positioning system navigation for powered wheelchairs.

Powered wheelchairs are an important mobility aid for the elderly and for persons with disability. According to World Health Organization statistics, most of the accidents were due to personal mistakes; if there is an auto-navigating system such as auxiliary, mistaken manipulation will decrease efficiency. This study attempted to improve the global positioning system (GPS) navigation of electric powered wheelchairs (EPWs) through the addition of an electric compass (EC) and tested the navigation of EPWs with EC-aided and non-EC-aided GPS navigation along a 25 m road. According to these tests, the use of the EC significantly reduces the errors in GPS navigation during movements such as go straight ahead, turn right and turn left. Therefore, the navigation reduced the error of the expected trajectories with the EC-aided navigation.

Phantom limb pain treated by far infrared ray.

We have treated a patient with severe phantom limb pain by a novel far infrared ray (FIR) therapy. The patient has suffered persistent and progressively worsening phantom limb pain after amputation ten years ago. He also experienced severe muscle spasm and twitch of stump during the attacks. His phantom limb pain was excruciating and was rated up to 9 by the Visual Analog Pain Scale. Various pain treatment modalities have been used but in vain, including medications and rehabilitation. He also underwent two episodes of sympathectomy, only achieving short-term effects for three months. Then he underwent our new treatment method. We applied FIR to the amputated limb site instead of the stump of the patient for 40 minutes for each treatment session twice a week. One month after the FIR treatment, he felt much improved and rated his phantom pain at 4, and down to 2-3 after two months of treatment. The duration of each phantom limb pain attack has significantly reduced from over 24 hours to only a few minutes or seconds after five months of FIR treatment. During a six-month post-treatment follow-up, his phantom limb pain occurred seldom for only a few seconds at a low 1-2 rating on the pain scale. The analgesic effect of FIR treatment has prevented him from the scheduled third sympathectomy and the risk of heart attack followed by severe twitch of stump. The results of this study demonstrate an easy, non-invasive and effective treatment modality for phantom limb pain.