We have developed a system that uses continuous magnetic stimulation for painless non-invasive treatment of urinary incontinence, especially stress incontinence and urge incontinence, without requiring clothes removal. The system consists of a functional continuous magnetic stimulator (FCMS), a saddle-type coil, a reclining chair and a cooler for the coil. Patients sit in the chair and receive continuous magnetic stimulation (CMS) or burst magnetic stimulation (BMS) for 15min once per treatment. BMS is CMS for 60 sec followed by a 30 sec break repeated cyclically. The CMS mode is used for urinary urge incontinence, and the BMS mode for stress incontinence. The stimulation conditions are a capacitor charge of less than 1, 000V and a 720μs pulse width (180μs rise time). The frequency of stimulation is 10Hz for urge incontinence and 20Hz for stress incontinence. BMS at a frequency of 20Hz for 15min was applied to the pelvic floor muscle or the pudendal nerves of two healthy subjects. The intensity was 55%. The urethral pressure of one of the subjects was 20-30cmH₂O before applying BMS, 40-50cmH₂O during the first 60-sec stimulation, and 20-30cmH₂O during the next 30 sec when stimulation was ceased. This indicates that magnetic stimulation caused contraction of the pelvic floor muscle or urethral sphincter (Rhabdosphincter) and that this system is useful for the treatment of urinary incontinence.

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This paper proposes a concept for a new tool that enables observation of three-dimensional (3D) medical images as a form of computer aided diagnosis and shows an example of implementation. In recent years, 3D medical images have become indispensable in real clinical medicine. Since the images consist of numerous two-dimensional (2D) slices, development of a new diagnostic method is highly anticpated as a means to reduce the workload on doctors. In particular, it is necessary to develop a tool which assists in the observation of 3D medical images. The goal of this paper is to realize a system which can provide a seamless observation environment for 2D and 3D medical images using 3D graphics hardware. The proposed system can seamlessly visualize a 3D medical image using a variety of observation methods such as slice display, 3D maximum intensity projection and 3D volume rendering in real time, without any stress to the system. Here ‘seamless’ means that a user can observe and manipulate 2D and 3D images without worrying about their dimensionality. Thus, the user can specify the region of interest on both 2D and 3D images in the same way. The region specified by the user on one of 2D (or 3D) images is immediately presented on the other 3D (or 2D) image. This operation is executed very quickly and the user can treat 2D and 3D display of the image input seamlessly. The proposed system enables doctors to perform ‘efficient observation of multiple slices’ and ‘easy understanding of the 3D shape of organ.’ We implemented the proposed system on a graphics workstation (SGI Octane MXB). The results showed that the user could efficiently find and analyze a suspicious region in 3D medical images.

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Responses of limb movement to external impulsive perturbation during human walking were studied. We measured hip, knee and ankle joint angles and instants of foot contact and lift of both right and left legs from a subject walking on a treadmill. The perturbation was applied at various phases of the locomotion cycle. The result was summarized in sequential changes of phase delay functions which represent phase-dependent dynamic responses to the perturbation. Walking rhythm was delayed for perturbations applied at early swing phases, advanced for late swing phases, and not modified for stance phases. Using the data from our study, we then discuss the neural control mechanism of human locomotion.

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Contamination of blink artifacts in electroencephalographic (EEG) records often causes serious misconceptions in EEG analysis and/or the processing of evoked potentials because the amplitude of the blink artifact is much larger than that of the EEG. This paper proposes a method for real-time processing of blink artifact elimination on EEG records. The feature of the elimination method is acquisition of an appropriate feature of the blink artifact waveform in resards to the respective amplitudes and durations. For realizing real-time processing, an algorithm for blink artifact elimination, consisting of preprocessing of the EEG, blink artifact detection, normalized averaging and denormalization, was derived using on-line algorithms and implemented in real time. The proposed method exhibited satisfactory performance for eliminating blink artifacts on recorded EEG data acquired from five subjects.

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One of the major problems in the clinical application of FES is muscle fatigue. M-waves have been found to be useful for detecting muscle fatigue in voluntary movements and FES control. We discuss a new method of using M-waves to detect and evaluate muscle fatigue in FES control. The method used double pulses with various inter-pulse intervals (IPIs), which were made by additional pulses inserted into a stimulus pulse train. In this paper, the new method was examined using four neurologically intact subjects by applying electrical stimulation through surface electrodes. M-waves from the vastus lateralis muscle and the isometric muscle force at the ankle joint were measured when the muscle was stimulated at supra maximum amplitude or the maximum amplitude that subjects could bear stimulation over 200s. We found that the peak-to-peak amplitude of M-wave, both V_aft and V_bef, which were evoked by the stimulus pulses just after or before the double pulse, respectively, showed good correlation with isometric muscle force. The peak-to-peak amplitude of the M-wave evoked by the second pulse, V_2nd, decreased sharply in the earlier stage as the IPI decreased. It was shown that V_bef could predict electrically induced muscle force. A new index to evaluate muscle fatigue using V_2nd, FI_2nd, was found to be useful. The results showed that the method of using double pulses with various IPIs has the ability to detect and evaluate muscle fatigue in more detail, and in the early stage of muscle fatigue.

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For immobile patients, pressure sores are one of the most severe diseases. When such people must continuously lay or sit in the same posture, pressure sores can from as a result. However, the mechanism that causes pressure sores is not fully understood. In this study, we examined the skin surface temperature (SST) under pressure loading and relief in rabbits, and discussed the influence of ambient temperature on SST at the ischemic area. When the pressure load duration was changed, SST at the compressed area was compared. Animals were healthy rabbits whose ears were compressed with a local external pressure of 40kPa for 10, 120 or 240min. As the ambient temperature was controlled constantly within 20.0-30.0°C, the SST was determined by a thermocouple. The results revealed that the SST of the complete localized ischemic area changed due to the different average of ambient temperature under the same pressure loading and relief. Under the optional ambient temperature, the SST at the compressed area increased during the initial 30min under pressure loading. It was shown that the recovery time of the SST at the compressed area when released from pressure loading became longer the lower the ambient temperature and the longer the duration of pressure loading. In order to prevent pressure sores, it is necessary to analyze not only the ischemic area released from pressure loading, but also physiological factors including SST.

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This paper describes a method for band-pass filtering of brain waves using the Haar wavelet and of detecting the P300 component of event-related potentials (ERPs). For the visual stimulus of the word-selecting experiments, 5 words were used. The words were selected in a pseudo-random sequence and displayed on a screen for 300-400ms with a cyclic period of. 500-700ms. The target word was randomly applied with a probability of 20%. The subject was instructed to keep a mental count of the number of target words. The P300 components were obtained from the target responses utilizing the following methods: 1) Band-pass filtering of the central frequency of 3Hz, 2) Averaging the single-trial responses to each stimulus 30 times, 3) Subtracting the common components in ERP responses for both target stimuli and nontarget stimuli, and 4) Cutting out the P300 using the time-window of the trapezoidal form. Results show that the P300 component can be used to detect the attention of the subject without any physical action. This P300 component is useful as a human-interface for communication aids.

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