Contralateral acute subdural hematoma occurring after evacuation of subdural hygroma: case report.
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Acute Disease↗
Biomedical subjects
H L Yen
Publications and source records attributed to H L Yen.
Multichannel ECG compression using multichannel adaptive vector quantization.
Adaptive vector quantization (AVQ) is a recently proposed approach for electrocardiogram (ECG) compression. The adaptability of the approach can be used to control the quality of reconstructed signals. However, like most of other ECG compression methods, AVQ only deals with the single-channel ECG, and for the multichannel (MC) ECG, coding ECG signals on a channel by channel basis is not efficient, because the correlation across channels is not exploited. To exploit this correlation, an MC version of AVQ is proposed. In the proposed approach, the AVQ index from each channel is collected to form a new input vector. The vector is then vector quantized adaptively using one additional codebook called index codebook. Both the MIT/BIH database and a clinical Holter database are tested. The experimental results show that, for exactly the same quality of reconstructed signals, the MC-AVQ performs better than single-channel AVQ in terms of bit rate. A theoretical analysis supporting this result is also demonstrated in this paper. For the same and relatively good visual quality, the average compressed data rate/channel is reduced from 293.5 b/s using the single-channel AVQ to 238.2 b/s using the MC-AVQ in the MIT/BIH case.
Algorithms↗
Patterns of palmar skin temperature alterations during transthoracic endoscopic T2 sympathectomy for palmar hyperhidrosis.
Transthoracic endoscopic T2 sympathectomy has been widely applied to the treatment of a variety of sympathetically mediated disorders. Palmar hyperhidrosis is probably the most common indication for thoracic sympathectomy, especially in certain subtropical areas. Which sympathetic ganglion is to be ablated and how extensive such ablation is enough to eliminate palm sweating are two important issues. Intraoperative monitoring of palmar skin temperature (PST) is the most frequently used method for assessing the accuracy as well as adequacy of ablation of the target sympathetic ganglia. With continuous monitoring of bilateral PST during the operative course of T2 sympathectomy, it was possible to depict the alterations of bilateral PST in response to specific surgical procedures in a real-time manner. For each case, a PST graph was obtained, which represented the graphical expression of intraoperatively recorded bilateral PST data plotted against time. The PST graphs of 93 consecutive cases were analysed. Three types of PST graphs existed, reflecting different responses of bilateral PST to different surgical procedures during the operation. In Type I PST graph pattern, found in 58 cases, skin incision and intercostal muscle dissection caused dramatic bilateral PST drop; and unilateral T2 sympathectomy induced synchronous bilateral PST elevation. Twenty-four cases demonstrated Type II PST graph pattern, in which unilateral T2 sympathectomy caused only ipsilateral PST elevation, although the PST-depressing effect of skin incision and muscle dissection was as significant as in Type I graph pattern. In the 11 cases who showed Type III PST graph pattern, neither skin incision nor T2 sympathectomy induced any apparent changes of PST on either side, giving rise to two rather flat PST curves on the PST graphs. These findings implicate that reciprocal interactions between bilateral sympathetic activities exist in the majority of cases, and that crossover sympathetic modulation may play a role in the neural control of the sudomotor and vasomotor activities of the palms. This study also provides information regarding how PST would possibly change following specific surgical procedures during transthoracic endoscopic T2 sympathectomy, which may be of importance to those who use intraoperative PST monitoring as a guide in determining whether or not the correct sympathetic ganglia are ablated for adequate sympathetic denervation of the palms.
Adolescent↗
Quality driven gold washing adaptive vector quantization and its application to ECG data compression.
The gold washing (GW) adaptive vector quantization (AVQ) (GW-AVQ) is a relatively new scheme for data compression. The adaptive nature of the algorithm provides the robustness for wide variety of the signals. However, the performance of GW-AVQ is highly dependent on a preset parameter called distortion threshold (dth) which must be determined by experience or trial-and-error. We propose an algorithm that allows us to assign an initial dth arbitrarily and then automatically progress toward a desired dth according to a specified quality criterion, such as the percent of root mean square difference (PRD) for electrocardiogram (ECG) signals. A theoretical foundation of the algorithm is also presented. This algorithm is particularly useful when multiple GW-AVQ codebooks and, thus, multiple dth's are required in a subband coding framework. Four sets of ECG data with entirely different characteristics are selected from the MIT/BIH database to verify the proposed algorithm. Both the direct GW-AVQ and a wavelet-based GW-AVQ are tested. The results show that a user specified PRD can always be reached regardless of the ECG waveforms, the initial selection of dth or whether a wavelet transform is used in conjunction with the GW-AVQ. An average result of 6% in PRD and 410 bits/s in compressed data rate is obtained with excellent visual quality.
Algorithms↗
Infectious disease of the spine: outcome of rehabilitation.
Infectious disease of the spine is infrequently seen in the rehabilitation setting. We examined retrospectively 26 patients with spinal infections admitted to the rehabilitation centre over a 6-year period to determine the demographic characteristics, clinical features and outcome after rehabilitation. Their ages ranged from 24 to 83 years (mean = 56.4); 65.4% were males. The infection was due to pyogenic bacteria in 14 patients (53.8%) and Mycobacterium tuberculosis in 12 (46.2%). Staphylococcus aureus was the causative agent in 69% of those with pyogenic infections. A history of diabetes mellitus was present in 35.7% of the pyogenic group but in only 8.3% of the tuberculous group. Localised back pain, fever and neurological deficits were the typical clinical manifestations. The most common site of infection was the thoracic region. Surgery was performed on 24 patients and all received prolonged courses of antibiotics. All but three patients completed the rehabilitation programme. The motor score for the lower limbs and the modified Barthel scores for activities of daily living (ADL) and mobility improved significantly (P < 0.05) for both pyogenic and tuberculous groups. The amounts of improvement achieved were not significantly different between the pyogenic and tuberculous groups except for ADL. Age, gender and the presence of diabetes mellitus did not appear to significantly affect the neurological or functional outcome in our study population. The majority of patients (87.5%) were discharged to their own homes.
Activities of Daily Living↗
Spinal injury rehabilitation in Singapore.
Traumatic spinal cord injuries (SCI) are often preventable. In order to determine the characteristics and rehabilitation outcome of our spinal injured, we carried out a retrospective study of SCI patients admitted between January 1990 and December 1995 to the only spinal rehabilitation centre in Singapore. There was a total of 231 patients with ages between 14 and 82 years. The majority (73.6%) were below the age of 50. There was a male preponderance (83.1%) and a significant proportion of foreigners (20.3%). The most common causes of injuries were falls (50.7%) and road traffic accidents (37.2%). Damage to the cervical spine predominated (53.7%), followed by the thoracolumbar junction (23.4%). At the end of rehabilitation, the number of patients who were Frankel D/E improved significantly from 61 to 136. Sixty-eight patients were able to ambulate independently without aid and total independence in activities of daily living was achieved in 45 patients. The majority (87.9%) were discharged to their own homes. Of those who returned for follow-up, 86.3% were gainfully employed at the time of injury but only 21.6% had returned to some form of vocation within 1 year.
Accidental Falls↗
Reflex sympathetic dystrophy in hemiplegia--two case reports and review of the literature.
Reflex sympathetic dystrophy (RSD) can be precipitated by a variety of events. We report two cases of RSD in hemiplegic patients detected within three months of the cerebrovascular accidents. Diagnosis of RSD was based upon clinical and scintigraphic findings. Management included elevation, range of movement of the affected joints and analgesics. With treatment, the pain and swelling subsided, range of motion of joints improved and the patients were able to participate in the rehabilitation programme. A high index of suspicion, early diagnosis and aggressive treatment were found to be essential for the successful treatment of RSD.
Cerebral Hemorrhage↗