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Biomedical subjects

H Benko

Publications and source records attributed to H Benko.

At least 19 recordsLinked to original sources
PubMed2002

Dermatome electrical stimulation as a therapeutic ambulatory aid for incomplete spinal cord injured patients.

Electrical stimulation of the L-3,4 dermatome during treadmill walking is proposed as a gait training modality in incomplete spinal cord injured patients. The dermatome stimulation proved to be efficient in diminishing the extensor tone occurring after loading of the paralyzed limb during the stance phase of walking and resulting in improved flexion of the leg during the swing phase.

Cervical Vertebrae↗
PubMed1997

Improvement in step clearance via calf muscle stimulation.

The aim is to study the influence of electrically stimulated calf muscles on the effectiveness of the swinging leg movement. The study is carried out with a group of patients with incomplete spinal cord injuries both under stationary conditions and during crutch-assisted walking. Before stimulation is applied to the ankle plantar flexors, the knee extensors are inactivated. In each cycle, after ankle plantar flexor stimulation, peroneal stimulation is started, triggering the flexion reflex. From a biomechanical point of view, functional electrical stimulation (FES) of the ankle plantar flexors results in increased ground clearance of the lower extremity. Additionally, the FES-assisted lifting of the heel results in the elimination of extensor tone and thus shortens the swing time.

Adolescent↗
PubMed1997

Effects of respiratory muscle training and electrical stimulation of abdominal muscles on respiratory capabilities in tetraplegic patients.

Thirteen tetraplegic patients were included in the study of the effects of respiratory muscle training and of electrical stimulation of the abdominal muscles on their respiratory capabilities. Each patient was subjected for three 1 month lasting periods of the study: for inspiratory muscle training, expiratory muscle training and for a period without training. The sequence of these three periods was random for each patient. Respiratory tests (RT) measuring forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were conducted before and following each monthly period. Measurements were taken under four sets of conditions: the patients' unassisted efforts, their efforts combined with pressure manually applied by a therapist to the upper part of their abdomen, and their efforts accompanied by electrical stimulation (ES) of the abdominal muscles during the early phase of expirium, once triggered by the therapist and once by the patients themselves. RT values were increasing following respiratory muscle training and inspiratory training apparently had a slightly greater effect than its expiratory counterpart. The increments of values of RT were statistically significant (P < 0.05) after the inspiratory muscle training. RT measurements were greater when the patient's voluntary effort was combined with ES of abdominal muscles than when it was not. This study concludes that respiratory muscle training is a potentially effective approach and that ES of the abdominal muscles has potentials to improve coughing in tetraplegic patients.

Abdominal Muscles↗
PubMed1997

Influence of electrically stimulated ankle plantar flexors on the swinging leg.

The influence of functional electrically stimulated ankle plantar flexors on the swinging lower extremity was studied in incomplete spinal cord injured persons. Stimulation sequences with different time and frequency parameters were delivered to ankle plantar flexors and knee extensors and to the peroneal nerve. The results of kinematic assessment showed that stimulated calf muscles provide noticeable forward and upward propulsion to the swinging leg.

Adolescent↗
PubMed1997

Wireless control of functional electrical stimulation systems.

With the assistance of crutches and functional electrical stimulation (FES), we are able to restore standing and simple gait in some spinal cord injured (SCI) patients. In present rehabilitative systems, the patient divides the gait cycle into stance and swing phases via pushbuttons mounted on the handles of the crutches, which are hardwired to the functional electrical stimulator. The surface-mount technology based telemetry system, which makes use of the radiofrequency medium at 40 MHz, was developed to provide wireless control of the FES system. Signals from crutch pushbuttons were coded and transferred from the transmitter to the receiver. The receiver was firmly attached to the patient's waist and was connected to the stimulator.

Crutches↗
PubMed1995

The influence of serum tumor necrosis factor-alpha and interleukin-6 concentrations on nonhematologic toxicity and hematologic recovery in patients with acute myelogenous leukemia.

To confirm the reported correlation of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) serum concentrations with nonhematologic toxicity after cytotoxic chemotherapy and to examine their possible effects on hematopoiesis, we evaluated serum TNF-alpha and IL-6 concentrations every 3 days during 21 chemotherapy cycles in 11 patients with acute myelogenous leukemia (AML) and one patient with chronic myelogenous leukemia in blast crisis (CML-BC). All patients developed grade IV hematologic toxicity. In 13 patient cycles, grade III-IV nonhematologic toxicity developed: hepatic (nine), pulmonary (six), and stomatitis (five). In these patient cycles, IL-6 concentrations increased from 10.1 pg/mL (4.6-15.6, 95% CI) before nonhematologic toxicity to 64.8 (5.3-124.2, 95% CI) at the onset of toxicity (p = 0.02). TNF-alpha concentrations were not detectable before nonhematologic toxicity but increased to 20.4 pg/mL (not detectable [ND]-45.5, 95% CI) at the onset of grade III-IV toxicity. In six patient cycles, grade II nonhematologic toxicity developed: hepatic (five), pulmonary (one), and stomatitis (two). In these six, IL-6 concentrations increased from 12.1 pg/mL (6.8-17.4, 95% CI) before toxicity to 21.4 (11-31.8, 95% CI) at the onset of toxicity (p = 0.03). TNF-alpha concentrations were detectable in one patient cycle before toxicity and detectable in only two patient cycles at the onset of toxicity. The peak IL-6 and TNF-alpha concentrations did not correlate with the onset of nonhematologic toxicity in 87% of patient cycles. In patient cycles with a cumulative IL-6 area-under-the-serum concentration vs. time curve (AUC) > 1000 pg/mL.d, platelet recovery (> 30 x 10(9)/L and platelet transfusion-independent) occurred earlier at 21.9 days (18.7-25.1, 95% CI) compared to the 30.6 days (23.6-37.5, 95% CI, p = 0.02) in patient cycles with an IL-6 AUC < 1000 pg/mL.d. Patient cycles with a cumulative TNF-alpha AUC > 150 pg/mL.d required a mean of 17.5 units of red blood cells (RBCs) (9.3-25.7, 95% CI) compared to patient cycles with an AUC < 150 pg/mL.d, which required only 8.9 units of RBCs (6.2-11.7, 95% CI, p = 0.03). The peak concentration and AUC for IL-6 and TNF-alpha were not significantly different between those receiving growth factors (G-CSF, six; GM-CSF, one) and those not receiving growth factors (14). Endogenous IL-6 and TNF-alpha serum concentrations increase in patients who experience nonhematologic toxicity and correlate with hematologic recovery after chemotherapy.

Antineoplastic Agents↗
PubMed1993

Treatment of chronic wounds by means of electric and electromagnetic fields. Part 2. Value of FES parameters for pressure sore treatment.

Subjects with spinal cord injury are often distressed by pressure sores, which usually appear after prolonged pressure (wheelchair, bed) across the soft tissue which has already lost sensibility and has diminished microcirculation. The healing ability and its dynamics depend on the state of the subject's overall health. Consequently, evaluation of a particular treatment requires careful consideration of as many as possible of the parameters relevant to healing and an adequate criterion for assessing the state of the pressure sore. Bearing in mind these two circumstances, the results of a multicentre clinical study are analysed. The aim of the study was to test two hypotheses: first that healing is faster when sores are also treated by electric currents (ECs) (in addition to conventional treatment); and secondly that there exist differences in the efficiency of the treatment if direct or low-frequency pulsed currents (FES parameters) are applied. The data analysed show that pressure sores are likely to heal twice as fast when treated with low-frequency pulsed currents. EC seems to improve the healing rate in cases where the natural healing mechanisms of the body are not sufficient (chronic wounds, older subjects).

Adult↗
PubMed1990

Symmetry of FES responses in the lower extremities of paraplegic patients.

Due to natural or artificial obstacles, gait is a less automatic and periodic process than it would appear when studying normal walking on the level. Pre-programmed functional electrical stimulation (FES) sequences, therefore, do not appear to be a suitable approach to the control of multichannel electrical stimulators in the restoration of paraplegic walking. Walking in paraplegic subjects must be, to a large extent, under voluntary control. To lessen the burden of this control, the symmetry of walking can be taken into account. Symmetric motion of the legs requires symmetric FES actuation. Symmetry of FES responses was studied in a group of 10 paraplegic subjects who had all undergone the FES training program. Recruitment curve, fatigue index and twitch delay were assessed. An average 80% symmetry was found in all parameters measured, thus allowing a reduction of complexity of control approach for FES locomotor aids.

Adult↗
PubMed1990

[Blood-pool-SPECT for imaging portosystemic collaterals in portal hypertension].

In 46 patients, 26 male and 20 female, age from 32 to 71 years (mean 47.4 +/- 11 years) a bloodpool-scintigraphy (BPS) with SPECT (single photon emission computed tomography) was performed. The in-vivo labelling of the erythrocytes with pyrophosphate and Tc-99m was performed in the usual way. The SPECT investigations were performed with a digital Anger-Camera (Elscint; Apex 401). In 14 patients without collaterals BPS was performed to compare the method with patients with liver diseases and collaterals. 29 patients with liver cirrhosis and portal hypertension were investigated with the BPS and additionally a scintisplenoportography (SSP) was performed. In patients with only cephalad collaterals all the results were concordant. In just 1 patient with cephalad and caudad collaterals we found a discordant result. In 8 patients we performed BPS, SSP and a katheterangiography (KA). Taking the KA as the "golden standard" we found a concordant result with the 3 methods in all patients with cephalad collaterals. In patients with cephalad and caudad collaterals we once found a discordant result with the SSP and twice with the BSP. In 2 patients the patency of surgical shunts were proved. 2 patients after sclerosis of the oesophageal varices have been proved by BPS and SSP and both patients showed good therapeutical results.

Adult↗
PubMed1989

Use of functional electrical stimulation in the rehabilitation of patients with incomplete spinal cord injuries.

When patients enter the Rehabilitation Centre a therapeutic electrical stimulation programme is immediately initiated. Three groups of patients were identified: (i) those in whom an improvement of both voluntary and stimulated muscle force was observed, (ii) those with an increase in stimulation response only, and (iii) patients in whom no effect of electrical stimulation training could be recorded. Isometric measurement of voluntary and stimulated knee joint torque revealed that in a great number of patients one leg was severely paralysed while the other leg was under sufficient voluntary control. Unilateral two-channel stimulation of knee extensors and the peroneal nerve was proposed as an orthotic aid for this group of patients. Exaggerated extensor tone was observed by assessment of spasticity around the knee joint. A two-channel peroneal stimulator was found to be a useful approach in order to inhibit this tone and thereby help the patients to initiate a step.

Adult↗
PubMed1986

Posture switching for prolonging functional electrical stimulation standing in paraplegic patients.

The presently employed posture for Functional Electrical Stimulation (FES) assisted standing in spinal cord injury (SCI) patients utilises the active locking of knee joints by tetanically stimulating the quadriceps muscle. The hip joints are in hyperextension and the ankle joints remain free. The upper limbs are used for balancing. This posture requires minimal corrective forces exerted by the hands, the weight is transferred across the legs, while very limited forward-backward sway is permitted. Knee jack-knifing may occur in the instance when the gravity knee bending moment exceeds the moment generated by the quadriceps muscle. Because of these effects and fatiguing of the M. quadriceps the standing time is short, lasting from several minutes up to an hour, depending on the condition of the patient's muscles. Cyclical FES with a duty cycle of 10-20 seconds (on/off) fatigues muscle considerably less. The use of different postures for standing requiring activation of different muscles permits the application of cyclical FES. The cyclic FES results in prolonging standing times by a factor of two to five. Utilising this improvement some patients can stand for up to five hours at a time. This functional achievement is comparable to the standing time of a normal man. The incorporation of the principle of posture switching also prolongs standing in patients with weak muscles, because of the possibility of cyclical coactivation of different synergistic muscle assemblies. It is shown that posture switching can be carried out automatically and that patients adapt quickly to it. In addition using co-contraction of two or three muscles with posture switching does further expand the range of suitable patients and improves standing with an increased permissible range of body sway. Also, the FES antigravity action obtained raises hopes for substantially improving FES induced reciprocal gait.

Electric Stimulation Therapy↗
PubMed1985

Electrical stimulation in treating spasticity resulting from spinal cord injury.

To study the efficacy of electrical stimulation in treating spasticity of six spinal cord injured patients, transcutaneous electrical nerve stimulation (TENS) was applied to the dermatomes belonging to the same spinal cord level as the selected spastic muscle group. Spasticity was assessed in knee extensors by a pendulum test in which the knee joint angle of a swinging lower leg was recorded with an electrogoniometer. TENS was found to produce a noticeable decrease of spasticity in three of the patients, but had little effect on the others.

Adult↗
PubMed1983

The use of a four-channel electrical stimulator as an ambulatory aid for paraplegic patients.

This article reports the use of electrical stimulation to provide paraplegic patients with complete lesions of the spinal cord the ability to rise from sitting to standing, to maintain a standing position, and to walk with a reciprocal gait. Four channels of electrical stimulation are sufficient for synthesis of a simple reciprocal gait pattern in these patients. During the double-stance phase, knee extensor muscles of both knees are stimulated, providing sufficient support for the body. Only one knee extensor muscle group is excited during the single-stance phase. The swing phase of the contralateral lower extremity is accomplished by eliciting the synergistic flexor muscle response through electrical stimulation of afferent nerves. The transition from the double-stance phase to the swing phase is controlled by two hand switches used by the therapist or built into the handles of the walking frame or crutches for use by the patient.

Electric Stimulation Therapy↗
PubMed1983

Gait restoration in paraplegic patients: a feasibility demonstration using multichannel surface electrode FES.

Recent advances in science have aided research toward the restoration of biped gait in paraplegic patients by means of functional electrical stimulation (FES). In this paper it is shown how FES-restrengthened muscles of paraplegic patients have been used for simple FES-assisted standing. Those experiments subsequently led to biped gait-initializing experiments and to simple forms of biped gait synthesis. The purpose of this paper is to show the feasibility of using FES for standing and for restoring biped gait in many paraplegic patients--to present the past achievements, focus on problems, and highlight directions for future research. The results of gait obtained in three complete spinal cord injured patients (out of a series of 17) are shown, using four to six channels of FES. It is also shown how preserved reflex mechanisms of the transected spinal cord can be incorporated and employed for obtaining improved function while at the same time simplifying the FES hardware. Of the three patients reported on in detail here, two patients have managed to walk in parallel bars while the third patient has mastered independent unassisted walking over shorter distances with the aid of a roller walker. The biomechanical and control problems of this last patient's gait are presented in detail.

Adult↗
PubMed1981

[Estimation of hepatic blood flow with 133-Xenon (author's transl)].

Regional hepatic blood flow was measured by two methods using 133-Xenon washout technique: 1. "portal method" (injection of 133-Xenon into the spleen), and 2. "arterial method" (direct application of 133-Xenon into the A. hepatica propria by an indwelling catheter after celiacography). The portal method was performed in 38 patients (30 patients with cirrhosis of the liver, 4 patients with chronic hepatitis, 4 controls with normal liver function). The results show that using this method regional liver blood flow can be measured accurately. Patients with cirrhosis of the liver had a highly significantly decreased hepatic blood flow in comparison to the control group. The advantage of this method is that extra- and intrahepatic shunts can be visualized simultaneously. However, using this method in patients with hemodynamically very effective extrahepatic collaterals the tracer does not reach the liver. In these patients regional hepatic blood flow can be estimated by the arterial method (12 patients with cirrhosis of the liver, 2 with normal liver function). However, no information about the morphology of the portal circulation can be obtained using this method. Direct comparison of the quantitative estimation of regional hepatic blood flow was performed in 6 patients. The data obtained by the 2 methods correlated highly significantly (r = 0.91).

Adult↗