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Biomedical subjects

E Knutsson

Publications and source records attributed to E Knutsson.

At least 55 records · Page 3Linked to original sources
PubMed1981

Gait control in hemiparesis.

Findings in gait analysis of patients with spastic hemiparesis are reviewed. The basis of recent analysis has been records of movement combined with EMG from several leg muscles. Though the interindividual variation in movement and muscle activation is large, the abnormal control of gait usually can be related to one of three types of disturbances. These are characterized by (1) exaggerated stretch responses disturbing an otherwise well preserved gait control, (2) abolishment or decrease of the centrally generated patterned muscle activation, or (3) abnormal coactivation of several muscle groups. By using a computer for collection and analysis of data, gait analysis can be used in clinical routine for guidance of therapy and training.

Electromyography↗
PubMed1981

Evaluation of the effects of muscle stretch and weight load in patients with spastic paraplegia.

Clinical observations on patients with spastic paraplegia have indicated that a training regime including weight load on the lower limbs may reduce the muscular hypertonus. Due to the spontaneous fluctuations and great variability in muscle tone it is difficult to judge from clinical findings how the effects may be related to muscle stretch and weight load. Therefore, quantitative determination of the effects on muscle tone by stretch and loading was made in 9 paraplegic patients. Muscle tone was measured before and after 30 min of stretch or weight load in 8 sessions on 4 consecutive days. Stretch was obtained by bracing the foot in maximal dorsal flexion with patient in supine position. For weight load on the lower limbs, the patient stood on a tilt-table at an angle of 85 degrees with feet in 15 degrees dorsal or plantar flexion. Resistance to passive movements was determined during a series of sinusoidal ankle joint movements at three different speeds. After weight load in standing with the feet in dorsal or plantar flexion, the average reduction was 32 and 26%, respectively. After stretch in supine, the average reduction was 17%. Thus, the three procedures tested all resulted in reduction of muscle tone. The largest reductions were obtained by weight load with stretch imposed upon the calf muscles.

Adult↗
PubMed1980

Dynamic motor capacity in spastic paresis and its relation to prime mover dysfunction, spastic reflexes and antagonist co-activation.

Dynamic motor capacity was studied in 24 patients with spastic paraparesis (18 cases) or hemiparesis (6 cases). Torque was recorded with an isokinetic dynamometer in voluntary dynamic knee extensions and flexions at maximum effort and in passive movements at preset speeds of 30, 90 and 180 deg . s-1. EMG was recorded with surface electrodes from the quadriceps and the hamstring muscles. The capacity to accelerate motion up to preset speed was deficient in all patients as compared with healthy subjects. The moment of muscle force in movements at maximum effort was generally more reduced in fast than in slow movements. Spastic restraint in passive movements was low in the great majority of legs examined except in the fastest flexion, where about half showed restraint greater than 10 Nm. In a few cases, spastic reflexes were inhibited in voluntary motion. Most commonly, the restraint was greater in voluntary than in passive movements at equal range and speed. In voluntary motion, antagonist restraint was more common at high than at low speed of motion, and when present at low speed, it usually became greater with increasing speed of motion. It often reached a considerable magnitude, as estimated from EMG and may constitute a crucial component in the motor handicap.

Adult↗
PubMed1979

Different types of disturbed motor control in gait of hemiparetic patients.

The pattern of muscle activation in walking was studied in a group of 26 hemiparetic patients. Electromyograms were taken with surface electrodes from 6 muscle groups of the paretic leg and analysed after rectification and time averaging. The sagittal rotations in hip, knee and ankle joint were determined with intermittent light photography. The muscle activation pattern of each patient was compared to that in healthy subjects as well as to the movements performed by the patient and to the normal movement pattern. The normal patterns of movement and muscle activation were assessed from compiled data from 10 healthy female volunteers and average values of angular displacements and amplitude of intergrated EMG were determined at each 5 per cent of the gait cycle. Change of muscle length was determined with a length recording transducer. Gait capacity varied highly in the group of patients studied and the movement pattern also varied markedly. Three types of abnormal muscle activation pattern were disclosed in the patients. In 9 patients, the calf muscles were prematurely activated in the stance phase, probably due to enhanced stretch reflexes (Type I). In another 9 patients, EMG activity was abolished or extremely low in 2 or more of the muscles examined (Type II). In 4 patients, there was a pathological coactivation of several or all of the muscles during part of the gait-cycle, thus disrupting the normal sequential shift of activity in antagonistic muscles (Type III). In the remaining 4 patients, the muscle activation pattern was more complex and no common pattern was discerned.

Adult↗
PubMed1976

Action of dantrolene sodium in spasticity with low dependence on fusimotor drive.

The effects of dantrolene sodium, an anti-spasticity drug with a site of action within the muscle fibres, were studied in 19 patients with spastic paresis. Oral doses were successively increased from 100 mg/day to a maximal tolerated level or up to 800 mg/day. Trial periods were 8-13 weeks. The responses of stretch reflexes to local cooling over the spastic muscles were used to differentiate alpha and gamma spasticity. In the knee extensor and flexor muscle groups, cryo-negative alpha-spasticity was seen in 25 and cryo-positive gamma-spasticity in 4 muscle groups. Ankle clonus was cryo-positive in 14 of 15 cases. Resistance to passive knee joint movements, ankle clonus and isometric or isokinetic muscle strength was determined quantitatively. The gait was recorded by intermittent-light photography and the muscle activation patterns in gait were studied in recordings of the average EMG from limb muscles. Functional disability and spasms were assessed from clinical examinations and interviews. Passive resistance at slow (6%/sec) and fast (30 degrees/sec) knee joint movements decreased by 32% in the extensor muscles (p = 0.005 resp. 0.001) and by 23-26% in the flexor muscles (not significant). Reduced passive resistance was observed in 16 of the muscles with alpha-spasticity and in all 4 of the muscle groups with gamma-spasticity. Clonus was diminished or abolished in 14 of 15 patients with this sign. Maximal isometric or isokinetic muscle strength was unaltered in the majority of the patients. In a few the strength was increased, in some it was decreased. The averaged EMG activity during walking as studied in 10 patients were increased in 35 of the 57 muscle groups examined. In some muscle groups, exaggerated activity attributable to spastic reflexes was reduced. Motor disability was decreased significantly in 10 patients. It was not significantly changed in 5 and deteriorated in 4 patients. Drowsiness and subjective muscle weakness were the most frequent side-effects. SGOT and SGPT were increased in 3 cases.

Adult↗
PubMed1974

Blood flow in resting (contralateral) arm and leg during isometric contraction.

1. Blood flow in resting forearm and calf were measured plethysmographically in healthy young men during isometric contraction performed both as a handgrip and as a dorsiflexion of the foot. The isometric contraction was maintained for 2 min at one third maximal voluntary contraction for the handgrip and half maximal voluntary contraction for the dorsiflexion of the foot. In some experiments the possible influence on blood flow of inadvertent muscle activation in the resting limb was checked by recording the e.m.g.2. Both handgrip and dorsiflexion of the foot produced substantial increases in heart rate and mean arterial pressure, the pressure rise being almost linear with time throughout the contraction.3. Isometric contraction produced a rapid increase in forearm blood flow which reached a maximum on average two and a half times the resting value after 1 min and then declined slightly. Similar increases in forearm blood flow were produced by handgrip and dorsiflexion of the foot.4. Unlike in the resting forearm, the blood flow in the resting calf increased only slightly during the first minute of contraction and then decreased again to the resting level.5. The flow increase in the resting limbs could not be ascribed to inadvertent muscle activation as judged from the e.m.g. recordings.6. It is concluded that isometric muscle contraction produces a rapid increase in blood flow in the resting forearm, but only a very slight flow increase in the calf. Since the flow increased faster than the arterial pressure it must to a certain extent be induced by active neurogenic vasodilatation. Similarly, the relative flow decrease during the latter half of the contraction concomitantly with a progressively rising arterial pressure suggests that the neurogenic effect on the resistance vessels changes character, becoming more vasoconstrictive, and this might be related to increased effort in sustaining the contraction.

Adult↗