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Biomedical subjects

W H Linssen

Publications and source records attributed to W H Linssen.

31 records · Page 2Linked to original sources
PubMed1993

Variability and interrelationships of surface EMG parameters during local muscle fatigue.

The inter- and intraindividual variability of the frequency power density spectral and surface EMG amplitude parameters and of the muscle fiber conduction velocity (MFCV) is studied in 26 healthy volunteers during fatiguing isometric ischemic intermittent exercise of the m. biceps brachii at 80% of the maximal voluntary contraction level, with a contraction rate of 30/min. No significant age effects were found. Males were significantly stronger compared with females. The higher initial SEMG amplitude and the stronger shift of the frequency power density spectrum (PDS) to lower frequencies appear to be significantly correlated with males. Fatigue induces an almost proportional compression of the SEMG frequency content. The muscle fiber conduction velocity has the highest intraindividual reproducibility (r = 0.81). Despite the definite and strong influence of the MFCV on the PDS, the shift of the PDS can not be explained by a change of MFCV alone.

Adult↗
PubMed1991

Fatigue in type I fiber predominance: a muscle force and surface EMG study on the relative role of type I and type II muscle fibers.

The relative proportions of fiber types within muscle and the characteristics of these fiber types are important determinants of the surface electromyogram (SEMG) during fatigue. In this study, patients suffering from congenital myopathy characterized by a strong type I fiber predominance were studied. Six patients with 95-100% type I fibers, 2 patients with 80% type I fibers, and 12 healthy volunteers participated in an ischemic, isomeric, intermittent exercise test of m. quadriceps femoris at 80% MVC. Considering the results of the morphometric analysis of muscle biopsy specimen and of the anthropometric estimated muscle-bone volume, it was found that type I muscle fibers had a lower force generating capacity than type II fibers. The initial conduction velocity along the muscle fiber membrane (MFCV) was low in patients with 95-100% type I fibers. During the ischemic exercise test, the 95-100% type I fibers showed less fatigability than type II fibers, which was reflected by a nearby absent decrease of the muscle membrane excitability as measured by the MFCV, and only a slight increase of the SEMG amplitude compared with patients having 80% type I fibers and controls. The absence of a definite MFCV decrease was related to the nearby lacking lactate formation in 95-100% type I fibers.

Adolescent↗
PubMed1991

Infective acute transverse myelopathy. Report of two cases.

Two children with acute transverse myelopathy following adenovirus and Borrelia Burgdorferi infections are presented. The diagnosis stems from the clinical presentation, the determination of specific antibodies in serum and the favorable response to penicillin treatment in the case of neuroborreliosis. Both children made a good recovery. The cerebrospinal fluid examination showed a highly increased myelin basic protein concentration, indicating demyelination.

Adenovirus Infections, Human↗
PubMed1991

Force and fatigue in human type I muscle fibres. A surface EMG study in patients with congenital myopathy and type I fibre predominance.

An isometric ischaemic intermittent m.biceps brachii exercise test is performed by 4 patients suffering from congenital myopathies which are characterized by a 100% type I fibre predominance, and by 26 healthy volunteers. Thirty contractions per minute are made at an 80% of maximal voluntary contraction level. It is found that type I muscle fibres have a fourfold lower force-generating capacity than type II muscle fibres. The EMG amplitude shows that more EMG voltage is needed per unit force in the patients with 100% type I fibres compared with controls. Under standardized fatiguing circumstances the power density frequency spectrum shows a weaker shift to lower frequencies in patients with 100% type I muscle fibres compared with controls. The muscle fibre conduction velocity (MFCV) of type I muscle fibres shows no decline during ischaemic exercise indicating an unimpaired muscle membrane excitability.

Adult↗
PubMed1991

Recurrent prolonged coma due to basilar artery migraine. A case report.

A 25 year old patient presented with recurrent prolonged episodes of life-threatening coma varying from 3 to 10 days. The clinical recovery was slow. The history and technical examinations led to the diagnosis of basilar artery migraine (BAM). The etiology of the coma episodes is thought to be related to ischemic dysfunction of the rostral part of the brainstem due to severe spasm of the basilar artery demonstrated by arteriography. Exceptional are the recurrent prolonged coma episodes of sudden onset, the severe spasm of the basilar artery, and the suppression-burst and FIRDA pattern on the EEG examinations during the coma episodes.

Adult↗
PubMed1990

Spinal angiomas. The meaning of cerebrospinal fluid lactic acid in the etiology and differential diagnosis of transverse myelopathy.

We report five out of eleven patients with transverse myelopathy due to spinal angiomas. Transverse myelopathy can be caused by a number of disorders. The formation of lactic acid points to ischaemia within the spinal cord, due to altered haemodynamics as in spinal angiomas. The meaning of cerebrospinal fluid lactic acid is discussed with respect to etiology and differential diagnosis of transverse myelopathy. The combined finding of CSF lactic acid and protein elevation in the absence of cell count and immunological and/or serological abnormalities points to an isolated vascular cause of the transverse myelopathy.

Adolescent↗
PubMed1990

Muscle fatigue in McArdle's disease. Muscle fibre conduction velocity and surface EMG frequency spectrum during ischaemic exercise.

The origin of fatigue in McArdle's disease is still a matter of debate. Both a reduction of muscle membrane excitability and failure of excitation-contraction (E-C) coupling have been suggested as causes. We performed intermittent isometric biceps brachii contractions (80% maximal voluntary contraction, rate 30/min) under local ischaemia in 5 McArdle's disease patients and 26 healthy controls. Our results show that in McArdle's disease the exerted force is less, the surface EMG (SEMG) amplitude steadily increases, and that the power density spectrum (PDS) shifts to lower frequencies, the latter without significant differences when compared with normals. The most important finding is that muscle membrane excitability remains unimpaired during ischaemic exercise, establishing a dominant role for intramuscular lactic acid formation in the reduction of muscle fibre conduction velocity seen in normal subjects. As is indicated by the shift of the PDS towards lower frequencies, as well as by the increase in SEMG amplitude, it can be concluded that during ischaemic exercise in patients with myophosphorylase deficiency, fatigue occurs without alterations in muscle membrane excitability and is due to a failure of E-C coupling.

Adolescent↗
PubMed1988

Acute transverse myelopathy as the initial manifestation of probable systemic lupus erythematosus in a child.

A 10-year-old girl was presented with acute transverse myelopathy. She had three mild relapses within one year. Systemic lupus erythematosus (SLE) was suspected on the basis of positive antinuclear antibodies (ANA), moderately decreased total hemolytic complement, antibodies to histone, immunological abnormalities of kidney and skin biopsy. Symptoms of SLE involving other organs were absent.

Antibodies, Antinuclear↗
PubMed1987

Amenorrhea after immunosuppressive treatment of multiple sclerosis.

Interviews on changes in the menstrual cycle were taken from 38 women of fertile age, several years after immunosuppressive treatment (IS) with prednisone and cyclophosphamide (CP) for definite multiple sclerosis (MS). Serum FSH, LH and 17-beta-oestradiol levels were determined at the time of interview. MS in itself did not change the experience of menstrual cycles; 17 patients developed hypergonadotrophic amenorrhea during or after IS. Symptoms related to climacterium (c. q. flushing) were present in 15 of these patients. The onset of amenorrhea depended on the age at the time of IS and on the cumulative dose of CP. Older patients developed amenorrhea at a lower cumulative dose of CP than did younger patients. High estrogen oral contraceptives are advocated in oncology to prevent disturbance of ovarian function by anti-mitotic treatment. This policy is advisable in female MS patients treated with drugs like CP or azathioprine.

Adult↗
PubMedDate not supplied

Vascular insufficiency of the cervical cord due to hyperextension of the spine.

A patient with acute transverse myelopathy after minor trauma due to hyperextension of the neck is reported. The pattern of neurologic deficit favors the diagnosis of acute central cervical spinal cord syndrome. The proposed causative mechanism is temporary vascular insufficiency of the spinal cord. The architecture of vascular supply of the spinal cord and specific cerebrospinal fluid abnormalities in this patient are compatible with the diagnosis. The differential diagnosis of traumatic vascular spinal cord lesions is discussed.

Child↗