Search PubMed⌕ Search

Biomedical subjects

J P Reulen

Publications and source records attributed to J P Reulen.

At least 19 recordsLinked to original sources
PubMed1993

[Survey of the number of electroencephalograms prepared in The Netherlands in 1975-1989; noticeable decrease in spite of substantially increased number of neurologic patients].

On the basis of data supplied by 89 Dutch neurological/clinical neurophysiological practices it is demonstrated that the number of electroencephalograms (EEGs) prepared in the Netherlands has gradually decreased between 1975 and 1989. In 57 clinics which supplied data on all these years, the decrease was found to amount to about 19%. This significant decrease occurred in spite of a marked increase of the numbers of new patients in the neurological outpatient clinic (about 60%, data from 42 practices) and neurological admissions (about 40%, data from 54 practices). There is no reason to assume that this development has been essentially different in the non-responding practices (n = 59). The findings of this study refute the statement made in an article published in this journal in 1989 that the number of EEGs had increased in spite of the introduction of the CT scanner. This erroneous conclusion, which led to the suggestion of overconsumption, proved to be due in the first place to obviously incorrect figures supplied by the Medical Insurance Board. In addition, the increase of the number of neurological patients had not been taken into account.

Central Nervous System Diseases↗
PubMed1989

Method for the measurement of susceptibility to decubitus ulcer formation.

A method for measuring the susceptibility of a patient to develop decubitus ulcers is described and initially evaluated. It is based on an indirect, noninvasive measurement of the transient regional blood flow response after a test pressure load which simulates the external stimulus for pressure-sore formation. This method was developed to determine the individual risk of a patient and to study the subfactors which contribute to the susceptibility. This would also offer the possibility of evaluating the effect of preventive treatment aimed at reducing the susceptibility. The method was found to discriminate between preselected elderly patients at risk on the one hand, and non-risk patients and healthy young adults on the other hand. No differences in blood flow responses were found between the non-risk elderly patients and the healthy young adults. This suggests that age per se is not a factor in the formation of pressure sores. In the risk group the recovery time after pressure relief was found to be three times as long as the duration of the pressure exercise. This indicates that the recovery time after pressure exercise may be as important as the period of pressure exercise in deducing the risk of developing decubitus ulcers.

Adult↗
PubMed1989

The pupillary light reflex in diabetes mellitus: evaluation of a newly developed infrared light reflection method.

Pupillary light reflexes were measured in 18 diabetic patients without clinical signs of neuropathy and in 18 control subjects, using a newly developed infrared light reflection technique called IRIS. This method has some important advantages. Apart from being non traumatic, it enables the recording of dynamic pupillary light reflexes simultaneously in both eyes. Furthermore, it has a large amplitude and time resolution (1 ms), permitting accurate determination of latency values. It was found that 78% of the diabetic patients show a significantly prolonged latency of the constriction reaction, while 39% of the diabetic patients show an abnormally prolonged dilatation latency. All patients with an abnormally prolonged dilatation latency also show a prolonged constriction latency. This finding suggests that in diabetes mellitus the parasympathetic system is affected before abnormalities of the sympathetic nervous system can be demonstrated. Assessment of the pupillary light reflex, using the sensitive IRIS method, is an easily applicable and reliable method for detection of subclinical autonomic nervous system dysfunction associated with diabetes mellitus. The method may also provide an objective tool for the assessment of therapy results in diabetic neuropathy.

Adult↗
PubMed1988

Autonomic nervous function in Huntington's disease.

Autonomic nervous system function was studied by means of a series of standardized tests in 11 patients with Huntington's disease (HD) and in 11 age- and sex-matched controls. Two statistically significant differences were found. The blood pressure response to sustained handgrip was diminished and the pupillary light reflex latency was increased in the HD group. The former probably reflects diminished input from higher centers on an otherwise intact sympathetic nervous system. The latter may indicate involvement of the pretectal or Edinger-Westphal nuclei in HD. No further signs of autonomic nervous system dysfunction were found.

Adult↗
PubMed1988

Pupillary light reflex and quantitative sensory and motor neural function tests in diabetic patients.

In 29 diabetic subjects with or without symptoms of diabetic peripheral and autonomic neuropathy, the association between the pupillary light reflex (the latency of the constriction of the pupil) and various sensory and motor neural measurements, duration of diabetes and quality of glycaemic control was evaluated. Compared with normal subjects the latency of the constriction reaction of the pupil was significantly prolonged in the group of diabetics (mean +/- SEM: 236.3 +/- 5.8 ms versus 210.5 +/- 3.7; P less than 0.001). Thermal discrimination thresholds were positively correlated with the latency of the constriction reaction of the pupil (r = 0.43, P less than 0.025). Vibratory perception threshold, motor nerve conduction velocity of the peroneal nerve, H-M interval of the Hoffmann reflex and duration of diabetes were not correlated with the constriction latency, whereas glycaemic control showed a weak correlation. It is concluded that there may be a relationship between autonomic (parasympathetic) pupillary dysfunction and peripheral small nerve fibre dysfunction.

Adult↗
PubMed1988

Oculomotor control in Gilles de la Tourette syndrome.

Saccadic eye movements, fixation and smooth pursuit were studied in 28 children with Gilles de la Tourette syndrome and found to be normal. A link has been postulated between Gilles de la Tourette syndrome and other movement disorders. The results obtained in the present series do not support this hypothesis.

Adolescent↗
PubMed1986

The diagnosis of multiple sclerosis. Contribution of non-clinical tests.

A group of 89 patients in whom multiple sclerosis (MS) has been clinically diagnosed with varying degrees of certainty, and 25 patients with optic neuritis (ON), were subjected to the following electrophysiological tests: visual evoked response (VER), auditory brainstem-evoked response (ABER), somatosensory-evoked response (SSER), blink reflex and electronystagmography (ENG). All these patients also underwent computerized tomography (CT scan) and analysis of cerebrospinal fluid (CSF). A new diagnostic procedure is proposed, combining optimum detection of definite MS with optimally economical use of the above-mentioned non-clinical tests. The results for the MS patients show that definite MS can be diagnosed much more frequently (72%) if abnormal results in the above-mentioned tests are accepted as evidence of a (subclinical) CNS lesion. Application of the clinical diagnostic criteria of McAlpine yielded "definite MS" only in 27% of our patient material. Our diagnostic criteria showed evidence for MS in 36% of the patients clinically diagnosed as having ON. The test results were inconclusive as regards the possibility of the remaining ON patients developing MS in the future.

Adult↗
PubMed1986

Horizontal and vertical saccadic eye movement abnormalities in Huntington's chorea.

With a newly developed infrared reflection technique, voluntary saccadic eye movements (VOLS), visually evoked saccades (VES) and unsuppressed visually evoked reflex saccades (USVERS) were measured in 11 patients with Huntington's chorea. Abnormalities, including latency increase, peak velocity decrease and undershoot dysmetria with multiple step saccades were found in all types of saccadic eye movements. Peak velocity decrease and undershoot dysmetria can be explained by dysfunction of the brainstem reticular formation in Huntington's chorea. USVERS and square wave jerks occurred abnormally frequently and showed direction-dependent differences. Both were more frequent in horizontal than in vertical direction. Frequency of USVERS and square-wave jerks tended to be correlated. These findings point to disinhibited superior colliculi as a possible common supranuclear origin of USVERS and square-wave jerks in Huntington's chorea.

Adult↗
PubMed1985

Electrophysiological disorders in multiple sclerosis and optic neuritis.

Visual evoked response (VER), auditory brainstem evoked response (ABER), somatosensory evoked response (SSER), blink reflex and electronystagmographic (ENG) investigative methods were applied to a group of 89 patients with Multiple Sclerosis (MS) and Optic Neuritis (ON). The MS patients were classified as definite (n = 31), probable (n = 31) and possible (n = 27). The aim of this study was to determine the diagnostic value of the five electrophysiological tests in MS. VER and ABER recordings were found to reveal the highest number of asymptomatic abnormalities (33 and 31 percent respectively). The combination of VER, ABER and ENG revealed all possible electrophysiological disorders. As these tests are completely non-invasive it is proposed, that a combination of two of these three tests is useful for the detection of a second silent lesion in patients with suspected MS showing purely spinal signs (VER, ENG, ABER) and/or a history of uncomplicated ON (ABER, ENG).

Adult↗
PubMed1985

Brainstem involvement in multiple sclerosis: a clinical and electrophysiological study.

A major aim of this study was to determine the diagnostic value of 4 electrophysiological tests in MS, and particularly their effectiveness in detecting signs of brainstem involvement. Therefore, auditory brainstem evoked response (ABER), somatosensory evoked response (SSER), blink reflex and electronystagmographic (ENG) investigative methods were applied to a group of 89 patients with definite, probable or possible multiple sclerosis (MS). The 4 methods yielded interdependent data, especially where the brainstem function was concerned, thus it can be concluded that a single demyelinating lesion may cause a combination of electrophysiological disorders within a small structure such as the brainstem. ENG recordings were found to reveal the highest number of asymptomatic abnormalities. The combination of ABER and ENG tests revealed electrophysiological disorders in 81% of all patients. The blink reflex and the SSER tests gave hardly supplementary information.

Adult↗
PubMed1984

Latency of visually evoked saccadic eye movements. I. Saccadic latency and the facilitation model.

The paper deals with the initiation of visually guided saccades, in order to break down the saccadic reaction time into functionally different periods of time. It takes into account that spatial processing of information is so basic that modelling of saccadic control properties should include spatio-temporal arrangements. The output signal of the saccadic system was measured in response to visual stimuli in which the time between the appearance of a visual stimulus in the peripheral field and the disappearance of the central fixation point was varied. The variation of the mean saccadic latency time, measured with respect to the onset of the peripheral stimulus, as a function of stimulus asynchrony was highly significant. This variation may be represented by a so-called gap-overlap curve, which is characterized here by means of five parameters. A facilitation model is introduced to fit the results of the gap-overlap experiments. The facilitation model for the initiation of visually evoked saccades incorporates a mechanism which governs the efficiency of processing of signals that arise from a stimulus presented at a particular position in space. It explains how visual information may be affected by other sensory information before it is used to command further saccades. It allows determination of saccadic system parameters, such as the peripheral and the foveal afferent processing time, the central processing time for a saccade and the degree of facilitation. These quantities were found to be characteristic for the given test subjects, and where these data could be compared with neurophysiological data, the agreement was within the experimental error.

Electronystagmography↗
PubMed1984

Latency of visually evoked saccadic eye movements. II. Temporal properties of the facilitation mechanism.

The validness of a model describing the relation between mean saccadic latency and stimulus asynchrony based on facilitation instead of suppression was tested experimentally. As a result, suppression of signals generated by the onset of a peripheral stimulus due to fixation of another target, giving rise to an increase of mean saccadic latency, does not seem very likely. The influence of the intensity of the fixation target on the latency of visually evoked saccades was studied. According to the facilitation model, the offset of the fixation target induces after an afferent delay, a transition of the state of the facilitation mechanism from the unfacilitated condition into a mode of maximal facilitation. The time-period during which this change is accomplished is called Facilitation-Rise-Time (FRT). An interpretation within the context of the facilitation model of gap-overlap latency data for different values of the intensity of the fixation stimulus suggests, in combination with computer-computations of the model, that lowering of this intensity causes an increase in FRT. The results in normal subjects of step stimulus experiments with a dim fixation point substantiate the hypothesis of a facilitation mechanism, which is triggerable not only by an external signal such as the offset of the fixation point, but also by some internal stimulus independent signal. Moreover, data for tracking by an amblyopic eye seem to support this conclusion. The findings of increased saccadic latencies in amblyopic and Optic Neuritis (ON) eyes suggest a slowing of processing of visual information in the sensory pathways from the central retina, subsequently utilized by the oculomotor system in the generation of saccades.(ABSTRACT TRUNCATED AT 250 WORDS)

Amblyopia↗
PubMed1984

Central nervous system involvement in optic neuritis.

Thirty patients with clinically uncomplicated optic neuritis were subjected to a battery of electrophysiological tests, including visual evoked response (VER), auditory brainstem evoked response (ABER) and somatosensory evoked response (SSER). Blink reflex, electronystagmography (ENG), and computed tomography examinations were also carried out on all patients. These non-invasive tests indicated that in 11 of the 30 patients (37%), the optic neuritis was a symptom of subclinical multiple sclerosis, and that another five patients showed signs of mild central nervous system (CNS) involvement which may develop into multiple sclerosis later. This was confirmed by cerebrospinal fluid (CSF) analysis, using isoelectric focusing, showing oligoclonal extra bands in 11 out of these sixteen. A new classification of optic neuritis is proposed on the basis of these findings.

Adult↗
PubMed1983

Eye movement disorders in multiple sclerosis and optic neuritis.

Horizontal saccadic and smooth pursuit eye movements were studied in 84 patients with multiple sclerosis (MS) and 21 patients with optic neuritis (ON). The MS patients were clinically classified as 'definite', 'probable', or 'possible'; subclinical eye movement disorder was found in 80 per cent of the definite, 74 per cent of the probable and 60 per cent of the possible category. Five of the ON patients (25 per cent) showed a subclinical eye movement deficit; these 5 were young patients with a recent history of ON. In a group of 27 MS patients with symptoms of spinal cord involvement only, 14 showed subclinical oculomotor disorder indicating the involvement of cerebral structures in the demyelination process. A study of the correlation between specific eye movement parameters and results of visual evoked response (VER) tests revealed that saccadic latency or smooth pursuit abnormalities are not correlated with prolonged VER latencies (P-100 peak latency). This indicates that lesions beyond the primary visual pathway contribute substantially to both parameters of oculomotor dysfunction. A significant correlation was found between prolonged saccadic latency and smooth pursuit deficit. An explanation for this finding based on functional aspects of the saccadic and smooth pursuit systems and their mutual interaction is presented. The occurrence of internuclear ophthalmoplegia (INO) is significantly related to an increase of saccadic latency. This finding indicates that demyelination in the patients manifesting INO may not be restricted exclusively to one or both medial longitudinal fasciculi, but may extend to other brainstem structures which are functionally involved in the programming of saccades. The findings confirm the value of standardized objective examination of eye movements in the detection and clarification of subclinical lesions in the central nervous system of patients with an early diagnosis of MS or ON.

Adolescent↗