Biomedical subjects

H Kingma

Publications and source records attributed to H Kingma.

41 records · Page 3Linked to original sources

PubMed1988

Head position in low-risk premature infants. Impact of nursing routines.

Head position preference in 15 low-risk pre-term infants studied in relation to conceptional age and nursing routines. A head position preference to the right is evident with respect to the head position imposed by the nurse. The observed spontaneous head position preference might be ascribed to the influence of the foregoing imposed head position, the influence of which diminishes with increasing observation time. After several spontaneous head turnings the low-risk pre-term infants show no head position preference anymore.

Analysis of Variance↗

PubMed1988

Indications of a differentiated regulation of sound transmission by the middle ear muscles of the rat.

Measurement of the middle ear muscle reflex is an important tool in audiologic examination; however, the precise function of the tensor tympani and stapedius muscle is not fully understood. The function of the middle ear muscles in speech discrimination and noise-induced hearing loss is the main object of our study. Morphologic and enzyme-histochemical properties of the middle ear muscles of the rat indicate a complex, fine-tuned function of the middle ear muscles. Both middle ear muscles are merely composed of relatively small fast-twitch fibers. Almost all fibers possess an enzymatic profile that allows aerobic as well as anaerobic metabolism. The innervation of the muscles is extensive, and motor end plates are well developed. In a parallel study, middle ear muscle contraction (to be analyzed by electromyography) will be correlated with a change of the sound transmission characteristics of the middle ear (measured by the electrocochlear and brainstem auditory evoked responses). Preliminary results of the electrophysiologic measurements (electrocochleogram and brainstem auditory evoked response) are presented.

Acetylcholinesterase↗

PubMed1987

A longitudinal study of brainstem auditory evoked potentials of preterm infants.

Brainstem auditory evoked potentials (BAEPs) of nine 'healthy' preterm infants were recorded at weekly intervals between 32 and 36 weeks conceptional age to study the relationship between stimulus intensity and central transmission time through the subcortical auditory pathway (i.e. the interval latency between peak I and peak V) as a function of conceptional age. Stimulus intensities of 70, 80 and 90 dB nHTL were used. Changes in click intensity produced changes in the absolute latency of all BAEP peaks, but the interval latency I to V remained constant. The absolute latencies and interval latencies reflected maturity, but varied widely between these preterm infants. The peak V latency and the I to V interval latency decreased with increasing conceptional age. Exponential regression analysis suggested that, above 70 dB nHTL, the time-constant of the calculated exponential function most likely represents maturation and function of the central subcortical pathway, and may give an indication of the infants' development.

Auditory Pathways↗

PubMedDate not supplied

Vertigo and electronystagmography in uni- and bilateral Ménière's disease.

In this study we performed standardized measurements of spontaneous nystagmus (SN), caloric tests and velocity step tests on a well-defined group of 92 Ménière patients as part of a diagnostic protocol. The aim of the study was to look for results that could contribute to the diagnosis, but more specifically to a possible classification, of Ménière's disease. Relations with average hearing loss, shape of the audiogram, average hearing loss, duration and severity of perceived symptoms of disease and differences between uni-and bilateral Ménière's disease were studied. Directional preponderance (DP) in unilaterally affected patients and labyrinthine preponderance (LP) in both uni- and bilaterally affected patients were significantly more often directed towards the unaffected (uni) or least affected (bi) side (p = 0.007, p = 0.001, p = 0.002, respectively). DP was correlated with LP (uni: R = 0.615, p < 0.001; bi: R = 0.438, p < 0.01), which means that the DP can be seen as a latent SN, directed to the unaffected side. With the caloric test parameters LP and DP it was possible to find unilateral weakness. In unilateral disease a duration of disease <2 years resulted in small asymmetry in time constant (T(asym)), large LPs and LPs not only directed to the unaffected, but also to the affected side, whereas a longer duration of disease gave large T(asym) and small LPs that were only directed to the unaffected side. Patients suffered more severe vertigo in the first two years of the disease. Studying the shape of the audiogram, it was found that patients having an LP to the affected side, suggesting that this was a hyperactive labyrinth belonging to a beginning of the disease, never had a flat audiogram. In this study the LP was the best diagnostic parameter to find unilateral weakness in patients with Ménière's disease. Together with the duration of the disease, the severity of symptoms, the asymmetry in T and the shape of the audiogram, it was possible to find two subgroups in the group of patients with unilateral Ménière's disease. Vestibular data in association with other test results of the diagnostic protocol may contribute to a more sophisticated classification of Ménière's disease.

Adult↗

PubMedDate not supplied

Clinical testing of the statolith-ocular reflex.

Quantification of eye torsion induced by stimulation of the statolith organ has recently become available (in the clinic) thanks to the development of video nystagmography. A major step forward has been the development of real-time measurement of eye torsion which enables interactive testing of the statolith-ocular reflex. The function of the statolith organs can be evaluated by the study of the impact of statolith stimulation upon the canal-mediated dynamic vestibulo-ocular reflex (VOR) or by measurement of the static VOR. The latter is more appropriate because instruction or alertness seems not to affect the reflex substantially. Four ways of inducing the static reflex are discussed and related experiments are described. In normal subjects, the gain of eye torsion upon lateroflexion (up to 45 degrees) and whole-body roll (up to 90 degrees) ranges from 0.13 to 0.22; eye torsion is 10.3 degrees maximal. Eccentric rotation inducing a maximal centrifugal force of 1 g results in a gain of eye torsion ranging from 0.15 to 0.23 with a maximal eye torsion of 7.8 degrees in normals. Sinusoidal sideward translation at accelerations of about 0.5 g at 0.3 Hz, which can be considered as specific dynamic statolith stimulation, induces a small but substantial eye torsion of maximally 4.1 degrees and with an eye torsion gain ranging from 0.10 to 0.15. Lateroflexion and body flexion do not require sophisticated stimulation equipment and therefore are attractive for implementation in the out-patient department. In patients, impairment of the statolith-ocular reflex is frequently found both in patients with normal as well as in those with defective dynamic VORs (caloric asymmetries). A qualitative concept is presented to describe the deflection pattern of the cilia upon lateroflexion, eccentric rotation and sidewards translational acceleration. According to this theoretical concept, a reduced static eye torsion might point to both a saccular and/or an utricular lesion. An asymmetry of ocular torsion is only expected upon eccentric rotation or sidewards translation in case of a unilateral saccular lesion.

Eye Movements↗