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J J Struijk

Publications and source records attributed to J J Struijk.

22 records · Page 2Linked to original sources
PubMed1991

Contact combinations in epidural spinal cord stimulation. A comparison by computer modeling.

The geometrical characteristics of longitudinal fiber populations in the dorsal columns (DC), recruited by various contact combinations in epidural spinal cord stimulation (SCS), were compared in a theoretical study. A 3-dimensional computer model was used, representing the geometry and electrical conductivity of the low-thoracic spinal cord and surrounding tissues, in combination with a model representing the electrical properties of a myelinated nerve fiber. It was calculated that, among usual dorsomedial contact combinations, the ratio of mediolateral and dorsoventral extent of the recruited area in DC only varied by 2-5%. The model predicts that in bipolar stimulation the relative lateral extent was smallest at a contact separation of 3-3.5 times the dorsal cerebrospinal-fluid width, which seems to fit the highest ratio of discomfort threshold/paresthesia threshold. It is concluded that the optimal combination varies with distance between cathode and DC and that a unique 'best contact combination' does not exist. When both a decrease of primary afferent diameter in DC and collateral branching near their entrance are considered, the model predicts that recruitment of cutaneous afferents will start in lateral DC and proceed medially at increasing stimulus, which fits clinical observations on the spread of paresthesia. The model predicts that large fibers in the posterior spinocerebellar tract will also be recruited in SCS.

Cerebrospinal Fluid↗
PubMed1991

How do geometric factors influence epidural spinal cord stimulation? A quantitative analysis by computer modeling.

Effects of both anatomic and electrode geometry on the recruitment of rostrocaudal fibers in the spinal cord were investigated by computer simulation of epidural spinal cord stimulation. A three-dimensional model was used, representing the geometry and electrical conductivity of the spinal cord and surrounding tissues, in combination with a model representing the electrical properties of a myelinated nerve fiber. Recruitment contours in the dorsal columns were calculated at various spinal geometries as a function of electrode position, combination and area. Cathodal position appeared to be most significant. Recruitment areas resulting from different contact combinations of a mediodorsal array were almost identical. It was shown that perception threshold largely depends on both dorsal cerebrospinal fluid width and fiber size. The usual bipolar contact separation appeared to approximate the theoretically optimal value, resulting in maximum fiber recruitment at minimum stimulus.

Analgesia, Epidural↗
PubMed1989

A modeling study of nerve fascicle stimulation.

A nerve stimulation model has been developed, incorporating realistic cross-sectional nerve geometries and conductivities. The potential field in the volume conductor was calculated numerically using the variational method. Nerve fiber excitation was described by the model of McNeal. Cross-sectional geometries of small monofascicular rat common peroneal nerve and multifascicular human deep peroneal nerve were taken as sample geometries. Selective stimulation of a fascicle was theoretically analyzed for several electrode positions: outside the nerve, in the connective tissue of the nerve, and inside a fascicle. The model results predict that the use of intraneural or even intrafascicular electrodes is necessary for selective stimulation of fascicles not lying at the surface of the nerve. Model predictions corresponded with experimental results of Veltink et al. on intrafascicular and extraneural stimulation of rat common peroneal nerve and to results of McNeal and Bowman on muscle selective stimulation in multifascicular dog sciatic nerve using an extraneural multielectrode configuration.

Animals↗