Abstract: The spinal cord stimulation device of this invention is configured for implantation into a patient so as to traverse the dura mater that surrounds the spinal cord. Placing the device in this location provides direct contact between the electrode and the cerebrospinal fluid (CSF), in close proximity to the spinal cord. The device has an intradural portion and an extradural portion that compresses and seals the dural membrane between them, securing the device in position and preventing leakage of CSF. The position of the device may be stabilized in relation to the spinal cord by way of a laminoplasty plate, bridging between the device and a vertebra. The device is electronically powered by an implanted pulse generator that produces a spectrum of signals to interrupt or otherwise attenuate transmission of pain mediating neural signals through the spinal cord.

Abstract: A seal arrangement provides a seal between a bore and a rod movable in the bore with a gap formed between the bore and the rod. The seal arrangement includes a floating elastomeric sealing ring which is accommodated in a circumferential groove around the rod. The sealing ring sealingly engages the wall of the bore. An annular resilient biasing device is also accommodated in the groove. The biasing device acts between one wall of the groove and the sealing ring to urge the sealing ring against an opposing wall of the groove. In addition, the biasing device is configured to allow passage of fluid past the biasing device between a region of the groove disposed radially inwardly of the sealing ring and the gap between the rod and the bore on the side of the sealing ring opposite the opposing wall. The biasing device has, at least at some circumferential positions therearound, a cross-sectional profile that reduces in radial width towards one wall of the groove.

Abstract: A seal arrangement is disclosed that provides a seal between a bore and a rod movable in the bore with a gap formed between the bore and the rod. The seal arrangement includes a floating elastomeric sealing ring which is accommodated in a circumferential groove around the rod. The sealing ring sealingly engages the wall of the bore. An annular resilient biasing device is also accommodated in the groove. The biasing device acts between one wall of the groove and the sealing ring to urge the sealing ring against an opposing wall of the groove. In addition, the biasing device is configured to allow passage of fluid past the biasing device between a region of the groove disposed radially inwardly of the sealing ring and the gap between the rod and the bore on the side of the sealing ring opposite the opposing wall. The biasing device has, at least at some circumferential positions therearound, a cross-sectional profile that reduces in radial width towards one wall of the groove.

Abstract: A number wheel counter has a worm wheel connected with the least significant number wheel. A worm gear engaged with the worm wheel is mounted for both rotational and translational movement about a spindle. Cam means are provided such that as the worm gear is rotated, it is also displaced bodily by the cam means so that the worm wheel remains unmoved. At the end of a defined travel of the cam means, the worm gear is returned rapidly to a rest position driving the worm wheel in the manner of a rack and pinion. In this way the number wheels are driven intermittently with the time interval during which the number wheels are between discreet number positions being minimized.