WO1999007279A1

WO1999007279A1 - Nerve testing device

Info

Publication number: WO1999007279A1
Application number: PCT/GB1998/002390
Authority: WO
Inventors: Steven Mark Guy Rolfe
Original assignee: Owen Mumford Limited
Priority date: 1997-08-09
Filing date: 1998-08-07
Publication date: 1999-02-18
Also published as: GB9716924D0

Abstract

A nerve testing device is a pen-like implement with a barrel (1) and a body (2) that telescopes into its rear end and is releasably retained thereby. A filament (13) is fitted to the forward end of the body (2) and can project by varying amounts through a narrow passage (14) at the forward end of the barrel (1). Nerve sensitivity is tested by end-on application of the filament (13) which buckles more easily the more it projects. The body (2) can also carry a supplementary nerve testing element (24) in a socket (18) at its rear end. A tip (25, 27) projects and is pushed back against a spring (19) in the socket (18). The element (24) may be reversible, with two different tips (25, 27), and when not in use may be housed in the part of the body (2) that telescopes into the barrel (1).

Description

NERVE TESTING DEVICE

This invention relates to nerve testing devices.

A standard test involves pressing the end of a filament against the skin of a patient. Depending on the length and thickness of the filament, it will remain straight until a certain force is exerted, and then it will buckle. If there is no reaction to the point pressure up to this buckling, then the doctor will know that the local nerves have lost a certain amount of sensitivity. The usual implement for carrying out this test consists simply of a bar from one end of which projects a filament.

The doctor holds the bar and presses the end of the filament against the patient's skin. The filament is of fixed length and thickness, and its buckling point occurs at a predeter- mined applied force. If the doctor wishes to test for a different level of sensitivity, then a different implement has to be found and applied.

It is the aim of this invention to have a device which is adjustable and can test for different levels of sensitiv- ity.

According to the present invention there is provided a nerve testing device comprising a barrel, a body adjustable longitudinally within the barrel, and a filament carried by the body to project from one, forward end of the barrel by controllable amounts.

If just a short length is projecting, then it requires considerable force to make the exposed length of filament bend simply by applying end-on pressure. As the filament projects further, so it becomes easier to make the filament bend or buckle .

The filament preferably emerges from the forward end of the barrel through an aperture in which it is a close fit. It will therefore be fully supported up to the point where it is exposed.

Conveniently the body and barrel have longitudinal slot and stud interengagement to limit the scope of adjustment, and preferably the slot is in the barrel and the stud on the body.

The stud may be on a resilient portion of the body enabling disengagement of the stud from the slot and separation of the body from the barrel. This allows the filament to replaceable, which may be necessary if it becomes contaminated, if it is bent to a non-recoverable position, or if a filament with different characteristics is required.

A replacement filament may be on a carrier that fits to the body and which has indicia to show through a window in the barrel to indicate the end-on force required to buckle the projecting filament. Elements of different stiffness may be used and so each can come with its own calibration.

Advantageously, the barrel and the body have mutually engageable detents whereby the body can be located at predetermined positions to project the filament by a selected amount. These detents may be provided by the stud and lateral deformations of the slot in which the stud can locate .

In the preferred form the body telescopes into the other, rear end of the barrel, leaving an exposed rear end portion, which can have a clip for retention of the device in a pocket .

The rear end portion of the body may also have a socket to receive a spring- loaded nerve testing element with a projecting tip which, in use, is pressed against a patient and forced to retract against the spring. The nerve testing element is preferably removable and reversible and has different tips at opposite ends, either of which tips can be made the projecting one. It may be a small lancet -like element such as that sold under our Trade Mark NEUROTIP. This has a sharp tip at one end, initially shielded by a break-away cap, and a blunt finger at the other end. The tip of the filament may be dimensioned somewhere between these two.

With the body removable from the barrel and the nerve testing element removable from the socket, the body can be adapted to provide a storage location for the nerve testing element when that is not required. Preferably, it is in the portion normally concealed within the barrel. For use, the element is taken out and entered in the socket, conveniently fitting a spring-loaded carrier retained by pin and slot engagement with said body. If the slot is in the body and the pin is on the carrier, the pin can be visible in the slot, which forms a gauge showing the amount of retraction and thus the force applied. For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a nerve testing device in an out-of-use state,

Figure 2 is a side view, in the direction A of Figure 1, of the out-of-use device,

Figure 3 is an axial section of the device in that state , Figure 4 is a side view of a filament carrying body forming part of the device with the filament being withdrawn,

Figure 5 is a side view in the direction B of Figure 4 showing the filament fully in place, and Figure 6 is a side view, from the direction opposite A, of the device in a ready-to-use state.

The device has a barrel 1 and a filament carrying body 2 whose forward end portion 3 telescopes into the rear end of the barrel. This portion 3 is bifurcated into a long arm 4 and a short arm 5, there being an enlargement 6 of the space between them near the root . The free end of the long arm 4 develops into a nose 7 similar in shape to the top of a -bottle. From the base of this nose a short finger 8 extends back almost to the free end of the short arm 5, which terminates with an outwardly projecting stud 9. The body 2 is of moulded plastics construction and the arms can flex, being shown in their relaxed condition in Figure 4. They are moulded angled out at about 10° so that, when straightened up, they bear snugly against the inside of the barrel by virtue of their tendency to revert to their natural shape. In Figure 3 the short arm 5 is pressed even further inwards to allow the barrel 1 to be removed or replaced.

Along the outside of the arm 4, there is a shallow groove 10 to receive a finger 11 projecting rearwardly from a cap 12 which fits closely over the nose 7. The exposed side of the finger carries numbers, as best seen in Figure 5, for assistance in setting the device. Extending forwardly from the cap 12 there is a filament 13, of nylon for example.

The barrel tapers at its forward end and through that there is a narrow passage 14 in which the filament 13 is a close fit. Filaments may be changed and some may be thinner than others. However, the difference between fattest and thinnest will be small (a typical range may be diameters of 0.48 to 0.50 mm), and so there will be negligible scope for the thinner filaments to deform within the passage 14 : they will all be well supported until they emerge from the barrel .

The rear end of the barrel 1 is fully open and the portion 3 is a close sliding fit in the rest of the barrel.

A longitudinal slot 15 extends from near the rear end of the barrel to a point shortly before the taper begins, and the stud 9 engages in this to limit the telescopic movement. The body 2 can be separated from the barrel 1 by squeezing the arm 5 to the Figure 3 position, this being done when the cap 12 with its filament 13 is to be changed for example.

At an intermediate point along the slot 15 there is a pair of opposed detents 16 in which the stud 9 can locate, thus projecting the filament 13 by one predetermined amount. There could be more of these detents. The detent 16a at the rear end is substantially larger so that the barrel 1 and body 2 can be mutually twisted and held by the stud 9 in the filament retracted position.

The rear end of the body 2 has an integrally moulded clip 17, so that the device can be held in a pocket like a pen. It also has a deep socket 18 open to this rear end, housing a coil spring 19 and a carrier 20. The movement of this carrier is limited by a pin 21 which travels in a slot 22, this having a notch 23 at its halfway point which acts as a gauge of how much the carrier 20 is retracted against the force of the spring 19. This will typically be 40gms, and be greater than the force required to buckle the filament 13.

The open end of the socket 18 receives a sensing element 24. It is like a lancet for a skin pricker, having a needle 25 at one end, its sharp tip initially being shielded by a break-off cap 26. At the other end it has a finger 27 considerably thicker than the needle 25 and the filament 13 and with a rounded end. The element 24 is reversible and can be set so that either the needle 25 or the finger 27 projects. Whichever one is selected can be pressed against the skin of a patient, whose reaction is noted when the pin 21 reaches the notch 23. There could be more marks or notches along the slot 22, for different applied forces.

For carriage, the element 24 can be housed between the arms 4 and 5, with the cap 26 in the enlargement 6 as shown in Figure 1. In order to make extraction easy, the arms are further reduced at 28 as best seen in Figure 2 so that the cap 26 is accessible and can be pressed out sideways, .

In use, the barrel 1 and body 2 are closed up from the

Figure 1 position until the filament 13 projects by the desired amount. In Figure 6 the barrel 1 is shown fully retracted, in which state the number '10' on the finger 11 appears in a window 29 in the barrel 1, indicating that the filament will buckle with a lOgm. force applied endwise.

The filament 13 is then applied against the patient's skin and the patient's reaction noted.

Claims

1. A nerve testing device comprising a barrel (1), a body (2) adjustable longitudinally within the barrel, and a filament (13) carried by the body (2) to project from one, forward end of the barrel (1) by controllable amounts.

2. A nerve testing device as claimed in Claim 1, characterised in that the filament (13) emerges from the forward end of the barrel (1) through an aperture (14) in which it is a close fit.

3. A nerve testing device as claimed in Claim 1 or 2 , characterised in that the body (2) and barrel (1) have longitudinal slot (15) and stud (9) interengagement to limit the scope of adjustment.

4. A nerve testing device as claimed in Claim 3, characterised in that the slot (15) is in the barrel (1) and the stud (9) on the body (2) .

5. A nerve testing device as claimed in Claim 4, characterised in that the stud (9) is on a resilient portion (5) of the body enabling disengagement of the stud (9) from the slot (15) and separation of the body (2) from the barrel

(1) ΓÇó

6. A nerve testing device as claimed in Claim 5, characterised in that the filament (13) is replaceable.

7. A nerve testing device as claimed in Claim 6, characterised in that the filament (13) is on a carrier (12) that fits to the body (2) and which has indicia to show through a window (29) in the barrel (1) to indicate the end- on force required to buckle the projecting filament (13) .

8. A nerve testing device as claimed in any preceding claim, characterised in that the barrel (1) and the body (2) have mutually engageable detents (9, 16) whereby the body (2) can be located at predetermined positions to project the filament (13) by a selected amount.

9. A nerve testing device as claimed in Claim 8 as appendant to Claim 3, characterised in that the detents are provided by the stud (9) and lateral deformations (16) of the slot (15) in which the stud (9) can locate.

10. A nerve testing device as claimed in any preceding claim, characterised in that the body (2) telescopes into the other, rear end of the barrel (1) , leaving an exposed rear end portion.

11. A nerve testing device as claimed in Claim 10, characterised in that the rear end portion of the body (2) has a clip (17) for retention of the device in a pocket.

12. A nerve testing device as claimed in Claim 10 or 11, characterised in that the rear end portion of the body has a socket (18) to receive a spring-loaded nerve testing element (24) with a projecting tip (25, 27) which, in use, is pressed against a patient and forced to retract against the spring (19) .

13. A nerve testing device as claimed in Claim 12, characterised in that the nerve testing element (24) is removable and reversible and has different tips (25, 27) at opposite ends, either of which tips can be made the projecting one.

14. A nerve testing device as claimed in Claim 13 as appendant to Claim 5, characterised in that the body provides a storage location (4, 5) for the nerve testing element (24) when that is not required, in the portion normally concealed within the barrel (1) .

15. A nerve testing device as claimed in Claim 12, 13 or 14, characterised in that the nerve testing element (24) fits a spring-loaded carrier (20) , retained by pin (21) and slot (22) engagement with said body.

16. A nerve testing device as claimed in Claim 15, characterised in that the slot (22) is in said body and the pin (21) is on said carrier (20) , visible in the slot (22) , which forms a gauge showing the amount of retraction and thus the force applied.