AU5888398A

AU5888398A - Arrangement and method for compensating for spasticity

Info

Publication number: AU5888398A
Application number: AU58883/98A
Authority: AU
Inventors: David Felhendler
Original assignee: Otto Bock Scandinavia AB
Current assignee: Otto Bock Scandinavia AB
Priority date: 1997-01-28
Filing date: 1998-01-23
Publication date: 1998-09-08
Also published as: JP2001510368A; EP0959828A1; SE9700226D0; NO993490D0; WO1998035637A1; SE9700226L; NO993490L; SE509977C2

Description

ARRANGEMENT AND METHOD FOR COMPENSATING FOR SPASTICITY

The present invention relates to a device and a method in accordance with the preamble of the independent claim 1.

THE BACKGROUND OF THE INVENTION AND THE STATE OF THE ART

A common problem burdening individuals suffering from neurologic deseases and injuries is that muscles are affected by spasticity. Stroke, multiple schleros (MS) and spinal marrow injuries are typical examples of such deseases and injuries.

A muscle affected by spasticity gets a higher basic tonus resulting in the muscle retracting and getting shorter. Medically spasticity is defined as a state involving considerable unnormal muscle tension and twitches.

If the spasticity process is allowed to proceed without any counteracting treatment taking place, this results in a gradually increasing disabilitation of the part of the body concerned. This does in turn result in that the affected person experiences difficulties in handling his everyday business. The problems are generally especially pronounced when the spasticity hits arms and hands.

Against the background of the problems above mentioned it is very important to keep the spasticity at such a low level as possible. Generally, this is done by tension of the affected muscles and by bringing the affected parts of the body in a position impeding the spasticity. Those measures for impeding spasticity in a specific part of the body usually result in a reduced spasticity also in adjacent parts of the body. Moreover, it is not unusual that this leads to a reduced spasticity also in the other body parts affected. When the spasticity is kept at a low level this also means that the affected person gets certain possibilities spontaneously to perform muscle movements.

The most common professional method used today for muscle tension in connection with spasticity relates to an active therapeutic treatment carried out by e.g. a physiotherapist. Further, pillows are used in an effort optimally to support the body parts concerned so that the affected muscles are stretched in a correct manner and so that a spasticity-arresting positioning is attained.

A spasticity-arresting positioning can be achieved e.g. by extension of the wrist and the finger and abduction of fingers. It is especially essential to bring the thumb into a full, or next to full, radial abduction and to full dorsal flexion.

In order for a therapeutic treatment to yield the desired effect it is of great importance that the muscle tension is long-lasting. By this is in this connection meant a tension lasting for at least 30 minutes. See e.g. "Neurologi" , Aquilonius and Fagius, Norsteds Forlag AB, Stockholm 1989, page 470. According to Aquilonius and Fagius a dayly long-lasting muscle tension can give a long-term spasticity reduction.

Normally, the demand for a long-lasting muscle tension cannot be completely satisfied by therapeutic treatment. Such treatment is time-consuming and the staff resources in the care sector are very limited. Neither do tension and positioning with the use of pillows yield a completely satisfactory result. The reason for this is on the one hand that it is difficult by arrangement of pillows to counteract a muscle retraction and to stretch, with a good precision, exactly the affected muscle, and on the other hand that it is very tiring for a person to lie or sit without movements for a longer time period and in a locked position. Obviously, simultaneous efforts to maintain a spasticity-arresting positioning further complicates this task. Additional problems do naturally arise when the patient wishes to be asleep during the time the pillow support is to be maintained.

From the specialist literature it is known that spasticity can be arrested by abduction of the patient's thumb and by extension of the wrist and the other four fingers. For that purpose there has been designed a foam-rubber orthos. It is adapted to the patient under treatment and is substantially shaped like a rectangular block with openings for the fingers and the thumb. The fingers are enclosed by the foam-rubber orthos proximately around the distal interphalangeal joint of the respective finger. See "Adult Hemiplegia, Evaluation and Treatment", Berta Bobath, Heineman Medical Books, third edition, London 1990 (first edition 1970), pages 66-67 and 109-111.

When the hands of persons suffering from spasticity are to be treated it is also important to avoid contact with the palmar surface of the fingers proximally around the distal interphalangeal joint of the respective finger, since this stimulates the clasp reflex thereby exerting a spasticity-increasing effect. See "Steps to follow", Patricia M. Davies, Springer-Verlag, Berlin 1985, page 40.

Due to the fact that it is important to avoid stimulation of the clasp reflex in order not to trigger a spasticity increase the foam-rubber orthos according to Bobath is not very suitable to counteract spasticity. Further, an extension of the wrist, if occurring, will be accidental and without precision.

A splint designed to counteract spasticity is previously known through "Restoration of motor function in the stroke patient", Margaret Johnstone, Churchill Livingstone, second edition, Hong Kong 1983 (first edi- tion 1978) , pages 21-22 and 74-71. That splint has the shape of a tubular, truncated cone and, in its longitudinal direction, it is provided with a zipper so that it can conveniently be opened and mounted around a forearm and hand of a patient. The splint is made stiff by air inflation. Johnstone underlines the importance of wrist extension as well as extension and abduction of fingers for the purpose of spasticity arrest. She does especially emphasize the importance of a wide radial abduction of the thumb. Johnstone does also teach the possibility, upon the mounting of the splint, of forcing abduction of the thumb in the interior of the splint. Finally, Johnstone establishes that treatment involving use of the splint has dramatically reduced spasticity.

Like the Bobath foam-rubber orthos the Johnstone ' s splint increases spasticity by stimulation of the clasp reflex. It is also difficult to apply the splint in such a way that an exact and durable thumb abduction is achieved.

In spite of the long-standing knowledge about the spasticity-increasing and spasticity-arresting factors above referred to and experiments using different types of auxiliary implements nobody has, as far as is known today, succeeded to present a method for counteracting spasticity by long-lasting muscle tension and spastici- ty-arresting positioning involving use of a device generating extension of the wrist as well as extension and abduction of the fingers, clasp reflex stimuli also being avoided.

The patent literature discloses a number of splints and similar devices. They are used i.a. for the purpose of treating and preventing rheumatoid arthritis and carpal tunnel syndrome and also for splinting in connection with orthopaedic-surgical treatment and operations. Such splints and devices are exemplified in the U.S. patent specifications US,A 3 581 740, US,A 4 941 460 and US,A 4 677 971.

The invention disclosed in US,A 3 581 740 prevents clasp reflex stimulation and extends the wrist and fingers. The device is constituted by a flexible base portion to be applied against the dorsal side of a hand and provided with annular loops for the fingers. The proximal end of the base is by means of straps attached around the wrist. The base is made stiff by inflation of air into a chamber located on its top surface. An essential disadvantage as compared with the present invention is that the radial abduction of the thumb is small and cannot be varied. Neither have the radial abduction of the thumb and the spasticity-arresting effects been observed, since the device is intended for treatment of rheumatoid arthritis.

The splints according to US,A 4 941 460 and

US, A 4 677 971 extend the wrist but not the fingers. They are less suited for use as spasticity-arresting devices as they do not stimulate the clasp reflex. THE PRESENT INVENTION

The object of the invention is to solve the above- mentioned problems and to provide a device and a method efficiently counteracting spasticity. The counteraction shall be attained by avoidance of clasp reflex stimuli simultaneously with extension of the wrist and the fingers and abduction of the fingers. It is especially important that the radial abduction of the thumb can be varied from light to full radial abduction and fixed in the corresponding position. The device shall not match the individual patient but be designed so as it can be used by several different persons. The invention constitutes a solution of the above-mentioned problems . The problem solution appears from the characterizing portions of the claims 1 and 10.

THE DRAWINGS

One embodiment of the invention is illustrated in the accompanying drawing, in which Fig. 1 shows a device according to the invention applied to the forearm and hand of a patient. Figs. 2 and 3 show the device in a top view and bottom view, respectively.

EMBODIMENTS

Fig. 1 shows the device according to the invention as applied on the forearm and hand of a person for the purpose of counteracting spasticity by long-lasting tension of the affected muscles and spasticity-arresting positioning. As appears from Fig. 1, the hand of the patient is fixed in position by means of a first splint 2 and retention straps 4, 5 relatively the forearm with the wrist extended. In this position the muscles acting between the hand and the forearm have the length they shall normally have when in rest and, thanks to the position fixation, they can neither retract.

The splint 2 is made of a material having a low elasti- city factor and a relatively high bending stiffness, a low density and it tolerates cleaning with soap and water. One example of a usable material is polypropylene.

The splint 2 is suitably die cast and then given a slightly rounded cross-sectional profile varying somewhat in the longitudinal direction of the splint and substantially following the dorsal surface shape of the forearm and the hand. The distal end of the splint 2 does essentially follow the geometric shape which is formed by the dorsal side of the hand, excluding the thumb, when the fingers are fully extended and slightly abducted. Due to the fact that the distal end of the splint 2 terminates in a hook and follows the finger tips of the index finger, the middle finger, the ring finger and the little finger from the dorsal side to the palmar side, the fingers are forced to full extension when the proximal end of the splint 2 is forced into full contact with the forearm by means of reten- tion straps 4, 5. Thanks to the fact that the distal end of the splint 2 terminates distally about the distal interphalangeal joint of the respective finger on the palmar side of the hand, stimulation of the clasp reflex is avoided.

It appears from Fig. 1 that a smaller second splint 3 grips around the thumb. The second splint 3 is suitably die cast and consists of the same material as the first splint 2.

At its proximal end the second splint 3 is somewhat bent, matches the surface shape of the first splint 2 and is fastened with a screw 8 or the like on the upper side of the first splint 2 adjacent to the hand dorsal side. More specifically, the fixation point will be located somewhere on the dorsal side of the hand in a point between the knuckles and the wrist. In some cases the fixation point can also be located proximally in relation to the wrist. However, in another embodiment the second splint 3 could be fixed to the underside of the first splint 2 facing, but necessarily not contact- ing, the dorsal sides of the forearm and the hand. In a still further embodiment the second splint 3 could run in a slot-shaped channel in the first splint 2. Naturally, the last-mentioned alternative presupposes that the first splint 2 does, at the channel, have a cross- section, the thickness of which exceeds the thickness of the second splint 3.

The second splint 3 is somewhat twisted longitudinally and extends from the fixation point along the dorsal side of the thumb, follows the thumb tip from the dorsal side to the palmar side and is terminated dist- ally around the interphalangeal joint. Due to its shape in combination with the screw 8 the second splint 3 extends the interphalangeal joint of the thumb and causes full dorsal flexion of the thumb and a radial abduction which can be adjusted in a stepless way. This is described more in detail below with reference to Fig. 2.

Those parts of the first splint 2 contacting the forearm and the hand are suitably provided with a lining 14 consisting of a foam rubber material returning slowly upon compression having open cells and tolerating cleaning with soap and water. The purpose of the lining 14 is to prevent the creation of pressure wounds and chafes. The open cell structure of the lining 14 also means that it can transmit heat and moisture from the skin. Also the portions of the second splint 3 contacting the thumb may be equipped with the same type of lining. The thickness of the lining 14 may vary in the longitudinal direction and the maximum thickness can have one value at the first splint 2 and another at the second splint 3.

It appears from Fig. 2 that a first slot 6 extends in the longitudinal direction of the first splint 2. The slot 6 runs centrally between the two outer edges of the first splint 2 and approximately from a point located one or a few centimeters proximally at the wrist to a point located some centimeters proximally at the hand knuckles. In the second splint 3 there is also a second splint 7 extending centrally between the outer edges. As illustrated in Fig. 2, the second slot 7 is located at the proximal end of the second splint 3 and has an extension normally not exceeding half of the width of the second splint 3.

The splints 2 and 3 are held in tight contact relatively each other by the screw 8 extending through the two slots 6, 7 and making it possible both to displace the second splint 3 in the longitudinal direction of the first splint 2 and to displace it in its own longitudinal direction and also to rotate it freely around an axis perpendicular to the contact surface between the splints 2 and 3. This makes it possible in such a way to position the splints relatively each other that, when they are in use, the radial abduction of the thumb of a patient can be varied and fixed in a selected position by tightening the screw 8. The radial abduction can then be changed by loosening the screw 8 and a subsequent new positioning and tightening. Thanks to this technical solution the radial abduction of a thumb can be varied from slight to full. Another advantage of the solution is that there is no need to match the device to one individual as it can be adjusted to fit different hand sizes. Nevertheless, it may be practical to have at least one specimen preset to child size and one to adult size.

The possibility to vary the relative positions of the splints 2 and 3 does not only admit a free control of the radial abduction but does also force the thumb to full dorsal flexion because the thumb tip is grasped by the second splint 3 and lifted upwards at the fixation of the first splint 2. Thanks to the fact that the second splint 2 follows the dorsal side of the thumb and then, starting approximately at the interphalangeal joint, twists itself around the thumb tip to its palmar side and is terminated distally at the interphalangeal joint, there is also generated an extension of that joint, stimulation of the clasp reflex being also avoided.

By loosening and removing the screw 8 it is easy to remove the first splint 2. If the second splint 3 is manufactured in two models, the one adapted to the thumb of a right hand and the other to a thumb of a left hand, a device according to the invention can, in a cheap and efficient way, be used on the right as well as on the left hand.

The retention straps 4 , 5 can be opened and reclosed and are constituted by loop-type velcro tapes which can be removed from the first splint 2 and the ends of which are secured to velcro tapes 13 of hook-type permanently attached to the top side of the proximal end of the first splint 2. By "top side" is meant that side which is directed outwardly and not facing the dorsal side of the forearm. As was mentioned above in relation to Fig. 1, the lining 14 promotes removal of heat and moisture from the skin. Those properties can be further improved by perforation of at least the first splint 2 and possibly also the second splint 3, said perforations forming channels 15 covering a considerable portion of the surface. Accordingly, the channels 15 do in cooperation with the lining 14 offer an efficient removal of heat and moisture from the skin. For the sake of clarity, in the drawing the channels 15 have been shown rather large. In reality, they may be very small and, instead of perforation, the material in the splints 2, 3 may have inherent properties enabling them, without any perforation, effenciently to transfer air and moisture.

It appears from Fig. 3 that the distal end of the first splint 2 has three fences 9, 10, 11 located between the index finger and the middle finger, the middle finger and the ring finger and the ring finger and the little finger, respectively.

The fences 9, 10, 11 are directed perpendicularly to the side of the first splint 2 contacting the dorsal side of the finger tips and the side contacting the palmar side of the finger tips. Consequently, the fences 9, 10, 11 define a compartment for each of the four fingers and force them to be slightly abducted.

Claims

1. A device (1) for counteracting spasticity by longtime tension of affected muscles and by spasticity- impeding positioning of affected parts of the body, comprising a first splint (2) , the proximal end of which is intended to be brought into firm contact with the forearm of a patient by two or more straps (4, 5) which are mounted on the splint and which can be opened and reclosed, the distal end of each of them being adapted to cause full extension of the patient's index finger, middle finger, ring finger and little finger and, simultaneously, a slight abduction in such a manner that only those parts of the palmar side of the hand which are in a distal position in relation to the distal interphalangeal joints in each of said four fingers can get into physical contact with any portion of the device, characterized in that a member (3) connected to said first splint (2) is arranged firstly to bring the patient's thumb to full dorsal flexion and to extend its interphalangeal joint, secondly to admit a stepless control of the radial abduction of the thumb from a slight to full radial abduction and, thirdly, to fix the thumb in its selected abduction position.

2. A device as claimed in claim 1, characterized in that in the longitudinal direction of said first splint (2) there is cut a slot (6) extending centrally between the outer edges of the splint, said member (3) being constituted by a smaller second splint which in its proximal end also exhibits a longitudinally extending second slot (7), said splints (2, 3) adjoining each other in tight contact by means of a screw (8) or the like passing through both said slots (6, 7) and permit- ting displacement of said second splint (3) in the longitudinal direction of said first splint (2) and in its own longitudinal direction as well as free rotation around an axis perpendicular to the interface between said splints (2, 3) which can be locked in fixed positions relatively each other and again loosened.

3. A device as claimed in claim 2, characterized in that said second splint (3) in its proximal end is slightly bent matching the surface shape of said first splint (2) and in its longitudinal direction somewhat twisted extending from a fixation point adjacent the dorsal side of the wrist, along the dorsal side of the thumb, along the thumb tip from the dorsal side to the palmar side and terminating distally around the interphalangeal joint, said fixation by means of the screw (8) forcing the thumb into full dorsal flexion and selected radial abduction.

4. A device as claimed in any of the preceding claims, characterized in that said second splint (3) is replaceable and adapted to match either a right hand or a left hand.

5. A device as claimed in any of the preceding claims, characterized in that the cross-sectional profile of said first splint (2) varies in its longi- tudinal direction substantially following the surface shape of the dorsal side of a human forearm and hand and in that its distal end substantially covers and follows the geometric shape defined by the dorsal side of the hand, excluding the thumb, when the fingers are fully extended and slightly abducted, said distal end embracing the index finger, the middle finger, the ring finger and the little finger by matching the shape of the finger tips from the dorsal side to the palmar side and terminating distally about the distal interpha- langeal joint of the respective finger.

6. A device as claimed in any of the preceding claims, characterized in that the distal end of said first splint (2) comprises three fences (9, 10, 11) located between the index finger and the middle finger, the middle finger and the ring finger, the ring finger and the little finger and extending perpendicularly between the side of said first splint contacting the dorsal side of the finger tips and the side contacting the palmar side of the finger tips whereby the four fingers are forced into a slight abduction.

7. A device as claimed in any of the preceding claims, characterized in that said retention straps (4, 5) are constituted by loop-type velcro tapes (12) which are releasable from said first splint and the respective ends of which can be attached to hook-type velcro tapes (13) fixed to the top side of the proximal end of the first splint (2) .

8. A device as claimed in any of the preceding claims, characterized in that both splints consist of a polypropylene plastic material or the like having a low elasticity factor, low density, tolerates cleaning by use of soap and water and in that the portion of the splints in contact with the forearm and the hand is provided with a lining (14) consisting of a slowly back-springing foam rubber material which has open cells, tolerates cleaning by use of soap and water, prevents the creation of pressure wounds and chafe wounds and can be penetrated by heat and moisture from the skin.

9. A device as claimed in any of the preceding claims, characterized in that either only said first splint (2) or, alternatively, also said second splint (3) over a large portion of its surface is perforated by channels (15) or the like or that the material in which said splints have been manufactured exhibits properties corresponding to said channels (15) .