Page Two P H Y S I O T H E R A P Y April, 1954. Jh e * Development of Electrical Diagnosis and Treatment ' L O ^ 4 **» * 0 • . ~ * of Reaction of Degeneration. M. F. H. HINZ State-licensed Physiotherapist K iel, T . P X Marburg, Lecturer in Electrotherapy, Pretoria H ospital School o f Physiotherapy W ITH t h e ’ developm ent o f modern electronic m ethods o f motor-unit stim ulation a much greater range o f treatment diagnosis and prognosis is possible. In order to understand these modern m ethods the physiological factors must be considered. These will be dealt with in greater detail in a further article. T o enable on e to appreciate the importance o f the newest methods I will first revise and point out the dis­ advantages o f th e 'o ld er methods. I. O B SO L E T E W AVE F O R M S FO R ELECTRICAL D IA G N O S IS A N D TR EA TM EN T I. Constant galvanic current for treatment and ionisation. N o t for diagnostic or stim ulation purposes. Interrupted galvanic current— manually or mechani­ cally— for stim ulation o f degenerated motor-units. I . M. A. M.S. i >o-ioob. III. Faradic c u rre n t— irregular a lte rn a tin g a nd interrupted current— Pulse duration 1 ms. at 50 cycles per sec. F or stim ulation o f normal motor-units. A n interrupted galvanic current causes a contraction o f a motor-unit i f the intensity o f the current is high enough. This current intensity causing a minimal contraction is called the R heobase or threshold intensity. The R heobase is the minimal current intensity needed to cause a minimal contraction with a square wave stimulus. The rheobase is lower in normal m otor-units show ing signs o f degeneration. Therefore the current intensity has to be increased in tests or treatment o f degenerated m otor-units. This is the prin- , ciple on which the galvanic-faradic test and treatment is based. This method considers only o n e factor o f electro­ physiology o f nerves and muscles— the rheobase. The galvanic-faradic' test has a purely qualitative diagnostic value not a quantitative or prognostic one. 1. A degenerated motor-unit does not respond to faradism, i.e. it is a qualitative diagnosis and provides n o connection to the degree o f paralysis. 2. The test has no . prognostic value. Frequently voluntary m ovement has returned before the faradic response. 3. The intensity o f the faradic current cannot be measured. The intensity o f the galvanic current can be read in m illiam ps; but the findings are inaccurate and vary from test to test due to :— . (a) Varying sizes oif active and inactive electroes.d The greater the difference in size between these .two, the greater will be the density o f the. current under the active electrode, and the less current will be needed to cause a contraction. (b) Varying resistance o f the patients’ tissues between the two electrodes will give rise to different readings. (c) Firmer as opposed to slight contact will give different readings. (d) The electrode not covering the m otor point accurately— the greater the distance between the m otor point and the electrode, the higher the readings. Before we enlarge on the more modern forms o f electrical diagnosis and treatment let us consider the effect o f current stimuli o f varying pulse duration and interval com pared with the effect o f the old current forms. The old current forms are produced mechanically. The direct or galvanic current may be interrupted manually or mechanically. N o mechanical interruption can give a duration o f a stim ulus short enough and a repetition rate rapid e n o u g h to cause a tetanic contraction o f a normal m otor-unit suitable for treatment, i.e. 1 ms. or less at a . repetition rate o f 50 per second . Therefore for treatment o f normal motor-units the faradic current was selected. (S e e ' D iagram 3.). In modern electrically operated apparatus practically every w ave form, impulse duration and rate o f repetition may be produced. Diagram 4. illustrates the current impulses produced by the Ritchie-Sneath Stimulator. The duration o f the long stimuli, 10 — 100 ms., would correspond to the interrupted galvanic current. The shorter durations o f -01 — I mms. correspond to the faradic range. These short pulse durations set at a repetition rate o f 50 per second, i.e. 20 ms. interval will cause a tetanic contraction o f a normal motor-unit. Applied to a degenerated motor-unit, the response will cease with the shorter stimuli o f -01, 0 -1 , or even 1 ms. depending on the degree o f degeneration. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) April/ 1954. P H Y S I O T H E R A P Y Page Three It must be realised by now that it is not the nature o f the current, alternating current or interrupted direct current, that gives the physiological effect, but it is the duration, form and repetition rate o f the impulses. There is no physio­ logical, therapeutic or diagnostic difference between a faradic current o f 1 ms. pulse duration at 50 per sec. and unidirectional impulses o f 1 ms. pulse duration at 50 per sec. N aturally there will be caustic effects when using unidirectional impulses which are n o t present with alter­ nating currents. This caustic effect is overcom e in many modern apparati by passing a current o f opposite polarity through the circuit during the interval between the impulses. The result is the so called de-polarized current. A de­ polarized current has. little or n o caustic effect. The stimuli or current impulses are normally negative. ' The reason for it will be discussed in the next article. IT TH E IN T R O D U C T IO N O F SQ U A R E WAVE IM P U L S E S O F P R E SE T D U R A T IO N Ritchie-Sneath Stimulator. The Ritchie-Sneath Stimulator gives square ■ wave impulses from -01 — 100 ms. duration. IV. h M . S . l F a R a j i c R a m & p . J G a l v a n i c R a n 6 £ . The duration o f the interval or the repetition rate can also be varied. Stimuli in the galvanic range from 1 or 5 per second. Stimuli in the faradic range from I, 5 or 50 per second. This apparatus is suitable for diagnosis— strength— duration m ethod, which considers also one quantitative factor in diagnosis. In diagnosis, voltage is plotted against pulse duration. Graphs obtained: V. - N orm al m otor-unit. --------------------- P .R .D . or recovering nerve. O O O O O O O ^ J ^ p A normal m otor-unit will respond to stimuli o f 01 ms. pulse duration. The voltage needed will be the sam e for stimuli o f 100 — 1 ms. or even to 0 1 ms. pulse d u r a tio n From then o n the voltage has to be increased rapidly as seen in the graph. Irregularities in the curve indicate a P .R .D ., or when starting from the C .R .D ., a recovery o f the motor-unit. Increased E .M .F . will be needed to cause a contraction, and possibly the m uscle will not respond to the very short stimuli. See Diagram 5, the curve will lie higher and will end at 0 1 or even 1 ms. pulse duration. The curve o f a muscle with C .R .D . will lie very much higher, i.e. m uch m ore voltage is needed to cause a con ­ traction. The denervated m uscle will respond only to stimuli in the galvanic range, i.e. from 1 0 — 100 ms. or only to 100 ms. Conclusion: 1. In this method we have a positive distinction between normal and degenerated motor-units. 2. It is a reasonably certain m ethod o f detecting a P .R .D . which is indicated, by irregularities in the curve. 3. It is also a method o f detecting recovery o f a m otor-unit before a voluntary m ovem ent ■ returns. The re-innervation is indicated— as said in 2— by irregularities in the curve. I f the tests are carried out carefully the electrical recovery should be visible approximately 4 weeks before the first signs o f recovery o f voluntary m ovement. This m ethod o f electrical diagnosis is definitely a step forward com pared with the galvanic-faradic m ethod. The advantages are; A voidance o f errors, as previously m entioned, which occur often with the galvanic-faradic technique. In the galvanic-faradic m ethod these factors give different readings. In the strength— duration technique they do not matter because the time factor is considered. It is stated above what the rheobase is, namely the minimal current intensity needed to cause a minimal con ­ traction with a square wave stimulius. If a square wave stimulus o f a current intensity corres­ ponding to the rheobase is applied to a m otor-unit it will cause a threshold or minimal contraction. I f now the duration o f the stimulus is gradually decreased there will finally be a point at which no contraction will occur. The minimal time o f current flow which is needed to cause a minimal contraction with a certain stimulus is the “effective tim e.” The effective time is very short— m illiseconds— in normal voluntary muscles. It is longer in involuntary muscles. It is stated above that the rheobase becom es higher in degenerated motor-units, correspondingly the effective time is longer in degeneration. The effective time is no, absolute factor but depends on the intensity o f the stimulus applied. Therefore at first the effective time o f a fixed current intensity equal to double the rheobase was selected. The time o f current flow needed to cause a minimal contraction with double the rheobase is the Chron- axie o f the nerve or muscle. The effective time or the chronaxie is the above mentioned time factor in this method o f electrical diagnosis. In the galvanic-faradic test only the rheobase is co n ­ sidered. In the strength-duration m ethod the current intensity necessary to cause a minimal contraction with a given impulse duration is found. The results are plotted as m entioned above. There are tw o different techniques: (a) V oltage can be plotted against duration o f stimulus (Ritchie-Sneath Stimulator). (b) Current intensity can be plotted against duration o f stimulus (Pantostat 523— square-wave stimuli). It m akes no difference whether voltage or current intensity is used. The curve is nearly a hyperbola in a normal motor-unit. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) Page Four P H Y S I O T H E R A P Y A p ril, 1 9 5 4 . It is not quite a hyperbola because its ends are parallel to the co-ordinates (See D iagram 5). It means that stimuli shorter than a certain pulse duration will n o t cause a con ­ traction however high the current intensity, and stimuli ' o f lower current intensity than the rheobase do not cause a contraction how ever lon g the duration. Treatment with the Ritchie-Sneath Stimulator is carried out according to the findings o f the test. It can be given either by single impulses o f set duration or by a series o f impulses o f set duration and interval. There is one disadvantage in this m ethod o f diagnosis and treatment. This apparatus gives only square wave impulses. A normal m otor-unit will respond readily to. such a stimulus. A degenerated m otor-unit will not respond so easily. The reasons for this fact will be discussed later on. Very high current intensities are needed to cause a contraction o f a com pletely degenerated muscle— up to 60— 80 mA'. Therefore neighbouring or antagonistic normal muscles will often contract before the degenerated muscle. III. T H E IN T R O D U C T IO N O F VARIABLE TR IANG ULA R C U R R E N T IM P U L S E S The next progression in electrical diagnosis and treat­ ment is the in tr o d u c tio n o f triangular current impulses o f variable current intensity, pulse duration, angle or velocity o f rise o f current and interval duration. V illa x ' M.A D U R A T I O N . ''z'&of GRADIENT I N T E R V A L . The Siemens Pantostat 523 produces : (a) Square wave impulses from 0 1— 1,000 ms. dura­ tion in a continuous range. (b) Triangular impulses from 0 1— 1,000 ms. duration in a continuou s range. With a longer duration o f a triangular impulse naturally there will be a slower rise o f current, i.e. the-angle o f the rise o f current is smaller, since the wave form o f these impulses is set as follow s: VII In the longer duration T a is smaller or the current rise is slower than in the shorter duration being greater or the current rise quicker. . 2 0 . . VU Ib Control R /T on 1./20. Control T on 0. Switch d on A (Triangular), shows a triangular impulse o f 1 ms. pulse duration and 20 ms. interval, i.e. ± 50 impulses per second. It is the current form nearest to the old faradic current and will cause a tetanic c o n tra ctio n in a normal m otor-unit. Control R /T on 50/2,000. Control t on 20. shows a slowly rising triangular im pulse o f 1 second, interval set at intervals o f 2 seconds. X . T h e Advantages o f this N ew Triangular Wave Form. The main factor o f this new impulse form is the .variable rise in time o f the current. W e have so far considered only two factors, the rheobase and the effective time. A n impulse o f high enough current intensity and long enough duration applied suddenly, i.e. the curent rises to maxim um without time d«lay, will cause a contraction o f a normal motor-unit. An im pulse o f the sam e intensity and duration but rising ' slowly to maxim um will not cause a contraction o f a normal m otor-unit. It is a well know n fact used when increasing intensity in constant current treatments, to avoid the so- called electric shock, i.e. an unpleasant sensory and even m otor nerve stimulation. A current o f given intensity and duration (a) rising to maxim um without time delay will cause a greater contraction o f a normal m otor-unit than the sam e current (b) rising slow ly, or in other words: in (a) the angle o f rise o f current is greater than in (b). T he conclusion is that a normal m otor-unit stimulated via the nerve has the property to accom m odate itself to a unidirectional current. The underlying physiological basis will be discussed in the next article. This process R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) April, 1954. P H Y S I O T H E R A P Y Page Five is called “A ccom m od ation .” The ability o f accom m odation is called “A ccom m odability,” its sign being alpha a. Only a normal m otor-unit can accom m odate because this process takes place in the nerve. A partially degenerated m otor- unit tends to lose this ability o f accom m odation. A co m ­ pletely degenerated m otor-unit has lost this ability com ­ pletely. It means that a m uscle with C .R .D . can still contract when stimulated - with a slowly rising current impulse, providing its intensity is high enough, whereas the neigh­ bouring or antagonistic normal muscles will not respond so easily because o f their ability o f accom m odation to a slowly rising current. It can be seen that this new impulse form offers a m ore accurate m ethod o f localising stim ulation than has been-possible previously. N aturally the effective time when testing or treating a com pletely degenerated m uscle has also to be considered. The duration o f the stim ulus must be long, from a minimum o f 50 ms. up to 500 ms. or more. There are 5 factors that can be set and reproduced exactly at any time in diagnosis or treatment with the Pantostat 523: 1. Current Intensity: The milliamperage can be preset exactly, with the patient’s circuit excluded. The resistance o f the apparatus is kept so high that when the patient is included in the circuit the resistance offered to the current does not give rise to different readings. 2. The Form o f the Stimulus: (a) square wave impulse; (b) triangular impulse. • 3. Pulse Duration: In a range'from 0 1 to 1,000 ms. 4. Interval Duration: In 3 fixed steps: 20, 500 and 2,000 ms. 5. Rising Time o f the Impulse: From 0— 1,000 ms. Diagnosis with the Pantostat 523: T w o curves are taken from every m otor-unit to be be tested: (a) Strength-duration curve, i.e. square wave impulses are used. Intensity is plotted against impulse duration. (b) Triangular impulse curve. Intensity plotted against impulse duration. Curves in a normal motor-unit. X — Strength-duration curve. --------------------- Triangular impulse curve. The strength-duration curve is found as usual and discussed in detail in II.. The triangular impulse curve lies higher, especially in the range o f the longer impulse durations. The reason for it is the above m entioned ability o f a normal motor- unit to accom m odate itself to a unidirectional current, i.e. higher current intensities have to be used when applying a slowly rising im p u lse as opposed to square wave impulses. The accom m odability a is found by dividing the milli­ amperage o f a triangular impulse by the rheobase o f the same pulse duration. It is best to select the values found in the longest p u lse, duration i.e. 1,000 ms. In D iagram 10 the quotient a is 2 5 / 5 = 5. The accom m odability a is an important diagnostic and prognostic aid as t changes definitely in degeneration and regeneration. In a normal m otor unit a is between 3 and 6. In C .R .D . a is 1, i.e. accom m odability is completely lost. In P .R .D . a s between 1 and 3, depending on the degree o f degeneration. In regeneration a will rise 2 to 3 m onths before v ol­ untary m ovem ent returns. XI. I . M A . ■ Square wave. ----------- Triangular impulse. 1. In P .R .D . the strength-duration curve and the triangular impulse curve lie, higher, i.e. the rheobase (square wave) and the thfeshold intensity (triangular impulse) are higher than normal. 2. B oth curves are placed slightly towards the right side. It means that the effective tim e o f this motor-unit is longer. 3. Accom m odability a is 1-5, i.e. between 1 and 3 which indicates P .R .D . XII. C .R .D . - ------------------- Square wave. v -------- ------ Triangular im pulse. 1. In C .R .D . both curves lie very much higher, i.e. rheobase and threshold intensity are considerably raised. 2. B oth curves are much more at the right side, i.e. the effective time is long, or in other words, the muscle responds only to the long stim uli from 150 ms. onw ards. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) Page Six P H Y S I O T H E R A P Y April, 1954 3. , , The accom m odability is lost, a is 1. The result o f the electrical test shows a C .R .D . Treatment is carried out according to the findings o f the test. A normal m otor-unit is treated with short impulses— 0 • l — 1 ms. at 20 ms. interval. The result will be a tetanic contraction. The form o f the impulse— square wave or triangular impulse— does not matter much in the short ranges. The current is either interrupted by means o f a key electrode or surged. The patient should be told to contract with the current. A partially degenerated motor-unit is treated according to the degree o f its degeneration. D iagram 11 shows a partially degenerated motor-unit which has little accom ­ m odability a is 1-5. Therefore a triangular impulse must be chosen for treatment. The duration o f the impulse must be somewhere between 50 and 500 ms. because the effective tim e o f this motor-unit will be longer than normal. The interval duration o f 2,000 ms. should be long enough for a partially degenerated motor-unit. The advantages o f this slowly rising impulse o f long duration is that: 1. The stimulus can be localised to a great extent. 2. The patient can try to contract the m uscle volun­ tarily with this slowly rising long impulse. A muscle show ing C .R .D .— Diagram 12— must be treated with triangular impulses o f long duration, 150— 600 ms. or more. The reasons are: the accom m odability is losO i.e. a is 1, therefore the triangular impulse is chosen. The effective time is very long— curve very much towards the right side. For the muscle shown in Diagram 12, a triangular impulse o f ± 500 ms. should be employed. If it proves that the duration o f the interval o f 2,000 ms. is to o short, i.e. the muscle shows signs o f fatigue after a few contractions, a slowly rising galvanic current o f preset rise and preset intensity should be applied. ' The current is manually interrupted. The duration o f the interval can now be chosen, it can be any time. The best interval for a muscle showing C .R .D . would probably be 5 to 10 seconds. BOOK REVIEW P relim inary E lectricity fo r the P hysiotherapist by B r e n d a S a v a g e , M .S c., m .c .s .p . (Teachers’ Certificates), 3 2 5 pp. 191 Figs. Published by Faber & Faber Ltd., 2 4 , Russell Square, London. Price 2 \s. net. M iss Brenda Savage has succeeded in writing a book which will be invaluable to the physiotherapy student. What few textbooks there are available on M edical Elec­ tricity are now badly in need o f revision, and in any case do not seem to have their texts planned as specifically for the physiotherapist as is the text o f this book. . There are three excellent preliminary chapters on the N ature o f Electricity, Static Electricity and Current Electricity. These form the basis for the division o f the b ook into three sections viz. low frequency currents, high frequency currents and radiations. The elementary physics is described clearly and simply, so as to provide an under­ standing for the chapters on electromechanics and machine construction. M ost obsolete material has been eliminated, though there are one or two inclusions, such as the dia­ thermy couch and diathermy massage, which seem a little out o f place in a modern text book. The progressive or triangular wave form is not described, though it seems that this will be a valuable asset in the diagnosis, prognosis and. treatment o f nerve lesions. The physiological effects and uses o f the apparatus are com paratively brief, but comprehensive, bearing in mind that this is a book for the preliminary physiotherapy examination. Throughout there are ample and clear diagrams, invariably on the sam e page as the text to which they refer a situation which is greatly appreciated after reading'text­ books in which this is not always the case. The whole text is set out clearly and is easy to read, and we must look forw ard to an equally excellent book by , Miss Savage on treatm ents by electrotherapy. . ' U E .D . G EN ERA L The next Postgraduate- course will be held at the University o f the Witwatersrand M edical School on April 30th, in the evening, and on M ay 1st. The subject will be “ Physiotherapy in Pre- and P ost-N atal Care.” We hope to include a film on childbirth, a lecture by a gynaecologist, a dem onstration o f classwork and o n e o f the Neumann- N eurode method o f infant exercises. The' timetable has not yet been finalised, but all interested postgraduates are asked to contact M iss Blair at the Medical School, or at the Johannesburg General H ospital. * * * * The C .E.C . is still trying to obtain a final ruling fromi The Transvaal Provincial A dm inistration regarding physio-1 therapists in the operating theatre. * * * * . A m emorandum has been sent to the M inister of Health setting out the Society’s difficulties, together with a request for an interview with the Minister. * * * * A n apology has been received and accepted from the Board o f the S.A. Nursing A ssociation for the publication o f an advertisement in the S.A . Nursing Journal in November for the Lindstrom C ollege o f Swedish M assage. - C H A N G E O F A D D R E S S Mrs. S. Patz has m oved to 33a, Viljoen Street, Middel- burg, Transvaal. M iss A . I. Burr has changed her address to 182, 10th Avenue, Highlands N orth, Johannesburg. M iss S. O osthuizen’s address is now P.O . B ox 6468, Johannesburg. * * * * BRANCH NEWS Southern Transvaal On M onday, January 11th, D r. H enry Yellowleesd gave a m ost amusing and fascinating lecture entitled “ Word’ and A ction .” W e were delighted to have this opportunity o f hearing him before he returned to England. There were approximately seventy people present. On February 22nd a Sym posium on Paraplegia was held at the Johannesburg General H ospital. A b out eighty people were present at this very interesting an d informative m eeting, at which the speakers were Dr. H. H aden, Mr. A. Rothberg and M iss J. Maurice. D r. H aden gave an introductory talk o n t h e pathology, different types o f paraplegia and aims o f treatment; Mr. Rothberg gave an excellent practical demonstration of the treatment, devoting the short time available to him chiefly to the m ethods o f rehabilitation o f walking for paraplegics. M iss M aurice talked to us about treatment of the paraplegic by occupational therapy while the patient is in hospital, and the vital question o f his re se ttle m e n t and vocational training after discharge. It is hoped that in the future a meeting m ay be held in the W .N .L .A . centre in Johannesburg, where Mr. Rothberg has promised to provide som e o f his non-Euro­ pean patients, with whom he can give a fuller demonstration and explanation o f treatment. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )