Lectures on electricity in its relations to medicine and surgery

Front matter

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JCITY

MEDICINE and SURGERY

Contents

LECTURE I.

Electro-Physics

LECTURE II.

Preface

The instruction that I have from time to time given to practitioners of medicine, on the theory and practice of Electro-Therapeutics, is here very incompletely embodied. The lectures were published in consecutive numbers of the Virginia Medical Monthly at the request of its Editor, and although necessarily much restricted in scope and practical detail, will, I trust, open to the reader a fair view of the field of Electro-Medicine and Surgery, as seen from the standpoint of the writer. It may be suggested, that in consideration of the more exhaustive work that has been for some years before the profession, this brochure was uncalled for. If any apology is due, it is offered in consideration of the fact, that in addition to its general survey of Electro-Therapeutics it gives some points that are not discussed in the present edition of our larger work ; and again that while a number ot books on this subject, equally concise, have been issued, in none of them are our methods of general faradization and central galvanization given any adequate consideration, and by some are not even mentioned. These methods, although sufficiently familiar by name to the profession, are yet but illy understood and appreciated, and until there prevails a wider experience in their modus operandi, and a better knowledge of their rationale and effects, it will be impossible to completely discard the error that electrization is merely an irritant and stimulant, and rise to a full conception of its tonic and soothing powers.

A. D. Rockwell.

46 -East 61st Street, New York.

LECTURES ON ELECTRICITY

AS RELATED TO

MEDICINE AND SURGERY

LECTURE I.

ELECTRO PHYSICS.

The subject of electricity in its relation to disease, upon which I am to speak to you, is sufficiently extensive to occupy far more time than is allowed us. I shall therefore content myself with dealing briefly with those points that are more especially practical, hoping that what I shall say and demonstrate may awaken an interest in an important, though neglected, field.

In one sense, there is no department of medicine in which there is greater activity than in electro-therapy. If we may believe the aphorism, however, of one of the truest philosophers of the century, "there is nothing more terrible than activity without insight ;" and it is this very activity that prevails, guided by no intelligent insight into the laws which govern and the principles which underlie electro-therapeutics, that has been its rock of offence and stone of stumbling.

Electricity, although the legitimate property of the educated physician alone, draws to it, more than any other therapeutic means, the folly, ignorance and cupidity of the land; and in every effort to wrest it from the hands of the charlatan, we are simply repeating the history of almost every special department of medicine. Much has indeed already been accomplished, and in all probability its future status is secured; for it rests on foundations too broad to be easily overthrown.

■L ELECTRO-PHYSICS.

J>ut it has grown and is still growing in spite of the opposition of many, who would relegate its use to ignorant attendants, or to the patients themselves, or who, with limited knowledge of the subject, and less experience in its use, assert that their efforts and results compass all that there is to electro-therapeutics.

The three main divisions of the subject are — 1st, Electro-physics; 2d, Electro-physiology; and 3d, Electro-therapeutics — the latter being the science that treats of the study of electricity in its relations to disease. Electro-therapeutics, therefore, includes both electro-medicine and electro-surgery.

Before proceeding to consider the subject of electro-physics, in so far as it is necessary to a clear understanding of electro-therapeutics, it may, perhaps, be not amiss to glance briefly at the history of electro-therapeutics. Like so many other departments of medicine, its beginnings are shrouded in obscurity. Its real history, however, may be divided into three eras: Era of Eranklinic Electricity; era of Galvanization; and era of Faradization.

In the Franklinie era, only franklinic electricity was used — galvanic and faradic electricity not yet having been discovered. The methods employed were by the electric bath, and electrization by sparks and shocks from the Leyden jar. There were many reports of cures by eminent members of the profession ; hut in a memoir presented by Maduyt in 1773, we find a most concise summing up of what experience lias since taught us to be a most accurate estimate of the therapeutic action of electricity. He reports it to be a "remedy of vast and varied powers — possessing a most powerful influence over nutrition, equalizing the circulation, materially affecting the pulse, the perspiration and the secretions, ami surprisingly efficacious in the treatment, not only of paralysis, but also of many other conditions, such as constipation and oedema."

The era of G-alvanization begins with the discovery of animal electricity by Galvani in 1786 ; but it was not until Volta invented the voltaic pile in 1800 that the medical use of the galvanic current was attended with any degree of satisfaction. Imperfect as it was, it was vastly superior to the metallic plates which had been employed since Galvani's discovery.

The discovery of Inductive Electricity, however, by Faraday, in 1831, changed the whole course of electro-therapeutics, since the electric machines, immediately constructed, were more convenient and reliable than the old voltaic piles.

From this time electricity began to be more extensively used — I should, perhaps, say abused — and by the laity more than by the profession. It is only within the last ten or twelve years (if we except the efforts of Remak and Duchenne) that any approach to systematic investigation has been attempted, and an agent powerful for good, but capable of vast injury, given a place in the armamentarium of the profession. Up to the time when inductive electricity was discovered, and for some time thereafter, it was used without any recognized method, and, as a rule, without any very clear ideas of the indications for its use. Gradually, however, as experiences began to be systematized and compared, distinct methods of electrization were introduced, embracing all applications of both faradic and galvanic electricity.

These methods are: Localized faradization, localized galvanization, general faradization and central galvanization — all of which I propose to speak of more in detail further on.

It is hardly necessary for me to assert that no one can be proficient in any department of science, without at the same time having a fair understanding of its foundation principles. [Now, in this presentation of the subject, it will be impossible for me to explain all even of the leading principles of electro-physics, much less to refer to all their practical bearings on electro-physiology and electro-therapeutics. These can, in detail, be gleaned from various treatises upon the subject, and at your leisure. I shall attempt simply to present certain of the most prominent and important features of the subject, sufficient for a ready understanding of what is to follow; and although some of you may be more or less proficient in this part of our topic, you will bear with me if I, for the time, regard my hearers as tyros and speak accordingly.

Electricity is a generic term, under which is included three general forms — viz., magnetism; statical or frictional, or franklinic electricity ; and current or voltaic, or dynamical electricity. With magnetism, we have very little concern. Artificial and natural magnets were at one time supposed to exert curative influences in the relief of pain, &c., and there have been various reports in its favor; hut it is quite evident that whatever benefit followed its use, was due quite as much to the influences of the imagination as to anything else. Statical or frictional electricity, as generated by the oldfashii Hied cylinder machine, you are all probably familiar with. It has been more used in hospitals than in private practice ; and although it is of unquestioned utility, yet it is generally admitted, that whatever can be done with it, can he accomplished hy dynamic electricity, while the latter has, also, a far wider range of usefulness. Static electricity, therefore, we shall not consider further.

The third form of electricity, viz., current or dynamic electricity, will mainly engage our attention, since it occupies the chief place in electro-medicine and surgery. Under this head we have — 1st. That form called galvanism or voltaic electricity — the result of chemical action; and 2d. Induced electricity, electro-magnetism or magneto-electricity — the result of current or magnetic induction. You are to understand that these varieties, just indicated, are called dynamical or current electricity— signifying electricity in motion, to distinguish it from static electricity — signifying the electrical condition of bodies, in which electricity remains insulated or stationary. And yet, under certain circumstances, dynamic electricity becomes, as it were, statical; for if the poles of a series of galvanic batteries are insulated, they manifest, before the current begins, the electric tension of a frictional machine.

Much confusion has arisen, and still exists, in regard to the different manifestations of current, because of the loose nomenclature that prevails. There is an indiscriminate use of the terms induced, constant, galvanic, direct, secondary, etc., serving only to mystify and mislead. The subject becomes very much simplified if we hear in mind that the third or dynamical kind of electricity, with which we have principally to deal, manifests itself, as I have before stated, in two forms of currents — viz., the galvanic, so-called after Galvani the discoverer of chemical action ; and, second, the faradic after Faraday, the discoverer of the principle of induction. Recollect, also, that the synonyms of the term galvanic are as follows — viz., constant, primary, voltaic and direct; the synonyms of the faradic being the induced, secondary, interrupted, electro-magnetic and magneto-electric — the latter synonym being used when the current is induced through a permanent magnet, instead of through chemical action. It is, I suppose, vain to hope that the two simple terms galvanic and faradic will be adopted in all references to the subject, and if, therefore, the synonyms above enumerated are remembered, much annoyance will be obviated.

I have emphasized this subject of nomenclature, but I think not unnecessarily ; for I constantly find the greatest amount of misconception existing among those who have batteries, and who are supposed even to be somewhat informed.

The history and nomenclature having been thus briefly disposed of, it remains for me to make as clear as possible the chemical action of the simple galvanic cell, in which is generated the galvanic current, and then to explain to you the principle of induction, through which we have the faradic current.

As you are well aware, in the formation of a single galvanic circle there are usually two metals and a liquid. The strength of the current generated depends mainly upon the strength of the solution, and the combination of elements immersed in it. It is well, therefore, that you should understand that the various elements that are used in batteries, have a natural electro-chemical arrangement — as, for example, zinc, copper, silver, platinum, gold, carbon. Each substance in this abbreviated series is positive to any substance below it, and negative to any one above it. Thus, copper, when associated in a galvanic pair in the proper fluid, with any one of the elements that follow it, generates positive electricity; but when associated with the element preceding it, generates negative electricity.

The more electro-negative any one of the elements in this series is to a given element, the more intense will be the current generated, when they are united in a galvanic pair. In other words, the further removed any two elements are from each other in this series, the greater is the tension of current when they are combined in a single cell. I have before you one of the simplest, but at the same time one of the most efficient, cells for practical purposes. It is called Smee's cell, and is composed of two plates of zinc and one of corrugated platinum. When Immersed in a solution of sulphuric acid, what takes place? In common language, simply this — an electrical disturbance is observed over all the surface of the zinc covered by the fluid. Positive electricity is generated at the zinc element and flows through the liquid to the platinum.*

The electricity is generated wholly by the chemical action of the acid upon the zinc, and other things being equal, the quantity of electricity set in motion will be proportional to the extent of zinc surface exposed to the acid.

Right here, there is one important practical point which I will mention, for a knowledge of it will enable you to tell in any galvanic battery which is the positive and which the negative pole. The zinc is said to generate positive electricity ; and yet it is always the negative pole, from the fact that, in the liquid, the positive electricity of the zinc flows towards the platinum, and the negative electricity of the platinum towards the zinc, and thence through the circuit outside the cells. Because for the sake of convenience, we speak of electricity as a current flowing in certain directions, it is not to be supposed that it is a real fluid.

This old Franklinic hypothesis has long since been abandoned. We may suppose that as light consists of undulations of ether, so we may believe that electricity consists of movements of a different kind — is, in short, simply a mode of motion.

At this point, there are two terms — quantity and tension — that should he explained. I shall refer to them in the simplest language, for a thorough scientific explanation would necessitate a consideration of Ohm's law, which, although of great importance, cannot he elucidated here. Tension — a re suit of electro-motive force — is that quality of electricity by which it overcomes resistance. The tension of a battery depends upon the number of its^cells ; while quantity,^ signifv-

*The chemical changes that take place in the battery will be considered when we come to speak of that part of electro-surgery termed electrolysis.

fThe ter.r. quantity is retained for convenience. By it more than by the term tension is understood the strength or working power of the current.

ing that amount of electricity which passes through a circuit in a given time, depends upon the size of the elements in the cells. The action of the liquid upon the surfaces of the zincs, causes the same electrical disturbances in each cell. The liquid becomes positive, while the zinc above the liquid becomes negative. The positive electricity of the liquid is conducted through the platinum plate (Smee's cell) to the negative zinc of the next cup, where it becomes exactly neutralized. We obtain, therefore, no more quantity from 100 cells than from a single cell, but a greatly increased tension. The relative meaning of these terms quantity and tension may be best understood by an illustration. A gallon of water heated to 100° has a much greater quantity of heat than a pint heated to 200° ; but the heat of the latter is much more intense.

Faradic electricity, the second division of current electriehVy, is the current of induction.

The current from a simple galvanic circle, passing through a coil of wire, induces, simply by proximity, a secondary current in a second coil of wire — differing altogether in its physiological effects from the galvanic current.

These induced or secondary cm-rents, again, have the power to induce currents in other coils of wire called tertiary currents, and so on for a long series. The strength of the current decreases, however, the higher they ascend ; hence, batteries constructed for therapeutical purposes have no more than the two coils. By putting a bar of soft iron, or a bundle of iron wires, within the primary coil, the current becomes very much strengthened, and in this way, the momentary action of the current, as it is closed, causes the iron bar or wires to become magnetic. As the current opens, this magnetism disappears — its disappearance inducing a current in the same direction as the disappearing primary current. For the uses of therapeutics, therefore, this iron core is a very convenient means for modifying the current. Instead of an iron core, however, the machines that are now constructed have their entire coil covered by a cylinder of tin. When this tube covers the helix, an indefinite number of branch currents arc induced in it, that interfere with the main current, and weaken it. In proportion as this is withdrawn, the induction of branch currents, and the consequent interference with the main current, grow less.

The wire of a primary coil is made quite large, because it is a law of electro-physics, that the thicker the wire the better is electricity conducted, and the more readily is magnetism excited in the iron core. The secondary coil is, however, made of very thin wire and of great length, so that as many turns as possible may be brought within the influence of the core and of the primary coil, and thus produce a secondary current. As with the galvanic or inducing current, the electro-motive force of the battery is proportionate to the number of cells, so with the induced or secondary current, the electro-motive force of the coil is proportionate to the number of turns or coils in it.

There are two forms of faradic batteries, varying materially in construction and in physiological action. These are termed, respectively, the single or continuous, and the double or separate coil machines. In the first named, there isa continuous'wi re, varying, however, in thickness in different parts of its course. This wire is tapped at different points, and the quality of the current generated, depends upon the length and thickness of the coils included in the circuit. In the separate coil machine, the helix is composed of two entirely separate and distinct wires, the inner or inducing coil of wire being thicker than the outer coil. Now, it is not a matter of indifference in what way a helix is constructed. Every modification of a conductor in length, thickness or constitution, more or less modifies the quality as well as strength of the current; and, therefore, the current proceeding from these different forms of helices, as well as from the different portions of the continuous coil helix, vary considerably in their action.

It is difficult, and perhaps impossible, to arrive at any satisfactory conclusion in regard to the relative therapeutic effects of the continuous and separate coil machines through physiological or theoretical considerations alone. Clinical experience serves us best here ; and guided by it, I have found that the current proceeding from the single or continuous coil is to be preferred in the treatment of nervous and hysterical patients, and for the production of those toni c effects that are aimed at in the administration of general fara dization. On the other hand, in many cases of anaesthesia and loss of electro-muscular contractility and impaired virility, the current from the separate coil answers a better purpose.

LECTURE II.

ELECTRO-PHYSIOLOGY.

Electro-Piiysiolouy is a subject of such extent and intricacy, that it is not a little embarrassing when there is such brief space for its consideration, to decide what method of presentation will best illustrate its value as a guide to the study of electro-therapeutics.

Animal electricity, although interesting and instructive, I shall not attempt to elucidate here. The most that 1 shall attempt will be : 1st, To state some facts (all of which I have myself verified) in relation to that peculiar modification of irritability that nerves and muscles undergo when acted upon by the galvanic current. 2d, To consider the action of the galvanic current on the brain, spinal cord, great sympathetic and pneumogastric. 3d, Its action on the nerves of special sense. 4th, The action ot both the faradic and galvanic currents on the voluntary and involuntary muscles. 5th, Their effects on nutrition.

1st, Ulectrotonos. — When, by means of two electrodes, the galvanic current is applied along the course of a nerve, that portion between, as well as a limited portion outside the poles, are said to be iu an electrotonic state, and that part of the nerve not included between the poles will deflect the needle of a delicate galvanometer. In other words, there becomes manifest a modification of the natural nerve current.

When the galvanic current and the nerve current flow in the same direction, the strength of the latter is increased, while its strength is decreased if the electric current flows in an opposite direction.

There are two modifications of the electrotonic condition, termed, respectively, anelectrotonos and catelectrotonos. Anelectrotonos is a condition of diminished irritability talcing place at and near the positive pole or anode ; while catelectrotonos is a condition of increased irritability taking place at and near the negative pole or cathode.

Somewhere between the poles, there is a part called the neutral point, where anelectrotonos meets catelectrotonos. If the strength of the current is medium, the neutral point is found midway between the poles ; if the current is weak, the neutral point is nearer the positive pole ; if it is strong, nearer the negative pole.

When an irritable nerve is brought under the influence of a rapidly interrupted galvanic current, the nerve-current gradually diminishes in strength until it is finally destroyed. Nothing is better established in physiology than the above fact ; and yet, paradoxical as it may seem, when a nerve, through injury or disease, has quite lost its irritability to the faradic current, it frequently regains it after several applications of the galvanic.

■In addition to these phenomena, due simply to the current passing in a single direction, we have other physiological effects, due to changes in the current, caused by closing, breaking or reversing. When the electrodes are applied to a nerve, and the current closed, we observe a momentary contraction, proportionate in vigor to the tension of the current, While the current is flowing continuously, no contractions take place ; but immediately on breaking the circuit, if the current be not too weak, muscular contraction again occurs.

The following is the statement of what physiological experiment has taught :

1st. The mildest currents applied to a nerve cause contraction only on closing the circuit, independently of direction.

2d. Currents of medium strength cause contraction both at the opening and closing in both directions.

3d. Strong descending currents cause contraction only at closing the circuit, while strong ascending currents cause it only at opening.

Although it is impossible to illustrate these laws by ex-

12 ELECTRO-PHYSIOLOCY.

periments on the living man, they can be readily verified on the fresh nerve of an animal. In experimenting on oneself, or on others, the strongest current that can be well borne, produces the effect only that follows the application of a very mild current directly to the nerve — viz., contractions only on closing the circuit independently of direction. Another effect of electrotonoa is the change of irritability which is caused by a change in the direction of the current. If a nerve is subjected for some time to the influence of a galvanic current in a certain direction, it loses some of its irritability, which it regains when the current is reversed. One noticeable result of the passage of the continuous galvanic current through an exhausted nerve is the marked refreshing effects which follow ; the nerve is, for the time, restored to its usual tone and level.

2d, Action of the Current on the Brain, Spinal Cord, $c. — It has been shown by Fritsch and H'Jtzig, using the galvanic current, followed by Ferrier, using the faradic, that there are centres in the cerebral convolutions for the production of voluntary muscular movements in various parts of the body. In these experiments, the applications were made directly to the substance of the brain; and interesting as they are, and as worthy of study, the practical gain to electro-therapeutics through such investigation amounts to but little. As practical men, we are most interested in knowing what external applications will accomplish. Physiological experiment has simply taught us, and clinical experience has confirmed the teaching, that very mild currents of galvanism, when externally applied, will directly, and not alone by reflex action, affect the brain. If it were possible in our treatment of diseases of the nerve-centres, to localize the action of the current, it can readily be seen what increased facilities would be ours in dealing with certain pathological conditions. This, unfortunately, we cannot do ; but as clinical experience has shown very conclusively the excellent results that follow simple external applications, it remains for us to utilize, so far as possible, this method.

When we come to consider the action of electricity on the spinal cord and sympathetic, we find that there is ample ground for speculation, and room for a wide diversity of opinion. It is no very difficult matter to expose the spinal cord in the living animal, and to show that the direct application of galvanism is sufficient to throw the muscles of the trunk and of the extremities into violent contractions. It is as easily demonstrated that if the cord be traversed for some time by the current, that portion which is under the electrical influence, finally becomes insusceptible to all forms of stimulus, mechanical or electrical. A so-called inhibitory effect is produced. Finally, it is agreed, that when the faradic current is applied directly to a certain portion of the cord near the sixth cervical vertebra (centrum cilio-spinale), the excitation is transmitted to the cervical sympathetic nerve, and thence to the radiating fibres of the iris which it animates ; similarly, by electrization of that part of the cord which traverses the fourth lumbar vertebra (ganglion genito-spinale), it is possible to induce very appreciable contractions of the vasa differentia, the bladder and rectum.

It is exceedingly difficult, however, to determine just to what extent it is possible to affect the spinal cord in the living man, by simple external applications. Yet, that it can ' be directly influenced and brilliant therapeutic results obtained, has been sufficiently attested. The eilio-spinal centre just mentioned is between the sixth and seventh cervical vertebra?, as can be demonstrated by external applications both of the galvanic and faradic currents, and is of great importance in general faradization. To a certain extent, yet not so decidedly, the ganglion genito-spinale can be directly affected — at least, by the galvanic current.

The effects of electrization on the exposed sympathetic nerve are so familiar as scarcely to need mention. In brief, it has been observed time and time again, that the condition of redness and injection of the conjunctiva, ears and nostrils, contraction of the pupils, secretion from the mucous surface of the eyes, &c, that follow division of the cervical filaments of the sympathetic nerve, entirely disappear when the cephalic extremity of the cut nerve is submitted to electrization. The effect, therefore, of direct galvanization of the cervical sympathetic is to contract the arterioles, through the medium

14 ELECTEO-PHYSIOLOGY.

of the vasomotor nerves. Galvanization of the inferior cervical ganglia of the sympathetic, as well as of the superior thoracic ganglia, accelerates the heart's action, while powerful galvanization of the six lower dorsal ganglia, and the splanchnic nerves to which they give rise, diminishes the peristaltic action of the intestines. Mild galvanization, on the contrary, has been found to increase the peristaltic action.

The effects of direct electrization of the pneumogastric vary with the strength of current used. If strong faradic currents are employed, coughing and vomiting are the result: while currents of medium strength produce sudden inspiration and forced expiration. Arrest of respiration is liable to l>e the result of galvanization of the laryngeal branch of the pneumogastric.

In attempting now to consider the effects of external applications to the sympathetic and pneumogastric of the living man, the same difficulty confronts us, as in the case of the brain and spinal cord. AW' cannot accurately localize the current in these nerves or any of their ganglia. A current of sufficient strength to appreciably affect the cervical sympathetic, necessarily at the same time influences, more or less, the pneumogastric, the depressor nerve and the cord.

The effects of external galvanization of the sympathetic arc not altogether uniform, but many trials have shown that a very constant effect of this method of operation — one electrode being placed in the mastoid fossa, and the other over the seventh cervical vertebra, is a slight and occasionally a profound feeling of drowsiness, together with a feeling of warmth through the system, accompanied by perspiration, and a decided effect on the pulse. In several cases, I have observed profound sleep, induced within a minute from the beginning of the application. The eyes would close, the head would drop and nod, and when the electrodes were removed, the transition from drowsiness to a wakeful condition would be slow, very much the same as is observed when one is awakened from a deep and natural sleep. In other cases, on the removal of the electrodes, the person would awaken immediately and become fully alive to his surroundings. These different phenomena were, of course, the result of varying idiosyncrasies. If we accept the theory that in sleep there exists a condition of cerehral anaemia, it is not difficult to believe that the slight feeling; of drowsiness that so frequently follows galvanization ot the sympathetic, and even of the brain, is in part, at least, due to a diminution of the blood supply. At all events, this result, which is so grateful and restorative in many nerve disorders, is constantly achieved in the experience of every practically competent electro-therapeutist.

3d. Action of Galvanism on the Nerves of Special Sense. — The galvanic current, applied so as to affect the retina or optic nerve, either directly or reflexly, causes flashes of light and perception of color. The faradic current, according to the method of its application, when applied in the ear, causes a humming or rumbling sound — due in part to susurri of the muscles.