Electrization of the Central Organs.
In electrization of the central organs of the nervous system, the Voltaic current is alone used, and in its application to the brain, the sympathetic nerves, or the organs of the senses, especial circumspection must be employed. As a general rule it should not be had recourse to when central excitement is contra-indicated, and in all cases the minimum dose should be commenced with, and the application discontinued upon the occurrence of giddiness, nausea, or cerebral symptoms. With these precautions the brain may be electrized by well-moistened sponges applied to each mastoid process, to each temple, or to the frontal and occipital protuberances. The sponges must be held immovable. To galvanize the superior cervical ganglion of the sympathetic, one electrode of small size must be deeply pressed into the auriculo-maxillary fossa, and the other with a good-sized sponge applied over the sixth or seventh cervical vertebra, or to the manubrium sterni, close to the border of the sterno-mastoid. The spinal cord may be electrized by keeping one sponge, usually the positive, stationary, and moving the other up and down by the sides of the vertebræ, or one pole may be applied to the spine, and the other held to a nerve or muscle. The retina by a moistened conductor to the closed eye, and the second to the temple or to the mastoid process of the same side. The auditory nerve by one conductor tipped with sponge and inserted to the bottom of the meatus, the second being held in the hand of the opposite side; or the meatus may be filled with tepid water, and a metallic wire traversing the axis of a vulcanite tube may be immersed in the water, the second conductor being a well-moistened sponge to the nape of the neck. Direct application to the ocular muscles or to the conjunctiva is usually inadmissible, but one pole may be placed over the facial nerve below the ear, and the other applied to the closed eyelid, or the operator may use the forefinger of his right hand, covered by a finger-stall of wet linen as an electrode, passing the current through his own body by holding a moistened sponge from one pole in his left hand, the conductor from the second pole being similarly held in one of the hands of the patient. This application is not only convenient, but it is calculated to allay the fears of a sensitive patient: or a pointed conductor, covered with wet leather, may be connected with one pole, and its point held immovable and firmly pressed down upon the orbital margin, as near as possible to the position of the muscle it is desired to excite, while the patient touches at intervals the sponge from the second pole held by its insulating handle in the operator’s disengaged hand.
Electrolysis Needles.
The chemical action of a continuous Voltaic current is sometimes useful in the removal or dispersal of tumours, and in the consolidation of aneurisms, one or more needles being introduced into the tumour, and connected with a Voltaic battery. I shall discuss this subject in our next Lecture, but I have here some of the most generally useful needles ([Fig. 16]), and I have had made for them holders with eyelet-holes for the attachment of conducting wires which render the operator independent of special conducting cords, for with a coil of insulated wire and a pocket knife he can fit up his needles in a few minutes in any way best adapted to his proposed operation.
Fig. 16. Electrolysis Needles and Needle-holders. By pressing the spring side B, the holder opens as shown in C, to grasp the needle D. The wire is twisted into the eyelet hole-A.
Precautions in mode of Application.
Having now considered the more generally useful methods of application, it may perhaps not be out of place to remind you in concluding this part of our subject that certain precautions are necessary to be observed. We must keep constantly before our attention that we are prescribing or administering an exceedingly powerful remedy, and with all new patients we should commence with a minimum dose, watch its effect, and if we need to increase it, do so gradually—e.g., muscular contraction being sought we must use the power just sufficient to produce it and no more—and so on with other applications; and it is especially necessary to use care in applying the Voltaic current to the face, neck, or any part of the head. Duchenne blinded a patient by suddenly applying a current from 40 cells to the facial muscles, and he had the candour to publish his misfortune. Sudden applications and sudden cessations should especially be guarded against. The cessation shock can, of course, only occur in cases where the conductors having been held immovable, and the current gradually increased, one or both of them has been abruptly, and it may be inadvertently, removed; and I have known a patient so frightened by such a cessation shock as to decline further treatment. The negative pole of a Voltaic battery will, if frequently applied to the same spot, soon cause a sore, and to avoid this the point of application should be slightly varied occasionally; and let me impress upon you, Gentlemen, the importance of always testing electricity upon yourselves before applying it to a patient. Use as many galvanometers, or so-called “instruments of precision,” as you like, but use in addition the back of your left hand as a convenient approximate test for the Voltaic, and your thumb muscles for the Faradaic current, except when about to apply electricity to your patient’s head or face, and make it then an invariable rule to first apply to your own face the same strength of current you are about to administer to your patient’s. If you authorize your patient to have treatment carried out at home impress this rule upon whosoever electrizes him. Under such circumstances it is especially imperative, for there is great belief, even with educated persons who ought to know better, that the benefit derived from electrization is in exact proportion to the pain given by it, and a little personal experience is a very wholesome corrective to such a notion. Graduate your dose, then, by the number of cells employed checked by testing its effect, and do this upon each application, for there is no certain means of securing that the strength of either a Voltaic or a Faradaic current shall not have varied from day to day.
We have now studied, Gentlemen, medical electricity, electrical instruments, and methods of application. In our next and concluding Lecture I propose to discuss the assistance that electricity affords us in diagnosis, prognosis, and treatment.