A system of practical medicine. By American authors. Vol. 4

by Unknown

Examination of a Patient.

As nearly all ear patients are afflicted with varying degrees of deafness, one of the first points of inquiry will be as to their hearing power. There are three tests commonly employed for this purpose: the ticking of a watch, the human voice, and the tuning-fork.

1st. The Watch.—By this method of examination the patient is placed with closed eyelids, so as to exclude the visual power as a factor in the examination, as it is a curious fact that many people are apparently unable to distinguish between seeing a watch and hearing its tick, and therefore so long as they can see the watch they will imagine that they can hear it ticking. Bring the watch (held by the physician) from a distance toward the patient until the tick is heard, and note the distance in inches. The plan of holding the watch close to the ear, and then slowly removing it until the extreme limit of hearing is attained, gives an incorrect result as regards the distance that the watch can be heard, due to the fact that the impressions produced on the terminal endings of the auditory nerve by the watch-tick continue a sensible time after the watch-tick has passed out of the nerve-limit, and therefore the watch-tick can still be noted. Prout has prepared a convenient method for recording the hearing power. Note the number of inches that the watch-tick can be heard by a normal ear, and let this serve as a denominator of a fraction, the numerator of which is the number of inches that the same watch-tick can be heard by the ear of the person under examination. For instance: a normal ear can distinguish my watch-tick at a distance of twenty inches; if, now, the patient's ear can perceive the same sound at only five inches, the hearing power would be noted as ⁵/20. By this it is not meant that the hearing power is one-fourth of normal hearing, as it would be only one-sixteenth of normal hearing, as the volume of sound is inversely in proportion to the square of the distance.

2d. The human voice tells more about the hearing power for practical purposes than does the watch. There are many persons who can readily hear the watch-tick at several inches, and yet who hear very imperfectly ordinary conversation, and also many who hear very well the human voice and very badly the watch-tick. The method of examination is to speak ordinary words in a tone that can be heard by the average ear a given number of feet, and to note the distance in feet that the ear under observation can detect the words that are spoken. In this way can be noted the hearing power of the human voice, the numerator of the fraction being the distance that the word can be heard by the observed ear, the denominator being the distance that the word can be distinguished by the normal ear.

The patient should always be examined with closed eyelids, as deaf people quickly learn by watching the movements of the lips of the speaker to know the words that are being spoken. Another precaution is to have the ear to be tested directly opposite the mouth of the observer, the other ear being firmly closed.

3d. The Tuning-Fork.—Bone-conduction of sound is used by this method. The great use of the tuning-fork is in determining diseased conditions of the auditory nerve and internal ear, and it enables one to make a differential diagnosis as to whether deafness is due to a diseased condition of the sound-conducting apparatus or whether the nerve portion of the ear is at fault. For instance: a patient complains of deafness. This may be due to some obstruction in the external auditory canal, such as impacted cerumen, or it may be due to a diseased middle ear, with thickening of its membranes, or it may be due to a diseased internal ear. The watch and human voice would only show the ear to be defective in its hearing power, and it may be from any of the above-mentioned causes. The tuning-fork, in vibration, placed on an incisor tooth or on the frontal bone, would bring out the fact that if the deafness was due to a diseased middle ear or obstruction in the external auditory canal, the tuning-fork would be heard best by the defective ear; but if due to a disease of the internal ear, it would be heard the least distinctly by the defective-hearing ear. Mack explains this by the supposition that the sound-waves are prevented from freely escaping through the sound-conducting apparatus, and are reflected back on the auditory nerve-elements, and thus make a double impression. Tuning-forks having the note C are best adapted for this examination.

EXAMINATION OF THE EXTERNAL CANAL AND TYMPANIC MEMBRANE.—This can be done by direct or by reflected light, better by the latter. A mirror and speculum are needed. The mirror should be concave, with a focal distance of from 5"-7" and a diameter of 2½"-3", with a ball-and-socket-joint and head-band, so as to allow of the two hands being free, the head holding the mirror in the required position. The mirror should have a central perforation of 2'"-3'", with a brass back, rendering it less liable to break. As a light-source can be used the light from an argand burner, but preferably sunlight reflected from a cloud or white wall.

The Ear Speculum.—The Wilde or Gruber speculum answers equally well. The Wilde speculum is cone-shaped, and best of German silver: it is easily cleansed and has four sizes. The Gruber speculum has a larger mouth and gives a large visual field. It has a parabolic curve, for the purpose of admitting more light; there are also four sizes. The speculum should be warm when in use, and is to be held in position in the canal by the thumb and forefinger of the left hand. Often in the examination of an external canal an angular-toothed forceps is needed to remove foreign substances.

The cotton-holder is a most important instrument, furnishing a means of thoroughly drying the external canal of any fluid with the least possible amount of irritation—much less than that caused by the use of the ear-syringe. It is a slender steel rod 6" long, having a number of serrations at one end to more easily allow cotton to be wrapped around it; the other end has a convenient handle. In using this instrument a small tuft of well-cleansed cotton is wrapped around the holder, so that one half of the length of the cotton tuft projects beyond the end of the instrument. By slight adaptation with the fingers the cotton roll can be made soft or quite firm, and large or small in proportion to the amount of cotton used. The cotton-holder should always be used under the light from the head-mirror.

The curette is of the same length as the cotton-holder, but is made of heavier steel, and terminates at one end in a small ring of a diameter of from 2-3 mm. It is useful in removing scabs, etc. from the external canal, also in loosening impacted cerumen.