Society of Laparoscopic & Robotic Surgeons | CHAPTER 10


The Larynx Illuminated
Early Laryngoscopy, Esophagoscopy/Gastroscopy

The great tragedy of science – the slaying of a beautiful hypothesis by an ugly fact.
-Thomas Huxley

Now, sometimes anatomy got the best of endoscopists. In the case of the upper GI the ugly fact was that it gave practitioners a good flummox. It took a great deal of endoscopic engineering magic, along with some sword-swallowers here and there, to overcome such ancient anatomical difficulties. As a result of these natural anatomical constraints, laryngoscopists1 proved to be some of the most clever innovators involved in the endoscope’s formative years. Some of these early pioneers even risked their own larynxes to figure out how to adapt endoscopy to this field. And as a consequence of this treacherous anatomical landscape, finding the perfect patient position became an especially creative undertaking. Sniffing and supine, end-over, down under, hanging; all manner of bodily contortion was contemplated in order to come up with just the right angle of repose for peering beyond the darkness.

All this was surely no walk in the park. It was demanding work navigating blindly down to the depths of the soft spiraling esophagus. Not all had the skill- or nerve- to perform these delicate maneuvers. And with only the early rigid endoscopes available, lit with only intermittent sunlight or the meager light of candles, it took great clinical judgment and knowledge of anatomy to avert danger. These early days were filled with suspense, as one small move in the wrong direction could easily spell disaster. And since the throat cavity is not expandable, it was more important than ever to make the light brighter and ensure it was reflected and directed deeper down the throat cavity (more difficult than the easier to access lower pelvic regions of the human anatomy). The instrumentation also had to be modified with more safety features and smaller dimensions in order to fit into the narrow recesses of the throat and esophagus.

In other words, when it came to laryngoscopy, we were essentially flung back to the time of Bozzini, having to deal with the original obstacles of insufficient lighting and problems getting the image reflected back to the eye.

The Earliest Pioneers
To meet these challenges, a whole progression of men and methods ensued, summoning their best efforts to overcome what seemed to be insurmountable odds. Many histories of laryngoscopy begin straight away with the story of Manuel Garcia, the most commonly cited founder of the discipline. However, more recent research has uncovered information about many others who preceded Garcia. Not surprising, Bozzini is cited by most as the true founder of laryngoscopy, for the obvious reason of having introduced the field of modern endoscopy in general, as well as because his auxiliary attachments were designed with the upper GI in mind2. Though ultimately Bozzini was unable to visualize the larynx in living patients, his main design principles served as blueprints for many years thereafter. The French surgeon Levret is the next most commonly cited predecessor to Garcia, whose device to view the larynx, though not as technically sophisticated, preceded Bozzini’s work by over fifty years. Introduced in 1743, Levret’s angled-mirror instrument for viewing the larynx indirectly, in addition to his novel way to ligature laryngeal polyps, apparently did enable practitioners to visualize the larynx. The historical records on this however are not clear.

Guy Babington – 1829
Aside from these few emboldened pioneers, because of the serious anatomical constraints, many abandoned the quest altogether. Only the truly persistent troubled to carry on. One such dogged individual insistent on finding a solution was Guy B. Babington, a physician from London. Babington is now cited as the first to have viewed the upper larynx3 using endoscopic principles. Babington’s “glottoscope,” presented in 1829, was unique in that his was the first instrument to combine the previously separate devices of a reflecting mirror (a common dentist’s mirror) and a tongue depressor into one clinically practical unit. Some of his later modifications were even more exceptional in that his design principles closely resemble modern-day laryngoscopes.

Though not especially mechanically challenging, Babington’s innovation nevertheless produced excellent results, for it freed up one hand which could then be used to hold or maneuver a second reflecting mirror into just the right angle to enhance the concentration of light. Prior to this innovation, physicians faced the cumbersome task of holding the viewing mirror in one hand with the tongue-depressor in the other, while an assistant blindly directed the use of the second reflecting device, finding the correct angles only as verbally instructed by the seeing physician. This awkward trio of tasks severely limited accuracy, visibility and mobility. With his simple innovation, Babington improved light reflection capabilities and increased the efficiency and safety of the entire procedure, allowing physicians to concentrate more fully on the actual therapeutic procedures.

As usual, some aspects of the record are unclear. For instance, it is not clear whether Babington was truly able to visualize the larynx. Part of the confusion stems from the fact that the details concerning Babington’s clinical trials were not found in the main body of his first article on the subject, but were added as an appendix at a later publication date. In any case, in these appended notes, Babington did claim to have visualized the larynx in a living patient using reflected light, a feat which would have made him one of the first in documented history to do so. Babington was also unique in his usage of two reflecting mirrors of different sizes, each held at 120 angles to achieve just the right results. The smaller one, held in the right hand, was used to reflect the image back to the eye, while the larger one, a “common hand looking-glass,” was held in the left hand and was used to concentrate the solar rays back toward the first mirror. As for the light source, Babington relied exclusively on natural sunlight instead of artificial illumination.

Despite his remarkable achievements, over the years Babington has been overshadowed by other pioneers in the field. However, many laryngoscopists today have now reconsidered the record and have come to view Babington’s contributions as nearly on par with others of repute, such as Garcia.

To the Larynx or Bust – Honorable Attempts
As it turned out, not every physician could achieve what Babington did in these early days. A great many tried and failed to replicate Babington’s methods. It seems it wasn’t just the technical innovations; the dexterity, judgment and skill of the physician came into play as well, factors we see affecting the outcome of endoscopic surgeries even today. A whole progression of men and methods followed in these early years of the 19th century. Some of the more well known to have tried but failed include of course Bozzini, then Senn from Geneva, Trousseau and Belloc of Paris, and John Avery of London.

Horace Green – 1838
With such high failure rates, those who did achieve any degree of success were often referred to as either virtuosos- or charlatans. Horace Green of New York (1802 – 1866) surely fell into the former category. Considered by many as the “father of laryngoscopy in America,” Green’s work was significant because he was the first to achieve direct visualization of the larynx, rather than relying on reflected images from mirrors4. Contrary to other historical accounts, it was Green– and not Kirstein or Tobold- who was first to achieve this. This change to direct viewing anticipated modern laryngoscopic methods and required fairly sophisticated manipulation of light sources for inspecting what had been generally considered inaccessible. Retrospectively, American laryngoscopists also credit Green for establishing the field of laryngoscopy, since he was also one of the first to limit his practice to diseases of the throat.

Green gave new meaning to the word industrious, and his unwieldy list of “firsts” bears witness to the prolific outpour that was his life work. Perhaps of most significance, Green was one of the first ever to perform what must be considered the first successful laryngoscopic operative procedure. His case involved an 11-year old girl who suffered from severe sleep apnea, caused in part by a mass obstructing her glottal aperture. At the time of this procedure, laryngotomy had been successfully achieved in only one adult patient. Green therefore decided to instead try excising the mass transorally; in other words, in a minimally invasive manner. Under direct visualization, using his whalebone5 laryngoscope and reflected sunlight as his source of illumination, Green removed the polyp, thus curing the patient.

In 1838 Green also was the first to introduce other forms of operative laryngoscopy, using his endoscope to deliver a sponge saturated with a cauterizing solution of 10% silver nitrate. Remarkable for his time too, Green was also apparently able to reach his treatment as far down as the lungs. Green’s ability to perform such difficult procedures defied the medical understandings of his day. In fact, few others could repeat his procedures. One professor of anatomy refused to believe his results, brashly declaring his work to be an “anatomical impossibility.” As a result of such skepticism, Green was repeatedly accused of fabricating his data and fellow colleagues demanded his expulsion from the New York Medical Society. A committee was even formed to investigate his claims, which were condemned as an “unwarrantable innovation into practical medicine.”

Yet Green possessed uncommon fortitude, for despite such hostility, he boldly continued his research and clinical practice, producing prolific volumes of work, including two textbooks, as well as groundbreaking articles. Ultimately, he was vindicated of all charges, as eventually other pioneers were able to understand his work and achieve similar results. Like so many innovators, Green had simply been too far ahead of his time.

Manuel Garcia – 1854
Despite the priority by many others in the field, medical historians conventionally date the beginning of laryngoscopy to 18546, when the Spanish voice professor, Manuel Garcia, demonstrated to London’s Royal Society of Medicine an endoscopic method for indirectly viewing his own larynx. Noted for his charisma and persuasive communication skills, Garcia was able to capture the medical community’s attention even without formal medical or scientific training. With his unique blend of personality and persistence, Garcia earned the title as one of the “fathers” of laryngoscopy.

Despite his acclaim, Garcia’s method appears to have been no more sophisticated than Babington’s work from twenty years earlier. Relying solely on the most rudimentary principles of endoscopy, Garcia utilized a simple dental mirror (which he warmed beforehand to decrease condensation) and a second hand-held mirror to reflect sunlight.

Though his ideas were not entirely original, Garcia nevertheless deserves mention in the history of endoscopy based on his tireless advocacy and persistent desire to perfect his technique. Famous for being the singing teacher to the opera stars of the day and filled with uncanny vigor, Garcia enjoyed a colorful and long life, living past the age of 100; and he was said to have maintained his sprightly spirit right until the very end.

1857 – The Tangled Tale of Turck and Czermak
Up until this time, the history of laryngoscopy had been rather staid, save for some of the more intrepid adventures of Horace Green. However, by the 1850s, as endoscopy in general began to take off as a legitimate field, things got a bit more complicated. Disputes over priority became common. Within the world of laryngoscopy, one of the most notable contestations occurred between Ludwig Turck and Johann Czermak. They are jointly cited as founders of laryngoscopy in Europe, though Czermak is generally given the bulk of credit.

Ludwig Turck
The story began in the fall of 1857 with Ludwig Turck, a professor of laryngoscopy from Vienna, Austria. Hearing of Garcia’s successes, Turck traveled to Paris himself to observe his work. Then, utilizing Garcia’s main principles, Turck modified the instrumentation somewhat by using a larger reflecting mirror. From this point however, some discrepancies exist concerning Turck’s degree of clinical success. Some sources refer to Turck as the initiator of clinical-diagnostic laryngoscopy, indicating that his work must have been fairly significant. However, others claim that his efforts were unsuccessful, stating that by 1858, he had completely “abandoned” further work in the field.

Johann Czermak
Entering the picture shortly after Turck was the Czechosovakian professor of physiology named Johann Nepomuk Czermak (1828–1873). Most accounts agree that Czermak learned the main tenets of laryngoscopy directly from Turck, even borrowing his instrumentation. It seems however that Czermak continued his work throughout the winter of 1857, just as Turck (who relied predominantly on sunlight) was said to be abandoning further experiments due in part to the lack of sufficient sunlight in the Viennese winter. This account is contested however, as other sources describe Turck as using an independent light source in the form of a “pump lamp with double wick.” Whatever the case, it was Czermak who is most often cited as being the one who overcame difficulties with sunlight by relying exclusively on an artificial light-source, an innovation which would have been one of the decisive factors for outperforming Turck. Czermak’s introduction of a concave head mirror to concentrate the light also played a role.

With these and other subtle changes, Czermak ultimately was able to produce better results than Turck. And by 1858, he was in front of the Viennese Medical Society claiming to be the first to visualize the living larynx using a practical method7. Though Turck vigorously contested this claim and Czermak apparently did apologize, the damage was done. Thereafter, Czermak came to be known as the founder of laryngoscopy. Today, medical historians have revisited the records and now both Czermak and Turck are named as the co- founders of the field of laryngoscopy.

Despite this contested beginning, Czermak’s work overall must take center stage for a few key reasons. To begin with, Czermak’s more successful adaptation of an artificial light source was a clear improvement over sunlight8, for it finally freed laryngoscopy from the “clock and the barometer,”9. As well, Czermak later affixed a tube to the simple dental mirror, which made his method closer in kind to our modern understanding of endoscopy.

A Crucial Milestone – Endoscopic Photography by Johann Czermak
However, Czermak stands out most especially for achieving one of the most significant firsts in endoscopic history by becoming the first ever to take a photograph endoscopically10. Introduced in 1858, Czermak’s ingenious idea was completely novel for his time in both technical and conceptual aspects. Though the first known photograph was taken over thirty years earlier by Nietce in 1829, no other person since that time had come close to adapting the existing photographic technologies for surgical applications.

Like Garcia before him, Czermak conducted his laryngoscopic experiments on himself. Using the techniques derived from Turck and others, Czermak photographed his own larynx. The photographic method itself was referred to as stereoscopy that consisted of a box that housed a system of several lenses. The images were captured using metal plates coated with silver nitrate. Amazingly, all of this was achieved using only magnified candlelight as the light source. Ever the ingenue, Czermak also demonstrated remarkable foresight with his innovation of a detachable eyepiece that allowed for up to four viewers to simultaneously view through the scope. Czermak’s work was especially remarkable too because many other physicians during this time were not even able to visualize the difficult to reach larynx endoscopically, let alone obtain photographs of it. Though the grainy images obtained are barely discernible by today’s standards, these early photographs inaugurated an entirely new concept in surgery– that of photodocumentation– which in turn set the stage for later breakthroughs relying on similar principles, such as videoendoscopy. For the first time too, physicians could examine images of living anatomy without having to be present during the procedure. This enhanced visual knowledge alone was responsible for generating a more sophisticated understanding of disease pathologies, which in turn led to better treatment options, not just for the field of laryngoscopy, but within all disciplines. Czermak’s innovations therefore marked a true turning point, one that helped to catapult endoscopy into the next stratosphere of progress. By recognizing the value of photographic technology, Czermak proved himself to be a true visionary, years ahead of the mainstream mindset.

Another Turning Point – 1867: First Electric-Based and Distally-Placed Light Source
Bringing light into the far reaches of the upper GI continued to be the greatest limiting factor for laryngoscopy, making successful therapeutic procedures a rarity. Yet laryngoscopists wanted desperately to achieve progress in this field, especially since mortality rates for injuries or obstructions involving the air passages were so high. One particularly telling report, published in 1867 by G. Adelman, describes a clinical analysis involving 314 patients with untreated foreign bodies of the esophagus, 109 of whom would ultimately succumb due to perforations of the heart, aorta, or other great vessels. Yet the limited and often risky endoscopic methods for treating such cases remained fraught with great uncertainty. Physicians therefore began experimenting with various forms of light energy in order to solve the formidable problem of insufficient illumination that so plagued laryngoscopists especially.

Galvanized platinum wires, which produced glowing hot light, stood in as the pre-Edison best contender for solving endoscopy’s illumination growing pains. Scientists were known to have experimented with galvanized light sources as early as the 1820s, driven especially by the growing interest in electromagnetism in general. Of course, experiments with non-medical applications of electromagnetism led to such famous outcomes as Faraday’s electric motor, Hertz’s wireless (radio) telegraphy, and Marconi’s continuation of the same.

One of the earliest surgical applications of electricity came in the form of electrocautery with Viennese dentist Moritz Heider in 1845 and Albrecht Theodor Middeldorpf of Breslau, Germany in 1854 as two of the early pioneers in this technique. Middeldorph in fact described his device for the cauterization of urethral strictures, though he described only theoretical concepts rather than work on living patients. Another early adaptation was the invention of electrolysis (electrochemistry) that was said to have been founded by Crussell in circa 1850.

However, applying this technology specifically as a light source for inside the living body was problematic because the heat generated from the electric wires was simply too intense for delicate human tissue. Many physician-inventors tried and failed to find a solution to this obstacle.

Julius Bruck and His Galvanized Platinum Wire
However, Julius Bruck, a dental surgeon, also from Breslau, started a new chapter in medicine when he provided one of the earliest and best theoretical solutions for addressing the dilemma of excess heat. His 186611 proposal to encase galvanized wires into a glass cooling system (aka, a precursor to the light bulb) as a source of internal illumination for endoscopic purposes therefore stands out as an important contribution. Of equal importance, it marked an important conceptual shift toward positioning light sources inside rather than outside a body cavity, as had been the only option in endoscopy’s candlelight era. The light emanated from galvanized wires encased inside a glass tube that contained a separate nested compartment in which to receive circulating water used to cool the device. Bruck then attached the light source to the distal tip of an endoscopic instrument (though to which type precisely, the records do not make clear); the complete ensemble at one time referred to as a galvanoscope.

Not surprisingly, there are considerable discrepancies within this historical account. Notwithstanding the symbolic significance of Bruck’s innovation, there is some room for questioning whether or not he actually used his invention in any clinical setting12. This becomes an especially glaring inquiry since very few specific details about the application of his device exist within the historical documents. Conflicting reports concerning priority also exist. One source describes the light source as an instrument and method invented by Mikulicz-Leiter sometime around 1880. Still other more valid sources explicitly state that Bruck was responsible for the entire package, cooling system and all. Based on a thorough analysis of all the various sources, it appears almost irrefutably likely that Bruck did in fact invent the instrument and technique, but that he only used it in a limited number of patients and in modest ways, such as partially inside the mouth. One source states that Bruck went on to use his new instrument to perform other procedures, such as a stomatoscopy, though this has not been verified by any other sources. Later, in the 1880s, the Mikulicz-Leiter team offered an improved version of the original idea which allowed them to carry out extensive and successful patient trials. Though these outstanding questions of fact remain unresolved, at the least Bruck’s documented attempts to harness an electric source helped to inaugurate the concept of using electricity (though only in its rudimentary form) for medical application.

Sword-Swallowing as Therapy: Adolf Kussmaul, the Sword-Swallower, and the First Direct Esophago-Gastroscopy
Though early 19th century laryngoscopists devised some of the most advanced and elaborate magnifying lamps for amplifying light, in the final analysis a laryngoscope in the early days really was essentially only your everyday dental mirror. Eventually though laryngoscopists did start adopting more sophisticated instrumentation, taking for instance Desormeaux’s urethroscope and rigging it for use in the upper GI tract. Adolf Kussmaul (1822-1902), of Freiburg, Germany, was one of the earliest to use a modified version of Desormeaux’s device, a factor that helped him to become the first to perform a direct esophagoscopy13. For this achievement, Kussmaul is considered an important pioneer whose work not only introduced gastroscopy as a diagnostic possibility, but also initiated the shift away from indirect approaches, toward the safer and more modern direct gastroscopy.

The procedure itself, performed in 1868, was ultimately made possible by Kussmaul’s insightful decision to engage the services of a professional sword- swallower whose unusual talent allowed for Kussmaul to understand more precisely how to navigate through the body’s most treacherous contours. Using Desormeaux’s urethroscope as the source of light and attaching his custom- designed 47 mm long and 13 mm in diameter tubing with speculum, Kussmaul was able to pass the scope all the way down to the stomach. This modified device is considered the first gastroscope. Several sources state that, in this manner Kussmaul was able to diagnose pathologies of the esophagus (though only on a few occasions), including specifically a cancer of the thoracic esophagus in one instance. Other sources contradict this, stating instead that Kussmaul was in fact unable to see anything. One of the most reliable of sources verifies that Kussmaul achieved modest levels of visualization, including the diagnosis of pathologies, but that, owing to patient difficulties in tolerating the long device, along with the suboptimal visibility, Kussmaul abandoned further efforts in the field. Of note too is that, though he did give live demonstrations of his techniques to medical societies, Kussmaul never followed up with any published reports. It was only through his well-known student, Killian, that we have learned of his work at all. Though his esophagoscopies were ultimately judged as unsuccessful, Kussmaul’s contributions were nevertheless influential in bringing to light important ideas and observations. Kussmaul’s gastroscope was repeatedly cited by later pioneers as the source of their inspiration. In fact, the famous Mikulicz-Leiter team (whose work we will examine shortly) held Kussmaul in such high esteem that they sought out his personal advice before proceeding with their own designs.

Johann Mikulicz – The First Successful and Practicable Esophago-Gastroscopy
Despite these and other such impressive first attempts, it was Johann von Mikulicz, in collaboration with Leiter, who is credited with performing the first successful and useful direct esophagoscopy in 1881. A Czechlasovakian hailing from Vienna, Mikulicz enlisted the help of the renowned instrument maker from Vienna, Joseph Leiter, to find a solution to the pesky and persistent problem of poor illumination. Drawing in part from the prior works of Kussmaul, Mikulicz and Leiter constructed the first clinically successful gastroscope, equipped with distally-placed galvanized wire as the light source and cooled by an ingenious cooling system.

The placement of the light source inside the body (a continuation of where Bruck left off) again signified one of the most crucial developments for endoscopy. The galvanized wire light source itself was exceptionally well designed, no doubt the result of Leiter’s brilliant input. The light derived from a distally-placed, u-shaped platinum wire that was encased in a double- barreled glass tube surrounded by tiny hollow circuits. Part of the water coolant system, these circuits served as the conduit for circulating water. The other end of the wire was attached to an external Bunsen battery unit that served as the energy source that lit (galvanized) the platinum wires. A unique method for minimizing the scope’s diameter was also invented. Not able to house both the specialized guiding mandarin and the optical system without increasing the diameter, Mikulicz-Leiter made these component parts modular so that, after introduction of the scope had been achieved, the guiding mandarin would be removed, thereby allowing room for the optical apparatus to then be inserted. Topping off these innovations were also improvements to the optical system, including the addition of a prism. In addition to these instrument improvements, Mikulicz also made several important clinical observations that contributed to greater overall clinical success. By recruiting his own version of a sword-swallower- a woman with a talent for swallowing instruments (don’t ask!?)- Mikulicz noted that the only necessary condition for ensuring safe insertion was that the head of the patient be angled into the ‘sword-swallower’ position. With this simple yet crucial observation, Mikulicz was able to more consistently achieve clinical success. The use of a general anesthetic was mentioned as being required for most patients. However, given the fact that most of the illustrations depicting Mikulicz’ procedures indicate an upright, awake patient, a cocaine anethetic was the most likely product used.

Not to spoil the fun, but one area of historical dispute must be mentioned. In 1879, before Mikulicz’s work, Nitze has been credited with working on a gastroscope with almost the exact features as that of Mikulicz-Leiter’s device. Further, it seems that Nitze was also working with Leiter to produce this instrument, but that later, after an altercation between the two, Leiter began working instead with Mikulicz. Even though it is not clear whether Nitze was able to get his device working before Mikulicz, some consideration to these facts must be given when exploring claims of priority. Putting aside this point of contention, the achievements of the Mikulicz-Leiter team were nevertheless undeniable smash hits. Mikulicz and Leiter were among the first to combine three of the most important elements which define endoscopy; the unification of an electric light source, an optical system, and a viewing tube into one device with proven clinically success. As a result of such substantial innovations, Mikulicz is considered one of the most significant pioneers and founding fathers of gastroscopy. In a strange twist of irony, sadly Mikulicz died fairly young of stomach cancer at the age of 55, the very sort of pathology he tried so diligently to endoscopically diagnose and treat throughout his lifetime.

Summary – 19th Century Laryngoscopy
By the late 19th century, the simple dental mirror that surely had aspired to be so much more, finally did transform into a true endoscopic superstar: fully- loaded, with advanced optics, distal light, and capable of diagnostic and therapeutic procedures once thought impossible. Driven in part by developing technologies in other fields, such as lens technology and electricity, the field of laryngoscopy gained considerable momentum toward the end of the 19th century and charged forward into the 20th century with whistles and bells and high hopes. Several of endoscopy’s finest, including the great pioneer, Georg Kelling, continued to make crucial advances to the field in the years just shy of the 20th century. We will review these developments in subsequent chapters. As we will see too, the plot ripened. Soon, the indirect method for viewing, so predominate in the 19th century (with the exception of Kussmaul and Mikulicz’s early direct attempts), would find itself scuttled to the scrap pile of history as the newer, safer, better direct approach found its groove. Still, despite such extensive efforts, for the next 70 years only the most skilled virtuosos could actually wield a rigid or semi-flexible laryngoscope well enough to make a living at it. We will have to wait until deep into the 20th century to see this story unfold, for it was only with the appearance of fully flexible instruments lit by fiber optics that the practice of laryngoscopy transformed into a more accessible surgical art form.

Summary of Part II
There is a loftier ambition than merely to stand high in the world. It is to stoop down and lift mankind a little higher.
-Henry Van Dyke

As for the field of endoscopy in general, the original four obstacles which had stood for so long as ancient impediments, were about to be challenged by a new generation of pioneers whose efforts would indeed stoop down and lift endoscopy a bit further with the help of the great late 19th century technological coup: electricity. For the next few decades, electricity would be the driving force behind endoscopic innovations and the decisive factor in overcoming the obstacle of poor visualization and illumination.

Progress toward achieving some relief from the fourth obstacle- expanding the field of vision- was also just about to materialize with the next wave of pioneers who quickly seized upon the latest lens technologies, creating finally a viewing range that was large enough to catapult endoscopy away from simplistic diagnostics and closer toward its greater operative potential.

1. Sub-specialization as we know it today did not truly exist during this time.
2. Per Bozzini’s own instructions.
3. There is some discrepancy in the record concerning whether Babington did in fact view the larynx.
4. Laryngeal introitus per Zeitels.
5. Some sources actually refer to his instrument as a probing, a long, curved probe made from a whale-bone.
6. The dates 1853 and 1854 have been also commonly cited. However, our research indicates that 1855 was the year in which Garcia actually introduced his technique to the Royal Society.
7. The records do not indicate whether mention was made of earlier pioneers, such as Babington and Garcia.
8. Others before Czermak had also added artificial light source, including John Avery in 1844. However, Czermak was the first to make its use practical and reliable.
9. Recall again that there are discrepancies as to whether Turck tended to rely predominantly on sunlight.
10. The specific technique was referred to as stereoscopic photography.
11. Other sources cite 1867.
12. The German source Reuter only alludes to the possibility that the device was placed “inside of the mouth.”
13. Not to get confused with being the first to view the larynx with direct visualization– as was mentioned, this was accomplished by Babington years earlier. The important distinction here is that Kussmaul was the first to actually perform a procedure using direct visualization.