Five historical innovations that have shaped modern otolaryngological surgery

Introduction

Otolaryngological surgery has undergone significant transformations throughout its history, driven by pioneering innovations that have revolutionised treatment strategies and enhanced patient outcomes. This article provides an overview of five key historical innovations that have played a transformative role in shaping modern otolaryngological surgery: the Operative Microscope, Hopkins Rigid Endoscope, Nerve monitoring, Cochlear implants and Laser surgery. By exploring the development, impact and ongoing relevance of these innovations, this article aims to highlight their substantial contributions to the field and underscore their enduring influence on contemporary practices.

The Operative Microscope has facilitated intricate procedures with enhanced visualisation and precision, enabling microsurgical advancements. The Hopkins Rigid Endoscope has revolutionised the field by enabling minimally invasive techniques, minimising patient trauma and expediting recovery. Laryngeal nerve monitoring has significantly reduced nerve damage risk during surgery, improving patient outcomes. Cochlear implants have revolutionised auditory rehabilitation by restoring hearing in individuals with profound hearing loss. Recently, laser surgery has offered precise incisions, reduced bleeding and faster recovery times, optimising surgical interventions.

By comprehensively exploring the historical context and impact of these innovations, this article seeks to deepen our understanding of their transformative influence on modern otolaryngological surgery. Recognising their contributions enables clinicians and researchers to build upon their foundations, pushing the boundaries of surgical techniques and further advancing patient care.

Through a scholarly examination of the development, impact and ongoing relevance of these historical innovations, this article contributes to the discourse surrounding otolaryngological surgery. By highlighting their pivotal role in shaping the field, it inspires further research and innovation to drive continuous improvement.

The innovations as described in the article were selected by the following process. A scoping review of the literature was performed which consisted of a PubMed search identifying systematic reviews, randomised controlled trials and meta-analysis. The terms searched included ‘innovations’, ‘otolaryngology’, ‘history’ and ‘advancements’. Authors of this article individually reviewed abstracts using COVIDENCE-literature review management software. Finally, papers from the literature search were analysed by a panel of expert otolaryngology consultants who gave their consensus on the final five innovations selected in this article. In subsequent sections, each innovation will be rigorously analysed, delving into their unique attributes, historical significance and contemporary relevance. By shedding light on these innovations, this article aims to provide a comprehensive overview that inspires future advancements and breakthroughs in otolaryngological surgery, ultimately benefitting patients globally.

ENT operative microscope

The microscope plays an essential role in today’s world of otolaryngology, from initial assessment of an ear to complex inner ear procedures. However, it first found its way into the operating room almost 80 years ago.

In 1921, the monocular operative microscope was first used by Carl Nylen, a 30-year-old Swedish otolaryngologist (Kriss & Kriss 1998). However, the idea of using a convex lens to magnify an image is likely attributed to Ibn al Haitham in the 11th century (Wollman et al 2015). Since then, there have been various reports of use of single lens magnification devices. However, inspiration for this design of the compound microscope can be traced back to the 16th–17th century in the Netherlands. It is unclear who invented the first compound lens microscope (Wollman et al 2015). During this time, Antonie van Leeuwenhoek famously published his findings of ‘cells’ in 1665, hence bringing microscopes into the scientific world (Wollman et al 2015). During the 18th century, significant development was made in increasing the resolution (discrimination between two magnified points so as to reduce blur) as well as reducing chromatic aberration. In 1876, Saemisch, a German physician, described the use of microscopic lenses in the medical field with his early use of loupes (Noylen 1954). In the 20th century, Carl Zeiss and Ersnt Abbe worked together on the discovery of the diffraction theory and semi-transparent mirrors to create the first binocular microscopes used for ophthalmologic examinations.

The earliest use of the monocular microscope in otology can be attributed to Kessles, Weber-Leil and Czapski, while the binocular microscope use in otoscopy is attributed to Amilio De rossi. However, due to the lack of manoeuvrability, it was not used much in practice (Wollman et al 2015). In November 1921, Carl Nylen used the monocular Brinell microscope in two cases of labyrinthine fistulas and one case of bilateral pseudo fistula. In 1922, his colleague Gunnar Holmgren used the binocular microscope for a fenestration operation which proved to give a better image (Ma & Fei 2021, Wollman et al 2015). However, due to limited field of view and working distance, the operating microscope was still difficult to use. In 1951, Hans Littmann (working for the Zeiss company) developed the Zeiss Opmi Model 1 (pictures in Figure 1), this microscope had selective magnification up to 40×, working distance of approximately 20cm, and illumination that entered the field through the objective, hence was in direct line of sight of the operator (Wollman et al 2015). Initially, the use was mainly in the final steps of an operation in mobilising the stapes, with surgeons preferring the magnifying loupes for other parts of the procedure. Over the course of the next 40 years, this technology had been improved to provide us with the microscopes we know of today.

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Figure 1

Zeiss Opmi Model 1 used by Hans Littmann in 1951 (Wollman et al 2015)

The surgical microscope is divided into a microscopic body, light source and supporting structure. All operating microscopes are binocular to allow for perception of depth. The light source (usually xenon, halogen or LED) is transmitted via fibreoptics through the objective lens to illuminate the surgical site (Ma & Fei 2021). In modern microscopes, the light is arranged in a co-axial arrangement where the light hitting the surface is reflected away from the lens to avoid shadows (Keyence n.d.).

The optical system has binocular objective lenses and a magnification (zoom) changer. The focal length of the objective lens dictates the working distance. The magnification is usually a series of lenses, or a lens that can be adjusted to change the magnification of the image. The focal length of tubes, focal length of objective lens, eyepiece and magnification value all affect the total magnification (eOphtha n.d., Ma & Fei 2021). A schematic setup of the microscope is shown in Figure 2. In addition to this, the supporting structure is important for any microscope. They can be wall or ceiling mounted, sit on a table or on casters. Modern microscopes can have advanced HD screens as well as extra viewing binoculars for assistants (Ma & Fei 2021).

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Figure 2

Schematic of the path of light from surgeon’s eyes to the surgical field (Cordero n.d.)

Historically, surgical microscopes have been used in ENT during otological procedures. From procedures varying from simple examination of the external auditory meatus and grommet insertion to more complicated middle ear dissections, mastoidectomies, inner ear surgeries such as cochlear implantation and even work on the base of skull. However, over time it has also found its way into laryngeal procedures. It has proved effective in improved visualisation during laryngeal surgery when used in conjunction with traditional scopes. This allows for imaging of the laryngeal structures and for advanced bimanual work such as sharp dissection and grafting. It has also been used in the surgical resection of various head and neck tumours such as nasopharyngeal tumours and oropharyngeal tumours. It has been shown to have low complications and has proven very useful in day case surgeries (Robinson 1989). In the rhinological field, the microscope has been shown to allow for bimanual operations with the aid of an autostatic speculum. It has also proven useful in procedures such as endonasal microscopic dacrostomies (Georgalas & Fokkens 2013).

Looking forward, many new microscopes are equipped with HD monitors and cameras, allowing greater resolution for the surgeon. Three-dimensional (3D) screens are being implemented for depth perception. However, studies have shown that in deeper surgeries they can still have suboptimal fields of view and hence are more superior in more superficial otological surgeries rather than deep work (Ma & Fei 2021). Although predominantly seen in neurosurgery, augmented reality and mapping is becoming increasingly popular as an aid for microscopes for more detailed intraoperative navigation. In addition, optical coherence tomography (OTC) is being adopted in various surgical specialities, including ENT especially in laryngeal operations as it measures scatter from light tissue to provide vital subsurface information as well as submillimetre resolution (Carrasco-Zevallos et al 2017).

Ever since the advent of the first microscopes, the technology has come a long way in aiding otolaryngologists to perform more complicated and safer surgeries on patients.

Hopkins rigid endoscope

The beginning of endoscopic surgery in ENT is widely accredited to Alfred Hirschmann in 1901 who used a modified cystoscope (Jacobs 1997), which he later published in 1903. In 1910, M Reichart performed rudimentary maxillary sinus manipulations, which are now regarded as the first attempt at endoscopic sinus surgery (Tajudeen & Kennedy 2017), although endoscopic sinus surgery was not popularised until decades later. Instead, it was mainly used for evaluation of the sino nasal cavity. In 1960, Professor Harold H Hopkins developed the rod optic endoscope system. At the time, the cystoscope consisted of a rigid tube with a light source at one end and a series of lenses at regular intervals along the tube to relay the image. Through consultation with James Gow, a Urologist, Hopkins redesigned the cystoscope by ‘switching’ the glass lenses and the air in between. As a result, the new cystoscope had a larger aperture as well as a clearer image quality, described by Gow as an 80-fold improvement. Of note, prior to this, Hopkins had also invented the fibreoptic scope, widely used in gastroscopy and fibreoptic nasoendoscopy the world over (Linder et al 1997, Tajudeen & Kennedy 2017, Whitaker 2012). It is a revolutionary invention in itself, however, not fully covered in this article.

This technology was quickly adopted in the otolaryngology community and in 1978 Messerklinger released a book on diagnostic endoscopy detailing various, previously vague, anatomy of the nose from studying fresh cadavers. This included areas such as the paranasal sinuses and the lateral nasal walls (Messerklinger 1978, Tajudeen & Kennedy 2017). With the detailed anatomy provided in this book, and lack of safe efficacious surgeries for chronic rhinosinusitis, several surgeons began adopting endoscopic methods for sinus surgery. Notably, Heinz Stammberger, who worked at the University of Graz with Messerklinger, worked on popularising the method. Together with David Kennedy of Johns Hopkins and the surgical instrument maker Karl Storz, the modern-day functional endoscopic sinus surgery technique was born – a technique they provided courses for world over (Figure 3). This was enhanced by the advent of endoscopic ear surgery largely championed by Muaaz Taarabichi who they worked alongside to introduce endoscopy into mainstream use in modern-day otolaryngology (Kane 2018, Taarabichi n.d., Tajudeen & Kennedy 2017).

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Figure 3

Hopkin’s rod with the glass ‘rod’ system shown above compared to the conventional glass lens system shown below (Guesmano)

In most modern-day procedures, the physician uses the endoscope attached to a camera, light source and a stacker system which has a screen where the camera projects the image from the scope. In modern endoscopes, the light source has traditionally been a xenon light source although LED is fast becoming more popular. This is transmitted to the tip of the scope using a ring of optical fibres. The angle of the illumination fibre, along with the negative lens used at the end of the scope, will dictate the angle of view the endoscope has, hence allowing the user to assess different fields of view (Argueta 2022, Davies n.d.).

The illumination light source hits the target tissue, disperses the light, which then subsequently enters the endoscope through a series of relay lenses and field lenses. The field lenses allow rays from larger object field angles to be accepted by the objective lens. These relay lenses were used by Hopkins instead of air because glass is a better conductor of light (Gow 1998). The image is then magnified into an eyepiece or displayed onto a digital camera sensor, which is then projected into the screen (Argueta 2022). A schematic of this is shown in Figure 4.

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Figure 4

Schematic depicting the passage of light through a rigid endoscope (Argueta 2022)

As mentioned previously, endoscopes have revolutionised the field of rhinology, with the advent of surgeries such as functional endoscopic sinus surgery which has become a mainstay of treatment for chronic rhinosinusitis. In addition, it has opened the gateway for more accurate diagnostic biopsies, endoscopic surgery for epistaxis and novel, minimally invasive approaches to the base of skull for surgeries such as hypophysectomies.

The endoscope has also been growing in popularity for ear surgery. Endoscopes have provided a way to assess the middle ear with a wide-angle lens and superior illumination without the need for peri-aural incisions in amenable cases, particularly in those with tortuous ear canals. It does have limitations such as one-hand dissection and limited instrumentation compared to traditional microscopic approaches.

The primary use of endoscopes in aural surgery had initially been limited to examination of the ear, especially as an adjunct to microscopic ear surgery for residual disease. In recent years, the endoscope has been used for cholesteatoma surgery, tympanic perforations and a variety of benign diseases (Ridge et al 2021 disperses the light, which then subsequently). It has also proven essential in laryngeal procedures from visualisation and laryngeal biopsies to base of tongue mucosectomies.

The endoscope has altered all aspects of otolaryngology, allowing clinicians better views, less invasive options and access to areas and anatomy that was once non-identifiable in a live patient. Moving forward, technologies such as 3D endoscopes are gaining popularity in laryngeal use; this allows for better stereopsis which aids in greater diagnostic certainty when removing transoral pathologies and trans nasal skull-based surgeries (Xin et al 2022). Technological advancements in imaging through multiplanar computed tomography (CT) imaging is gaining popularity as is 3D computer X-ray tomography stereoscopic imaging which allows the surgeon to evaluate the image using depth.

Laryngeal nerve monitoring

The idea of intraoperative neuromonitoring in modern clinical surgery practice can be traced back to the field of neurosurgery in 1930, when a Canadian called Wilder Penfield used low lever currents to try to pinpoint areas causing seizures in patients with focal epilepsy (Deniwar et al 2015, Nuwer 2013, Shedd & Durham 1966).

It is thought that one of the first reports of recurrent laryngeal nerve stimulation was published by Ridell et al in 1966 on a canine model that had an endotracheal (ET) tube with a pressure recording system placed in the larynx. Results showed pressure changes within the tubes upon stimulation of the recurrent laryngeal nerve. This was later shown in human models as well in 1970 (Sari et al 2010).

This has opened the gates to various operative techniques involved in identifying the laryngeal nerves using intraoperative stimulation. This has included laryngeal palpation, glottic pressure monitoring, glottic observation, laryngeal electrodes, ET-based electrodes and post cricoid surface electrodes. ET tube-based electrodes have gained popularity due to their non-invasive nature, ease of use and ability to capture large electromyography potentials (Milner 1977, Sinclair et al 2019).

For nerve monitoring, the ET tube is equipped with a pair of recording electrodes that contact the vocal cords. The surgeon will use a stimulator probe to deliver a small electrical current of 1–2mA to a structure they suspect to be neural tissue. The stimulatory and recording grounding electrodes are usually placed on the sternum. The grounding electrodes and the nerve stimulator and recording equipment are all connected to an interface connector that is connected to a monitoring device. This allows for tracking of the visual amplitude in conjunction with auditory stimuli, which is emitted from the monitor depending on type of tissue stimulated (Deniwar et al 2015). The setup is shown in Figure 5.

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Figure 5

Schematic diagram depicting the set up of a nerve monitor as described (Chen & Stack 2022)

It is important to note the surgeon and anaesthetist need to work closely, and it is preferable for the patient to have minimal or no neuromuscular blockade if a nerve stimulator is to be used (Carrillo-Torres et al 2023). In addition, it must be confirmed that the tube is positioned correctly, with the recording electrodes in contact with the vocal cords.

Intraoperative nerve monitoring has proven very popular among modern otolaryngologists and has been used in various surgeries including thyroid surgery, mastoid and parotid surgeries in a bid to aid in identification and presentation of key nerves in the area (Flukes et al 2013).

Moving forward, continuous nerve monitoring has been gaining popularity (Ku et al 2021). This involves an additional continuous stimulation to the vagus nerve which allows for a higher degree of nerve mapping certainty, especially in the more infantile stages of a dissection where the position of the recurrent laryngeal nerve is uncertain.

Cochlear implants

The history of experiments related to electrical stimulation of the auditory system can be traced back to the inventor of the battery, Alessandro Volta, who in the early 1800s passed a direct current through his head from one ear to the other, describing a ‘crackling, jerking or bubbling’ sensation. This was reproduced in 1855 by Duchenne de Boulogne who used alternating current to stimulate the cochlea (Eshraghi et al 2012).

The idea of recovering hearing through the stimulation of the cochlea was from the Bray-Weaver effect described in 1930 through experiments on a cat that showed sound played at 100–5000Hz produced a similar frequency firing in the nerve (Wever & Bray 1930). Hence, in Paris, in 1957, Charles Eyries places an electrode designed by Charles Djourno onto a stump of the auditory nerve of a human patient. An induction coil with a return electrode was placed in the temporalis muscle. This allowed the patient to discriminate between different intensities, but discrimination between frequencies was still lacking. In addition, the device failed within a few weeks of implantation, discouraging Eyries to continue (Djourno & Eyries 1957, Eshraghi et al 2012).

Nevertheless, this experiment inspired Los Angeles based otologist William F House to create an implantable auditory prosthesis designed to stimulate the auditory nerve. Along with neurosurgeon John Doyle, this was implanted in their first patients in 1961. The first implants were inserted into the scala tympani via the round window membrane. Although patients could identify close set words and discriminate basic frequencies, patients experienced issues with biocompatibility (Mudry & Mills 2013).

In 1967, Dr House and an electrical engineer by the name of Jack Urban created what is regarded as the first cochlear implant system, which can be used outside of the laboratory for multiple years (Figure 6). These designs, however, still used two electrodes (Eshraghi et al 2012, House & Urban 1973). In 1970, Merzenich and his team worked to design implants with single electrodes. Over time, acceptance has grown in the scientific community as well as the deaf community for such devices as the efficacy for these devices has improved (Merzenich et al 1973).

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Figure 6

William House (rear) and Jack Urban (Blue shirt) testing Charles Grasier circa. 1974 (Henkel 2014)

The cochlear implant consists of an external component and an internal component. The external component consists of a microphone, speech processor and a transmitter. The microphone captures sound from the environment which is converted into electrical signals via the processor. These signals are analysed and enhanced by being separated into different frequency channels (Deep et al 2018).

The internal component is surgically implanted under the skin; this consists of an implant receiver and an electrode array. The processed electrical signals from the external component are transmitted through a transmitter coil to the internal component and onto the array. The array itself, which is usually preshaped, is inserted with the help of a stiffening element into the cochlea where each of its electrodes corresponds to a specific frequency or pitch. Perimodiolar arrays are usually inserted via a cochleostomy, while lateral wall arrays can be inserted via the round window (Deep et al 2018, Mistrik et al 2017). The components of this are shown in Figure 7.

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Figure 7

Components of a cochlear implant (Brand 2014)

Cochlear implantation has changed the field of otology, allowing for interventions in individuals with severe to profound deafness. In babies born with external or middle ear abnormalities, it has been used successfully to aid in hearing and language development, and also for children who lose their hearing during childhood, as well as adults with profound deafness and more (Forli 2011, Merzenich et al 1973).

In conclusion, cochlear implantation has changed the landscape of otological treatment for patients with profound sensorineural hearing loss, providing hearing for patients who would otherwise have not had the option. Moving forward, cochlear implant arrays and implant materials aim to push this technology forward.

Laser surgery

Laser therapy was first used in otolaryngology in 1972 by Strong and Jacko for the excision of a laryngeal lesion (Karkos et al 2020). This was the culmination of Charles Townes’ work commenced in 1954. Townes’ work involved creating a proton flux through the amplification of magnetic waves, facilitated by a device known as microwave amplification by stimulated emission of radiation (MASER). However, these waves were hard to manage. Over the course of the next decade, he worked on this idea to amplify radiation along with Arthur Schowlow and Gordon Gould. Eventually in 1960, Tomas Maiman is credited with creating the first synthetic ruby laser (Figure 8). This idea was expanded upon by Kumar Patel in 1963 and at Bell Labs he created the first carbon dioxide (CO₂) laser.

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Figure 8

First ruby laser created in 1960 (Cowen 2019)

This is notably more efficient and cost effective than the already existent ruby laser (Benoussan 2016). Over the next five years, the popularity of the laser was realised in many industries as a cutting tool. It was noted that at the wavelength of 10.6µm, light will transmit into thermal energy in water, cutting tissue with little heat dissipation (Orgain et al 2018). In 1967, Jako and Polyani showed that CO₂ laser technology can be used in cadaveric larynxes to provide precise incisions with measured depth of penetration and minimal heat transfer to adjacent tissues (Yan et al 2010).

Subsequently, in 1968, Jako was able to excise predetermined amount of normal laryngeal vocal cord tissue using a CO₂ laser in dogs (Jakó 1972). Simultaneously, in 1968, Bredemier developed the micromanipulator to deliver CO₂ through a microscope (Yan et al 2010). This prior work led to Strong and Jako performing the first laser operation in otolaryngology in 1971 (Jakó 1972). This led to an explosion in research around lasers in otolaryngology over the next 40 years, including work by Goode in 1979 to use focused and defocused CO₂ laser to perform otologic surgery in the form of a laser myringotomy (Goode 1982).

Light Amplification by Stimulated Emission of Radiation (LASER) is useful due to three properties: line width, coherence and power. Control of the linewidth allows the operator to control the frequency of the light emitted, as this tightly controlled laser technology is very close to being monochromatic. As the laser is coherent, it will allow the energy to be focused on a fixed distance. Finally, the power will allow the laser to deliver high energy to an object. In the field of otolaryngology, this is critical as a laser beam at a specific wavelength of 10.6µm can be delivered with high intensity to a precise location (Figure 9).

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Figure 9

Schematic diagram showing that have had population inversion releasing energy to return to a lower state, causing same phase energy release (Kwok-San & Shiu-Sing n.d.)

The laser beam is created in a cavity with a mirror on one side and a semi-reflective mirror on the other. A substance with a specific low-energy state, high-energy state and a meta-energy state is chosen. When electrons in the low-energy state are excited, they enter a high-energy state called spontaneous absorption; the state usually lasts a few nano seconds. When the high-energy-state electron drops back to the low-energy state, it emits a light wave with an energy and wavelength of a specific length, which is known as spontaneous emission. Some elements are in an intermediate state, with electrons at a slightly lower energy level, referred to as the meta-energy state. A population inversion is induced to have more electrons stay in this state. Hence, while in this state, if they encounter an emitted light wave, they will fall back to the low-energy state and release a wave in the same phase as the light wave that established it. The waves travelling between the mirrors will be potentiated and as one is only semi-reflective some will leave the cavity, hence causing the laser beam as we know it (Goode 1982, Huether 1983, Patil 2008).

In ENT, CO₂ laser is used which creates an infrared beam, as this is invisible it is always aided with a guiding beam. It can be used to cut the tissue precisely and hence is used in operations to cut and seal tissue and vessels. Potassium-titanyl phosphate (KTP) lasers with a wavelength of 532mm are also becoming more commonplace along with argon, as they can be absorbed by substances such as oxyhaemoglobin and haemoglobin, respectively, and have a role to play in haemostasis in ear surgery (Orgain et al 2018).

Laser surgery has famously been used for laryngeal cancer surgery (on T1 tumours) as well as phonatory surgery (Figure 10). It has also been used in benign diseases such as subglottic haemangiomas and arytenoidectomies. In rhinology, the CO₂ laser has been shown to be useful in reduction of hypertrophied turbinates, and the non-contact mode in the Nd:YAG laser has been used to show good effect in coagulation. In otology lasers, especially KTP/532 which has proven useful in revision procedures as well as in stapedectomies due to their low heat dissipation (Betka et al 2013, Haque 2020).

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Figure 10

Schematic diagram of laser (in this case the medium is ruby) (Shaik n.d.)

In cancer surgery, OTC is being trialled to assist laser surgery to give real-time feedback on epithelial tissues by identifying precancerous lesions due to its high sensitivity. The growing use of thulium:YAG laser has shown promising results in various fields including transoral surgery. Van Abel et al have shown its increased efficacy compared to electrical surgery due to decreased thermal damage, improved visualisation and finer cutting (Gunalan & Mattos 2023, Van Abel et al 2012).

In conclusion, from the first experiments of Jako on cadaveric larynxes, laser surgery had grown to be a big part of modern otolaryngology in all disciplines, improving patient outcomes through more precise cutting, less thermal damage and ability to aid in haemostasis.

Conclusion

In conclusion, the history of otolaryngological surgery is rich with innovations that have had a significant impact on patient outcomes and treatment options. The historical innovations examined in this article, including the Operative Microscope, Hopkins Rigid Endoscope, Laryngeal nerve monitoring, Cochlear implants and Laser surgery, have played a pivotal role in shaping the contemporary landscape of otolaryngological surgery. These innovations have yielded substantial advancements in surgical precision, minimally invasive techniques, nerve preservation, auditory rehabilitation and surgical outcomes. By acknowledging their historical context and profound impact, clinicians and researchers are positioned to build upon these foundations for further enhancements in patient care. Sustained vigilance towards emerging technologies and developments is imperative to sustain the progress in the field. The enduring significance of these innovations underscores the dynamic and evolving nature of medical science, necessitating a steadfast commitment to innovation and research to optimise patient outcomes.