Factors influencing the genesis of neurosurgical technology

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For any new technology to gain acceptance, it must not only adequately fill a true need, but must also function optimally within the confines of coexisting technology and concurrently available support systems. As an example, over the first decades of the 20th century, a number of drill designs used to perform cranial bone cuts appeared, fell out of favor, and later reappeared as certain supportive technologies emerged. Ultimately, it was the power source that caused one device to prevail.

In contrast, a brilliant imaging device, designed to demonstrate an axial view of the lumbar spine, was never allowed to gain acceptance because it was immediately superseded by another device of no greater innovation, but one that performed optimally with popular support technology. The authors discuss the factors that have bearing on the evolution of neurosurgical technology.

Abstract

For any new technology to gain acceptance, it must not only adequately fill a true need, but must also function optimally within the confines of coexisting technology and concurrently available support systems. As an example, over the first decades of the 20th century, a number of drill designs used to perform cranial bone cuts appeared, fell out of favor, and later reappeared as certain supportive technologies emerged. Ultimately, it was the power source that caused one device to prevail.

In contrast, a brilliant imaging device, designed to demonstrate an axial view of the lumbar spine, was never allowed to gain acceptance because it was immediately superseded by another device of no greater innovation, but one that performed optimally with popular support technology. The authors discuss the factors that have bearing on the evolution of neurosurgical technology.

The development of a new technology usually starts with an idea of how to solve a problem. If that problem is one that is, or becomes, widely accepted as an important one, deserving of solution, and if the idea can realistically and efficiently be implemented through currently and readily available means, a new form of technology may emerge.

In today's world of highly complex technology, the devices that enable practitioners to implement their techniques are rarely manufactured by a practitioner. Because of the high cost, in both money and labor, that eventual production demands, manufacturers rarely make a device available unless they believe that it will be widely accepted (and purchased) in a competitive market.

Bronze instruments, recently unearthed in Pergamon, show what appears to be an oral suction device on one end and a tip on the other end, which bears a strong resemblance to the tip of a modern cataract-extraction device. It is believed that the 2nd century A.D. Roman physician, known as Galen, used these for just that purpose at that time. Presumably, it would not have been that hard for a respected physician (particularly if he were the chief physician for the emperor's gladiators) to request a local metalworker to fashion such a simple device. In today's market, that might be much more difficult.

In the 21st century, new devices are generally much more complex and, hence, much more expensive than those made in the 2nd century. Accordingly, a substantial and realistically dependable market must be established before any company would undertake such an endeavor.

Although these unearthed devices make it evident that cataract extraction was at least attempted in the ancient world, it did not seem to flourish as a surgical treatment in the ensuing years, and the technique did not realistically become commonplace until the 21st century. A discussion of those factors that facilitate or hinder the wide acceptance and development of new technology is the substance of this paper.

To illustrate the interplay of factors involved in the rise, decline, and eventual renaissance of certain functionally related technologies, we examine 2 technologies. As the first example, methods for opening the human cranium without damaging the underlying structures are examined, from prehistoric trephination through modern craniotomy. As the second example, a very short-lived radiographic technique for the demonstration of an axial view of the lumbar spine is examined.

Neurosurgical Technology

The Genesis of the Technology of Opening the Skull

The custom of trephination is known to have been present in multiple areas of the Eastern and Western hemispheres as far back as prehistoric times. One example, from Western Europe, may even have been Cro-Magnon.12

Techniques have varied widely, from those as crude as simply scraping the cranium away with a rough stone to others as complex as drilling small holes in a circle and outlining a larger disk, which was then tapped out and removed.12 Some of these trephinations were occasionally so extensive as to resemble a 21st century decompressive craniectomy or trauma flap.12

One of the more ingenious techniques has long been attributed to the Incas of the Peruvian highlands but was probably developed by more coastal tribes, many centuries earlier. This involved the “tumi,” a more or less hemispheric blade attached to a perpendicular handle that could be rocked back and forth, creating a cut through the bone, which could be repeated in a rectangular (or tic-tactoe) fashion, allowing a central rectangle to be cut out and removed. What is ingenious about this technique is that the wide curve of the blade allowed a long enough cut to be made in the bone before the device could penetrate very far. Hence, it was much more difficult to “plunge” with this instrument than with others, with the possible exception of the simple scraping of a rough stone, a technique that was presumably extraordinarily inefficient and time consuming.

Cookie cutter–like circular trephinations were subsequently practiced, almost continually, from as early as the Hellenistic period onward. These were usually created with a short cylindrical device that had a long handle on one end and serrations on the other. The long handle was rapidly rotated using either the surgeon's opposing palms or, more often, a bow (Fig. 1).12 Although the circumferential engraving on these cylinders might have offered some protection against plunging, the straight design must have been less reliably safe than the tumi.

Fig. 1.
Fig. 1.

Drawing showing the cranial perforation devices used in ancient and medieval times, often called terebra serrata.

In certain late Medieval and Renaissance manuscripts, one notes a new device for “powering” these trephines, one that was more or less functionally indistinguishable from a 20th century Hudson brace. At roughly the same time (but not necessarily in the same manuscripts), there appeared a tapering sheath for the perforating drill, which would preumably effect a safety feature similar to that created by a tumi.12

Interestingly, straight cylindrical perforating trephines were frequently, if not routinely, seen in surgeons' instrument cases as late as the American Civil War.7 The tapered cylinder was also frequently seen, but not universally (Fig. 2).

Fig. 2.
Fig. 2.

Photo showing an American Civil War surgeon's instrument case. Note the cylindrical and tapered trephines. The Hey saw is the hatchet-shaped device seen just to the right of the trephines. Published in J Neurosurg 78:838–845, 1993.

Again, as late as the American Civil War, most trephines were powered by a T-shaped handle, perpendicular to a short staff, which extended up from the cylinder. The Hudson brace–like device seemed to fall out of use, until the early 20th century. At that time, the tapered trephine began to be replaced by a perforator drill bit that was used to create a bur hole with the subsequent application of a round bur drill bit (Fig. 3).2 The initial perforation was made with a tapered device that had a gradual incline, somewhat similar in concept to the tumi (Fig. 4). This is often referred to as the Cushing perforator, although it is more correctly named the Doyen perforator.2

Fig. 3.
Fig. 3.

Drawing showing the spherical bur preferred by Cushing. Published in BMJ 1:221–226, 1918.

Fig. 4.
Fig. 4.

Drawing showing the Doyen perforator, often mistakenly referred to as the “Cushing” perforator. Published in BMJ 1:221–226, 1918.

To create a larger craniotomy than the trephine could effect, bur holes were connected with cuts between each of them. Although we generally think of this as a 20th century technique, there is evidence that Galen performed such procedures in the 2nd century. Again, this evidence consists of unearthed bronze instruments, to which we will return subsequently.

During the last 2 decades of the 19th century and the first 2 decades of the 20th century, bur holes were connected using a multitude of techniques. Hatchet-shaped, serrated saws, such as the Hey saw, were used, but these offered little or no protection from plunging (Fig. 2). Surgical skill and care were the necessary prerequisites. Rongeurs, such as the Montenovesi forceps, were used, but these were, no doubt, clumsy and depressed the dura mater and underlying brain, if not actually damaging them (Fig. 5).2

Fig. 5.
Fig. 5.

Drawing showing the Montenovesi rongeur. Published in BMJ 1:221–226, 1918.

Multiple permutations on the theme of a circular saw cutting through the bone over a metal guard, protecting the dura, were used but none remained in the mid- and late 20th century neurosurgical armamentarium (Fig. 6).1,4,8,9 By far the most efficient device for the task in question has been the barbed wire–like saw invented by Dr. Gigli for use in cutting the symphysis pubis in cases of dystocia. Adapted for use in the skull, this has been the most reliably effective instrument to appear.9

Fig. 6.
Fig. 6.

Drawing showing the Krause saw, typical of the circular saws with integral DuraGuard. Published in Surgery of the Brain and Spinal Cord Based on Personal Experiences, Vol 1. New York, Rebman Co., 1909, pp 21–25.

Nevertheless, one of the previously mentioned mechanical devices stands out and has, in a slightly different form, remained alive. Moreover, its direct lineage extends back nearly 20 centuries. In 1897, a dentist named Matthew Cryer published a description of a small button on the bottom of a post, on which a rotating saw rested. The design was absolutely indistinguishable from a modern craniotome (such as the Midas Rex) (Fig. 7).1,9 Interestingly, a device consisting of a rotating saw attached to a distal button without a supporting arm was also known and was called a “frise” (Figs. 8 and 9).4,9

Fig. 7.
Fig. 7.

Drawing showing the Matthew Cryer cranial cutting device. Note the similarity to its modern counterpart. Published in Medical News 70:129–133, 1897.

Fig. 8.
Fig. 8.

Photograph showing drill bits used with the Hartley and Kenyon engine (Note that no. 7 is the frise.) Published in Ann Surg 45:481–530, 1907.

Fig. 9.
Fig. 9.

Photograph showing the compressed air drive for the Hartley and Kenyon device. Published in Ann Surg 45:481–530, 1907.

Even more surprisingly, a supporting arm, ending in the button and bearing a sharp edge on the inner surface of the arm, was fashioned in bronze and is seen in what is thought to be the armamentarium of Galen, in the 2nd century. Presumably, this was hammered from trephination to trephination, using a mallet (Fig. 10).11

Fig. 10.
Fig. 10.

Drawing showing the “lenticular” (A) used by Galen in place of an unguarded saw (B).

An evaluation of the aforementioned chronology suggests certain trends. If we review the different methods of initial perforation, we find that only the tumi exhibited the significant safety feature of a tapered approach, until, that is, the advent of the device seen in Renaissance manuscripts. Note that this appeared at approximately the same time as the increased “power” of the Hudson brace–like device.

As most neurosurgeons can attest, even without the white plastic safety guard on modern twist drill bits, a hand-turned device, without the additional mechanical power of a brace, can be controlled so it will not plunge by using a basic neurosurgical tactile technique. In other words, the safety taper of the tumi presumably offered significant benefit and was no doubt quite ingenious. Nevertheless, without power beyond the hand, wrist, or even the bow (and, perhaps, the fear of law suits), the need for such a safety device was probably not as crucial as it became after the mechanical advantage of this brace gained popularity.

The appearance of the cutting device attached to a dura-protecting button, in existence for so many years before its wide acceptance, seems less an example of absent need and more an example of absent power. One can only imagine the time, effort, and frustration experienced by Galen creating his cranial incisions in such a manner. Somewhat less frustrating, but still highly unsatisfactory, was the lack of rotational torque provided by the small electric motor, and even less by the hand crank, which Dr. Cryer proposed for his device (Fig. 7). His design was ingenious, but for lack of the availability of adequate torque power, it was a little before its time.

In their comprehensive review of the neurosurgical engine, Pait et al.9 described a number of craniotome-like devices that were available during the last few years of the 19th century and the first 2 decades of the 20 century. Most of them have completely vanished. Hartley and Kenyon,4 the developers of the compressed air–driven engine that some consider to be the best of these, saw the clear surgical benefit of the fast cut made by such a device. They favored a rotating drill very similar to the one that remains in use today. However, Hartley and Kenyon, themselves, complained that the cut made by that drill was too wide. It was not until the high torque of the currently available engines appeared that the drill design they favored became thin enough to guarantee its ultimate acceptance

The Desire for an Axial View of the Spine

In 1975, an understanding of the role of the hypertrophied facet joint in lumbar radicular disease was rapidly gaining acceptance. A desire for an axial view of the bony anatomy was evident. In that year, the Journal of Neurosurgery published 2 back-to-back articles by Robert Jacobson et al.,5,6 in which the authors described a technique for radiographically visualizing the spine, along its axis, using polytomography, which had previously been used for fine resolution imaging of head and neck bony anatomy. In polytomography, an x-ray tube and an imageintensifier move in opposite directions, creating a central high resolution in-plane “section” superimposed by two large out-of-plane anatomical volumes of data. This technique, first described two years earlier by the same group, was called transverse axial tomography.

At the time, the images were thought to be too difficult to interpret, and 2 years later, whole-body axial CT scanning made the elegant invention of transverse axial tomography as obsolete as the audiocassette made the 8-track tape. To a generation of neurosurgeons used to looking at anatomy from an axial viewpoint, however, the images are not hard to interpret at all (Fig. 11).

Fig. 11.
Fig. 11.

Typical images from Jacobson's transverse axial tomography. Published in J Neurosurg 42:412–419, 1975.

Of note, the mathematical equation that made CT possible was devised by Radon in 1917.10 Radon's equation remained theoretical until the invention of the computer, decades later. Ultimately, its use for tomography was made practical with minicomputers that were the computational tool for the EMI Mark-I, the first CT scanner for which Hounsfield received the Nobel Prize in medicine in 1979. In contrast, Dr. Jacobson's brilliant marriage of preexisting technologies and applications to fulfill an unquestioned need, just 4 years earlier, has been all but forgotten.

Conclusions

In his book, Guns, Germs and Steel, Jared Diamond posits the thesis that technology is never simply the result of a brilliant idea that fulfills a clear need but rather the result of such an idea and such a need, existing in an environment that already offers everything required to support its growth and development.3 This is so, even if the potential benefit of that technology is clearly evident. Unless all of this is present, technological ideas, no matter how ingenious, will never gain popular acceptance. Neurosurgical technology is no exception to this.

Disclaimer

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Portions of this work were presented in poster form at the 2007 Annual Meeting of the American Association of Neurological Surgeons, Washington, D.C.

References

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Article Information

Address correspondence to: Raymond A. Schulz, M.Sc., 3100 Hansen Way, Palo Alto, California 94304. email: raymond.schulz@varian.com.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Drawing showing the cranial perforation devices used in ancient and medieval times, often called terebra serrata.

  • View in gallery

    Photo showing an American Civil War surgeon's instrument case. Note the cylindrical and tapered trephines. The Hey saw is the hatchet-shaped device seen just to the right of the trephines. Published in J Neurosurg 78:838–845, 1993.

  • View in gallery

    Drawing showing the spherical bur preferred by Cushing. Published in BMJ 1:221–226, 1918.

  • View in gallery

    Drawing showing the Doyen perforator, often mistakenly referred to as the “Cushing” perforator. Published in BMJ 1:221–226, 1918.

  • View in gallery

    Drawing showing the Montenovesi rongeur. Published in BMJ 1:221–226, 1918.

  • View in gallery

    Drawing showing the Krause saw, typical of the circular saws with integral DuraGuard. Published in Surgery of the Brain and Spinal Cord Based on Personal Experiences, Vol 1. New York, Rebman Co., 1909, pp 21–25.

  • View in gallery

    Drawing showing the Matthew Cryer cranial cutting device. Note the similarity to its modern counterpart. Published in Medical News 70:129–133, 1897.

  • View in gallery

    Photograph showing drill bits used with the Hartley and Kenyon engine (Note that no. 7 is the frise.) Published in Ann Surg 45:481–530, 1907.

  • View in gallery

    Photograph showing the compressed air drive for the Hartley and Kenyon device. Published in Ann Surg 45:481–530, 1907.

  • View in gallery

    Drawing showing the “lenticular” (A) used by Galen in place of an unguarded saw (B).

  • View in gallery

    Typical images from Jacobson's transverse axial tomography. Published in J Neurosurg 42:412–419, 1975.

References

1

Cryer MH: The surgical engine and its use in bone surgery. Medical News 70:1291331897

2

Cushing H: Notes on penetrating wounds of the brain. BMJ 1:2212261918

3

Diamond J: New YorkW W. Norton & Co1997. 480

4

Hartley FKenyon J: Experiences in cerebral surgery. Ann Surg 45:4815301907

5

Jacobson REGargano FPRosomoff HL: Transverse axial tomography of the spine. Part 1: axial anatomy of the normal lumbar spine. J Neurosurg 42:4064111975

6

Jacobson REGargano FPRosomoff HL: Transverse axial tomography of the spine. Part 2: the stenotic spinal canal. J Neurosurg 42:4124191975

7

Kaufman HH: Treatment of head injuries in the American Civil War. J Neurosurg 78:8388451993

8

Krause F: Surgery of the Brain and Spinal Cord Based on Personal Experiences Vol 1:New YorkRebman Co1909. 2125

9

Pait TGDennis MWLaws ER JrRizzoli HVAzzam CJ: The history of the neurosurgical engine. Neurosurgery 28:1111281991

10

Radon J: Uber die bestimmung von Funktionen durch ihre intergralwerte langs gewisser Mannigfaltigkeiten. 69:2622771917

11

Walker AE: The Genesis of Neuroscience Park Ridge, IllinoisAANS Publications1998

12

Walker AE: A History of Neurological Surgery BaltimoreWilliams & Wilkins1951

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