Hippocrates, Galen, and the Uses of Trepanation in the Ancient Classical World

Symeon Missios, M.D.

Disclosures

Neurosurg Focus. 2007;23(1):E11 

In This Article

Hippocrates and the Teaching of Trepanation

Hippocrates of Cos (460-377 BC; Fig. 1) lived during the "golden age of Pericles," which represents the pinnacle of ancient Greek civilization. His full name was Hippocrates Asclepiades, which means a direct descendant of Asclepios, the god of medicine, although it is unclear whether that was his real name or it was attributed to him later in life in honor.[8] He was an extraordinary physician, scientist, and thinker, free from the superstitions that pervaded his world. He revolutionized medicine in ancient Greece and, using the principles of observation and clinical examination, established medicine as a discipline distinct from theology and mysticism. Hippocrates led the intellectual evolution of medicine, including surgery and neurosurgery, during the classical period, and he is referred to as the "father of medicine" in recognition of his enormous contribution. He practiced at several places in ancient Greece, most likely including ancient Athens during the Peloponnesian War (431–404 BC), and is mentioned in the works of Plato, but very little information about his biography and his personal life has managed to survive through the centuries.

Figure 1.

Hippocrates. Engraving by Peter Paul Rubens, 1638. Courtesy of the US National Library of Medicine.

Despite the lack of knowledge concerning Hippocrates' life, his legacy includes a great collection of medical works, which comprise the Hippocratic corpus. The first known edition of it dates to Roman times, during the reign of the emperor Hadrian (reign 117-138 AD; Fig. 2). It is a collection of approximately 70 works, including textbooks, lectures, research notes, and philosophical essays on various subjects in medicine, in no particular order.[3,9,15] The texts display no uniformity in their style of teaching or prose, and it has been recognized, even in antiquity (by Alexandrian scholars), that some works were written by persons other than Hippocrates, most likely his students.[16] The corpus includes various works, most directed toward the physician and some directed more toward laymen. Some works are more theoretical and philosophical in nature, discussing professionalism in medical practice and the role of medicine as an entity distinct from religion and mysticism. None of the works are based on scientific experimentation, and only one of the books, The SacredDisease, describes animal dissections.[3,29] Human dissection was not practiced in ancient Greece, and the study of human anatomy was based on observation, external palpation, and analogies derived from animal dissections.[20] Nevertheless, certain recurring themes emerge among the different works of the corpus, including Hippocrates' lack of belief in cursed diseases and miraculous cures, as well as the belief that environmental factors-including hygiene, diet, and climate-have a profound influence on both mind and body.[15]

Figure 2.

Photograph of the cover of Omnia Opera Hippocratis. The first Greek edition of Hippocrates' complete works, it was printed in Venice in 1526. Courtesy of the US National Library of Medicine.

On Injuries of the Head

Hippocrates' greatest contribution to ancient neurosurgery is his book On Injuries of the Head, written around 400 BC. The book is a treatise on cranial anatomy and head trauma.[31] Using the skills of observation, documentation, and examination, the author describes the anatomy of the skull, the different types of cranial trauma and fractures, the evaluation of the patient with head injury, and management, both operative and nonoperative. Hippocrates, like all ancient Greeks, was not a stranger to head trauma and its significance, given the numerous military conflicts that burdened ancient life. As reflected in the works of Homer, Herodotus, and Thucydides, it was recognized early that head wounds were especially dangerous and that when a head lesion was sufficiently significant, death was inevitable.[7,10,14,25,26]

In On Injuries of the Head, Hippocrates describes five main types of traumatic head lesions and recommends appropriate management. The first type is defined as "bone contusion with a fissured fracture" and comprises injuries that result in linear skull fractures. Hippocrates describes the wide variation of these injuries and states that the fractures can vary in terms of size, thickness, distance, and degree of penetration (full or partial) through the bone. Simple "bone contusion without fracture" is the second type of head injury. The contusion may involve partial or full bone thickness, and Hippocrates accurately explains that

 

it is not possible to recognize any of these varieties by the sight, so as to determine their form and extent; neither, indeed, is it visible to the eyes when any mischief of this kind takes place. [32]

This type of injury was assumed when no fracture was seen in the cases of high-impact blunt head trauma. "Depressed skull fractures" constitute the third type of cranial trauma, and again the author describes their variability in terms of depth of depression and extent of bone involved. The fourth type of head trauma involves "dinted fractures." These occur when a weapon hits the skull and leaves an indentation on the bone, which Hippocrates calls a "hedra" (´εδρα).

These injuries invariably involve bone contusion at the site of the hedra, and they are occasionally accompanied by a fracture. The size and depth of the hedra depends on the features of the weapon used and the force applied. Distinguishing these injuries from depressed skull fractures depends on the integrity of the surrounding bones, as explained by the author:

 

The cleft or notch which occurs in the bone, to whatever length or breadth, is a hedra, if the other bones comprehending the cleft remain in their natural position, and be not driven inwards; for in this case it would be a depression, and no longer a hedra. [32]

The fifth mode of head injury involves "injuries at distant sites." Hippocrates recognized that a head injury can take place in a different part of the head from the wound and recognizes the limitations of pure observation in the prompt identification of these lesions:

 

For this misfortune, when it occurs, there is no remedy; for when this mischief takes place, there is no means of ascertaining by any examination whether or not it has occurred, or on what part of the head. [32]

Hippocrates makes a special mention of head injuries that are close to the cranial sutures or involve the sutures directly. He describes a "natural weakness" of the bone at suture lines and advises for careful observation of a hedra with a fracture near the suture line in order to determine if the fissure involves the suture itself.[20,32] If it does, then the patient is likely to sustain a much greater injury and will require trepanation:

 

For a person wounded to the same . . . extent . . . will sustain a much greater injury, provided he has received the blow at the sutures, than if it was elsewhere. And many of these require trepanning. [32]

Surgical Management of Head Injuries

Hippocrates' recommendations for surgical management of head injuries involve incision and wound exploration and trepanation. Wound incision and exploration is recommended in cases in which the bone is injured and denuded of flesh and when the wound is not large enough to allow proper inspection and determination of the presence and degree of injury.[20] The incision is made proportional to the wound size in a direction selected to make "the wound of a long form." Hippocrates warns against making any incision over the temple due to potential injury to a large vessel in that region. He states that injury to that vessel will lead to contralateral convulsions of the patient.[32] The vessel described probably represents the superficial temporal artery and vein, but it is unclear why the association between the vessel and the development of seizures was made. Once the incision has been made, the flesh is separated from the bone "where it is united to the membrane," probably the pericranium. Then the wound is filled with lint soaked in a "cataplasm," a mixture of boiled flour and vinegar, and left for 24 hours.[8,20] The next day the wound is explored and proper assessment of the injury is made. If the injury is not readily identifiable but highly suspected, then the bone is scraped with a raspatory. If a dint or hedra is identified, then scraping the bone over the affected region is recommended. If, however, the fracture extends deep and is not likely to disappear with scraping alone, then trepanation is required. The intervention should be performed within 3 days from the initial injury and should not be delayed.

According to Hippocrates, injuries that require trepanation include cases of fissured fractures, bone contusion with or without associated fracture, and hedra injuries with associated bone contusion with or without fracture.[32] Interestingly, Hippocrates recommends against trepanation in cases of depressed skull fractures and states that the depressed fractures "which are most pressed and broken require trepanning the least." Healing of those injuries involved allow the wound to granulate and the depression to rise "when flesh grows below." Injuries in proximity to the sutures are described as often requiring trepanation; the practitioner is warned against making a hole over the suture itself, but no explanation is provided.[20] There is no mention of the sinuses or other vascular structures underneath the sutures. The sutures were considered points where the skull bones are weaker, and perhaps trepanation over those regions was thought to be more dangerous and to entail a higher likelihood of plunging and injuring the intracranial contents.

The Technique of Trepanation

In regard to the technique of trepanation, Hippocrates states that the bone should be sawed down until only a very thin layer remains, covering the meninges. The meninges themselves should never be exposed due to the high likelihood of subsequent infection or direct injury to them from the instrument. The thin layer of bone falls out by itself in time. Hippocrates recommends taking time to drill the hole and using water to cool down the trepan due to the heat generated from the friction of drilling.[1,20,32] If, however, the physician has not followed the patient from the initial onset of trauma and substantial time has passed since the initial injury, then the cranium should be sawed down to the layer of the meninges. Hippocrates recommends using a "serrated trepan" (πρι´ον) for this purpose and again pausing several times during the procedure and inspecting the hole with a "sound" (ì´ηλη) a probe to assess the depth of the hole, the motility of remaining bone, and the integrity of the meninges. Any meningeal injury would predispose to infection, brain abscess formation, and death. Warnings are provided about performing trepanation in children, due to the softness and thinness of their cranium.

Wound healing following wound incision or trepanation included allowing the wound to drain and granulate. The wound was never closed but rather was packed open and allowed to granulate. Pus formation and suppuration were prerequisites for healing and were considered part of the normal healing process.[20] Information is also provided for significant head injures deemed incurable or ones that were diagnosed too late. The contused or broken bone becomes necrotic and the patient develops a fever within 7 days. The wound becomes erythematous and the bone turns dark and purulent. The patient develops tongue sores and becomes delirious. Seizures may occur on the contralateral side of the injury, and patients die within 7 days in the summer or 14 days in the winter.[32]

The Tools of Trepanation

There are four neurosurgical tools described by Hippocrates for the performance of trepanation. They involve two different types of bone-penetrating instruments, the trepan and the serrated trepan (πρι´ον), which was used in cases of delayed identification of head injury that required sawing of the bone all the way down to the meninges. The "sound" (ì´ηλη) is the probe that was used while trepanning, to determine the depth of the hole and the mobility of the underlying bone. Finally the raspatory (ξυστ´ηρ) was used in cases in which the wound was explored and the contused bone and fracture were scraped down to the level of healthy bone.[9,19]

Analysis of On Injuries of the Head

Contemporary historical analysis of the treatise OnInjuries of the Head has raised several arguments regarding the use of trepanation in ancient Greece as well as the identity of the treatise's author and his personal expertise in the procedure. It is known that several of the works included in the Hippocratic corpus were actually written by authors other than Hippocrates, and there are arguments that support the notion that On Injuries of the Head represents one of these works.[16] Regardless of its authorship, the book appears to have been written by an experienced surgeon of the time, whose description about the use and technique of trepanation, however, leaves several questions unanswered.

The author recommends trepanation for a wide variety of head injuries, to be performed within the first 3 days after injury, but the precise reason for trepanning is never explicitly stated. There is no mention of trepanning in order to drain an underlying hematoma or whether trepanation was used as a means to protect against the development of a brain abscess. Similarly, trepanation is not recommended for the repair of depressed skull fractures and the removal of necrotic bone fragments, and these injuries are allowed to heal by granulation. The technique of allowing a thin layer of bone over the hole is strangely hesitant and constitutes a source of speculation that the author was not personally experienced in trepanation.[16] This technique was not recommended by later practitioners of trepanation, who proposed the complete removal of bone to the level of the meninges.

At the time On Injuries of the Head was written, trepanation was commonly practiced in Europe among the Celts, whose territory spread from France along the Danube to the Black Sea.[16] The majority of findings indicate that the Celts employed the more traditional scraping technique of trepanation, but a minority of Celtic settlements along the southern Viennese basin adopted the practice of drill trepanations.[1] These settlements were located along the amber trade route from Western Europe to the Mediterranean and were the sites of cultural exchange between the Celtic and Greek worlds.[1] It is possible that the author of the treatise had some exposure to Celtic tradition and trepanation practices, which influenced his writing. The importance of the book On Injuries of the Head is that it represents the first historically recorded account of the use of trepanation in ancient Greece and reflects the transition of the practice from Western Europe to the Mediterranean and its use, as a neurosurgical procedure, for strictly therapeutic rather than mystical purposes. In subsequent medical texts, specifically Epidemics IV and Epidemics V, written approximately 70 years later, cases treated by trepanation are described; the recommendations for its use are expanded to include elevation of depressed skull fractures, drainage of intracranial abscesses, and removal of necrotic bone; several new surgical instruments are also introduced.

Early fourth-century classical surgeons were probably hesitant to perform early trepanation, and little evidence of trepanned skulls has been discovered, given the presumed frequency of head trauma in ancient Greece.[10,12] However, literary evidence proves that trepanation was a procedure known to Hippocratic physicians and that it was becoming more common over the years, although it was often used as a last resort. The contributions of Hippocrates and his contemporaries and the intellectual environment of Ancient Greece allowed trepanation, and with it ancient neurosurgery, to evolve from an ancient, oral, disorganized, and mystical tradition that was likely Celtic in origin, to a written, scientific, and systematic topic of study, devoid of superstitions and religious influences.

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