Early Descriptions of Cranial Morphology and Cranial Sutures
The first documented report describing the diversity of cranial morphology dates to 440 BCE in Herodotus’ work, The Histories ( Ἱστορίαι Historíai ). Herodotus (484–425 BCE), an ancient Greek historian, hypothesized through a study that environmental factors contributed to the observed variation in cranial thickness between different human populations. Hippocrates of Kos (460–370 BCE), the Greek physician who is widely praised as the “Father of Medicine,” provided one of the earliest and most comprehensive accounts of cranial anatomy and suture morphology in the treaties, On Head Wounds ( Περι των εν κεφαλη τρωματων ). Hippocrates classified four discrete skull patterns based on suture arrangement, which he likened to the shape of the Greek letters, and proposed the concept of anatomic variability. The treaties also emphasized the clinical significance of cranial thickness in the management and outcome of head injuries.
Variation in the shape of the cranium and cranial sutures were later recognized by Galen of Pergamon (130–200 BCE), a Roman physician to the gladiators. Through his anatomical studies, which were primarily on animals, he identified the cerebral aqueduct, characterized seven cranial nerves, and correlated characteristic cranial features with the condition hydrocephalus. , , In his work, De Ossibus ad Tirones ( On the Bones for Novices ), he provided descriptions of the cranial sutures, the number of bones that form the cranium, and the shape of a normal skull. Galen also defined the term oxycephaly, introducing the notion of craniosynostosis. , Association of cranial deformities with craniofacial abnormalities like palatal defects was written by Oribasius (320–403), a Greek medical writer and personal physician to the Roman emperor Julian the Apostate.
One of the earliest illustrations of the cranium and cranial sutures was recorded several centuries later during the Medieval Period. Avicenna (980–1037), a Persian physician and polymath, depicted the structural framework of the cranium and the cranial sutures in his work, al-Qānūn fī al-Ṭibb ( Canon of Medicine) , the most comprehensive medical textbook of its time ( Fig. 1.1 ). He distinctly named and described the different cranial sutures, portraying the coronal suture as “an arc in whose center a perpendicular line has been set up” ; distinguishing the sagittal suture as the suture partitioning the skull into two halves, and regarding the squamosal suture as a “false” suture as they “do not penetrate the bone but overlap like fish scales.” Additionally, he accurately explained the configuration and articulation of the bones of the cranial vault, stating that the “frontal bone is located anteriorly; behind it are two parietal bones which are above the temporal bones and the occipital bone which is more compact and protects the back of the brain posteriorly.”
The knowledge of cranial anatomy and suture deformity expanded during the Renaissance through the works of key anatomists. A German physician, Johannes Dryander (1500–60) published the first detailed pictorial textbook on neuroanatomy in 1536, Anatomia Capitis Humani , which comprised of eleven elegantly engraved woodcuts. In one of his illustrations, he clearly displayed the configuration of specific cranial sutures ( Fig. 1.2A ) and alluded to the presence of the metopic suture, which “moved across the forehead to the nose.” , In 1543, a Flemish physician, Andreas Vesalius (1514–64), wrote and illustrated the monumental textbook of human anatomy ( Fig. 1.3A ), De Humani Corporis Fabrica Libri Septum ( On the Fabric of the Human Body ). Observations made from numerous dissections of human cadavers allowed Vesalius to appreciate anatomic variability. , He described a wide range of morphologic aberration of the shape of the skull and the arrangement of the sutures. He displayed one “natural” and four “unnatural” skulls, demonstrating how absence of certain sutures can lead to cranial malformations, namely craniosynostosis ( Fig. 1.3B ). , ,
Early Insight into Calvarial Growth and Craniosynostosis
Modern understanding of craniosynostosis arose in the late 18th century with Samuel von Sömmering’s (1755–1830) observations of cranial sutures’ significant role in the growth of the cranial vault. In 1791, the German physician recognized the association that failure of growth at a particular suture consequently led to cranial deformity. The term “craniosynostosis” was first defined by Adolph Wilhelm Otto (1786–1845) soon after in 1831. , Based on Otto’s studies in humans and animals, Sömmering asserted that premature closure of sutures led to cranial deformity through a combination of isolated growth restriction and compensatory expansion elsewhere, thereby postulating the first scientific explanation of the condition. , ,
In 1851, German pathologist and anthropologist Rudolph Carl Virchow (1821–1902) ( Fig. 1.4 ) expanded upon Otto’s theories and published a seminal paper entitled, Ueber Kretinismus namentlich in Franken und über pathologische Schädelformen (Cretinism, Particularly in Franconia, and Pathological Skull Forms). In his attempt to describe the demographics, pathology, and etiology of cretinism, Virchow created a classification system summarizing the various pathologic skull shapes observed in craniosynostosis. , He concluded that premature closure of a cranial suture restricted calvarial growth in a perpendicular direction, resulting in a compensatory overgrowth at the remaining unaffected sutures , thereby allowing the rapidly developing brain to grow. He also postulated that craniosynostosis was associated with disturbance of thyroid function or inflammation of the meninges. , ,
Virchow’s impact was momentous and provided the impetus for further exploration and dissemination of craniosynostosis studies over the next century. Reports of craniosynostosis with other congenital anomalies sprouted, leading to the recognition and classification of syndromic craniosynostosis. In particular, Eugène Apert (1868–1940), a French pediatrician, and Octave Crouzon (1874–1938), a French neurologist, identified syndromes in 1906 and 1912, respectively, which continue to bear their names. Crouzon also asserted that there may be a genetic contribution to the pathogenesis of craniosynostosis.
The theory of Virchow’s law was challenged in 1959 by Melvin Moss (1923–2006), an American orthodontist, who proposed that premature sutural fusion is a secondary outcome and not a cause of cranial growth restriction and malformation. , Moss highlighted that expansion of the brain primarily influences the growth of the calvarium, which is the fundamental basis for his “functional matrix theory.” He hypothesized that craniosynostosis resulted from aberrant development of the cranial base, producing altered biomechanical forces that transmitted to the sutures via the dura mater, causing premature fusion. , , His opposing postulation stemmed from the observation that similar cranial vault deformities have been noted in the absence of suture fusion, and from his thesis research which demonstrated that removal of calvarial sutures in growing rats did not affect neurocranial development. , , Experimental studies and surgical interventions directed at extirpation of the fused sutures have since undermined Moss’ theory, demonstrating that release of the fusion can inhibit the perpetuation of the induced abnormal growth pattern and reverse the deformity of the cranial base and vault. , , ,
Advancement of Surgical Concepts
Half a century after Virchow’s hypothesis, surgical treatment of craniosynostosis was first introduced. Although the condition of craniosynostosis was well recognized by the late 19th century, it is believed that many of the initial interventions were likely performed on nonsynostotic microcephaly. The concept of craniectomy or craniotomy, was suggested by a Canadian anatomist and surgeon, William Fuller, who was the first to trephine out portions of the skull of a child with “mental imbecility” in 1878. In 1888, an American surgeon, Levi Cooper (L.C.) Lane (1831–1902) performed the first cross-shaped craniectomy on a child with mental imbecility and “decidedly microcephalic” cranium, who, unfortunately died 14 hours later reportedly due to complications with anesthesia. Lane performed a second H-shaped craniectomy in 1892 on an “imbecile microcephalic infant” who fared well this time with improvement of the mental status.
A French surgeon ( Fig. 1.5 ), Odilon Marc Lannelongue (1840–1911) is credited for performing the first bilateral parasagittal linear craniectomies in 1890 for the correction of sagittal craniosynostosis, which was proposed to mitigate intracranial pressure and allow for physiologic expansion of the brain. , The patient was a 4-year old child with a severe psychomotor handicap, who reportedly had near complete neurologic recovery. The idea that craniectomy could alleviate imbecility incited initial enthusiasm; however, microcephaly resulting from primary brain abnormalities was often misdiagnosed as craniosynostosis, leading to poor case selection and futile interventions. , Consequently, the outcomes were disheartening with significant refusion of the operated sutures and reversion of the cranial deformity and growth constriction. Harvey Cushing (1869–1939), a highly influential American neurosurgeon of his time, criticized and warned against these early attempts, and surgery for craniosynostosis was ultimately discontinued after Abraham Jacobi (1830–1919), a German physician and a pioneer of the field of pediatrics in America, reported high mortality rates in 1894.
Nearly three decades passed until the resurgence of craniosynostosis surgery. In 1921, Mehner revived the concept of suturectomy and published his technique and outcome of craniectomy for complete removal of a synostosed suture. More extensive open craniectomies were discussed by Faber and Towne in 1927, who recommended decompressive craniosynostosis surgery to prevent complications of blindness secondary to elevated intracranial pressure. In 1943, Faber and Towne proposed the notion of early prophylactic linear suturectomy, around the age of 1 to 3 months, for preservation of neurologic function and cosmetic improvement. , By the mid-1900s, with the advent of radiological studies to confirm the diagnosis and progressive refinement of surgical techniques, linear suturectomies became the standard treatment of craniosynostosis; however, outcomes were inconsistent and often plagued by early reossification at craniectomy sites and inadequate correction of the cranial vault. Efforts to line the craniectomy edges with numerous products (e.g., polyethylene film, tantalum foil, silastic strips, and other substances) to prevent suture refusion also failed. ,
By the 1960s, development of anesthesia, blood management, and operative technique provided the opportunity for more complex and safer craniosynostosis surgery, allowing for consideration and emphasis on cosmesis as a key indication for surgical correction. , , And so began the modern era of craniofacial and craniosynostosis surgery. Led by Paul Tessier (1917–2008), a French surgeon ( Fig. 1.6A ) who is widely considered as the father of craniofacial surgery, together with Gérard Guiot (1912–98), a French neurosurgeon ( Fig. 1.6B ) and a pioneer in transsphenoidal surgery, novel techniques were designed to replace the simpler variety of craniectomy procedures which focused on cranial sutures. By removing, remodeling, and stabilizing large segments of the cranial vault, fronto-orbital bandeau, and maxillofacial complex, the desired modifications in the configuration and volume of the calvarium were established intraoperatively and preserved postoperatively. Cranial vault reconstruction was further explored and enhanced by the likes of Epstein, Jane, , and McComb, , and became the mainstay of craniosynostosis treatment. Nonetheless, these innovative techniques were associated with lengthy surgical times and hospital stays, significant blood loss requiring transfusion, need for postoperative intensive care unit monitoring, and complications including relapse requiring reoperation. These inadequacies provided a group of surgeons the incentive to employ new technologies to formulate the minimally invasive endoscopic surgery.
