Cranial Dysraphism Mistaken for Trephination T. D. STEWART Division of Physical Anthropology, National Museum of Natural History, Washington, D . C. 20560 K E Y WORDS Skull. Dysraphism . Trephination . New England Peru Paleopathology. ’ ABSTRACT Attention is called to a disputed diagnosis of trephination reported for a perforated skull of a prehistoric New England Indian. The perforation, surrounded by a saucer-like depression, is located exactly in the midline just in front of bregma. The finding of a similar lesion in a prehistoric Indian skull from the North Coast of Peru -where, as in New England, good evidence of the practice of trephination is lacking - provides support for a more reasonable diagnosis for both cases: congenital cranial dysraphism, specifically encephalocele. Information about dysraphic states from modern clinical experience is summarized. In 1970 Bernard W. Powell of Wilton, Connecticut, published a report in Science entitled, “Aboriginal trephination: Case from southern New England?” Note the question mark. The skull with the putative trephination (fig. 1, left) is part of a skeleton encountered and partly disturbed by laborers working on a road at a known site of Indian occupancy on a glacial terrace bordering Long Island Sound at Norwalk, Connecticut. Powell’s subsequent investigation revealed that this individual -a young adult, probably male- had been buried semiflexed in a deep layer of loam during the Woodland Period. He named the site Spruce Swamp for reasons given in another publication (Powell, ’65) and designated the skeleton Spruce Swamp burial 1 (B.1). In his report Powell summarized the opinions of seven persons (including the writer) with whom he had discussed the nature of the cranial perforation. Four unnamed pathologists “were flatly of the opinion that it was a trephination and not meningioma or other disease.” Milton Helpern, the New York City Medical Examiner, “suggested that a downward invasion of a basal-cell tumor of the scalp could cause the condition, but he declined ultimately to say definitely what the lesion represented.” I “suggested that [it] might be from a cyst or tumor . . . [but] conceded that [I] had never seen anything quite like this specimen.” And lastly, H. AM. J. PHYS. ANTHROP.,42: 435-438. Jaffee of the Hospital for Joint Diseases in New York City “raised the possibility that the anomaly might result from a longstanding lesion which prompted attempts to scrape and treat it.” The article in Science attracted the attention of Detroit-neurosurgeon H. Harvey Gass and led him to write a letter to the Editor giving his diagnosis of the case (Gass, ’71). The following extract conveys the point of the letter: The skull may become “saucerized” by benign tumors within it and growing out of it, or resting upon it, especially in young individuals. When this process is present exactly in the midline and an aperture pierces the skull at the bottom of the “saucer,” a diagnosis of congenital cranial dysraphism seems mandatory. I suspect that many physical anthropologists missed Dr. Gass’ letter, or, if they saw it, failed to grasp its full significance. For this reason, I a m using my chance discovery of a second prehistoric skull with a comparable lesion a s an excuse to put both cases on record in a n anthropological journal and to summarize what is known about cranial dysraphism. Hopefully, fuller understanding of what appears to be a rare manifestation of a congenital state will prevent human paleopathologists from repeating a diagnostic error. The new specimen is a n isolated skull without lower jaw bearing the catalogue number 264,629 in the National Collection (fig. 1, right); it is one of some 600 skulls 435 436 T. D. STEWART Fig. 1 Left: Skull B.1 from the Spruce Swamp site at Norwalk, Connecticut (Courtesy of Bernard W . Powell). Right: Skull U.S.N.M. No. 264,629 from the Chicama Valley on the North Coast of Peru. Both skulls show signs of a herniated sac - encephalocele - in the midline a t or j u s t in front of bregma. picked up by HrdliCka in 1910 from the surface of unrecorded sites in the Chicama Valley on the North Coast of Peru. A note in unidentified handwriting on the catalogue card for this specimen reads: “Trephining? at bregma.” I judge the skull to be a young-adult female. The lesion in this Peruvian skull is remarkably similar in appearance to the one in the New England skull as pictured in Science. The main difference is that in the Peruvian skull both the perforation and the surrounding “saucer” are smaller and situated just at bregma, rather than a centimeter or so anterior to bregma. To the extent that the “saucers” are indicative of tumor sizes, neither one can be considered large. The rim of each “saucer” is prominent anteriorly and fades away on either side, somewhat like the bow-waves of a ship. Dr. Gass explained the raised rim in his letter as follows: Brain pulsations transmitted through the aperture [in the skull] meeting against the bone edge cause the bone to “build up” a t this edge, receiving the pulsations maximally. I can add that in the Peruvian skull the aperture appears circular only when viewed frontally and just over the rim of the “saucer.” Endocranially the posterior margin of the perforation is slightly grooved. Apparently, therefore, the tumor was connected with the endocranial structures by a stalk or pedicle directed anteroposteriorly. Information is lacking on this point in the skull from New England. For further enlightenment on dysraphic states Dr. Gass (personal communication, December 18, ’73) kindly referred me to some text-books on neurology. In one of them (Dekaban, ’59) I learned that dysraphism embraces two related conditions commonly called spina bifida and cranium bifidum. The term is descriptive in that it CRANIAL DYSRAPHISM MISTAKEN FOR TREPHINATION 437 refers to the embryological stage of closure pends mostly upon the amount of brain of the neural canal and in particular to damage prior to repair, in pre-surgical defects along the line of closure (Dys-, times the prognosis for survival to adultGr. 8vu bad; raphe, Gr. pa+< seam; -ism, hood would have been favorable only for Gr. L(TFOI,expressing the thing done). In small meningoceles. Dekaban's words (p. 177), This information from modern clinical experience accords so well with the evi. . . the neural canal begins to form at about the nineteenth day of gestation and is comdence in the two prehistoric specimens pletely closed in both cephalic and caudal as to rule out an exotic explanation such regions by the end of the first month of intraas trephination. It is true that Pedro Weiss uterine life . , . A noxious factor or occasionally a ge('58) claims to have found evidence in the netic lesion may disturb the development form of supra-inion depressions for proof a segment of the neural axis as well a s phylactic trephination having been practhe overlying primitive mesenchymal tissue. ticed in the Chicama region. But I have This can lead to severe malformation and to a defect i n the d u r a mater and cranial explained these depressions in more nator spinal bones. ural and reasonable ways (Stewart, '71; Judging from recently collected cases, manuscript). Besides, Chicama is located cranial dysraphism is six and one-half well away from that part of Peru where times less common than spinal dysra- the established type of trephination was phism. In the present U . S. population, practiced (Stewart, '58). As for New Engaccording to Dekaban's estimate, the for- land, there does not appear to be any mer occurs about once in 6,500 births. other kind of evidence that the Indians As seen in the head of a living child, the there had developed a surgical capability. condition consists of a pulsating tumor of LITERATURE CITED variable size located usually in the midDekaban, A . 1959 Neurology of Infancy. Willine, most commonly in the occipital region liams and Wilkins. Baltimore. and next most commonly in the naso-fron- Gass, H. H. 1971 Skull from Spruce Swamp: tal region. It is not clear from the termiCase of cranial dysraphism? Science, 171 : 1268. nology used in the tabulation whether the Powell, B. W . 1965 Spruce Swamp: A partially drowned coastal midden in Connecticut. Am. region of bregma is included in the nasoAntiq.. 30: 4 6 0 4 6 9 . frontal region, or in the less-susceptible 1970 Aboriginal trephination: Case from parietal region. southern New England? Science, 170: 732-734. Pulsation is due to the tumor being a Stewart, T. D. 1958 Stone age skull surgery: A general review, with emphasis on the New sac that has herniated through a defect World. Smithsonian Rep. for 1957, pp. 4 6 9 4 9 1 . in the skull. When the sac contains only 1971 Pseudo-trephination. Am. J. Phys. fluid and strands of leptomeninges with Anthrop., 35: 29&297 (abstract). (Manuscript) Are supra-inion depressions a few blood vessels, it is called a cranial evidence of prophylactic trephination? meningocele; when in addition it contains Sublett, A. J., and C. F. Wray 1970 Some exa portion of the brain or cerebellum, it is amples of accidental and deliberate h u m a n skelcalled an encephalomeningocele. There are etal modification in the Northeast. Bull. N. Y. State Archaeol. Assn., 50: 14-26. other still more severe grades that need Pedro 1958 Osteologia cultural, praticas not concern us here. Considering that in Weiss, cefalicas. la. parte: Cabezas trofeos, trepanacithis age of miraculous surgery the progones, cauterizaciones. An. Facultad. Med. Univ. nosis for the two less-severe grades deNac. Mayor San Marcos, Lima, 41 (4): 5054355. Note added in proof: After the above was accepted for publication I discovered in the literature another case of cranial dysraphism mistaken for trephination (Sublett and Wray, '70). The illustration accompanying the description (fig. 14, p. 20) shows the top anterior half of the skull of a middle-aged female Seneca Indian from Boughton Hill, New York (16701687 A.D.). Exactly at bregma is a perforation in a saucer-like depression. This perforation appears to have been enlarged through breakage. In any case, the sloping borders of the perforation are surrounded, except posteriorly, by a low rounded ridge. A s should now be recognized, all of these features are characteristic of a herniated encephalocele.