Incidence of separate neural arch in the lumbar vertebrae of Eskimos

Abstract

By the phrase 'separate neural arch' most writers in English refer to an anomaly which has its greatest frequency in the lumbar vertebrae, but which has been reported as occurring also in other segments of the column. The term ' spondylolysis ' (or ' spondiloschise ' of Neugebauer ) has been applied to this condition, especially by foreign writers, and usually to indicate its relationship to spondylolisthesis. Thus, separate neural arch and spondylolysis both designate the condition in which there is found a break in continuity of the neural arch, usually between the superior and inferior articular processes Bnd either on one or both sides. When this defect is present on both sides, the vertebra consists of two parts, of which the larger ventral portion is formed by the vertebral body with the pedicles, transverse processes, and superior articular processes, while the smaller dorsal portion contains the inferior articular processes, laminae, and spinous process.When the two part-components of an anomalous vertebra become separated through displacement of the body ventralward, while the inferior articular processes retain their position, the result is the so-called ( spondylolisthesis. ' The latter condition when occurring in women constitutes an obstruction in the birth canal and, in the earlier days of obstetrics and gynecology, was diagnosed only in the course of pregnancy. Naturally, therefore, the condition seemed formerly 'Read before the second meeting of the American Association of Physical Anthropologists, Cleveland, 1930.

Spondylolysis of the sacrum in Alaskan and Canadian Inuit skeletons

“…Several possibilities must be considered. To some extent this phenomenon is likely just part of the prevalence of spondylolysis in these people generally (Stewart, 1931(Stewart, , 1953. It should be noted, however, that high frequencies of lumbar spondylolysis have been recorded for some prehistoric North American Indian groups as well, particularly those from Indian Knoll (Archaic), Kentucky (Snow, 19481, the Larson site (Arikara), South Dakota (Bradtmiller, 1984), and Birch Bay (Upper Puget Sound), Washington (Lundy, 1981).…”

“…Also, skeletons obtained from archaeological sites usually allow for direct, bare bone observation of any lysis, even early stages, thus avoiding the difficulty of visualizing these defects radiographically (Wiltse et al, 1975;Merbs, 1989aMerbs, ,b, 1995. Some or all of the eight Alaskan cases of S1 spondylolysis described here are in collections originally studied by Stewart (1931Stewart ( , 1953, but his observations did not include sacra. Cases 15 and 16 were briefly described and illustrated previously (Merbs, 1983).…”

“…Inuit skeletons make ideal subjects for studies of spondylolysis because these people have an unusually high frequency of the condition, most likely the highest in the world (Stewart, 1931(Stewart, , 1953Lester and Shapiro, 1968;Kettelkamp and Wright, 1971;Merbs, 1983;Simper, 1986). Also, skeletons obtained from archaeological sites usually allow for direct, bare bone observation of any lysis, even early stages, thus avoiding the difficulty of visualizing these defects radiographically (Wiltse et al, 1975;Merbs, 1989aMerbs, ,b, 1995.…”

Dysplastic spondylolysis is caused by mutations in the diastrophic dysplasia sulfate transporter gene

“…Moreover, the reported incidence of spondylolysis and spondylolisthesis in family members of index patients was 22% (16), compared with 8% in the general population (17), suggesting it is genetically heterogeneous. Interestingly, spondylolysis was found to be very frequent in Alaskan Eskimos (18).…”

Spondylolysis in Inuit skeletons from Arctic Canada

“…The incidence of the condition appears to vary considerably from group to group and through time, with frequencies of less than 5% to over 50% having been recorded (Stewart, 1931;Merbs, 1996a). Very ancient cases have been reported for 4,000 year old maritime archaic skeletons from Port au Choix, Newfoundland, Canada (Anderson, 1976), and a 3,000-4,000 year old La Jollan woman from Punta Minitas, Baja California, Mexico (Merbs, 1980).…”