Craniofacial bone atrophy in Parry Romberg syndrome demonstrated using a Bayesian hierarchical model

PurposeParry Romberg syndrome (PRS) is a condition characterized by progressive hemifacial atrophy, predominantly affecting the soft tissues. Associated bone retraction is a common clinical feature of PRS but has never been assessed. Here we used 3D imaging and Bayesian statistics in order to demonstrate and quantify bone atrophy in PRS.Materials and methodsTen non-operated patients with PRS (4/10 males) and 12 age-matched controls (7/12 males) were included into the study. The average age at CT-scan was 9.67 ± 4.13 years for PRS patients and 12.5 ± 4.37 years for controls. Soft and hard tissue atrophy levels were quantified using computed tomography scans, based on the distances between surfaces of the affected side and the non-affected contralateral side, both for the skin and the bone. We used a hierarchical Bayesian model with clinical priors in order to assess the relationship between hard and soft tissue atrophies.ResultsPRS patients had significant hard tissue atrophy, and atrophy extents were similar for soft and hard tissues. There was a trend for a correlation between the extent of hard tissue retraction and the extent of soft tissue retraction, and we could not demonstrate that the relationship between hard and soft tissue retractions was different in PRS and controls.ConclusionOur results indicated that bone atrophy was most probably a primary process rather than a phenomenon secondary to soft tissue retraction. We have provided the first assessment of bone atrophy in PRS patients using Bayesian statistics.     

Phylogenetic reconstruction of Bantu kinship challenges Main Sequence Theory of human social evolution

Kinship provides the fundamental structure of human society: descent determines the inheritance pattern between generations, whereas residence rules govern the location a couple moves to after they marry. In turn, descent and residence patterns determine other key relationships such as alliance, trade, and marriage partners. Hunter-gatherer kinship patterns are viewed as flexible, whereas agricultural societies are thought to have developed much more stable kinship patterns as they expanded during the Holocene. Among the Bantu farmers of sub-Saharan Africa, the ancestral kinship patterns present at the beginning of the expansion are hotly contested, with some arguing for matrilineal and matrilocal patterns, whereas others maintain that any kind of lineality or sex-biased dispersal only emerged much later. Here, we use Bayesian phylogenetic methods to uncover the history of Bantu kinship patterns and trace the interplay between descent and residence systems. The results suggest a number of switches in both descent and residence patterns as Bantu farming spread, but that the first Bantu populations were patrilocal with patrilineal descent. Across the phylogeny, a change in descent triggered a switch away from patrifocal kinship, whereas a change in residence triggered a switch back from matrifocal kinship. These results challenge “Main Sequence Theory,” which maintains that changes in residence rules precede change in other social structures. We also indicate the trajectory of kinship change, shedding new light on how this fundamental structure of society developed as farming spread across the globe during the Neolithic.Kinship is the key structure underlying human society: descent determines how wealth, land, and position are inherited across generations, whereas residence describes the rules governing where a couple should move to once they are married (1). In turn, descent and residence patterns determine other key relationships within society such as alliance, trade, and marriage partners (2). Contemporary hunter-gatherer societies, which are often considered a model for preagricultural human societies, are predominantly bilateral, tracing descent through both lines, and multilocal, with each couple choosing where to live (2–4, but see ref. 5), allowing for flexibility in those societies. In the last 10,000 years, however, a number of groups developed agriculture, which led to the expansion of food production techniques, cultures, and in some cases their populations too (6). The emergence of farming is thought to have coincided with more sex-biased dispersal and unilineal kinship (7).From their ancestral homeland in the Benue valley in Eastern Nigeria 3,000–5,000 BP (8, 9), possibly using a grassland corridor that opened up through the Cameroon rainforest (10, 11), the Bantu undertook one of the great farming expansions of the Neolithic (6). The history of their kinship is therefore key to debates about the fundamental processes that drove the evolution of human society during the Holocene. However, there are disagreements about the ancestral pattern of Bantu kinship and how this evolved through time.Vansina (12) suggests that proto-Bantu society had a bilateral descent and bilocal residence system (definitions in SI Appendix, Table S1) that was adaptive for expanding populations. Based on linguistic reconstruction, such as the proto-Bantu word for “house” being sex neutral, he argues that residence was flexible (13). Hunting required cooperation and mobility, and would be best served by males having a choice about their residence rather than being constrained by unilocality (12). Vansina suggests that only in the 18th or 19th century did unilineal descent and residence patterns begin to emerge, due to increased wealth and the disorder faced by some Bantu-speaking people (12).The second theory proposes a unilineal descent and unilocal residence system in the ancestral Bantu population (14). Hage and Marck argue, based on the linguistic reconstruction of kin terms, that the early Bantu speakers were, in fact, matrilocal and matrilineal (see also ref. 3), and dispute the sex neutrality of the proto-word for “house.” They also suggest that matriliny is consistent with a people that face an external threat experienced as populations expand and colonize new territory, arguing that absent males would trust their sisters, but not their wives, to look after their common lineage interests (15). Crucially, Marck and Bostoen (7) argue that matrifocal Bantu cultures dissolved with residence changing first from matrilocal to patrilocal, thus supporting Divale’s (16) proposal that changes in residence drive changes in inheritance patterns for a migrating population. This suggestion provides support for “Main Sequence Theory,” which proposes that worldwide there is a pattern of change with residence rules driving change in other social structures (2). In particular, Murdock argues “when any social system undergoes change, such change regularly begins with a modification in the rule of residence” (ref. 2, p. 221). Changes in descent follow and are always consistent with the change in residence. Changes in kinship terminology are affected by changes in both residence and descent and may follow some considerable time afterward (2).There is therefore no agreement among researchers about the ancestral states or patterns of change in kinship traits among Bantu societies based on historical linguistic methods. There are a number of problems with relying solely on reconstructions of ancestral vocabulary to infer social organization in the past. First, although linguists use systematic methods of reconstructing proto-forms based on regular sound changes (13, 14), there is still an element of subjectivity in this approach, which can lead different researchers to suggest contradictory results based on the same words (7, 13, 14). Furthermore, the inference of social organization in a past society is a further step removed from this process and assumes a direct relationship between particular words and particular forms of organization. Although it may be possible to reconstruct the sound of a particular lexical item, the meaning of such a word is less clear because of the possibility of semantic shifts (17).Phylogenetic comparative methods, adapted from evolutionary biology, offer an alternative way of reconstructing the evolutionary history of cultural traits such as kinship structures. These techniques map the traits of interest (in this case descent and residence) onto a phylogenetic tree, which represents the way societies are related to each other historically. The likely forms of these traits in past societies can then be inferred by using an explicit statistical model of trait evolution. Importantly, these reconstructions are probabilistic, meaning it is possible to assess how much confidence to place in any particular reconstruction. The likelihood of alternative hypotheses for the pattern of evolution of traits over the tree can then be estimated. Furthermore, performing analyses over a sample of phylogenetic trees can explicitly incorporate uncertainty about the historical relationships between societies. These methods can be used to estimate the cultural history of a language family, even where historical records or archaeological evidence are absent, and have been used to examine the history of residence patterns in both the Indo-European and Austronesian language families (18, 19).The Bantu speaking people of sub-Saharan Africa represent one of the major early farming expansions; the advantage of agricultural food production allowed a single language group to displace and expand into the lands of previous hunter-gatherer populations (6). This process has allowed for language phylogenies of Bantu societies to be generated (9, 20–22), which can be combined with comprehensive data on extant kinship patterns across a large number of Bantu cultures (23, 24) to infer historical patterns of cultural evolutionary change. A previous attempt to infer the ancestral state of descent for the original Bantu population (25, 26) was inconclusive, possibly because of the small sample size, the single phylogeny (20), or the maximum likelihood methods used.Here, we advance previous attempts to reconstruct the kinship traits across the Bantu language family by applying Bayesian phylogenetic comparative methods (27–29) to a dataset of 122 Bantu ethnolinguistic groups to infer the ancestral state and evolutionary trajectory of Bantu kinship patterns. Analysis of basic vocabulary items (30) has enabled the phylogenetic relationships among more than 500 Bantu languages to be inferred (9), which has increased the scope for the number of different Bantu cultures that can be analyzed and enabled the incorporation of groups that were underrepresented in previous analyses. In particular, the current sample includes a number of additional societies from the “Northwest” and “Forest West” regions, which may be particularly important in inferring trait states at the earliest nodes in the trees. Furthermore, Bayesian phylogenetic methods, which can incorporate uncertainty about the phylogenetic relationships between cultures, provide a more accurate picture of the inferences that can be drawn from comparative data. In this way, it is possible to infer the ancestral states of kinship traits and, hence, reconstruct the cultural history of the Bantu expansion, which means it is possible to estimate the likely order of trait change and test whether changes in residence rules precede changes in inheritance patterns as proposed by Main Sequence Theory (2, 7, 16).     

Comparative outcomes of open versus laparoscopic sacrocolpopexy among medicare beneficiaries

Introduction and hypothesis

Since the first reported laparoscopic sacrocolpopexy in 1991, a limited number of single-center studies have attempted to assess the procedure’s effectiveness and safety. Therefore, we analyzed a national Medicare database to compare real-world short-term outcomes of open and laparoscopically assisted (including robotic) sacrocolpopexy in a United States sample of patients.

Methods

Public Use File data for a 5 % random national sample of all Medicare beneficiaries aged 65 and older were obtained from the Centers for Medicare and Medicaid Services for the years 2004–2008. Women with pelvic organ prolapse were identified using ICD-9 diagnosis codes. CPT-4 procedure codes were used to identify women who underwent open (code 57280) or laparoscopic (code 57425) sacrocolpopexy. Individual subjects were followed for 1 year post-operatively. Outcomes measured, using ICD-9 and CPT-4 codes, included medical and surgical complications and re-operation rates.

Results

Seven hundred and ninety-four women underwent open and 176 underwent laparoscopic (including robotic) sacrocolpopexy. Laparoscopic sacrocolpopexy was associated with a significantly increased rate of re-operation for anterior vaginal wall prolapse (3.4 % vs 1.0 %, p?=?0.018). However, more medical (primarily cardiopulmonary) complications occurred post-operatively in the open group (31.5 % vs 22.7 %, p?=?0.023). When sacrocolpopexy was performed with concomitant hysterectomy, mesh-related complications were significantly higher in the laparoscopic group (5.4 % vs 0 %, p?=?0.026).

Conclusion

Laparoscopic sacrocolpopexy resulted in an increased rate of reoperation for prolapse in the anterior compartment. When hysterectomy was performed at the time of sacrocolpopexy, the laparoscopic approach was associated with an increased risk of mesh-related complications.     

Population-based trends in ambulatory surgery for urinary incontinence

Introduction and hypothesis

Surgical procedures for stress urinary incontinence (SUI) have become progressively less invasive and easier to perform with the development of new technologies such as the midurethral sling. For these reasons, it seems logical to conclude that midurethral slings would supplant other surgical treatments for incontinence. The purpose of this study was to assess the impact of this technology on trends in ambulatory surgery for incontinence over the past decade.

Methods

We searched Current Procedure Terminology codes and the State Ambulatory Surgery Database from 2001 through 2009 to identify all ambulatory procedures for incontinence. Next, we calculated age-adjusted rates separately for each procedure. We then fit a multilevel model to characterize patient and regional factors associated with the preferential use of midurethral slings over alternative treatments.

Results

Midurethral slings and submucosal injections comprised >90 % of all ambulatory procedures for SUI during the time period examined. Age-adjusted rates of midurethral slings increased dramatically, from 2.36 to 9.45/10,000 population (p?<?0.001), whereas rates of submucosal injections remained relatively stable, from 1.75 to 1.41/10,000 population (p?=?0.226). Not surprisingly, older ([odds ratio (OR) 0.61; 95 % confidence interval (CI) 0.56–0.66] and more infirm patients (OR 0.60; CI 0.44–0.83) were more likely to receive submucosal injection therapy than to receive midurethral slings.

Conclusions

Rates of midurethral slings have increased significantly by fourfold. Rates of submucosal injections, however, have remained fairly stable during this time period, suggesting that sling dissemination has led to an increase in rates of incontinence procedures as opposed to replacing old technologies in the ambulatory setting.