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Biomedical subjects

R G Burwell

Publications and source records attributed to R G Burwell.

At least 19 recordsLinked to original sources
PubMed2006

Patterns of extra-spinal left-right skeletal asymmetries in adolescent girls with lower spine scoliosis: relative lengthening of the ilium on the curve concavity & of right lower limb segments.

Extra-spinal skeletal length asymmetry have been reported for the upper limbs and periapical ribs of patients with thoracic adolescent idiopathic scoliosis. This paper reports (1) a third pattern with relative lengthening of the ilium on the concavity of lower spine scolioses, and (2) a fourth pattern of relative lengthening of the right total leg and right tibia unrelated statistically to the severity or side of lower spinal scolioses. The findings pose the question: are these anomalous extra-spinal left-right skeletal length asymmetries unconnected with the pathogenesis of AIS. Or, are they indicative of what may also be happening to some vertebral physes as an initiating pathogenic mechanism for the scoliosis?

Adolescent↗
PubMed2006

Left-right upper arm length asymmetry associated with apical vertebral rotation in subjects with thoracic scoliosis: anomaly of bilateral symmetry affecting vertebral, costal and upper arm physes?

Left-right skeletal length asymmetries in upper limbs related to curve side and severity have been detected with adolescent idiopathic scoliosis (AIS). This paper reports upper arm length asymmetry in thoracic scoliosis related significantly to apical vertebral rotation in school screening referrals. The reason(s) for the association of upper arm length asymmetry with apical vertebral rotation is unknown and three factors are considered: (1) neuromuscular mechanisms from primary or secondary causes, (2) relative concave neurocentral synchondrosis overgrowth, and (3) relative concave periapical rib length overgrowth, A putative anomaly of growth plates (physes) of ribs, neurocentral synchondroses and upper arms, would account for the findings. A solution to this dilemma may emerge from the results of surgery should concave periapical rib resections become evaluated further for right thoracic AIS in girls.

Adolescent↗
PubMed2006

Etiologic theories of idiopathic scoliosis: neurodevelopmental concept of maturational delay of the CNS body schema ("body-in-the-brain").

Several workers consider that the etiology of adolescent idiopathic scoliosis (AIS) involves undetected neuromuscular dysfunction. During normal development the central nervous system (CNS) has to adapt to the rapidly growing skeleton of adolescence, and in AIS to developing spinal asymmetry from whatever cause. Examination of evidence from (1) anomalous extra-spinal left-right skeletal length asymmetries, (2) growth velocity and curve progression, and (3) the CNS body schema, parietal lobe and temporoparietal junction, led us to propose a new etiologic concept namely of delay in maturation of the CNS body schema during adolescence. In particular, the development of an early AIS deformity at a time of rapid spinal growth the association of CNS maturational delay results in the CNS attempting to balance a lateral spinal deformity in a moving upright trunk that is larger than the information on personal space (self) already established in the brain by that time of development. It is postulated that the CNS maturational delay allows scoliosis curve progression to occur - unless the delay is temporary when curve progression would cease. The putative maturational delay in the CNS body schema may arise (1) from impaired sensory input: (2) primarily in the brain; and/or (3) from impaired motor output. Oxidative stress with lipid peroxidation in the nervous system may be involved in some patients. The concept brings together many findings relating AIS to the nervous and musculo-skeletal systems and suggests brain morphometric studies in subjects with progressive AIS.

Aging↗
PubMed2006

Patterns of extra-spinal left-right skeletal asymmetries and proximo-distal disproportion in adolescent girls with lower spine scoliosis: ilio-femoral length asymmetry & bilateral tibial/foot length disproportion.

Anomalous extra-spinal left-right skeletal length asymmetries have been detected in girls with adolescent idiopathic (AIS) in four sites (1) upper limbs, (2) periapical ribs, (3) ilium, and (4) right leg and right tibia. This paper on adolescent girls with lower spine scoliosis reports (1) a fifth pattern of left-right ilio-femoral length asymmetry associated with sacral alar height asymmetry, and (2) bilateral anomalous lengthening of the tibia relative to the foot. The findings are consistent with the hypothesis that at the time of diagnosis of AIS in girls there are anomalies of skeletal proportions associated with a predisposition to curve progression; these proportions are in three dimensions--left-right, cephalo-caudal in the trunk (proximo-distal in the lower limbs), and front-back in the trunk. The origin of these anomalies is unknown but possible causes, and of the associated AIS, are genetic and environmental factors acting in embryonic life not expressed phenotypically until years after birth.

Adolescent↗
PubMed2006

Indoor heated swimming pools: the vulnerability of some infants to develop spinal asymmetries years later.

Evidence reported in an earlier paper suggests that infants introduced to indoor heated swimming pools in the first year of life show an association with spinal asymmetries including progressive adolescent idiopathic scoliosis (AIS) and in normal subjects vertical spinous process asymmetry. Indoor heated swimming pools may contain a risk factor that predisposes some infants to develop such spinal asymmetries years later. What the risk factor(s) may be and its possible portal of entry into the infant's body are unknown and possibilities are examined. New teenage controls were obtained after mothers of AIS patients mentioned that they had taken their child to an infant swim class. In a further group of 18 normal teenagers introduced to an indoor heated swimming pool in the first year of life, 15 had vertical spinous process asymmetry. This prevalence of 83% of those at risk confirms our previous observation of vertical spinous process asymmetry in 61% of teenagers who were introduced to indoor heated swimming pools in the first year of life. Subject to confirmation of our observations consideration should be given to chemical risk factors, possible portals of entry, toxicology, environmental epigenomics and disease susceptibility to altered spinal development. If the risk factor is confirmed there may ultimately be a place for the prevention of AIS in some subjects.

Adult↗
PubMed2006

Etiologic theories of idiopathic scoliosis: the breaking of bilateral symmetry in relation to left-right asymmetry of internal organs, right thoracic adolescent idiopathic scoliosis (AIS) and vertebrate evolution.

In the search to understand the etiology and pathogenesis of adolescent idiopathic scoliosis (AIS) some workers have focused on mechanisms initiated in embryonic life including a disturbance of bilateral (left-right or mirror-image) symmetry highly conserved in vertebrates. The normal external bilateral symmetry of vertebrates results from a default process involving mesodermal somites. The normal internal asymmetry of the heart, major blood vessels, lungs and gut with its glands is also highly conserved among vertebrates. It results from the breaking of the initial bilateral symmetry by a binary asymmetry switch mechanism producing asymmetric gene expression around the embryonic node and/or in the lateral plate mesoderm. In the mouse this switch occurs during gastrulation by cilia driving a leftward flow of fluid and morphogen(s) at the embryonic node (nodal flow) that favors precursors of the heart, great vessels and viscera on the left. Based on the non-random laterality of thoracic AIS curves, the hypothesis is suggested that an anomaly of the binary asymmetry switch explains the excess of right/left thoracic AIS. Some support for this hypothesis is the prevalence of right and left scoliosis curve laterality associated with situs inversus. There is recent evidence that vertebrates within their bilateralised shell retain an archaic left-right asymmetric visceral body organization evident in thoracic and abdominal organs.

Adolescent↗
PubMed2006

Etiologic theories of idiopathic scoliosis: enantiomorph disorder concept of bilateral symmetry, physeally-created growth conflicts and possible prevention.

The detection of anomalous extra-spinal left-right skeletal length asymmetries in the upper limbs, periapical ribs, ilia and lower limbs of subjects with adolescent idiopathic scoliosis (AIS) raises questions about skeletal bilateral symmetry of vertebrates in health and disorder, its origin and control. The vertebrate body plan externally has mirror-image bilateral symmetries that are highly conserved culminating in the adult form. The normal human body can be viewed as containing paired skeletal structures in the axial and appendicular skeleton as 1) separate left and right paired forms (eg long limb bones, ribs, ilia), and 2) united in paired forms (eg vertebrae, sternum, skull, mandible). Each of these separate and united pairs are mirror-image forms--enantiomorphs. Left-right asymmetries of growth plates (physes) may cause (1) in long bones length asymmetries, (2) within one or more vertebral physes putative growth conflict with distortion as deformity, and (3) between ribs and vertebrae putative growth conflict that triggers thoracic AIS suggesting preventive surgery on spine and ribs. There is evidence of a possible role for environmental factors in AIS development. Genes and the environment (nature/nurture) may interact pre- and/or post-natally to explain both the deformity of AIS and its association with widespread anomalous skeletal length asymmetries. If substantiated there may ultimately be a place for the prevention of AIS in some subjects.

Humans↗
PubMed2005

Relative anterior spinal overgrowth in adolescent idiopathic scoliosis--result of disproportionate endochondral-membranous bone growth? Summary of an electronic focus group debate of the IBSE.

There is no generally accepted scientific theory for the etiology of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The text for this EFG was written by Professor Jack Cheng and his colleagues who used whole spine magnetic resonance imaging (MRI) to re-investigate the relative anterior spinal overgrowth of progressive AIS in a cross-sectional study. The text is drawn from research carried out with his co-workers including measurement of the height of vertebral components anteriorly (vertebral body) and posteriorly (pedicles) in girls with AIS and in normal subjects. The findings confirm previous anatomical studies and support the consensus view that in patients with thoracic AIS there is relatively faster growth of anterior and slower growth of posterior elements of thoracic vertebrae. The disproportionate anteroposterior vertebral size is associated with severity of the scoliotic curves. In interpreting the findings they consider the Roth/Porter hypothesis of uncoupled neuro-osseous growth in the spine but point out that knowledge of normal vertebral growth supports the view that the scoliosis deformity in AIS is related to longitudinal vertebral body growth rather than growth of the canal. In the mechanical mechanism (pathomechanism) they implicitly adopt the concept of primary skeletal change as it affects the sagittal plane of the spine with anterior increments and posterior decrements of vertebral growth and, in the biological mechanism (pathogenesis) propose a novel histogenetic hypothesis of uncoupled endochondral-membranous bone formation. The latter is viewed as part of an 'intrinsic abnormality of skeletal growth in patients with AIS which may be genetic'. The hypothesis that AIS girls have intrinsic anomalies (not abnormalities) of skeletal growth related to curve progression and involving genetic and/or environmental factors acting in early life is not original. While the findings of Professor Cheng and his colleagues have added MRI data to the field of relative anterior spinal overgrowth in AIS their interpretation engenders controversy. Three new hypotheses are proposed to interpret their findings: (1) hypoplasia of articular processes as a risk factor for AIS; (2) selection from the normal population to AIS involves anomalous vertebral morphology and soft tissue factors--this hypothesis may also apply to certain types of secondary scoliosis; and (3) a new method to predict the natural history of AIS curves by evaluating cerebro-spinal fluid (CSF) motion at the cranio-cervical junction. What is not controversial is the need for whole spine MRI research on subjects with non-idiopathic scoliosis.

Adolescent↗
PubMed2004

Platelet calmodulin levels in adolescent idiopathic scoliosis (AIS): can they predict curve progression and severity? Summary of an electronic focus group debate of the IBSE.

There is no generally accepted scientific theory for the etiology of idiopathic scoliosis. As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate of extant knowledge on important topics. This has been designated as an on-line Delphi discussion. The text for this EFG was written by Professor Thomas G Lowe MD and drawn from research carried out by himself and his co-workers on platelet calmodulin levels in patients with adolescent idiopathic scoliosis. To explain the relationship of platelet calmodulin levels to scoliosis curve changes in AIS brought about spontaneously, by brace treatment, or surgery Dr Lowe attributes the platelet calmodulin changes to paraspinous muscle activity and suggests that the calmodulin acts as a systemic mediator of tissues having a contractile system (actin and myosin). Controversy includes: 1) the lack of normal data and the large variability in baseline levels of platelet calmodulin, necessitating the use of the AIS subjects as their own controls; 2) calmodulin is not usually used as a marker of platelet activation; 3) whether the platelet calmodulin changes which appear to reflect an abnormality of a portion of the spine are related to local and/or regional changes in muscles, nervous system, or immature vertebrae. What is not controversial is the need for more research on platelets and the immature deforming skeleton in relation to etiology and prognosis.

Adolescent↗
PubMed2003

A new concept for the etiopathogenesis of the thoracospinal deformity of idiopathic scoliosis: summary of an electronic focus group debate of the IBSE.

There is no generally accepted scientific theory for the etiology of idiopathic scoliosis, and treatment is pragmatic and unrelated to such knowledge. As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate of extant knowledge on important topics. This has been designated as an on-line Delphi discussion, and has proven very successful. The text for this EFG was written by Professor Sevastik and drawn from the extensive research carried out by himself and his co-workers. The thoracospinal concept of etiopathogenesis applies only to girls with right thoracic adolescent idiopathic scoliosis (Rcx-T-AIS-F). According to this concept, increased longitudinal growth of the left periapical ribs triggers the thoracic curve simultaneously in the three cardinal planes. The concept does not deal with factors involved in curve progression. Sevastik advocates mini-invasive operations on the ribs as a treatment for early progressive thoracic curves. Areas of controversy include whether or not there is overgrowth of the left periapical ribs in Rcx-T-AIS-F, and the question of whether there should be a clinical trial of mini-invasive operations on the ribs.

Adolescent↗
PubMed2002

The early detection of adolescent idiopathic scoliosis in three positions using the scoliometer and real-time ultrasound: should the prone position also be used?

The standing forward bending position is in general use for the early detection of adolescent idiopathic scoliosis. It also reveals humps caused by leg-length inequality and for this reason some workers have advocated using the sitting forward bending position. Most recently the prone position has been evaluated and even recommended. The introduction of B-mode and subsequently real-time ultrasound to measure rib rotation and spinal rotation has involved using the prone position. The numerical description of back humps in scientific studies requires measurements at several levels on the back from T1-S1. This paper utilizes 30 subjects referred by school screening for scoliosis from whom 10-level Scoliometer Angle of Trunk Inclinations (ATIs) were obtained twice in each of three positions--standing forward bending, sitting forward bending and prone. The ATIs were converted to 18 levels and (1) analysed for reproducibility, (2) compared in the three positions, and (3) compared with real-time ultrasound data of rib rotation obtained in the prone position. Several statistical methods are used. The reproducibility is best in the sitting and prone positions. While the prone position produces lower ATI readings, R squared values are significantly higher and Residual Mean Square (RMS) values significantly lower than those for each of the standing and sitting forward bending positions. Though the prone position has clear advantages, it is not advocated in clinical practice for various reasons. More research is needed. The evidence supports the view that the sitting forward bending position has advantages for the early detection of adolescent idiopathic scoliosis.

Adolescent↗
PubMed2002

The NOTOM hypothesis for idiopathic scoliosis: is it nullified by the delayed puberty of female rhythmic gymnasts and ballet dancers with scoliosis?

Nachemson suggested that there are more girls than boys with progressive adolescent idiopathic because of a different timing between skeletal maturation and postural maturation in the sexes during adolescence. We termed Nachemson's concept the neuro-osseous timing of maturation (NOTOM) hypothesis and used it to propose a possible medical treatment for idiopathic scoliosis by delaying puberty through the pituitary using gonadorelin analogues as in idiopathic precocious puberty. The prevalence of scoliosis is reported to be increased in rhythmic gymnasts (RGs) in Bulgaria and in ballet dancers (BDs) in the USA. Both groups exhibit delayed puberty, which, at first sight, nullifies the NOTOM hypothesis for idiopathic scoliosis. While constitutional and environmental factors may determine these scolioses, the different curve types in RGs and BDs suggest that the exercise pattern over many years determines which type of scoliosis develops, although not the curve severity. We support the view that scoliotic RGs should be included in a group of sports-associated scoliosis separate from idiopathic scoliosis. Hence the delayed puberty of RGs and BDs with scoliosis does not nullify the NOTOM hypothesis as their scolioses are not idiopathic. There is a need to focus research on such subjects who have defined constitutional and environmental factors related to their scolioses.

Adolescent↗
PubMed2002

Etiologic theories of idiopathic scoliosis: neurodevelopmental concepts to be evaluated.

There is increasing interest in the concept that neuromuscular mechanisms and the central nervous system (CNS) are somehow involved in the etiology and pathogenesis of idiopathic scoliosis (IS). Yet in the extensive neuroscience research of idiopathic scoliosis certain neurodevelopmental concepts have been neglected. These include: (1) a CNS body schema for posture and movement control generated during development and growth by establishing a long-lasting memory; (2) pruning of cortical synapses at puberty; and (3) neuromorphic engineering. Memory of developing posture and movement might be established in neurons of the CNS body schema in the form of novel proteins; these could be coded by modified genes obtained by the recombination (crossing over) of DNA in a similar way to that in the production of immunological antibodies and during meiosis. These concepts need evaluation in relation to (1) the etiopathogenesis of IS and (2) a possible new treatment approach to idiopathic scoliosis involving a neuromorphic device to control the output for muscle stimulators that are inserted and driven with telemetry.

Adolescent↗
PubMed2002

Etiologic theories of idiopathic scoliosis: the apical spinal deformity--relevance to surgical practice.

UNLABELLED: The current successful management of idiopathic scoliosis is an orthopaedic and not a paediatric responsibility. Hence the immediate aim of etiologic research is to improve surgical treatments based on a better understanding of the causation of the deformity. This focuses attention on the pathomechanisms of the spinal and ribcage deformities. The mechanisms of spinal deformity about the apex are unresolved but may be caused by forces created in the anterior spinal column. Some current theories with practical application involve (1) front-back spinal growth mechanisms, (2) rib growth asymmetry and (3) muscles. CONCLUSIONS: The application of theory to surgical practice is advanced for concepts of front-back spinal growth asymmetry but rib hump reassertion occurs after surgery and these concepts ignore the ribcage as a possible factor in scoliosis pathogenesis. A theory of ribcage asymmetry involving concave rib overgrowth is beginning to be evaluated surgically. After surgery for IIS and AIS reassertion of the deformity has been shown to involve preoperative spinal and concave rib factors; the larger the concave rib-spinal angle the better results at 2-5 year. Muscular factors that may trigger/exacerbate the apical spinal deformity of scoliosis need more research. The concept that AIS pathogenesis involves putative neuromuscular dysfunction that deforms an immature spine is considered likely by several workers.

Adolescent↗
PubMed2002

Back shape assessment in each of three positions in preoperative patients with adolescent idiopathic scoliosis: evaluation of a 10-level Scoliometer method interpolated to 18-levels.

A Scoliometer was used by one observer (RKP) to assess the reproducibility of angle of trunk inclinations (ATIs) in 13 preoperative patients with AIS (thoracic 7, thoracolumbar 6, mean Cobb angle 50 degrees, right 9, age 15.4 years, girls 10). Three positions were used namely standing forward-bending, (FB) sitting FB and prone. Readings of ATI on the back were obtained at each of 10 levels (T1-S1). The subject was repositioned after walking around the room and a second set of readings obtained (repeats). All readings were converted by a computer program to 18 levels and plotted. The readings from 18 levels were analysed by level, as well as summated and averaged both without and with correction for the side of the curve. Conclusions. Back surface asymmetry measured with a Scoliometer in these preoperative patients with AIS is less in the prone position than in each of the forward bending positions. The standing FB position has the best reproducibility which supports the practice of using this position to measure Scoliometer ATIs in preoperative patients with AIS.

Adolescent↗
PubMed2002

Spine-rib rotation differences at the apex in preoperative patients with adolescent idiopathic scoliosis: evaluation of a three-level ultrasound method.

This paper evaluates a new real-time ultrasound method to assess the difference between axial spinal (laminal) rotation and rib rotation at the apex of the scoliosis curve. An Aloka SSD 500 portable ultrasound machine with a veterinary long (172mm) 3.5 MHz linear array transducer was used to assess the reproducibility of the method in 13 preoperative patients with AIS. With the subject in a prone position and her head supported, readings of laminal and rib rotation were made directly on the back at 18 and 12 levels respectively The subject was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). All the readings were made by one observer (ASK). After plotting on graphs three levels of maximal difference between spine rotation and rib rotation about the apex were chosen visually by one observer (RGB) for which the mean apical spine-minus-rib rotation difference (SRRD) was calculated for each repeat. Findings for apical SRRDs. The mean apical SRRDs for the two repeats are 7.1 degrees and 6.9 degrees (range 2-18 degrees) with coefficients of variation of 49% and 62% respectively. Reproducibility. Graphic representation of spinal and rib rotation by 12 levels shows a fairly good agreement between repeats for most subjects. Spinal rotation is always greater than rib rotation. A paired t-test for the mean apical SRRD of the repeats shows no significant difference. Linear regression analysis of the mean apical SRRD repeats correlate significantly (r=0.70, P=0.008) with a residual mean square of 6.9 degrees (rms = 2.6 degrees). The technical error of the measurement (TEM) is 2.3 degrees and coefficient of reliability (R) 0.66. Conclusions. Real-time ultrasound can assess the difference between spinal and rib rotation about the apex of the scoliosis curve without the altered position detectably affecting the findings. The error (2-3 degrees) is high relative the mean apical SRRD (6-7 degrees). The apical SRRD findings have relevance to the pathogenesis of AIS.

Adolescent↗