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Biomedical subjects

R Cailliet

Publications and source records attributed to R Cailliet.

At least 19 recordsLinked to original sources
PubMed1999

A review of biomechanics of the central nervous system--Part I: spinal canal deformations resulting from changes in posture.

OBJECTIVE: To discuss how the spinal cord deforms as a result of changes in posture or biomechanical alterations of the spine. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from the Index Medicus sources were collected, with special emphasis placed on spinal canal changes caused by various postural rotations and translations of the skull, thorax, and pelvis. RESULTS: All spinal postures will deform the spinal canal. Flexion causes a small increase in canal diameter and volume as the vertebral lamina are separated. Extension causes a small decrease in canal diameter and volume as the vertebral lamina are approximated. Lateral bending and axial rotation cause insignificant changes in spinal canal diameter and volume in cases without stenosis. CONCLUSIONS: Rotations of the global postural components, head, thoracic cage, and pelvis cause changes in the diameter of the spinal canal and intervertebral foramen. These changes are generally a reduction of less than 1.5 mm in extension, compared with a small increase in flexion of approximately 1 mm. These small changes do not account for the clinical observation of patients having increased neurologic signs and symptoms in flexion.

Biomechanical Phenomena↗
PubMed1999

A review of biomechanics of the central nervous system--part II: spinal cord strains from postural loads.

OBJECTIVE: To review spinal cord strains arising from postural loads. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from the Indexed Medicus sources were collected, with special emphasis placed on spinal cord strains caused by various postural rotations and translations of the skull, thorax, and pelvis RESULTS: All spinal postures will deform the neural elements within the spinal canal. Flexion causes the largest canal length changes and, hence, the largest nervous system deformations. Neural tissue strains depend on the spinal level, the spinal movement generated, and the sequence of movements when more than one spinal area is moved. CONCLUSIONS: Rotations of the global postural components (head, thoracic cage, pelvis, and legs) cause stresses and strains in the central nervous system and peripheral nervous system. Translations of the skull, thorax, and pelvis, as well as combined postural loads, need to be studied for their effects on the spinal canal and neural tissue deformations. Flexion of any part of the spinal column may generate axial tension in the entire cord and nerve roots. Slight extension is the preferred position of the spine as far as reducing the magnitude of mechanical stresses and strains in the central nervous system is concerned.

Animals↗
PubMed1998

Can the sagittal lumbar curvature be closely approximated by an ellipse?

For the sagittal lumbar curvature, existing spinal models are based only on the anthropomorphic radiographic characteristics of one individual, or, at best, of only a few individuals. This raises questions of applicability of the modeling results to clinical situations. Because spinal coupling and loads on spinal tissues have been shown to be functions of the initial static posture, a rigorously derived neutral lumbar lordosis would be important for clinicians and spine researchers. This study presents modeling of the sagittal lumbar spine in the shape of an ellipse. Vertebral body and disc heights, derived from digitized lateral lumbar radiographs of 50 normal subjects, were used to create an ellipse along the posterior body margins from the inferior of T12 to the superior sacral base. Additional data to create an elliptical lumbar model were determined from a least-squares analysis of passing ellipses through the digitized posterior body points. This confirmed that an elliptical model closely fit the lumbar curvature with a least-squares error of 1.2 mm per digitized point. The elliptical model is approximately an 85 degrees portion of a quadrant. The semi-major and semi-minor axes, a and b, are parallel to the posterior body margin of T12 and parallel to the inferior body endplate of T12, respectively, with a semi-minor to semi-major radio of b/a=0.39. The elliptic model has a height-to-length ratio of H/L=0.963, where height is the vertical distance from inferior T12 to superior S1 and length is the arc length along George's line (along the posterior longitudinal ligament) from T12 to S1.

Adult↗
PubMed1998

Elliptical modeling of the sagittal lumbar lordosis and segmental rotation angles as a method to discriminate between normal and low back pain subjects.

Clinical significance of lumbar lordosis has not been agreed on. Our purpose is to compare lordotic measurements of normal and pain subjects and to test the validity of a new anthropometric model of lumbar curvatures. Digitized radiographic points (body corners) from standing lateral lumbar radiographs were modeled with ellipses in a least-squares method and were used to create segmental angles, a global angle at L1-L5, a Cobb angle from T12 to S1, Ferguson's sacral base angle, and an angle of pelvic tilt. Fifty normal subjects were matched in age, sex, weight, and height with 50 acute pain subjects, 50 chronic pain subjects, and 24 pain subjects with radiographic abnormalities. Of 11 angles, 2 distances, and 2 ratios, statistical analysis was significantly different across groups for 12 of these measurements, with the alternative hypotheses accepted for the other 3 measurements. The lordosis of both normal and low back pain subjects can be successfully modeled with a portion (approximately 86 degrees) of an ellipse, but with different major and minor axis ratios. The normal group's average elliptic lordosis has the smallest least-squares error, approximately 1 mm per digitized point, with (minor axis)/(major axis) ratio = 0.39, L1-L5 global angle = 40 degrees, and Cobb angle = 65 degrees. The chronic and radiographic abnormalities pain groups have an elongated ellipse with hypolordosis, reduced L1-L5 global angle = 29.6-35 degrees, reduced Cobb angle = 57-58 degrees, and elliptic axis ratio = 0.27-0.30. The acute pain group is hyperlordotic with the largest L1-L5 global angle, largest Cobb angle = 70 degrees, largest Ferguson's angle, and largest pelvic tilt angle.

Acute Disease↗
PubMed1997

Radiographic mensuration characteristics of the sagittal lumbar spine from a normal population with a method to synthesize prior studies of lordosis.

Standing lateral lumbar radiographs of 50 normal healthy subjects were retrospectively selected for evaluation of lumbar lordosis. The objective was to evaluate, in a normal population, global and segmental contributions to lordosis in the standing position, and to devise a method to compare the seemingly unrelated multitude of lordotic values in the literature. Because of a variety of positioning and measurement methods of lordosis in live subjects and cadavers, correlation of results is difficult. While often relying on simple pain questionnaires, studies of normal subjects rarely have complete medical history, physical, neurological, and orthopedic examinations. Standing lateral lumbar radiographs of 50 subjects, who had complete histories and normal examinations, were analyzed to determine overall lordosis, segmental contributions, and vertical sagittal alignment. Using posterior body tangents, the mean L1-L5 angle was -39.7 degrees, CobbT12-S1 = -65 degrees, Ferguson's sacral angle = 39 degrees, pelvic tilt angle was 49 degrees, and average RRAs (segmental angles) were RRAT12-L1 = -3.6 degrees, RRAL1-L2 = -4.1 degrees, RRAL2-L3 = -7.6 degrees, RRAL3-L4 = -11.7 degrees, RRAL4-L5 = -16.8 degrees, and RRAL5-S1 = -32.4 degrees. Using segmental rotation angles as a method to compare past and current literature, a normal standing lumbar lordosis of CobbT12-S1 = -61 degrees, range -55 degrees to -65 degrees, was determined with specific segmental angles.

Adolescent↗
PubMed1985

Vagotonic effect of inversion therapy upon resting neuromuscular tension.

Inversion therapy has become a popular treatment for low back pain but little experimental evidence is available to suggest a physiological basis for such use. On the basis of earlier work showing a vagotonic influence of inversion upon the cardiovascular system, it was our purpose to test the hypothesis that such vagotonic effects are also operative in the nervous system and thus cause decreased electrical activation of the resting musculature. To test this hypothesis 12 healthy subjects, seven female, five male (age 19-37, M = 28.9 +/- 5.8 years) were selected from among 45 who were screened on the basis of having resting IEMG scores at least one S.E. above electrical silence. Each subject acted as his own control and visited the laboratory on four occasions of which two involved EMG testing pre and post inversion for two minutes and the other two were control before and after an equivalent period of rest. The mean reduction in neuromuscular tension after inversion was 28.3 percent compared with 7.1 percent after control. This difference was significant at P less than 0.04. A two minute period appears to be sufficient and the effect may persist for as much as two hours. Heart rate and blood pressures taken before and after inversion were not significantly different from controls.

Adult↗
PubMed1968

Pain in the neck and arm. Diagnosis by history and examination.

The cause of pain in the neck or pain in the arm coming from the neck can be accurately diagnosed by proper clinical examination. This requires knowledge of normal functional anatomy and understanding where pain can originate and what factors initiate the pain. The examination consists of testing for these abnormalities of motion and reproducing the symptoms by these motions. Weighing the history, both of trauma and indications of deep-seated tension or anxiety, against the conditions observed on physical examination, is important to correct diagnosis.Recognizing abnormal neck posture and activities reproducing pain in the neck and arm examination reveals the mechanism of pain. Treatment becomes evident.

Arm↗