Biomedical subjects
R C Hilton
Publications and source records attributed to R C Hilton.
Comparison of the structure of human intervertebral discs in the cervical, thoracic and lumbar regions of the spine.
Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.
In-vitro mobility of the lumbar spine.
As part of a systematic study of the spine between D11 and S1 the response to stress has been assessed by measuring radiologically the total and segmental mobility of 103 specimens. The method was shown to be reproducible to within 10% of total mobility. No significant sex difference was seen. Total mobility varied widely, but mean total mobility fell with age. All lumbar segments became less mobile up to the fifth decade. Between the fifth and the eighth decade the mobility of the fifth lumbar segment continued to fall, whereas other lumbar segments became more mobile. The mobility of each segment also varied widely, but the mean segmental mobility fell progressively from L5 to D11. However, this smooth pattern of movement was seen in only 16 cases, mostly adolescents and young adults. Among the remainder, in which movement was irregularly distributed, there were 7 cases (4 aged less than 30 years) in which the mobility of at least 1 segment was more than 2 standard deviations above the mean. The cause of this hypermobility was not evident radiologically. It is suggested that segments with abnormally high mobility may be at risk.
Hemisphere function and binocular depth perception.
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Vertebral end-plate lesions (Schmorl's nodes) in the dorsolumbar spine.
The distribution of end-plate lesions (Schmorl's nodes) and their relationship to bone density and disc degeneration have been studied in 50 post-mortem spines below D9 in subjects aged 13-96 years. Lesions were present in 76% of cases with a predominance in males. They were found more frequently in the lower than in the upper vertebral end-plate. They were also more common and more severe in the dorsolumbar (D10-L1) region than in the lower lumbar (L2-L5 region). In adults they were unrelated to age and bone density. Lesions were significantly related to disc degeneration in the D10-L1 region but not in the L2-L5 region. It is suggested that end-plate lesions arising in adolescence (or before) may predispose the dorsolumbar spine to disc degeneration in later life.
Chronic progressive external ophthalmoplegia.
The clinical features and investigative findings of 50 patients with chronic progressive external ophthalmoplegia (CPEO) were analysed. The group was found to be clinically, genetically and histologically heterogeneous. With the possible exception of patients with "ophthalmoplegia plus," namely those who in addition to muscular weakness had evidence of central and/or peripheral nervous system abnormality, there was no apparent justification for separating out from among the group patients' subgroups which were distinctive enough to be recognized as syndromes. CPEO therefore seems to represent a number of different degenerative disorders whose common denominator is ophthalmoplegia and for which there are to date no adequate criteria for further classification.
Proceedings: Mobility, end-plate defects, and disc degeneration in the lower spine.
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Judgment of the visual vertical and horizontal in patients with Parkinsonism.
Judgment of the visual vertical and horizontal in the upright body position was abnormal in 19 (29 percent) of 66 patients with Parkinson's disease. The magnitude of errors correlated with the degree of rigidity and of tremor in the limbs, but not with bradykinesia or other clinical features. The results suggest that the effect on visual perception of the vertical and horizontal coordinates in patients with parkinsonism is brought about by specific changes in the basal ganglia and is not, as in the case of other visual-motor tasks, determined merely by the overall severity of cerebral pathology.