Biomedical subjects

James Mahood

Publications and source records attributed to James Mahood.

4 recordsLinked to original sources

PubMed2006

A pilot study of magnetic resonance imaging-guided closed reduction of cervical spine fractures.

STUDY DESIGN: We report on a prospective selective case series of 17 patients with cervical fracture-dislocations treated with closed reduction under MRI guidance. OBJECTIVE: To demonstrate the safe and effective use of in-line axial traction in the reduction of cervical fracture-dislocations using MRI guidance. SUMMARY OF BACKGROUND DATA: Closed reduction of the cervical spine for acute fracture-dislocations has been a traditional technique used for restoring vertebral alignment and providing neural element decompression. The safety of this technique has been questioned, with concerns of disc migration and overdistraction causing neurologic worsening cited as reasons to choose operative reduction and decompression as a safer option in some circumstances. METHODS: Seventeen patients with fracture-dislocations of the subaxial cervical spine were given a trial of traction under MRI guidance between 1999 and 2003. The incidence of posteriorly herniated disc material was noted, and the diameter of the spinal canal at the injured level was recorded before and after traction. RESULTS: All patients tolerated traction without neurologic worsening. Pretraction disc disruption was found in 15 of 17 (88.2%) of patients, with posterior herniation in 4 of 17 (23.5\%). Traction caused a return of herniated disc material toward the disc space in all cases. Canal dimensions improved in 11 of 17 patients, with canal diameter increasing by a factor of 1.1 to 3.0, with a mean improvement of 1.73. The process of reduction was observed to be a gradual one, with progressive, significant improvement in canal dimensions occurring before anatomic realignment. As distracting force was increased, sequential MRIs showed that canal dimensions did not diminish at any time in any patient. CONCLUSIONS: MRI monitoring in closed cervical reduction is a useful research tool for this technique. Closed reduction appears to be safe as used in this preliminary study and is effective in achieving immediate spinal cord decompression.

Adult↗

PubMed2005

Evaluating MRI as a technique for visualizing the neurocentral junction.

STUDY DESIGN: Magnetic resonance imaging (MRI) of the neurocentral junction (NCJ) was correlated with gross anatomic and histologic sections acquired at the same position. OBJECTIVES: To determine the composition of the MRI of the NCJ and to explore the long-standing discrepancy between the ages of closure of the NCJ as determined by anatomic and imaging studies. SUMMARY OF BACKGROUND DATA: Disparate growth at the site of the NCJ has been implicated as a potential cause of adolescent idiopathic scoliosis since the early 1900s. Although anatomic studies have refuted this theory by maintaining that the NCJ closes before the age of 10 years, recent MRI studies have suggested that the NCJ remains open until adolescence. METHODS: One hundred fourteen porcine NCJs in various stages of development were visualized using MRI. Gross anatomic and histologic sections were acquired at the same position as MRI for correlation. RESULTS: The presence or absence of NCJ cartilage was represented by the presence or absence of a line on MRI. However, the NCJ image overestimated the width of the NCJ cartilage in the anteroposterior direction during development. As the NCJ underwent the process of closure, the NCJ image underestimated the extent of closure in the medial-lateral direction. CONCLUSIONS: Although MRI underestimated the extent of NCJ closure, MRI accurately showed whether cartilage was present or absent at the NCJ site. MRI determination of the age of NCJ closure appears reliable, and further exploration of the asymmetric growth hypothesis is required.

Aging↗

PubMed2002

The effects of exposure to intense, 24 h light on the development of scoliosis in young chickens.

The aetiology of adolescent 5 coliosis remains unknown and hindering research is the absence of an appropriate animal model. It is now well-established that pinealectomy in young chickens results in the development of scoliosis that has many of the characteristics seen in patients with adolescent idiopathic scoliosis but the mechanism underlying this phenomenon remains elusive. The principle product of the pineal gland is melatonin and so many studies have focused on studying the effects of reduced levels of this hormone. The results have been mixed and the role of melatonin remains unclear. As melatonin production is inhibited by light, it was hypothesised that providing the chickens with an environment consisting of intense, continuous light would reduce serum melatonin levels and avoid any of the potential artifacts involved with the pinealectomy surgery. Consequently, pinealectomised and normal chickens were exposed to very intense light for complete 24 h in each day. At the end of 22 days in this environment serum melatonin levels had been reduced to very low levels in all chickens. Most importantly, 15% of the normal chickens had developed scoliosis and the number of pinealectomised chickens that developed scoliosis increased from 50% to 80%. The results showed that a method for reducing serum melatonin without pinealectomy has been established and which can be used in further experiments. Furthermore, the results also showed that reduced levels of serum melatonin has significant effects on the development of scoliosis. The indication is that there is a threshold level of serum melatonin below which scoliosis may develop probably in conjunction with some other factor which has yet to be identified.

Adolescent↗

PubMed2002

Assessment of the validity of observing three-dimensional images of the spine using polarising, synchronised techniques.

Three-dimensional imaging is an emerging technique in radiology. It might be used to help view the spine and assist in improving evaluation of scoliosis. These images are currently computer generated and although very effective are actually optical iflusions. Questions remain as to the reliability and validity of these images which are important considerations when treatment regimens are being developed and surgery contemplated. Using a constructed three-diemnsional image of a box, this study assessed the inter- and intra-reliability of viewing a specific point on this box and also the inter-reliability of identifying the coordinates of this same point. There was good reliability for viewing a single point in the X and Z axes which formed the plane of the computer but there was a 10X decrease in reliability along the Y-axis (depth). This pattern was repeated when considering the relationship between observers to identify the actual coordinates of the same point.

Artifacts↗