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Biomedical subjects

J Mahood

Publications and source records attributed to J Mahood.

At least 19 recordsLinked to original sources
PubMed2006

Prediction of brace treatment outcomes by monitoring brace usage.

Brace treatment is the most commonly used non-surgical treatment method for adolescent idiopathic scoliosis (AIS). This study determined whether curve progression can be predicted by how often and how well children with AIS wear their braces. Twenty subjects (3M, 17F) who were diagnosed with AIS and had worn their braces from six months up to 1 year participated into this study. All subjects were prescribed Boston style braces and have now completed their brace treatment. On average, the brace was used 57% of the prescribed time. Peterson's risk of progression (Risser sign, age, apex of curve and imbalance of curve) predicted only 3-8% of the curve progression of brace subjects. Knowing how brace subjects used their braces in terms of brace tightness increases the prediction rate to 12-21%; and wear time further increase it to 25-36%. Adding the multiple of brace tightness and wear time improves curve progression prediction to 41-54%. To be most effective, the brace should be worn as prescribed in both tightness and time manners.

Adolescent↗
PubMed2006

Associations between quality-of-life and internal or external spinal deformity measurements in adolescent with idiopathic scoliosis (AIS).

In theory, quality-of-life measures should correlate with impairments such as spinal deformity. The goal was to determine the ability of the SRS-22 and surface topography measures to predict internal deformity. Data from 227 females with AIS were collected. Correlations and regression were used to predict Cobb angle or category. In subjects treated conservatively, the Cobb angle correlated with pain, self-image, satisfaction and total score. Only self-image correlated with surface topography. In subjects having had surgery, Cobb angle correlated with self-image, mental health, satisfaction and total scores. The cosmetic score was the only external deformity measure to correlate with the SRS-22. Function, self-image and trunk-twist predicted subjects within 3 categories (Cobb <30 degrees , 30-50 degrees , >50 degrees) with 57% accuracy compared to 53% when using self-image only. Accuracy in predicting subjects with curves smaller or larger than 50 degrees was 79% (using self-image, trunk-twist) or 72% (self-image only). Correlations between quality-of-life and deformity measures were low. However, it was possible to predict subjects within clinically meaningful categories of internal deformity using SRS-22 scores.

Adolescent↗
PubMed2006

Improving brace wear with active brace system.

There is considerable controversy regarding the effectiveness of brace treatment for patients with adolescent idiopathic scoliosis (AIS). Researchers believe that to be effective, patients must wear their braces as prescribed including both compliance and tightness. Compliance is how much time the brace is worn relative to the prescribed time. Brace tightness is usually prescribed by orthotists during brace fitting session. Asking the patient or examining the brace for wear are the most common methods to evaluate the brace usage. A low powered microcomputer system was developed to monitor and maintain loads exerted by braces used to treat children with spinal deformities during daily living. This system records brace usage information and helps patients to wear their brace at the prescribed tightness. Laboratory tests have been performed and six patients have used the system for four weeks. The patients reported that the system helped them to wear the brace properly. The time that the patients wore the braces at the prescribed tightness level increased from 48+/-16% during the monitor period (first 2 weeks) to 63+/-18% during the automatic adjustment period (last 2 weeks).

Adolescent↗
PubMed2006

Intra-operative spinal load and displacement monitoring: towards a better understanding of scoliosis correction mechanics.

Surgical correction of scoliosis reduces deformation and improves overall function and esthetics. Understanding and monitoring of mechanics during scoliosis surgery is an invaluable tool to optimize correction without compromising patient safety. Our objective was to use intra-operative monitoring tools to study how spinal load and displacement relates to obtained correction and chosen instrumentation. Instrumented pedicle screws, a "gripper" and active markers were developed. Instrumented pedicle screws provided three-dimensional forces at the screw-vertebra interface while the instrumented "gripper" measured the force and the rotation applied by the surgeon to the rod rotator. Vertebral displacement was monitored with light-emitting diodes and motion capture technology. These instruments were used successfully with 16 scoliosis subjects. Analysis of applied force, displacement, and curve flexibility influence on correction percentage is the long term goal. Raw results for instrumented screws and gripper showed that recorded force decreased with respect to percentage of correction obtained. Measured force increased with respect to the pre-surgical Cobb angle while percentage of correction obtained decreased as pre-surgical Cobb angle increased. Active marker results showed three-dimensional vertebral rotation and translation during correction, with axial rotation and caudal-cranial translation having the greatest magnitudes. Using greater correction forces does not necessarily result in an increased correction; flexibility and Cobb angle also play a role in the mechanics of correction. Further data collection will provide better understanding of the interconnected role between these factors helping complete the description of surgery mechanics.

Biomechanical Phenomena↗
PubMed2004

Using magnetic resonance imaging to characterize pedicle asymmetry in both normal patients and patients with adolescent idiopathic scoliosis.

STUDY DESIGN: Morphometric analysis of vertebrae from normal patients and patients with adolescent idiopathic scoliosis. OBJECTIVES: To use magnetic resonance imaging to assess pedicle asymmetry in normal patients and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development and to determine if patients with adolescent idiopathic scoliosis exhibited a consistent vertebral morphology. SUMMARY OF BACKGROUND DATA: To date, most studies of vertebral morphology in adolescent idiopathic scoliosis have produced conflicting data, especially on pedicle length, and have been conducted on patients in the late stages of scoliosis development, which may affect the patterns of vertebral morphology detected. Magnetic resonance imaging enables in vivo assessment of curves during development and permits improved acquisition of transverse images. METHODS: Magnetic resonance images of 76 pedicles from 8 normal patients and 80 pedicles from 10 patients with adolescent idiopathic scoliosis were examined retrospectively. Recorded parameters included pedicle lengths, pedicle widths, pedicle areas, pedicle perimeters, and lamina lengths. The extent and direction of asymmetry in vertebrae from normal patients and patients with adolescent idiopathic scoliosis were determined and compared. RESULTS: Normal patients displayed significant neural arch asymmetry, with the left sided measurements being greater. Patients with adolescent idiopathic scoliosis also displayed significant neural arch asymmetry; however, the longer pedicle was not consistently on the convexity or the concavity. CONCLUSIONS: The baseline used to assess adolescent idiopathic scoliosis vertebral morphology must take into consideration the extent and direction of normal vertebral asymmetry. The pattern of vertebral asymmetry seen inadolescent idiopathic scoliosis may depend on the specific cause of the disorder, with no consistent pattern evident when data from different causes are pooled together.

Adolescent↗
PubMed2002

MRI characteristics of the neurocentral synchondrosis.

BACKGROUND AND OBJECTIVES: The neurocentral synchondrosis (NCS) is a cartilaginous growth plate that since the early 1900s has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS). Previous studies have focused only on the closure age without characterizing normal NCS development. Using MRI, the normal development of the NCS image can be characterized, and the stages preceding the disappearance of this image can be specified. METHODS: A total of 405 NCSs were visualized in 11 normal pediatric patients using T1 and T2 transverse and sagittal MRI views. The images were correlated and the variety of images recorded to categorize the NCS into developmental stages. RESULTS: The development of the NCS was categorized into five developmental stages. The image of the NCS became absent in a specific pattern along the vertebral column, first in the cervical region (age 6), then in the lumbar region (age 12), and finally in the thoracic region (age 14). CONCLUSION: The normal development of the NCS at the level of individual vertebrae and also along the vertebral column as a whole was determined using MRI. These patterns of development are valuable and necessary to evaluate the role of the NCS in pathological conditions.

Adolescent↗
PubMed2002

The development of scoliosis following pinealectomy in young chickens is not the result of an artifact of the surgical procedure.

Pinealectomy in young chickens consistently results in scoliosis which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the aetiology of AIS and can lead to the development of novel treatement methods.

Animals↗
PubMed2002

Brace monitoring system for the treatment of scoliosis.

Determining the efficacy of brace treatment for AIS has been hampered by poor data on the wear pattern of those children prescribed this treatment. Although there is some information on brace compliance, there is very little on how well the brace is secured and the resulting loads imposed on the trunk. The purpose of this study was to determine the daily brace wear pattern of adolescents prescribed Boston braces. The brace monitoring system consists of a force transducer and a microcomputer unit. A force transducer was placed in the lining of the Boston brace. The microcomputer unit was carried while the brace was worn. The force imposed by the brace pad during daily activity was recorded at 1 minute intervals over a period of 3 to 14 days. The samples were stored by the microcomputer. Five subjects (3F;2M; age: 14+/-2 years) who were to wear the brace full time were studied. The subjects adjusted their braces to a prescribed level of tightness as indicated by a light on the microcomputer. Overall compliance, compliance during school days, and forces imposed by the brace were analysed. The force provided by the Boston brace varies considerably during daily activity. Overall brace compliance was lower than expected, with 2 of 5 subjects wearing their brace infrequently. The compliance rate during school time was not different than during the rest of the study period. Peer pressure at school did not appear to affect brace compliance.

Adolescent↗
PubMed2002

Development of the neurocentral junction as seen on magnetic resonance images.

The neurocentral junction (NCJ) is a cartilaginous growth plate in the vertebra that has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS) since the early 1900s. Studies to date have focused on the age of closure without characterizing normal NCJ development. Using MRI, the normal development of the NCJ image can be determined and the stages preceding the disappearance of the NCJ image can be characterized. 405 NCJs from 11 pediatric patients were examined using MRI and the various images were categorized. NCJ development encompassed five stages, with a specific pattern of absence of the NCJ image noted in each vertebra and in the vertebral column as a whole. The image of the NCJ first became absent in the cervical region (age 6), then in the lumbar region (age 12) and finally in the thoracic region (age 14). These patterns of development serve as a baseline to evaluate NCJ pathology in conditions such as adolescent idiopathic scoliosis (AIS).

Adolescent↗
PubMed2002

The components of the magnetic resonance image of the neurocentral junction.

The neurocentral junction (NCJ) is a cartilaginous growth plate located between the vertebral centrurn and the neural arch. In characterizing the age of closure of this growth plate, anatomic studies have suggested that the NCJ closes before age 10, whereas MRI studies have suggested that the NCJ does not fuse until adolescence In this study, gross anatomic and histologic sections were correlated with MR images to determine the components of the NCJ image. The NCJ image appeared as a thick white line that was shown to encompass the cartilage of the growth plate, the surrounding woven bone and a portion of the trabecular bone of the vertebra. Although the MR pixels were too large to completely resolve the tissues that surround the growth plate, MRI was shown to be a valuable technique of visualizing the NCJ cartilage and further MRI studies of the human NCJ are needed.

Age Factors↗
PubMed2002

Long-term follow-up of surgically treated AIS patients.

The aim of this study was to determine the long-term changes in spine and trunk alignment in patients who have undergone scoliosis surgery. Twenty-three (16F; 7M; at age of surgery 15.7 +/- 4.9 years) patients with adolescent idiopathic scoliosis agreed to participate and had posterior-anterior radiographs and surface topography prior to derotation surgery, within 6 months of surgery, at 2 years post-operatively and 5-10 years (mean follow-up period 6.11 +/- 1.6 years) after surgery. Cobb angles, surface trunk rotations, and cosmetic scores were measured at each visit. A questionnaire assessed back appearance and pain at the 5-10 year follow-up. The results of the questionnaire were compared to 25 patients with idiopathic scoliosis who had recently undergone surgery. A paired two-tailed Student's t-test with p=0.05 was used to compare the deformity between visits. The Cobb angle and cosmetic score improved after surgery while the change in trunk rotation was insignificant (p=0.37). Between the two-year and 5-10 year review, the Cobb angle, cosmetic score, and surface trunk rotation significantly increased. Self-perception of appearance and pain were similar to the control group. Surgical correction of scoliosis is not completely maintained during adulthood although the radiographic and surface deterioration does not appear to be clinically significant.

Adolescent↗
PubMed2002

Assessing the impact of pelvic obliquity in post-operative neuromuscular scoliosis.

The goal of this pilot study was to explore the relationship between pelvic obliquity and patient pain, sitting tolerance, pressure sores, and function. Five neuromuscular patients who underwent spinal surgery 6-26 weeks prior to assessment took part in this on-going study (4F; 1M); age at surgery (14.6 +/- 2.6 years). Pelvic obliquity was measured from pre- and post-operative anterior-posterior radiographs. A force-sensing pad with a grid of sensors was placed on a flat surface and the weight distribution pattern was recorded. The pressures were divided into left and right sides and peak levels were noted on each side. The parents or caregivers completed a questionnaire on their child's pain, sitting tolerance, pressure sores, and functional abilities. Pelvic obliquity was reduced after surgery by approximately 50% depending on the method used to assess pelvic obliquity. The major curve was reduced from 64 degrees(10 degrees) to 39 degrees (10 degrees). Post operatively, the average pressure (left/right side) ranged from 1.2 to 2.0 (average 1.6). The peak pressure ratio ranged from 1.1 to 1.9 (average 1.4). The ratio of left/right pressure correlated with improvement in pelvic obliquity (r2=0.9). Pain was moderate/severe in the 2 patients with the least correction as measured with the Cobb angle from surgery; both improved following surgery. Two patients suffered pressure sores pre-operatively and one post-operatively. Only 3/5 felt sitting endurance had increased. All parents felt their child sat straighter after surgery. The outcome measures of pain, pressure sores, sitting tolerance, and function were not well related to the amount of pelvic obliquity. More candidates and a longer follow-up may shed light on the many relationships.

Activities of Daily Living↗
PubMed2001

Development of scoliosis following pinealectomy in young chickens is not the result of an artifact of the surgical procedure.

Pinealectomy in young chickens consistently results in scoliosis, which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity, or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the etiology of AIS and can lead to the development of novel treatment methods.

Animals↗
PubMed2001

The critical stage of pinealectomy surgery after which scoliosis is produced in young chickens.

STUDY DESIGN: Stages of the surgical procedure for pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. OBJECTIVES: To determine the critical stage of surgery for pinealectomy after which scoliosis develops in young chickens. SUMMARY OF BACKGROUND DATA: Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. METHODS: Five distinct stages in the pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. RESULTS: Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. CONCLUSIONS: Cutting the pineal stalk was identified as the critical stage of pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.

Animals↗
PubMed2000

Xeroderma pigmentosum: the role of phototesting.

We report three patients newly diagnosed as having xeroderma pigmentosum (XP). Previous photobiological studies have implicated ultraviolet (UV) B as the activating waveband in XP, causing a delayed and prolonged erythemal response. This characteristic reaction pattern has been used as a quick screening test in patients suspected of having XP, while awaiting confirmatory DNA repair studies. Two of our patients showed no abnormal erythemal responses, and one showed severe photosensitivity from 330 to 400 nm but normal UVB responses, with a peak erythema at 24 h. We conclude that the erythemal responses in XP are highly variable and cannot be considered as a reliable screening test in the diagnosis of XP.

Child↗
PubMed1999

The production of scoliosis after pinealectomy in young chickens, rats, and hamsters.

STUDY DESIGN: This study involved weekly radiographic examination of pinealectomized rats, hamsters, and chickens to observe the development of scoliosis. OBJECTIVES: To determine whether pinealectomy produces scoliosis in animals more closely related phylogenetically to humans than to chickens, namely rats and hamsters, which are representative of mammals. SUMMARY OF BACKGROUND DATA: Pinealectomy in 3-day-old chickens has consistently resulted in the development of scoliosis with many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. It has not been determined whether this phenomenon is restricted solely to chickens or is applicable to other animals, especially those more closely related to humans. METHODS: The pineal gland was removed from young rats, hamsters, and chickens. All animals underwent radiography weekly to detect the development of any scoliosis. Weight and length measurements were also taken weekly, and serum melatonin levels were determined at the time the animals were killed. RESULTS: Scoliosis was not observed in either the rats or the hamsters. In contrast, scoliosis developed in 10 of 21 chickens. Serum melatonin levels in all pinealectomized animals were zero. CONCLUSIONS: In contrast to the chickens, pinealectomy does not seem to cause scoliosis in either young rats or hamsters. The reasons for this discrepancy may include differences in the physiology and spinal morphology of the rat and hamster in comparison with the chicken. In the pinealectomized chickens, the results also suggest that future scoliosis development might be indicated by a significant increase in size when they are compared with pinealectomized chickens that do not develop scoliosis. Such differences in growth rates also distinguish patients with adolescent idiopathic scoliosis.

Animals↗
PubMed1999

The effects of melatonin therapy on the development of scoliosis after pinealectomy in the chicken.

The mechanism underlying the development of scoliosis after pinealectomy in young chickens is unknown. However, since the main product of the pineal gland is melatonin, melatonin remains an obvious focus in studies designed to discover this mechanism. One confounding factor is that serum melatonin levels are close to zero after pinealectomy but scoliosis does not develop in all chickens that have had this procedure. Therefore, the role of melatonin in the development of scoliosis in chickens after pinealectomy remains controversial. In the current investigation, two pilot studies demonstrated that a physiological therapeutic dose of melatonin (2.5 milligrams per kilogram of body weight) restored the circadian rhythm of melatonin, as measured by serum assay. In the main study, this dose was administered daily starting either immediately after the pinealectomy or two weeks after it, when scoliosis had developed. Scoliosis was assessed on weekly radiographs, and the Cobb angle was determined for all chickens in which scoliosis developed. Overall, scoliosis developed in only 56 percent (fifty) of the eighty-nine chickens that had had a pinealectomy; this rate was consistent throughout all experimental groups. Scoliosis did not develop in any of the control chickens, which did not have a pinealectomy. On the basis of the average Cobb angles in the chickens in which scoliosis had developed, it was determined that neither the prevalence nor the pattern of the scoliosis was affected by the therapy in any of the experimental groups. It was thus concluded that melatonin therapy after pinealectomy in young chickens has no effect on the development or progression of scoliosis. These results raise doubts regarding the role of melatonin in the development of scoliosis after pinealectomy in the young chicken.

Animals↗