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Biomedical subjects

Peter O'Sullivan

Publications and source records attributed to Peter O'Sullivan.

10 recordsLinked to original sources
PubMed2006

Altered patterns of superficial trunk muscle activation during sitting in nonspecific chronic low back pain patients: importance of subclassification.

STUDY DESIGN: A cross-sectional comparative study between healthy controls and two subgroups of nonspecific chronic low back pain (LBP) patients. OBJECTIVES: To determine differences in trunk muscle activation during usual unsupported sitting. SUMMARY OF BACKGROUND DATA: Patients with LBP commonly report exacerbation of pain on sitting. Little evidence exists to confirm that subgroups of patients with nonspecific chronic LBP patients use different motor patterns in sitting than pain-free controls. METHODS: A total of 34 pain-free and 33 nonspecific chronic LBP subjects were recruited. Two blinded clinicians classified nonspecific chronic LBP patients into two subgroups (active extension pattern and flexion pattern). Surface electromyography (sEMG) was recorded from five trunk muscles during subjects' unsupported "usual" and "slumped" sitting. RESULTS: No differences in trunk muscle activity were observed between healthy controls and nonspecific chronic LBP groups for usual sitting. When the classification system was applied, differences were identified. Compared with no-LBP controls, the active extension pattern group presented with higher levels of cocontraction of superficial fibers of lumbar multifidus (12%), iliocostalis lumborum pars thoracis (36%) and transverse fibers of internal oblique (43%). while the flexion pattern group showed a trend toward lower activation patterns (lumbar multifidus, -7%; iliocostalis lumborum pars thoracis, -6%, and transverse fibers of internal oblique, -5%). The flexion relaxation ratio of the back muscles was lower for nonspecific chronic LBP (superficial lumbar multifidus: t = 4.5; P < 0.001 and iliocostalis lumborum pars thoracis:t = 2.7; P < 0.001), suggesting a lack of flexion relaxation for the nonspecific chronic LBP. CONCLUSION: Subclassifying nonspecific chronic LBP patients revealed clear differences in sEMG activity during sitting between pain-free subjects and subgroups of nonspecific chronic LBP patients.

Abdominal Muscles↗
PubMed2006

Evaluation of the flexion relaxation phenomenon of the trunk muscles in sitting.

STUDY DESIGN: A normative, single-group study was conducted. OBJECTIVE: To investigate the flexion relaxation phenomenon in the thoraco-lumbopelvic muscles among a pain-free population when moving from an upright to a slump sitting posture. SUMMARY OF BACKGROUND DATA: The presence of the flexion relaxation phenomenon (FRP) of the back muscles is well documented at end-range spinal flexion when standing. This phenomenon is commonly found disrupted in low back subjects. However, whether FRP occurs in sitting remains controversial. METHODS: The sample consisted of 24 healthy pain-free adults. Surface electromyography was used to measure activity in the superficial lumbar multifidus (SLM), the thoracic erector spinae (TES), and the transverse fibers of the internal oblique (IO) muscles while subjects moved from an erect to a slump sitting posture. An electromagnetic motion-tracking device simultaneously measured thoracolumbar kinematics during this task. RESULTS: There was a significant decrease in both the SLM and the IO activity when moving from an erect to a slump sitting posture (P = 0.001 and P = 0.004, respectively), indicating the presence of FRP. TES activity was highly variable. While 13 subjects exhibited an increase in activity (P = 0.001), 11 demonstrated a decrease in activity (P = 0.001), indicating the presence of FRP. FRP occurred in the mid-range of spinal flexion for the SLM, IO and TES when present. CONCLUSION: The findings show that the SLM and the IO are facilitated in neutral lordotic sitting postures and exhibit FRP at mid range flexion while moving from upright sitting to slump sitting. These findings show that FRP in sitting differs from that in standing. Variable motor patterns (activation or FRP) of the TES were observed. These findings suggest that sustaining mid to end-range flexed sitting spinal postures result in relaxation of the spinal stabilizing muscles.

Adult↗
PubMed2006

Differences in sitting postures are associated with nonspecific chronic low back pain disorders when patients are subclassified.

STUDY DESIGN: A comparative study. OBJECTIVES: To investigate sitting postures of asymptomatic individuals and nonspecific chronic low back pain (NS-CLBP) patients (pooled and subclassified) and evaluate the importance of subclassification. SUMMARY OF BACKGROUND: Currently, little evidence exists to support the hypothesis that CLBP patients sit differently from pain-free controls. Although classifying NS-CLBP patients into homogeneous subgroups has been previously emphasized, no attempts have been made to consider such groupings when examining seated posture. METHODS: Three angles (sacral tilt, lower lumbar, and upper lumbar) were measured during "usual" and "slumped" sitting in 33 NS-CLBP patients and 34 asymptomatic subjects using an electromagnetic measurement device. Before testing, NS-CLBP patients were subclassified by two blinded clinicians. Twenty patients were classified with a flexion motor control impairment and 13 with an active extension motor control impairment. RESULTS: No differences were found between control and NS-CLBP (pooled) patients during usual sitting. In contrast, analyses based on subclassification revealed that patients classified with an active extension pattern sat more lordotic at the symptomatic lower lumbar spine, whereas patients with a flexion pattern sat more kyphotic, when compared with healthy controls (F = 19.7; df1 = 2, df2 = 63, P < 0.001). Further, NS-CLBP patients had less ability to change their posture when asked to slump from usual sitting (t = 4.2, df = 65; P < 0.001). CONCLUSIONS: Differences in usual sitting posture were only revealed when NS-CLBP patients were subclassified. This highlights the importance of subclassifying NS-CLBP patients.

Adult↗
PubMed2006

Lumbopelvic kinematics and trunk muscle activity during sitting on stable and unstable surfaces.

STUDY DESIGN: A single-group comparative study. OBJECTIVES: To compare lumbopelvic kinematics and muscle activation patterns while sitting on stable and unstable surfaces. BACKGROUND: Unstable surfaces are commonly used during the rehabilitation of certain low back pain disorders. The benefits postulated are increased muscle activity and facilitation of sustainable midrange positions via neuromuscular control. The use of unstable sitting devices in the workplace is controversial, as the postulated increase in muscle activity is thought to lead to a muscle fatigue/pain response. However, little evidence exists for or against the ability of these devices to alleviate or prevent spinal pain. METHODS AND MEASURES: This study included 26 healthy adults (14 male, 12 female). Fastrak 3-dimensional motion analysis detected lumbar curvature, pelvic tilt, and postural sway during sitting on a stable and unstable surface over 5-minute periods. Surface electromyography was used to measure activity in the superficial lumbar multifidus, transverse fibers of internal oblique, and iliocostalis lumborum pars thoracis. RESULTS: Spinal postures were similar for sitting on a stable and unstable surface. Significant increases in postural sway were detected (P = .013) in 3 dimensions of movement during sitting on an unstable surface. Gender differences were noted. No EMG amplitude or variance differences were detected between seating conditions. CONCLUSIONS: Preliminary data show that sitting on unstable surfaces induces greater spinal motion, but does not significantly alter the lumbosacral posture nor the amount of activity in the superficial trunk muscles under investigation.

Adult↗
PubMed2005

Diagnosis and classification of chronic low back pain disorders: maladaptive movement and motor control impairments as underlying mechanism.

Low back pain (LBP) is a very common but largely self-limiting condition. The problem arises however, when LBP disorders do not resolve beyond normal expected tissue healing time and become chronic. Eighty five percent of chronic low back pain (CLBP) disorders have no known diagnosis leading to a classification of 'non-specific CLBP' that leaves a diagnostic and management vacuum. Even when a specific radiological diagnosis is reached the underlying pain mechanism cannot always be assumed. It is now widely accepted that CLBP disorders are multi-factorial in nature. However the presence and dominance of the patho-anatomical, physical, neuro-physiological, psychological and social factors that can influence the disorder is different for each individual. Classification of CLBP pain disorders into sub-groups, based on the mechanism underlying the disorder, is considered critical to ensure appropriate management. It is proposed that three broad sub-groups of CLBP disorders exist. The first group of disorders present where underlying pathological processes drive the pain, and the patients' motor responses in the disorder are adaptive. A second group of disorders present where psychological and/or social factors represent the primary mechanism underlying the disorder that centrally drives pain, and where the patient's coping and motor control strategies are mal-adaptive in nature. Finally it is proposed that there is a large group of CLBP disorders where patients present with either movement impairments (characterized by pain avoidance behaviour) or control impairments (characterized by pain provocation behaviour). These pain disorders are predominantly mechanically induced and patients typically present with mal-adaptive primary physical and secondary cognitive compensations for their disorders that become a mechanism for ongoing pain. These subjects present either with an excess or deficit in spinal stability, which underlies their pain disorder. For this group, physiotherapy interventions that are specifically directed and classification based, have the potential to impact on both the physical and cognitive drivers of pain leading to resolution of the disorder. Two case studies highlight the different mechanisms involved in patients with movement and control impairment disorder outlining distinct treatment approaches involved for management. Although growing evidence exists to support this approach, further research is required to fully validate it.

Adaptation, Psychological↗
PubMed2005

Collet-Sicard syndrome: a rare presentation of metastatic prostate adenocarcinoma.

Metastatic spread of prostate adenocarcinoma to the temporal bone is rare. Involvement the jugular foramen may result in Collet-Sicard syndrome. This extremely uncommon clinical entity is characterized by paralysis of the lower four cranial nerves. A case of metastatic prostate adenocarcinoma involving the temporal bone causing a Collet-Sicard syndrome associated with an ipsilateral lower motor facial palsy and a mixed sensorineural and conductive hearing loss is presented. This case highlights the potential of prostate adenocarcinoma to cause symptoms referable to the temporal bone region and histopathologic analysis of biopsy material should include immunohistochemical staining for prostate specific antigen.

Adenocarcinoma↗
PubMed1997

Altered patterns of abdominal muscle activation in patients with chronic low back pain.

This study investigated patterns of abdominal muscle recruitment during the abdominal drawing in manoeuvre in subjects with chronic low back pain (CLBP) and radiological diagnosis of spondylolysis or spondylolisthesis. Data were collected using surface electromyography from 12 physically active subjects with CLBP and 10 controls. The control subjects displayed an ability to preferentially activate internal oblique with minimal activation of upper rectus abdominis during the action of drawing in the abdominal wall. The group with CLBP were unable to achieve this. This finding may reflect the presence of neuromuscular dysfunction in this group. Further study is required to investigate if these findings are linked to the ability of patients with CLBP to provide dynamic stability of their lumbar spine.

Journal Article↗