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Biomedical subjects

Michael J Cohen

Publications and source records attributed to Michael J Cohen.

15 recordsLinked to original sources
PubMed2006

Effects of motor imagery training after chronic, complete spinal cord injury.

Abnormalities in brain motor system function are present following spinal cord injury (SCI) and could reduce effectiveness of restorative interventions. Motor imagery training, which can improve motor behavior and modulate brain function, might address this concern but has not been examined in subjects with SCI. Ten subjects with SCI and complete tetra-/paraplegia plus ten healthy controls underwent assessment before and after 7 days of motor imagery training to tongue and to foot. Motor imagery training significantly improved the behavioral outcome measure, speed of movement, in non-paralyzed muscles. Training was also associated with increased fMRI activation in left putamen, an area associated with motor learning, during attempted right foot movement in both groups, despite foot movements being present in controls and absent in subjects with SCI. This fMRI change was absent in a second healthy control group serially imaged without training. In subjects with SCI, training exaggerated, rather than normalized, baseline derangement of left globus pallidus activation. The current study found that motor imagery training improves motor performance and alters brain function in subjects with complete SCI despite lack of voluntary motor control and peripheral feedback. These effects of motor imagery training on brain function have not been previously described in a neurologically impaired population, and were similar to those found in healthy controls. Motor imagery might be of value as one component of a restorative intervention.

Adult↗
PubMed2006

Endovascular treatment of obliterative hepatocavopathy with inferior vena cava occlusion and renal vein thrombosis.

We describe the endovascular treatment of an occlusion of the inferior vena cava (IVC) due to obliterative hepatocavopathy with renal and iliac vein thrombosis. A 34-year-old man with nephrotic syndrome and hepatic dysfunction presented to the hospital after a 3-month history of lower extremity swelling with an acute deterioration in his condition. Magnetic resonance venography diagnosed a massive IVC occlusion with thrombosis of the entire IVC, iliac veins, and renal vein. He was treated with thrombolysis, and a chronic occlusion of the infrahepatic IVC was discovered. After venous stenting of the IVC and iliac veins, he dramatically improved. After 24 months, he remains symptom-free with a patent IVC and iliac veins.

Adult↗
PubMed2005

Brain motor system function after chronic, complete spinal cord injury.

Most therapies under development to restore motor function after spinal cord injury (SCI) assume intact brain motor functions. To examine this assumption, 12 patients with chronic, complete SCI and 12 controls underwent functional MRI during attempted, and during imagined, right foot movement, each at two force levels. In patients with SCI, many features of normal motor system function were preserved, however, several departures from normal were apparent: (i) volume of activation was generally much reduced, e.g. 4-8% of normal in primary sensorimotor cortex, in the setting of twice normal variance in signal change; (ii) abnormal activation patterns were present, e.g. increased pallido-thalamocortical loop activity during attempted movement and abnormal processing in primary sensorimotor cortex during imagined movement; and (iii) modulation of function with change in task or in force level did not conform to patterns seen in controls, e.g. in controls, attempted movement activated more than imagined movement did within left primary sensorimotor cortex and right dorsal cerebellum, while imagined movement activated more than attempted movement did in dorsolateral prefrontal cortex and right precentral gyrus. These modulations were absent in patients with SCI. Many features of brain motor system function during foot movement persist after chronic complete SCI. However, substantial derangements of brain activation, poor modulation of function with change in task demands and emergence of pathological brain events were present in patients. Because brain function is central to voluntary movement, interventions that aim to improve motor function after chronic SCI likely also need to attend to these abnormalities of brain function.

Adult↗
PubMed2005

Improving mental health assessment and service planning practices for older adults: a controlled comparison study.

This study evaluated the effectiveness of a guided assessment and service planning intervention in improving the clinical practices of non-physician community mental health providers caring for older persons. Thirteen agencies, 44 clinicians, and 100 consumers (age 60 and older) were assigned to the intervention or a comparison group receiving usual care. Baseline interviews of clinicians and chart reviews found that clinicians' routine evaluation and service planning practices showed inattention to key domains such as substance abuse (over 33% of clinicians), suicide risk and dangerous behaviors (over 40%), and caregiver burden and risk of neglect or abuse (over 75%). At 1-year follow-up, the intervention was associated with increased rates of routine assessments of major symptom, functioning, and support domains. There was also significant improvement in the specificity of treatment planning within the intervention condition. Implications for quality improvement are discussed.

Aged↗
PubMed2005

Brain activation during execution and motor imagery of novel and skilled sequential hand movements.

This experiment used functional magnetic resonance imaging (fMRI) to compare functional neuroanatomy associated with executed and imagined hand movements in novel and skilled learning phases. We hypothesized that 1 week of intensive physical practice would strengthen the motor representation of a hand motor sequence and increase the similarity of functional neuroanatomy associated with executed and imagined hand movements. During fMRI scanning, a right-hand self-paced button press sequence was executed and imagined before (NOVEL) and after (SKILLED) 1 week of intensive physical practice (n = 54; right-hand dominant). The mean execution rate was significantly faster in the SKILLED (3.8 Hz) than the NOVEL condition (2.5 Hz) (P < 0.001), but there was no difference in execution errors. Activation foci associated with execution and imagery was congruent in both the NOVEL and SKILLED conditions, though activation features were more similar in the SKILLED versus NOVEL phase. In the NOVEL phase, activations were more extensive during execution than imagery in primary and secondary cortical motor volumes and the cerebellum, while during imagery activations were greater in the striatum. In the SKILLED phase, activation features within these same volumes became increasingly similar for execution and imagery, though imagery more heavily activated premotor areas, inferior parietal lobe, and medial temporal lobe, while execution more heavily activated the precentral/postcentral gyri, striatum, and cerebellum. This experiment demonstrated congruent activation of the cortical and subcortical motor system during both novel and skilled learning phases, supporting the effectiveness of motor imagery-based mental practice techniques for both the acquisition of new skills and the rehearsal of skilled movements.

Adult↗
PubMed2004

Cerebral and cerebellar sensorimotor plasticity following motor imagery-based mental practice of a sequential movement.

Motor behavior and sensorimotor activation of the cerebrum and cerebellum were measured before and after motor imagery-based mental practice (MP) and physical practice (PP) of a sequential motor task. Two-button-press sequences (A, B) were performed outside a magnetic resonance imaging scanner and at 2 Hz inside the scanner during a pretest. Participants (n = 39) completed PP, MP, or no practice (NP) of Sequence A for 1 week and were posttested. Sequence A performance improved 121%, 86%, and 4% for the PP, MP, and NP groups, respectively (p < 0.05), while Sequence B improved 56%, 40%, and 38% (p > 0.05). PP improvements were accompanied by increased striatal and decreased cerebellar activation, while MP improvements were accompanied by increased cerebellar, premotor, and striatal activation. The efficacy of MP for activating cerebral and cerebellar sensorimotor networks suggests that MP might be an effective substitute or complement to PP to activate compensatory networks for motor rehabilitation.

Adult↗
PubMed2003

An fMRI investigation of hand representation in paraplegic humans.

OBJECTIVE: Cortical reorganization can occur after deaf-ferentation due to loss of a limb, but the nature of the cortical reorganization after spinal cord injury (SCI) is still in debate. METHODS: Using a 1.5T MRI, we scanned paraplegic and noninjured participants during hand movement and palm stimulation, to determine whether longterm paraplegics would show different patterns of cortical activity from the noninjured participants. RESULTS: The SCI group showed stronger activation in areas posterior, rather than superior, to the areas activated by non-SCIs. Conversely, the non-SCIs showed stronger activation in more anterior areas. The signal at each individual's maximally significant voxel had a greater modulation for the SCI group than for the non-SCIs, in response to movement. CONCLUSIONS: In this study of sensory and motor representations within the same subjects, the authors show for the first time the increase in the BOLD fMRI signal modulation in SCI. The authors do not find evidence of expansion of the hand representation into nearby cortical areas, and they corroborate previous EEG studies indicating a posterior shift for hand motor representation after SCI, while showing that the sensory representation does not undergo a posterior shift of similar magnitude. The difference between the reorganization found here and the reorganization typically found following amputations suggests a rationale for the differences in neuropathic pain symptoms following a spinal cord injury or amputation.

Adult↗
PubMed1988

MMPI changes following behavioral treatment of chronic low back pain.

A large sample of patients with chronic low back pain were studied on admission to a behaviorally oriented in-patient pain program, at program completion, and at 1 month follow-up. Cluster analysis of admissions MMPI scores were used to identify 4 patient subgroups each for males and females. There were no subgroup differences found on any of the admissions demographic, pain report, or physical function measures, or differential treatment outcome based on subgroup. All groups began with high levels of pain and disability, yet improved dramatically following treatment. There was a general normalization of the MMPI reflected by elevated MMPI scales found at admission showing significant decreases at follow-up testing. Subgroups derived from follow-up MMPI testing were related to physical functioning at follow-up and pain report measures, with the elevated subgroups showing higher levels of continued pain and disability.

Adaptation, Psychological↗
PubMed1988

Comparing chronic pain from spinal cord injury to chronic pain of other origins.

Acknowledged as a serious complaint of spinal cord injured (SCI) patients, chronic pain in this population is neither well studied nor well understood. To assess the quality and intensity of pain, a group of 49 SCI patients seeking treatment for chronic pain was compared to a general group of 95 patients from the Comprehensive Pain Clinic (CPC) on selected demographic variables, the McGill Pain Questionnaire (MPQ) and the Minnesota Multiphasic Personality Inventory (MMPI). The SCI patients were categorized as functionally incomplete SCI (SCI-I) or complete SCI (SCI-C). Multivariate analyses revealed differences among groups on the MPQ for Number of Words Checked, Rank Sum, and the Affective dimension. In all cases the CPC group scored higher than the SCI-C group. The MMPI profiles were elevated and typical for the CPC and SCI-C groups and substantially less elevated for the SCI-I group. We suggest in cases where chronic pain is secondary to a chronic medical catastrophe, aspects of the MPQ and the MMPI assess the person's total medical disability and not just the meaning and impact of pain.

Adult↗
PubMed1987

Treating chronic low back pain. I. Admissions to initial follow-up.

For a normative study of chronic low back pain (CLBP), 702 consecutive admissions to a large multidisciplinary CLBP treatment program were assessed at admission, discharge, and 1-month follow-up, using a variety of psychological and functional performance instruments. Both univariate and multivariate approaches to appraising success are evaluated. Psychological profiles demonstrated a substantial degree of disability at admissions, which is significantly reduced at follow-up. Both behavioral and cognitive aspects of performance, as evidenced by objective assessments of patients' physical abilities and verbalizations, improved as a direct function of length of stay in the treatment program and continued to show modest improvement through follow-up. Composite indices of improvement demonstrated favorable outcomes for no less than four in every ten, and as high as nine in every ten participants. Because of the large sample size, relationships both within and across measurement domains can be assessed statistically: the separate sets of outcome measures, with the exception of psychological profiles, are generally independent of each other.

Adult↗
PubMed1987

Treating chronic low back pain. II. Long-term follow-up.

Appraisal of chronic low back pain (CLBP) treatment outcome is incomplete unless results can be shown to be stable over an extended follow-up period. This paper concentrates on methods by which the long-term trends of objective outcome assessments can be studied and predictions developed given incomplete data. Employment and litigation status, self-rating of pain, activities, medications, and hospitalizations related to pain were periodically assessed in up to 210 graduates of a CLBP treatment program, over a period of 6 months to 5 years following treatment. Favorable outcomes were achieved by many of the respondents, and a good degree of stability in outcomes was observed in several of the measures. Few indicators were found which adequately predict long-term outcomes, however. Attrition in the sample and other possible systematic sources of bias are discussed.

Back Pain↗
PubMed1985

Comprehensive assessment of chronic low back pain patients and controls: physical abilities, level of activity, psychological adjustment and pain perception.

A comprehensive functional evaluation designed for patients with chronic low back pain (CLBP) is described. The evaluation includes measures from 4 domains of the CLBP syndrome; physical abilities, level of activity, psychological adjustment and pain perception. New measures for standardized assessment of physical abilities and employment of body mechanics are introduced. Evaluation data from 68 CLBP subjects and 35 age-matched, pain-free, controls is presented. Results indicate important deficits in physical abilities and psychological adjustment for the CLBP group compared to the controls. Factor analysis of the evaluation measures yielded a general conditioning factor and a general psychological adjustment factor but complicated factor structures for report of pain and time in activities. Further analysis demonstrated a strong relationship between objective disability and psychological and psychosocial adjustment but little relationship between level of pain and other disability measures.

Activities of Daily Living↗
PubMed1983

Signal detection and threshold measures to loud tones and radiant heat in chronic low back pain patients and cohort controls.

Eleven chronic low back pain (CLBP) and 11 age- and sex-matched control subjects were tested during two separate sessions for the perception of radiant heat and uncomfortably loud tones. Following the determination of a subject's pain threshold (PT) for radiant heat, a standard signal detection methodology was used to present 26 trials each of 4 stimulus levels. The stimuli were rated on a 9-point scale ranging from 'nothing' to 'very strong pain.' A similar procedure was used for the tone stimuli with the 9-point scale ranging from 'nothing' to 'very strongly uncomfortable.' It was found that the CLBP group had both higher heat pain and tone discomfort thresholds than the control group. For radiant heat only, the CLBP group had poorer discrimination as determined by P(I). The results are discussed within the framework of the hypervigilance and adaptation theories of pain perception.

Adult↗
PubMed1982

Does the MMPI differentiate chronic illness from chronic pain?

This study examines the relationship between MMPI scales and functional limitation for the chronic illness populations of chronic low back pain, migraine headache, hypertension and diabetes. Average MMPI profiles for these groups approximate those of previous studies with the chronic low back group having the most disturbed profile and showing elevations especially on the Hs, Hy and D scales. Several kinds of analyses, however, demonstrate that, in general, the MMPI group differences can be accounted for by individual self-rated functional limitation. The data do not support attempts at defining a low back pain or chronic pain personality profile apart from the emotional disturbance associated with chronic limitation and disruption of activity.

Adult↗