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Biomedical subjects

K A Lindgren

Publications and source records attributed to K A Lindgren.

At least 19 recordsLinked to original sources
PubMed2004

Deficient saccadic inhibition in Asperger's disorder and the social-emotional processing disorder.

BACKGROUND: Both Asperger's disorder and the social-emotional processing disorder (SEPD), a form of non-verbal learning disability, are associated with executive function deficits. SEPD has been shown to be associated with deficient saccadic inhibition. OBJECTIVE: To study two executive functions in Asperger's disorder and SEPD, inhibition and task switching, using a single saccadic paradigm. METHODS: 22 control subjects and 27 subjects with developmental social processing disorders-SEPD, Asperger's disorder, or both syndromes-performed random sequences of prosaccades and antisaccades. This design resulted in four trial types, prosaccades and antisaccades, that were either repeated or switched. The design allowed the performance costs of inhibition and task switching to be isolated. RESULTS: Subjects with both Asperger's disorder and SEPD showed deficient inhibition, as indicated by increased antisaccade errors and a disproportionate increase in latency for antisaccades relative to prosaccades. In contrast, task switching error and latency costs were normal and unrelated to the costs of inhibition. CONCLUSIONS: This study replicates the finding of deficient saccadic inhibition in SEPD, extends it to Asperger's disorder, and implicates prefrontal cortex dysfunction in these syndromes. The finding of intact task switching shows that executive function deficits in Asperger's disorder and SEPD are selective and suggests that inhibition and task switching are mediated by distinct neural networks.

Adult↗
PubMed2000

Six-month test-retest reliability of MRI-defined PET measures of regional cerebral glucose metabolic rate in selected subcortical structures.

Test-retest reliability of resting regional cerebral metabolic rate of glucose (rCMR) was examined in selected subcortical structures: the amygdala, hippocampus, thalamus, and anterior caudate nucleus. Findings from previous studies examining reliability of rCMR suggest that rCMR in small subcortical structures may be more variable than in larger cortical regions. We chose to study these subcortical regions because of their particular interest to our laboratory in its investigations of the neurocircuitry of emotion and depression. Twelve normal subjects (seven female, mean age = 32.42 years, range 21-48 years) underwent two FDG-PET scans separated by approximately 6 months (mean = 25 weeks, range 17-35 weeks). A region-of-interest approach with PET-MRI coregistration was used for analysis of rCMR reliability. Good test-retest reliability was found in the left amygdala, right and left hippocampus, right and left thalamus, and right and left anterior caudate nucleus. However, rCMR in the right amygdala did not show good test-retest reliability. The implications of these data and their import for studies that include a repeat-test design are considered.

Adult↗
PubMed1999

Thalamic metabolic rate predicts EEG alpha power in healthy control subjects but not in depressed patients.

BACKGROUND: EEG alpha power has been demonstrated to be inversely related to mental activity and has subsequently been used as an indirect measure of brain activation. The hypothesis that the thalamus serves as a neuronal oscillator of alpha rhythms has been supported by studies in animals, but only minimally by studies in humans. METHODS: In the current study, PET-derived measures of regional glucose metabolism, EEG, and structural MRI were obtained from each participant to assess the relation between thalamic metabolic activity and alpha power in depressed patients and healthy controls. The thalamus was identified and drawn on each subject's MRI. The MRI was then co-registered to the corresponding PET scan and metabolic activity from the thalamus extracted. Thalamic activity was then correlated with a 30-min aggregated average of alpha EEG power. RESULTS: Robust inverse correlations were observed in the control data, indicating that greater thalamic metabolism is correlated with decreased alpha power. No relation was found in the depressed patient data. CONCLUSIONS: The results are discussed in the context of a possible abnormality in thalamocortical circuitry associated with depression.

Adult↗
PubMed1999

Back and hip extensor muscle function during therapeutic exercises.

BACKGROUND: Therapeutic exercises are widely used in the treatment of low back problems. Clinical knowledge about targeting the load in these exercises, however, is insufficient. This study assessed the L2 and L5 level paraspinal and gluteus maximus muscle activities in different therapeutic exercises. Intramuscular and surface electromyography (EMG) measurements were obtained to study whether surface EMG measurements can be used in the assessment of multifidus muscle function. METHODS: Eleven healthy subjects (5 men, 6 women) 21 to 38 years of age volunteered for the study. The subjects performed 18 different therapeutic exercises. During the exercises paraspinal EMG was recorded using fine wire and surface electrodes. The normalized peak and average muscle EMG activities (percentage of amplitude in maximal voluntary contraction [MVC]) during each task were determined. RESULTS: The correlations between the average intramuscular and surface activities of the normalized EMG (% of MVC) at the L2 and L5 levels were .928 and .950, respectively. The peak and average EMG amplitudes of the exercises were below 50% and 25% of MVC, respectively. At the L5 level, the multifidus peak and average EMG amplitudes (% MVC) were higher in women than in men, whereas no significant difference was found at the L2 level. In women, the normalized multifidus EMG amplitude was higher at the L5 level than at the L2 level, whereas no significant difference was found in men. In both sexes, the normalized EMG amplitude was higher in the multifidus than in the longissimus muscle. CONCLUSION: Surface EMG measurements may be used in the assessment of multifidus muscle function. Simple therapeutic exercises are effective in activating the lumbar paraspinal muscles.

Adult↗
PubMed1998

Metabolic rate in the right amygdala predicts negative affect in depressed patients.

The role of the amygdala in major depression was investigated. Resting regional cerebral metabolic rate (rCMRglu) was measured with [18F]fluorodeoxyglucose positron emission tomography (PET) in two samples of subjects using two different PET cameras. The samples consisted of 10 and 17 medication-free depressives and 11 and 13 controls, respectively. Using coregistration of PET and magnetic resonance images, regions were individually delineated for the amygdala and thalamus, the latter of which was used as a control region. Within the depressed groups, right amygdalar rCMRglu was positively correlated with negative affect. Thalamic rCMRglu was not related to negative affect, and amygdalar rCMRglu accounted for a significant portion of variance in depressives' negative affect scores over and above the contribution of thalamic rCMRglu.

Amygdala↗
PubMed1997

Movement disturbances of the lumbar spine and abnormal back muscle electromyographic findings in recurrent low back pain.

STUDY DESIGN: A cross-sectional analysis was done of patients with recurrent low back pain referring to the lower limbs. OBJECTIVES: To analyze dynamic radiographs of forward and backward bending of the lumbar back and to determine, using routine neurophysiologic measurements, the functional state of the lower nerve roots in patients with recurrent low back pain radiating to the lower limbs. METHODS: Clinical and neurophysiologic studies showed eight of the 108 patients with low back pain to have ventral root impingement at either L5 or S1 level. The remaining 100 patients, 56 women and 44 men (mean age, 37.6 years; range, 17-62 years), made up the study group for continuing investigation. History of low back pain ranged from 4 months to 20 years. RESULTS: Disturbed intervertebral movement was found in 51 of 100 patients. Twenty-seven percent had L5 or L4 anterolisthetic hypermobility, and 35% had L4 or L3 vertebral retrolisthesis. Vaguely delineated radiating sensations in the lower limbs were common (62%). Back muscle electromyographs were mostly (86%) normal in patients whose low back pain was localized. Conversely, almost three-fourths of those experiencing radiating or referred pain had abnormal electromyographs, consistent with a mild degree of axonal damage in the posterior branch of the lumbar nerve root innervating the medial paraspinal muscles. This finding was most common among patients with retrolisthesis and simultaneous degenerative changes. CONCLUSIONS: Evaluation of low back pain should include tests for degenerative retrolisthesis, especially in patients experiencing radiating sensations with no evidence of root impingement, because abnormal electromyographic findings showing denervation of the paraspinal muscles was most common in patients with degenerative retrolisthesis. To improve the functional support of the lumbar region, rehabilitation should be directed to the medial back muscles because they provide the most effective support for intervertebral motion and because mild disturbances appear to be associated with their innervation in recurrent low back pain.

Adolescent↗
PubMed1997

Conservative treatment of thoracic outlet syndrome: a 2-year follow-up.

OBJECTIVE: To evaluate a conservative therapy program that aims to restore normal function to the upper thoracic aperture in patients with thoracic outlet syndrome (TOS). DESIGN: A descriptive study of consecutive patients with a positive TOS index seen from 1988 to 1993. After therapy, the patients were followed for a mean period of 24.6 months. SETTING: Therapy was initiated primarily in an inpatient rehabilitation ward over an 11.4-day (range 4-24 days) stay. PATIENTS: One hundred nineteen patients (28 men and 91 women) with a positive TOS index participated. At admission, 50% of the patients were employed, 48% were on sick leave or retired, and 2% were unemployed. INTERVENTIONS: The patients received instructions on how to restore the normal function of their cervical spine and upper thoracic aperture by means of home exercises. MAIN OUTCOME MEASURES: The efficacy of the treatment program was assessed by the frequency of return to work, normalization of the motion of the cervical spine and upper thoracic aperture, and subjective satisfaction with the outcome. RESULTS: At the follow-up examination, 88% of the patients were satisfied with the outcome of their treatment, and the ranges of motion of the cervical spine and upper thoracic aperture had normalized in 8 of 10 patients. Seventy-three percent of the patients returned to work after the therapy, either directly or after retraining, and 88% of the patients carried through the recommendations given at discharge during long-term follow-up. Normalized grip strength and Tinel's sign predicted patient satisfaction (p < .001) and return to work (p < .001). Return to work was more often successful if the work was sedentary rather than heavy (p < .05). CONCLUSIONS: The treatment program provides relief to most patients with symptoms of TOS. If the symptoms are not relieved, the differential diagnosis should be reviewed. Conservative therapy with the aim of restoring the function of the upper thoracic aperture is to be recommended, and long-term follow-up is advisable.

Adult↗
PubMed1997

[TOS (thoracic outlet syndrome)--a challenge to conservative treatment].

Functional impairment and pain in the upper extremities may indicate a functional deficit in the thoracic outlet. Static work posture, trauma and whiplash injury may be predisposing factors. The younger generation who often spend long hours in front of a computer are in danger of becoming a future risk group. The primary care physician should be familiar with the syndrome which can be identified by careful clinical examination. Timely intervention can prevent much of the disabling symptomatology. Treatment is primarily conservative and should be aimed at the restoration of functional capacity. As in other disorders, the individual constellation of symptoms is dependent on circumstantial factors, an aspect meriting particular attention in treatment and follow-up. Optimisation of ergonomic conditions is important feature of treatment, and long-term follow-up is necessary. Transient exacerbation is not an indication for surgical treatment. If cervical and thoracic outlet function has normalised but the patient still has symptoms, then the differential diagnosis should be reconsidered. Examination and treatment of patients with pain in the upper extremities requires the collaboration of the physician and physical and occupational therapists. Treatment can be delivered in the primary care setting.

Age Factors↗
PubMed1995

Thoracic outlet syndrome--a functional disturbance of the thoracic upper aperture?

We describe a young woman with typical neurovascular symptoms of thoracic outlet syndrome (TOS). A three-dimensional computerized scan showed a "dislocation" of the first rib at the costotransverse joint. The patient responded to a conservative approach to treatment. The patient presented here demonstrates the functional compromise of the upper thoracic aperture that is frequently seen in young women.

Adult↗
PubMed1995

Long-term outcome of surgery for thoracic outlet syndrome.

BACKGROUND: Thoracic outlet syndrome (TOS) is one of the most controversial symptom complexes in surgery today. Even the existence of TOS is questioned and where it seems to exist, the incidence varies from one country to another. Surgery is often considered the primary treatment; however, the frequency of good results after surgery varies from 24% to 100%, and in recent years the surgical approach has been questioned. PATIENTS AND METHODS: In this study 45 patients who had undergone surgery for TOS symptoms over a period of 21 years were examined by an independent clinician an average of 8 years after the operation. RESULTS: Forty-three percent of the performed operations were found to have been successful. Preoperative nocturnal and neck pain were more frequent in the unsuccessful group; no other preoperative characteristics had a predictive value. Preoperative radiographic and neurophysiologic examinations were also not predictive of the outcome. CONCLUSION: It is recommended that the feasibility of conservative therapeutic approaches should be evaluated before undertaking surgery for TOS symptoms.

Adolescent↗
PubMed1995

Dorsal ramus irritation associated with recurrent low back pain and its relief with local anesthetic or training therapy.

Nerves leave the spinal cord as mainly motor primary rootlets and sensory rootlets. These join to nerve root before leaving the spinal canal. After the root canal, the nerve root branches into the ventral root, which contains sensory and motor fibers innervating the extremities, and the dorsal root, that is, the dorsal ramus, which innervates the posterior structures, for example, back muscles: the dorsal ramus itself may become irritated (dorsal ramus syndrome). Especially predisposed to entrapment is the medial branch of the dorsal ramus, which innervates the multifidus muscle and also contains pain fibers. Here we describe the influence of local anesthesia and back-muscle-training therapy on subjective and objective pain parameters in 21 low-back-pain patients who had similar clinical status and neurophysiologic findings and whose recurrent low back pain was most apparently associated with dorsal ramus neuropathy, without any radiologic or neurophysiologic evidence of more proximal ventral nerve root damage in the spinal cord or at the nerve root origin. After treatment, all were pain free and back muscle activity during lumbar-pelvic rhythm was normalized.

Adult↗
PubMed1993

Thoracic outlet syndrome with special reference to the first rib.

The thoracic outlet syndrome (TOS) is a highly controversial concept. The incidence of TOS is high in the United States, essentially unknown in Australia and seldom diagnosed in Great Britain. In spite of the skepticism in the recent medical literature many patients are still surgically treated with resection of the first rib for a symptom complex diagnosed as TOS. Resection of the first rib is the most extensively used surgical approach in the treatment of TOS. This operation gives a good result in 24% to 100% of the patients. The reasons for this huge variation are considered to be related to difficulties in patient selection, variable examination procedures, operative techniques and a lack of proper follow-up. The goal of this review is to bring forth the diverging results after first rib resection for TOS and to pinpoint the importance of further studies concerning the possible functional disturbance of the thoracic outlet in these patients. Conservatism is encouraged.

Humans↗
PubMed1993

Exercise therapy effects on functional radiographic findings and segmental electromyographic activity in lumbar spine instability.

Flexion-extension and traction-compression radiographs as well as functional electromyographic (EMG) analysis were used to assess nine patients with chronic low back pain and segmental instability symptoms. After a treatment program, at which time most of the patients were asymptomatic and their physical status normalized, the patients were reexamined using EMG and radiographs. No significant change was found in the functional radiographic examination, whereas the myographic findings were significantly improved. Although the number of subjects was small, the results suggest that radiographic findings correlate poorly with clinical findings. Because of the improvement of the physical and myographic findings, the term "segmental dysfunction" may better describe the disability and symptoms than does the term "segmental instability."

Adult↗