Biomedical subjects

C Straus

Publications and source records attributed to C Straus.

40 records · Page 3Linked to original sources

PubMed1996

Assessment of the voluntary activation of the diaphragm using cervical and cortical magnetic stimulation.

The twitch occlusion technique is a promising tool for use in accessing central drive to the diaphragm and determining maximal transdiaphragmatic pressure (Pdi) from submaximal efforts. It clinical use is limited by difficulties inherent to bilateral electrical stimulation (BES) of the phrenic nerves. This study was designed to revisit the technique using cervical magnetic stimulation (CMS). In addition, the effects of a voluntary contraction on diaphragm response to magnetic stimulation of the cortex (CxMS) were studied. Seven volunteers aged 23-33 yrs were studied. Pdi was determined at relaxed functional residual capacity (FRC) in response to BES (Pdi,P-ES) and CMS (Pdi,p-CMS), and the effects of an increasing voluntary contraction (Pdi, vol) were assessed, The same procedure was applied to CxMS. Pdi,p-CMS at relaxed FRC was 27.5 +/- 2.2 cmH2O (mean+/-SEM), about 20% higher than Pdi,p-ES, and reported previously. Pd,p-CMS linearly decreased with Pdi, vol, and six out of seven subjects were capable of producing voluntary contractions sufficient to extinguish the twitch. More complex patterns were observed with CxMS. Cervical magnetic stimulation provides diaphragmatic twitch occlusion data very similar to bilateral electrical phrenic stimulation. Magnetic stimulation, be it cervical or cortical, could probably be helpful for the assessment of central and peripheral mechanisms of diaphragmatic dysfunction in the clinical setting.

Adult↗

PubMed1996

Assessment of the motor pathway to the diaphragm using cortical and cervical magnetic stimulation in the decision-making process of phrenic pacing.

BACKGROUND: Phrenic nerve pacing is a recognized substitute to positive pressure ventilation via tracheotomy in patients with high cervical cord lesions or central hypoventilation. Although its indications are infrequent, reliable strategies need to be used in the determinations of patients who may benefit from this treatment; contraindications should be carefully respected. STUDY OBJECTIVES: To determine whether modern and noninvasive means to study the motor pathway to the diaphragm, namely cortical magnetic stimulation (CxMS) and cervical magnetic stimulation (CMS), can contribute to the selection of patients who may benefit from phrenic pacing. DESIGN AND SETTING: Prospective study (18 months), on a consecutive basis, of patients referred for possible phrenic pacing to a 10-bed ICU associated with a respiratory neurophysiology laboratory. PATIENTS: Seven patients (high cervical cord injury, n = 5; central hypoventilation following neurosurgery, n = 1; idiopathic acquired central hypoventilation, n = 1). INTERVENTION, MEASUREMENTS, AND RESULTS: Electromyography of the diaphragm and transdiaphragmatic pressure were assessed in response to CxMS and CMS. In three cases, no interruption of the corticodiaphragmatic pathway was evidenced, the decision of pacing was postponed, and the patients eventually recovered a spontaneous breathing activity. In two cases, the diagnosis of irreversible peripheral phrenic dysfunction was reached and pacing was denied. In two cases, complete interruption of the corticodiaphragmatic pathway and integrity of peripheral conduction led to the decision of phrenic pacemaker implantation. CONCLUSION: CxMS and CMS can be used to refine the assessment of patients proposed for phrenic pacing. CxMS can possibly identify those in whom there is a possibility for eventual recovery, and therefore substantiate a decision to postpone the pacing.

Adolescent↗

PubMed1996

[Iatrogenic disorders in the active respiratory systems (respiratory center and its performance].

Amongst the undesirable effects of medical intervention which touch on the respiratory apparatus one can distinguish schematically those disorders which affect the "passive respiratory system" (lungs, pleura, bronchi and vessels) and those which concern the "active respiratory system (SRA)" (nerve centres, respiratory muscles) which are less often described. After a brief reminder of the principles and limits of the available methods of investigation, this chapter reviews the different iatrogenic disorders of SRA according to their level and their aetiology. Peripheral disorders are touched on such as alterations of phrenic conduction (with particular mention of satellite lesions from cardiac surgery), those of neuromuscular transmission (most often induced by medication) and of intrinsic muscular properties (mainly steroid induced myopathies). Central disorders are described principally as the respiratory effects of neurotropic and non-neurotropic medications and the harmful effects of different substances on the sleep/respiration interaction. The secondary effects of therapy on SRA are all the more marked if there are underlying respiratory or neuromuscular disturbances which allow a large place for preventive measures. The diagnosis is made difficult by the complexity of the structures and functions involved and it is clear that the development of pathophysiological studies, which are still too scarce, should enable better understanding of their clinical significance.

Diagnosis, Differential↗

PubMed1994

Idiopathic coccygodynia. Lateral roentgenograms in the sitting position and coccygeal discography.

STUDY DESIGN: The authors hypothesized that the source of coccygodynia was a lesion of the coccygeal disc. OBJECTIVES: This study analyzed the motion of the painful coccyx in the sitting position as compared with the lateral decubitus in a patient and a control group and reported the first results of coccygeal discography (dynamic study). SUMMARY OF BACKGROUND DATA: Coccygodynia are usually attributed to soft tissue injuries or psychologic disturbances. No previous study has assessed the coccygeal discs as a source of pain. METHODS: Fifty-one patients with coccygodynia and 51 controls sustained a dynamic study. Coccygeal mobility was documented by superimposing graph paper with a double reading. The accuracy of the measurement was +/- 2.6 degrees intra- and interobserver variations 15.3 and 12.5%. This dynamic study was followed by coccygeal discography in the patient group. RESULTS: An abnormal motion (luxation or hypermobility) of the coccyx that occurred in the sitting position and spontaneously was reducible when placed in the lateral decubitus position was found in 25 patients. Such lesions could be responsible for the pain because no similar findings were seen in the controls and coccygeal discography was positive in these cases. Of the 26 patients with a normal dynamic study, coccygeal discography, using a combination of provocation and anesthetization, was positive in 15 of 21. CONCLUSIONS: Common coccygeal pain could come from the coccygeal disc in approximately 70% of cases.

Coccyx↗