Biomedical subjects

Jean-Pascal Lefaucheur

Publications and source records attributed to Jean-Pascal Lefaucheur.

27 records · Page 2Linked to original sources

PubMed2003

The regeneration process of the striated urethral sphincter involves activation of intrinsic satellite cells.

The regeneration of adult skeletal muscle is mediated by satellite cells. Classically, these are considered to be somitically derived cells that colonize the limbs during early embryogenesis. The striated urethral sphincter presents specific developmental characteristics that distinguish it from skeletal muscles, such as the non-somitic origin of its precursor cells and the late formation of its myofibers. This prompted us to determine whether the striated urethral sphincter can regenerate after injury by the same mechanism as skeletal muscles. By means of the single myofiber explant culture technique we investigated the presence of satellite cells in the striated urethral sphincter of male mice and evaluated their ability to recapitulate a myogenic program. In addition, a myotoxic substance (notexin) was injected into the sphincter in order to provoke rapid destruction of the myofibers; the regeneration process was studied by means of electrophysiological and histological techniques. Satellite cells expressing pax7 were found attached to the sphincteric myofibers. They proliferated and expressed MyoD, Myf5 and desmin after 2 days in culture. After 10 days, they formed multinucleated myotubes expressing alpha-actinin-2. In vivo, complete recovery of the striated urethral sphincter, as assessed by normalization of muscle strength and of myofiber number and diameter, was observed after 3 weeks, and resulted from the fusion of myogenic cells. These results demonstrate that the striated urethral sphincter can regenerate by means of a myogenic program involving intrinsic satellite cells. The therapeutic implications of this knowledge and the possible origin of the sphincteric satellite cells are discussed.

Animals↗

PubMed2002

Paresis acquired in the intensive care unit: a prospective multicenter study.

CONTEXT: Although electrophysiologic and histologic neuromuscular abnormalities are common in intensive care unit (ICU) patients, the clinical incidence of ICU-acquired neuromuscular disorders in patients recovering from severe illness remains unknown. OBJECTIVES: To assess the clinical incidence, risk factors, and outcomes of ICU-acquired paresis (ICUAP) during recovery from critical illness in the ICU and to determine the electrophysiologic and histologic patterns in patients with ICUAP. DESIGN: Prospective cohort study conducted from March 1999 to June 2000. SETTING: Three medical and 2 surgical ICUs in 4 hospitals in France. PARTICIPANTS: All consecutive ICU patients without preexisting neuromuscular disease who underwent mechanical ventilation for 7 or more days were screened daily for awakening. The first day a patient was considered awake was day 1. Patients with severe muscle weakness on day 7 were considered to have ICUAP. MAIN OUTCOME MEASURES: Incidence and duration of ICUAP, risk factors for ICUAP, and comparative duration of mechanical ventilation between ICUAP and control patients. RESULTS: Among the 95 patients who achieved satisfactory awakening, the incidence of ICUAP was 25.3% (95% confidence interval [CI], 16.9%-35.2%). All ICUAP patients had a sensorimotor axonopathy, and all patients who underwent a muscle biopsy had specific muscle involvement not related to nerve involvement. The median duration of ICUAP after day 1 was 21 days. Mean (SD) duration of mechanical ventilation after day 1 was significantly longer in patients with ICUAP compared with those without (18.2 [36.3] vs 7.6 [19.2] days; P =.03). Independent predictors of ICUAP were female sex (odds ratio [OR], 4.66; 95% CI, 1.19-18.30), the number of days with dysfunction of 2 or more organs (OR, 1.28; 95% CI, 1.11-1.49), duration of mechanical ventilation (OR, 1.10; 95% CI, 1.00-1.22), and administration of corticosteroids (OR, 14.90; 95% CI, 3.20-69.80) before day 1. CONCLUSIONS: Identified using simple bedside clinical criteria, ICUAP was frequent during recovery from critical illness and was associated with a prolonged duration of mechanical ventilation. Our findings suggest an important role of corticosteroids in the development of ICUAP.

Aged↗

PubMed2002

Severe acute polyneuropathy complicating orthotopic liver allograft failure.

BACKGROUND: Neuromuscular dysfunction complicating orthotopic liver transplantation (OLT) has rarely been described. We report three cases of severe acute motor deficit after OLT in a context of graft dysfunction. METHOD: From December 1999 to December 2000, the muscle strength of all patients who underwent OLT in our hospital was checked during their stay in the intensive care unit. Patients having a severe motor deficit underwent electrophysiological examination within 2 weeks after the onset of deficit. RESULTS: Three patients developed acute quadriplegia concomitant with early allograft failure in a series of 30 patients. In these three patients, electrophysiological signs of sensorimotor axonal polyneuropathy were found. No sepsis was observed; hepatic failure, together with acute renal insufficiency in two cases, was the only risk factor identified for critical illness neuropathy. CONCLUSION: The physicians who take charge of patients after OLT must be aware of the possible occurrence of severe polyneuropathy in case of early allograft dysfunction.

Acute Disease↗

PubMed2002

Diaphragmatic silent period to transcranial magnetic cortical stimulation for assessing cortical motor control of the diaphragm.

This study was designed to determine whether a silent period could be elicited in the diaphragm electromyographic (EMG) activity by transcranial magnetic stimulation (TMS) of the motor cortex and, if so, to assess the influence of reflex or voluntary control of breathing on diaphragmatic cortical silent period (cSP). Diaphragmatic EMG activity was recorded in six healthy volunteers after motor cortex TMS triggered by the inspiratory flow peak and applied during forced inspiration (FI), voluntary hyperventilation (vHV) and reflex hyperventilation (rHV) to a CO(2) stimulus. Electrophysiological and respiratory parameters were studied, including diaphragmatic cSP duration and transdiaphragmatic pressure swing (DeltaPdi). A diaphragmatic cSP was found and correlated with DeltaPdi values. DeltaPdi and cSP duration were similar in the vHV and rHV conditions but were significantly increased during FI. This study established for the first time the existence of a diaphragmatic cSP to motor cortex TMS. The diaphragmatic cSP duration depended on the magnitude of the respiratory effort, as assessed by DeltaPdi, but not on the mechanism (volitional or reflex) of diaphragm activation.

Adult↗

PubMed2002

Clinical relevance of electrophysiological tests in the assessment of patients with Huntington's disease.

Assessment programs recently designed to follow-up patients with Huntington's disease (HD) in therapeutic trials have not included electrophysiological testing in the list of mandatory examinations. This omission is likely due to the current lack of data establishing a clear correlation between the electrophysiological results and those of clinical assessment. We address this issue in a cohort of 36 patients at relatively early stages of the disease (I and II). Electrophysiological studies comprised the recording of palmar sympathetic skin responses (SSRs), blink reflexes (BRs), thenar long latency reflexes (LLRs), cortical somatosensory evoked potentials (SEPs), and electromyographic silent periods evoked by transcranial magnetic stimulation (SPs). Results were analyzed with reference to disease duration and staging and to specific cognitive, psychiatric, and motor alteration. SEPs were the most and very sensitive markers, because they were abnormal in 94% of patients. Except for LLRs, alteration of electrophysiological results increased in parallel to the evolution of the disease. Except for LLRs and SSR latency, electrophysiological results correlated with those of specific clinical examinations. In particular, an increased BR latency or a reduced amplitude of the N20 component of SEPs correlated with the extent of bradykinesia, whereas a reduced amplitude of SSRs or of the N30 component of SEPs correlated with hyperkinesia. Overall, electrophysiological tests, in particular SEPs and BRs, appeared sensitive and interesting in the follow-up of HD patients and correlated with various clinical parameters, suggesting that these easy to perform and noninvasive repeatable examinations could be added fruitfully to the assessment programs for HD.

Adult↗

PubMed2002

Respective value of pudendal nerve terminal motor latency and anal sphincter electromyography in neurogenic fecal incontinence.

Fecal incontinence may be related to a neurogenic injury. Electrodiagnostic tests including pudendal nerve terminal motor latency (PNTML) and external anal sphincter electromyography (AEMG) have been proposed to reveal anal nerve damage. The aim of this study was to assess the respective value of PNTML and AEMG in the diagnosis of fecal incontinence. This study included 80 women (range 23-85 years) with fecal incontinence secondary to obstetrical and/or surgical trauma. They were evaluated by performing PNTML and AEMG. The electrophysiological results were compared and interpreted in the light of anorectal manometry (ARM) results. Electrodiagnostic test abnormalities were found in 64 of 80 patients (80%), including 28 patients with abnormal results for both tests and 36 patients with only one abnormal test. Overall, a neurogenic AEMG pattern was found in 64% of patients and a prolonged PNTML in 51%. No correlation was found between PNTML value and either AEMG grade or ARM parameters, while AEMG grade strongly correlated with squeeze pressure measured by ARM. This study showed that AEMG and PNTML did not give redundant information and allowed to explicit the mechanisms of neurogenic fecal incontinence. We found that AEMG was more sensitive and more closely related to the anal functional status (ARM parameters) than PNTML. These electrodiagnostic tests, particularly AEMG as performed in everyday practice, are useful in the assessment of neurogenic fecal incontinence.

Adult↗

PubMed2002

The correlation between muscle and nerve fiber conduction velocities in thenar muscle is lost in case of carpal tunnel syndrome.

OBJECTIVE AND METHODS: This study investigated the relationship between muscle fiber conduction velocity (MFCV) and motor nerve conduction velocity (MNCV) in thenar muscle of 20 normal subjects and of 20 patients suffering from a moderate carpal tunnel syndrome. Our goal was to confirm the positive correlation between MFCV and MNCV and to assess the influence of carpal tunnel syndrome on this relationship. MFCV was calculated in voluntarily contracted thenar muscle using a multi-channel surface recording and a spike-triggered averaging technique. RESULTS: MFCV values ranged between 2.6 and 7.2 m/s (mean+/-SEM: 4.5+/-0.3) in normal subjects and between 3.5 and 6.9 m/s (4.7+/-0.2) in patients. Subjects and patients did not differ regarding MFCV values, but a correlation between MFCV and MNCV was found in normal subjects (P=0.0005) and not in patients (P=0.54). CONCLUSIONS: A correlation between muscle and nerve conduction velocities existed in healthy subjects but was lost in case of moderate carpal tunnel syndrome. MFCV appeared to be insensitive to focal nerve conduction slowing.

Adult↗

PubMed2002

The antalgic efficacy of chronic motor cortex stimulation is related to sensory changes in the painful zone.

Epidural motor cortex stimulation (MCS) could achieve good pain control in patients with drug-resistant chronic neurogenic pain. In the search for parameters associated with the favourable outcome of this surgical procedure, quantitative sensory testing was performed in a series of 31 patients treated by MCS for chronic pain. Non-nociceptive and nociceptive sensory thresholds were measured in the painful area and its contralateral homologous zone with the stimulator in 'off' and in 'on' position. All 13 patients who exhibited normal or quite normal non-nociceptive thermal thresholds within the painful area benefited from MCS. Of the remaining 18 patients with altered thermal sensory thresholds, eight patients nevertheless experienced good pain control by MCS. In these eight 'good responders', sensory thresholds were improved by switching 'on' MCS. In contrast, the last 10 patients showed abnormal thermal thresholds that were not modified by switching 'on' MCS, and did not respond clinically to MCS. Therefore, 'good responders' to MCS could be identified by the absence of alteration of non-nociceptive sensory modalities within the painful area, or by abnormal sensory thresholds that could be improved by MCS. These results additionally suggest that MCS acts on neural pathways involved in sensory discrimination that, in turn, are able to modulate the transmission of pain signals.

Adult↗

PubMed1999

Chronic motor cortex stimulation in the treatment of central and neuropathic pain. Correlations between clinical, electrophysiological and anatomical data.

Thirty-two patients with refractory central and neuropathic pain of peripheral origin were treated by chronic stimulation of the motor cortex between May 1993 and January 1997. The mean follow-up was 27.3 months. The first 24 patients were operated according to the technique described by Tsubokawa. The last 13 cases (eight new patients and five reinterventions) were operated by a technique including localisation by superficial CT reconstruction of the central region and neuronavigator guidance. The position of the central sulcus was confirmed by the use of intraoperative somatosensory evoked potentials. The somatotopic organisation of the motor cortex was established peroperatively by studying the motor responses at stimulation of the motor cortex through the dura. Ten of the 13 patients with central pain (77%) and ten of the 12 patients with neuropathic facial pain had experienced substantial pain relief (75%). One of the three patients with post-paraplegia pain was clearly improved. A satisfactory result was obtained in one patient with pain related to plexus avulsion and in one patient with pain related to intercostal herpes zooster. None of the patients developed epileptic seizures. The position of the stimulating poles effective on pain corresponded to the somatotopic representation of the motor cortex. The neuronavigator localisation and guidance technique proved to be most useful identifying the appropriate portion of the motor gyrus. It also allowed the establishment of reliable correlations between electrophysiological-clinical and anatomical data which may be used to improve the clinical results and possibly to extend the indications of this technique.

Adult↗