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Biomedical subjects

S Nguyen The Tich

Publications and source records attributed to S Nguyen The Tich.

8 recordsLinked to original sources
PubMed2003

Paramyotonia congenita with an SCN4A mutation affecting cardiac repolarization.

Paramyotonia congenita (PC) is linked to mutations of the skeletal muscle voltage-gated sodium channel alpha-subunit gene SCN4A. The authors report a family where the proband and three of her four children have PC (mutation R1448C) and present repolarization abnormalities at electrocardiogram. They demonstrate that the SCN4A alpha-subunit gene is expressed in normal human heart. Cardiac consequences of mutations of the SCN4A gene may be insignificant in standard conditions, but critical if patients with PC are treated with drugs inducing QT prolongation.

Adult↗
PubMed2000

[Neurogenic mixed evoked potential monitoring during scoliosis surgery: retrospective analysis of 149 cases].

INTRODUCTION: We report a retrospective analysis of spinal cord monitoring with neurogenic mixed evoked potentials (NMEPs) combined with somatosensory evoked potentials (SSEPs) in 149 patients undergoing surgery for spinal deformity. MATERIAL AND METHODS: 149 patients (104 females and 45 males), mean age 28 yrs (13-72 yrs) were studied. NMEPs were elicited by electrical spinal cord stimulation in the rostral part of the surgical field, via two needle electrodes set in the epidural space and in the interspinous ligament above. They were recorded from the sciatic nerve at the knee and the sural nerve at the ankle. SSEPs were recorded from the scalp after stimulation of the posterior tibial nerve at the ankle. A decrease in amplitude of more than 50 p. 100 and/or an increase in latency of more than 10 p. 100 were defined as significant warning criteria. RESULTS: No false-negative result was observed. NMEP modifications did not reach critical value in 143 cases. In 6 cases, significant changes were observed. Moving the stimulation electrodes along the spinal cord allowed spinal lesion localization and helped the surgeon to perform the adapted maneuver, clearly avoiding the occurrence of postoperative neurological defect in 5 of the 6 cases. CONCLUSION: NMEP monitoring is a sensitive and specific method useful for detecting an impending lesion of the spinal cord. NMEPs are also helpful in localizing the spinal level of the lesion. They represent a primary choice tool for neuromonitoring during scoliosis surgery.

Adolescent↗
PubMed1999

The effects of desflurane on the nervous system: from spinal cord to muscles.

UNLABELLED: Monitoring of motor pathways via muscle contraction recording is sensitive to anesthetics, particularly volatile anesthetics. However, the specific action sites of these anesthetics on the spinal cord and the peripheral nervous system are not well known in humans. Therefore, we studied proximal and distal motor and sensory nerve conduction, neuromuscular junction transmission, and spinal cord excitability (H/M amplitude ratio and F-wave amplitude and persistency) using standard neurophysiological techniques in 10 patients who underwent orthopedic surgery. Muscle potentials evoked by spinal cord stimulation were recorded in five additional patients. Desflurane was introduced to achieve end-tidal concentration of 3.7% and 7.4%, in 50% O2/N2O and in 100% O2. Measurements were obtained before desflurane administration and 20 min after obtaining a stable level of each concentration. Peripheral nerve conduction and neuromuscular function were not significantly affected by desflurane. However, spinal cord excitability was significantly decreased by desflurane administration (H/M ratio 37% +/- 9%, 12% +/- 5%, 7% +/- 4% at desflurane concentration 0.0%, 3.7%, and 7.4% in 100% O2, respectively). Muscle potentials evoked by spinal cord stimulation were abolished by desflurane. These data rule out the possibility that desflurane specifically alters peripheral nerve conduction or synapse transmission at the neuromuscular junction. They demonstrate that desflurane acts preferentially at the level of the spinal motoneuron. IMPLICATIONS: We used neurophysiological techniques to assess the effects of desflurane on spinal cord conduction and excitability, motor and sensory peripheral nerve conduction, and neuromuscular transmission. Our data demonstrate that desflurane acts preferentially at the level of the spinal motoneuron, providing useful information for neurophysiological monitoring and immobilization during surgery and for minimum alveolar anesthetic concentration definition.

Action Potentials↗
PubMed1998

[Monitoring the neurogenic mixed evoked potentials during surgery of the spine: a good solution?].

Spinal deformity surgery carries a risk of rare but dramatic neurological complications. Intraoperative spinal cord monitoring has been initially performed using somatosensory evoked potentials (SEP). However, false-negative cases have been reported and neurophysiologists supplement SEPs with concurrent motor evoked potentials. The so-called neurogenic mixed evoked potentials (NMEPs) represent an alternate choice, allowing combined monitoring of motor and somatosensory central pathways. They are recorded from a peripheral nerve after spinal cord stimulation. NMEPs have been experimentally and clinically shown to be sensible for detecting spinal cord injury. They are easily and rapidly recorded, and NMEP monitoring may be continuously performed during the critical steps of surgery.

Evoked Potentials, Motor↗
PubMed1996

[Severe periventricular leukomalacia: characteristic electroencephalographic features].

Periventricular leukomalacia is an infrequent but severe lesion in the premature neonate. The presence of positive rolandic sharp waves (PRSW) on the electroencephalogram, regardless of their morphology, is a reliable marker of periventricular ischemia, justifying systematic EEG monitoring during the first three weeks of life for infants born at less than 34 weeks of amenorrhea. A retrospective study of 32 premature neonates with extensive cavitary periventricular leukomalacia confirmed the early occurrence of positive rolandic sharp waves in 84% of premature newborns. The mean rate of PRSW was 1.54/min, but showed great variability. In C(Z), these sharp waves which were more frequent or isolated in one case, had the same value as those recorded in C3 or C4. Four neonates had no PRSW, but late periventricular leukomalacia was diagnosed at one month of age. As all these premature infants were born before 29 weeks of amenorrhea, longer EEG monitoring was justified. The prognosis was very poor: 17 newborns died, 11 had motor, sensory and intellectual impairment, and three had motor lesions.

Electroencephalography↗