Resistance to curare, upper motor neuron dysfunction, and antiepileptic treatment.
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Biomedical subjects
Publications and source records attributed to M Gemma.
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Increased catecholamines are one of the factors responsible for post-operative arterial hypertension. In order to prevent this severe complication labetalol, an alpha and beta blocking drug, was infused following the closure of the dura mater in half of the patients studied. For two hours after surgery blood pressure values in treated patients were constantly lower than those recorded in the control group, thus confirming the efficacy of this drug in preventing the cardiocirculatory effects of increased adrenalin and noradrenalin.
Plasma exchange has been reported to be a successful therapeutic procedure for the treatment of severely compromised myasthenic patients, but the optimal regimen in terms of costs or clinical benefit has not so far been determined. We have investigated the efficacy of a short plasmapheresis protocol of two exchanges 1 day apart in a series of 70 patients with severe forms of myasthenia gravis. Patients were evaluated before and 7 days after the first exchange. A positive outcome was observed in 70% of the plasma exchange cycles performed. Disease severity did not seem to be a negative prognostic factor for the efficacy of this short protocol, which was well tolerated by patients. In only 1 case were major side-effects observed. In spite of its short duration, the exchange treatment plus concomitant immunosuppressive drug therapy was not followed by early clinical deterioration.
Recently submaximal train-of-four stimulation of motor nerves has been reported as a reliable technique for monitoring the neuromuscular function in patients awakening from anaesthesia, in order to prevent residual curarization. On the basis of the similarity between curarization and Myasthenia Gravis, we studied the neuromuscular impairment of four myasthenic patients by means of a commercially available monitor, which has been designed for routine application in the operating room. We demonstrate that the cardinal features of Myasthenia Gravis can be easily detected with this simple and painless method.
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Sensitivity to the action of nondepolarising relaxants was compared in muscles of upper and lower limbs in four syringomyelic patients undergoing elective neurosurgical procedures. It was observed that muscles with signs of lower motor neurone dysfunction are supersensitive to the action of nondepolarising relaxants. Terminal sprouting of motor axons and the occurrence of newly formed neuromuscular junctions may be responsible for a low synaptic efficacy and may explain the high sensitivity to factors that reduce the safety margin of neuromuscular transmission.
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Supersensitivity to depolarization produced by succinylcholine and resistance to pancuronium were observed in paretic muscles of a patient with a right frontoparietal tumor. The abnormal sensitivity to relaxants is compared with observations reported in patients with myasthenia gravis and hemiparesis. We hypothesize that upper motoneuron dysfunction may be followed by the appearance of "new" junctional receptors, which may occasional a supersensitivity to depolarization and a poor affinity for both curare and anti-acetylcholine-receptor antibodies. A decrease in acetylcholinesterase activity of "decentralized" muscles should also be considered.
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A 62-year-old male suddenly developed a severe paraparesis after epidural anaesthesia. He recovered gradually over the next few months. He had an acute relapse one year later and a selective spinal angiography showed a dural T8 arteriovenous fistula with large draining veins. Intravascular embolisation of the fistula produced immediate and sustained clinical improvement. The mechanism commonly held responsible for neurological disturbances in spinal dural arteriovenous fistulas is cord hypoxia secondary to venous hypertension. The 20-ml of local anaesthetic solution injected into a narrow spinal canal with osteophytosis may have caused further venous engorgement, cord hypoxia and acute neurological deficit.
We examined the distribution pattern of the corticospinal fibres in cervical and lumbar enlargements of the rat spinal cord with the Fink-Heimer silver impregnation method, after extensive cortical ablation. Corticospinal fibres are bilateral and run in the lateral and anterior funiculi. The distribution at the cervical and lumbar levels does not differ. The main area of termination are: 1) the lateral part of the ventral horn basis; 2) an area surrounding the motoneurons group posteriorly. At the electron microscope we were unable to find degenerating boutons of the corticospinal projections contacting HRP labelled motoneurons retrogradely. This indicates that at both levels few monosynaptic corticospinal fibres or none at all end on the motoneurons. Our study does not support the suggestion of differences in the termination pattern of the corticospinal tract of the rat between cervical and lumbar enlargements made on the basis of electrophysiological studies.
15 chronic cluster headache patients in whom pain was induced by nitroglycerin received acute intravenous treatment with a calcium entry blocker. At the time of peak pain we noted a sudden decrease after the Verapamil injection. The mechanism by which the calcium entry blocker afforded relief is unlikely to have been vasodilatation in patients whose blood vessels had just been dilated by nitroglycerin. A more probable mechanism is blockade of the release of the pain-inducing neurotransmitters. The vasodilatation phase is not a primary factor in the onset of pain.
BACKGROUND: To compare early and late complications after either conventional surgical or percutaneous dilatational tracheostomy. DESIGN: Prospective, randomized study. SETTING: General intensive care unit and neuro-surgical intensive care unit in a university hospital. PATIENTS: 50 consecutive patients, requiring tracheostomy for prolonged mechanical ventilation. INTERVENTIONS AND MEASUREMENTS: Patients were randomly allocated to receive either surgical (surgical group, n = 25) or percutaneous dilatational tracheostomy (percutaneous group, n = 25). Occurrence of perioperative complication were carefully evaluated during ICU stay. Late complications were evaluated with both physical and endoscopic examination at 1, 3 to 6 months after tracheostomy. RESULTS: All surgical and percutaneous tracheostomies were successfully completed and no deaths directly related to the tracheostomy procedures were reported. Completion of the procedure required 41 +/- 14 min in the surgical group and 14 +/- 6 min in the percutaneous one (p < 0.0001). The incidence of early perioperative complications was higher in the surgical group (36%) than in percutaneous one (12%), (p < 0.05). The endoscopic follow-up demonstrated one segmental malacia and one stenosis of the trachea in the percutaneous group only (p = n.s.). Skin repair was better after percutaneous tracheostomy than in the surgical group (p < 0.01). CONCLUSIONS: In experienced hands, percutaneous dilatational tracheostomy is as safe and effective as the conventional surgical tracheostomy. The percutaneous technique is less time-consuming and has a lower rate of early infectious complications with better cosmetic results than the surgical technique.
The diffusion of magnetic resonance imaging as a powerful non-invasive diagnostic procedure has led to an increasing request for general anaesthesia in patients who cannot lie still and/or who cannot guarantee adequate spontaneous breathing during the procedure. We report our own experience in 100 patients of this kind, in whom the need for general anaesthesia was due to neurological problems and/or tender age. Anaesthesia and monitoring devices were either devoted of ferromagnetic properties (allowing their location near the patient; as the ARM-S88 portable ventilator, which we used for adult patients) or connected to the patient with long connectors (allowing their location outside the resonance magnetic field; as the Draeger-Babylog pressometric ventilator, which we used in pediatric patients). On these bases administration of intravenous (86 patients) and inhalation (14 patients) anaesthesia during magnetic resonance proved safe in our experience.
Pre- and postoperative serum CK activity is evaluated in 142 children submitted, "uneventfully", to diagnostic muscle biopsy under halothane (77 patients), ketamine (50 patients) or "local" (15 patients) anaesthesia. The purpose was to ascertain whether or not anaesthesia-induced-rhabdomyolysis (AR) was an asymptomatic (and unrecognized) complication of "uneventful" anaesthesia. The majority of patients with low preoperative CK values showed a slight increase of serum CK activity on the first postoperative day. On the contrary, a postoperative decrease was observed in the majority of patients with high preoperative values (namely in almost all ketamine patients and in 2/3 of halothane-patients). In no case postoperative increase reached a value suggesting the occurrence of AR even though a postoperative value of 16480 U/I was observed in a patient with Duchenne muscular dystrophy after halothane anaesthesia. Sudden interruption of motor activity induced by general anaesthesia seems to be the most important factor in reducing the release of CK from muscle. When preoperative release is low, any further postoperative reduction is not sufficient to balance the moderate increase of CK produced by the surgical procedure; the opposite should happen in patients presenting with high preoperative release. So far as anaesthetics are concerned, our data seem to suggest that ketamine has a higher "protective" role compared to halothane.