Sensitivity to vecuronium after botulinum toxin administration.

When used to treat focal dystonias, botulinum toxin may cause a transient impairment of neuromuscular transmission in muscles distant from those injected. These systemic effects are not clinically evident, but should not be ignored when patients are exposed to other drugs or conditions that also impair neuromuscular transmission. A patient is described who underwent general anesthesia twice during treatment with botulinum toxin for a long history of blepharospasm. On both occasions, the neuromuscular block produced by vecuronium (0.05 mg kg-1) was monitored in the abductor digiti minimi muscle. Compared with that observed in 24 individuals who were free from neuromuscular problems, the patient's sensitivity to vecuronium was low 90 days after the seventh treatment with toxin and normal 8 days after the ninth. The possibility is considered that repeated treatments with the toxin may cause continuous remodeling of neuromuscular junctions and may cause the patient to develop some tolerance to the action of neuromuscular blockers.

Upper motor neuron dysfunction reduces the EMG evidence of myasthenia gravis.

Hyposensitivity to the action of nondepolarizing muscle relaxants has been frequently observed in patients with upper motor neuron dysfunction and in patients treated with antiepileptic drugs. To ascertain whether the same conditions are also characterized by a reduced sensitivity to the effects of anti-acetylcholine-receptor antibodies occurring in myasthenia gravis, bilateral investigations of neuromuscular transmission were conducted on proximal and distal muscles of a myasthenic patients with a long history of hemiparesis and epilepsy. It was observed that electromyographic evidence of myasthenia gravis was absent in distal muscles (and low in proximal ones of the paretic side. Even though the influence of antiepileptic treatment could not be assessed with certainty in this patient, indirect evidence suggests that hyposensitivity to anti-acetylcholine-receptor antibodies is an unlikely consequence of neuromuscular changes induced by anticonvulsants.

Epilepsia partialis continua associated with NADH-coenzyme Q reductase deficiency.

We report the clinical, neuroradiological and biochemical features of a patient with epilepsia partialis continua (EPC). MRI studies disclosed multiple cortico-subcortical areas of abnormal signal intensity. The activity of complex I of the mitochondrial respiratory chain was markedly reduced in skeletal muscle. The biochemical defect was reflected in vivo by a failure of brain and skeletal muscle bioenergetics, as shown by exercise and phosphorus magnetic resonance spectroscopy (31P-MRS) studies. Muscle morphology was repeatedly normal, and molecular genetic analysis of mitochondrial DNA was not informative. On the basis of in vivo and in vitro findings, the observed defect of the mitochondrial respiratory chain was considered the underlying biochemical pathogenesis of the disease. The observation of an oxidative defect in the brain and skeletal muscle of a patient with EPC emphasizes the importance of studying mitochondrial energy metabolism in patients with EPC not associated with primary CNS lesions when clinical and morphological findings suggesting a mitochondrial disorder are lacking. 31P-MRS can be a useful method to uncover deficits of CNS mitochondrial function and provide the indication for further biochemical studies.

Combined central and peripheral acute demyelination.

We describe a patient with multiple sclerosis who had a bout of central demyelination associated with an acute inflammatory demyelinating polyneuropathy. The contemporary involvement of central and peripheral nervous system due to a demyelinating disease has been reported anecdotically in humans, and can be induced experimentally in animals. It may be sustained by a common pathogenetic factor.

Neurological examination in patients recovering from general anesthesia.

We performed serial neurological evaluations on 86 patients who underwent surgery for herniated lumbar disk during the first 3 hours after the end of anesthesia (isoflurane-N20-02 for 25 patients, halothane-N20-02 for 38, fentanyl-droperidol-N20-02 for 23). At time 0, the idiomuscular response to percussion of the extensor carpi muscle was present in every patient, while tendon reflexes were always absent. Hyperreflexia was as frequent as shivering, but it took place earlier; we could determine no correlation between these two phenomena. There was no correlation between shivering and rectal temperature of the patients. Although almost all the patients were cooperative and could correctly calculate 100-7, the post-hyperventilation-apnea test was positive in 35 patients at time 120 minutes: this suggests that many patients considered "awake" still exhibit neurological abnormalities, such as inadequate respiratory drive.

[General anesthesia for magnetic resonance. Experience on 100 cases]. / Anestesia generale per la risonanza magnetica. Esperienza su 100 casi.

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.

[Labetalol in the prophylaxis of postoperative arterial hypertension in surgery of the posterior cranial fossa]. / Il labetalolo come profilassi della ipertensione arteriosa post-operatoria nella chirurgia della fossa cranica posteriore.

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.

Submaximal nerve stimulation with the Datex relaxograph NMT monitor in myasthenia gravis.

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.

Sensitivity to curare in patients with upper and lower motor neurone dysfunction.

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.