Cerebrovascular circulation "steal" syndrome secondary to a voluminous retrotracheal goiter.

A case of recurrent transient ischaemic attacks in the brain resolved after removal of a voluminous retrotracheal goiter is presented. The presence of congenital atretic left vertebral artery, associated with impairment of left carotid artery blood flow by a very large inferior thyroid artery, probably caused the episodes to transient ischaemic attack.

Severe hypophosphatemia after head injury.

Hypophosphatemia occurs in a variety of clinical conditions. It develops in parallel with phosphate depletion from body losses or more commonly as a sequel to the redistribution of phosphate from the extracellular to the intracellular compartment. Hypophosphatemia is a multisystem disturbance capable of involving the neurological, immunological, and muscular systems, among others. In this report, we describe five patients with severe head injury who developed marked hypophosphatemia (less than 1 mg/dl) within 24 hours of hospitalization. This fall in serum phosphate coincided with the induction of respiratory alkalosis consequent to mechanical ventilation. In four of the five patients, as acid-base parameters returned to normal, serum phosphate values rose, in all instances reaching values greater than 2.5 mg/dl. Urinary phosphorus excretion, ordinarily negligible after hypophosphatemia induced by hypocapnia, was still present in Cases 1 and 4 (greater than 600 mg/24 hours). This is unexplained by any of the known hormonal or fluid alterations that accompany head injury. These five patients developed severe, yet transient, hypophosphatemia that resolved upon correction of hyperventilation-induced acid-base abnormalities. We discuss the pathophysiology of this entity and the implications for the head trauma patient.

Regional cerebral blood flow measurements using stable xenon enhanced computed tomography: a theoretical and experimental evaluation.

Several theoretical and practical aspects of regional cerebral blood flow measurements using stable xenon gas and CT are discussed. It is shown that by comparing the enhancement at any time T1 with that at saturation or any other time T2, the need to use arbitrary means to bring the arterial concentration data and the CT enhancement data to the same system of measurement units can be eliminated. If CT is performed continuously during the washin phase, say at intervals of 1 min, least squares analysis of the enhancement data can be used to obtain the best possible estimates for the flow rate constant kappa and the saturation enhancement. However, if only a limited number of scans can be performed, as may be the case in human studies, it is also possible to get a good estimate of kappa from a knowledge of the ratio of the enhancement at any time T1 with that at any other time T2. Combinations of T1 = 2.0 min and T2 = 4.0 min, T1 = 1.0 min and T2 = 6.0 min, or T1 = 2.0 min and T2 = 5.0 min were found to be the most convenient. It is also shown that the end-tidal xenon concentration in the exhaled air can be accurately assessed indirectly by measuring the oxygen, CO2, and water vapor concentrations, thereby eliminating the need for more expensive methods involving the use of a mass spectrometer or a thermal conductivity gas analyzer.

Nutrition and the neurosurgical patient.

There has been a rapid expansion of knowledge in the field of nutrition and metabolism with regard to the general surgical patient. However, only recently has there been greater appreciation of the benefits of adequate nutrition and appropriate metabolic care of the neurosurgical patient. In this review, the authors attempt to outline 1) the metabolic response to stress in general, and how it applies to the neurosurgical patient; 2) how best to provide adequate nutritional support for the neurosurgical patient; 3) the effects of nutrition on neurotransmitters; and 4) the effect of diet and nutrition on patients with malignant brain tumors.

Intravenous amiodarone in the treatment of various arrhythmias following cardiac operations.

In a group of 95 patients having cardiac operations with extracorporeal circulation, intravenous (IV) amiodarone, administered in doses of 2.5 to 5 mg/kg, was used in the treatment of various perioperative arrhythmias. Conversion to sinus rhythm was achieved in 55 (61%) of 90 patients with supraventricular arrhythmias, the other patients showing a satisfactory slowing of their heart rate. Total suppression and control was obtained in 18 patients with persistent ventricular extrasystoles associated with various supraventricular arrhythmias. Amiodarone was administered in five patients with life-threatening ventricular arrhythmias resistant to other antiarrhythmic agents: Suppression was obtained in one of two patients with recurrent ventricular tachycardias and control was achieved in three patients with repetitive ventricular tachycardia and ventricular fibrillation, allowing the effective use of intra-aortic balloon counterpulsation (IABP) needed for hemodynamic support. Seven patients experienced minor side effects such as nausea or flushing. No complete atrioventricular (AV) block was noted. Significant hypotension occurred at the end of the IV injection in 17 (18%) patients. In all but five patients, hypotenion was transient, without clinical complications. In the five others, adrenergic drugs in four cases and IABP in one case were necessary. Those five patients had marked cardiomegaly with poor myocardial contractility. IV bolus injection of amiodarone seems prohibited in such patients; constant infusion would be preferable.