Enhanced vagal activity and normal arginine vasopressin response in carotid sinus syndrome: implications for a central abnormality in carotid sinus hypersensitivity.

The relation between arginine vasopressin and vagal activity in carotid sinus syndrome was studied in 10 patients and 17 age matched controls using head up tilt as a stimulus. Of the controls, seven had unexplained syncope and 10 were healthy elderly subjects with no previous history of syncope. Subjects were studied supine for 45 min and thereafter during 120 min head up tilt to 40 degrees. Phasic arterial pressure and heart rate were monitored throughout. Serum was sampled at frequent intervals to measure arginine vasopressin, noradrenaline, and adrenaline concentrations. Seventy per cent of carotid sinus patients had vasovagal syncope at (mean(SD)) 25(4) min after tilt compared with 43% of subjects with unexplained syncope and one healthy elderly control. The maximum (mean(SD)) fall in systolic blood pressure and heart rate was 70(20) mmHg and 20(7) beats.min-1 (p less than 0.001 and p less than 0.01 respectively). Arginine vasopressin, noradrenaline, and adrenaline concentrations rose significantly in syncopal subjects (p less than 0.001, p less than 0.01, and p less than 0.05 respectively). Changes in systolic blood pressure, heart rate, and hormone concentrations were similar for patients with carotid sinus syndrome and control subjects. For those who completed the tilt period without the development of symptoms, systolic blood pressure and arginine vasopressin and adrenaline concentrations were unchanged, whereas noradrenaline concentrations and heart rate rose significantly. Vasovagal activity is thus appreciably increased in carotid sinus syndrome. Furthermore, the afferent limb of the carotid sinus reflex appears to be intact in patients with carotid sinus syndrome since the pattern of arginine vasopressin release was not different from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in the duration of the Achilles reflex in euthyroid goiter in children]. / Izmeneniia dlitel'nosti akhillova refleksa pri "éutireoidnom zobe" u detei.

Changes in the duration of the Achilles reflex were studied in subclinical disturbances of thyroid function. For this purpose the duration of the Achilles reflex, the levels of T4, T3, iodine protein bound TSH and cholesterol were investigated in children admitted to hospital with the general diagnosis of the "euthyroid goiter". Clinical and laboratory findings revealed subclinical types of the diffuse toxic goiter, hypothyrosis, chronic thyroiditis, endemic goiter, nodular goiter, pubertal struma and sporadic euthyroid goiter. The aim of the study was to define the diagnostic importance of reflexometry in subclinical disorders of thyroid function and to assess the relationships between metabolic derangements and the duration of the Achilles reflex. Changes in the duration were shown to correspond to disorder of thyroid function. In 76% of the cases reflexometry brought about the correct assessment of the patient's thyroid status. A significant conformity of the levels of TSH, T3, T4 to the duration of the Achilles reflex was shown.

Frequency and clinical progression of the vitamin E deficiency neurologic disorder in children with prolonged neonatal cholestasis.

To determine the frequency of biochemical vitamin E deficiency and of the clinical signs of the vitamin E deficiency neurologic syndrome in children with prolonged neonatal cholestatic disorders, we studied 46 children (aged 1 month to 17.0 years) with chronic forms of intrahepatic neonatal cholestasis and 47 children (aged 4 months to 8.0 years) with extrahepatic biliary atresia. Based on serum vitamin E concentrations and the ratios of serum vitamin E concentration to total serum lipid concentration, 64% of the intrahepatic and 77% of the extrahepatic cholestasis groups were vitamin E deficient. Prior to age 1 year, neurologic function was normal in all children. Between ages 1 and 3 years, neurologic abnormalities were present in approximately 50% of the vitamin E-deficient children; after age 3 years, neurologic abnormalities were present in all vitamin E-deficient children. Areflexia was the first abnormality to develop between ages 1 and 4 years; truncal and limb ataxia, peripheral neuropathy, and ophthalmoplegia developed between ages 3 and 6 years. Neurologic dysfunction progressed to a disabling combination of findings by ages 8 to 10 years in the majority of vitamin E-deficient children. Neurologic function was normal in the vitamin E-sufficient children. We conclude that vitamin E status should be evaluated in infants in whom cholestasis is diagnosed, and effective therapy should be initiated to prevent or treat vitamin E deficiency at an early age.

Effect of high haematocrit on alertness.

Patients with high-normal or above-normal haematocrit were found to have impaired alertness when compared with a control group matched for age and occupation. On retesting the controls had improved alertness scores attributable to a practice effect; but the patients, when retested after reduction of haematocrit by venesection, had improved significantly more than the controls. Improvement in alertness correlated very well with the increase in cerebral blood flow which followed venesection. Levels of venous haematocrit that are generally accepted as normal may not necessarily be optimum.

Autonomic hyperreflexia and its differentiation from pheochromocytoma.

Conceivably pheochromocytoma may have to be differentiated from autonomic hyperreflexia as the cause of paroxysmal hypertension. Elevated urinary catecholamine metabolites may occur in both conditions. However, marked elevations of serum dopamine-beta-hydroxylase (DBH) accompanied by relatively slight elevations of plasma catecholamines are observed during hypertensive paroxysms in patients with autonomic hyperreflexia, while marked elevations of plasma catecholamines with little if any change in serum DBH concentration are characteristic of hypertensive paroxysms caused by pheochromocytoma.