Diencephalic and Frontal Lobe Lesions: Effect on Sodium Metabolism in Dogs

Introduction  Abnormalities of serum sodium levels and salt excretion in patients with cerebral disease have attracted considerable attention in recent years.^1-7 Persistent, excessive sodium loss in the urine with hyponatremia and even circulatory collapse is a rare syndrome which has been described in detail.⁶ Hypernatremia is much more common, may be complicated by azotemia, and occurs with particular frequency in patients with damage to the frontal lobes and/or hypothalamus.^1,7 It has been postulated that these latter cases are due to chronic dehydration, related in all probability to dulling of the sensation of thirst, with or without an associated diabetes insipidus.^8-10 However, such an explanation has not found universal acceptance.In experimental animals, Lewy and Gassman¹¹ found hyperchloremia and hypochloruria following passage of coagulating currents into the "paroptic" region of the hypothalamus, while Keeler¹² observed sodium diuresis in the first 24 hours after paraventricular lesions.