Which of the following statements about head injury and concomitant hyponatremia are true?

A. There are no primary alterations in cardiovascular signs.

DISCUSSION: Acute symptomatic hyponatremia is characterized by central nervous system signs of increased intracranial pressure. Changes in blood pressure and pulse are secondary to increased intracranial pressure. In the absence of hypovolemia, asymptomatic patients may be treated by restriction of water intake; however, in such patients, hyponatremia should be partially corrected by parenteral sodium administration. Rapid correction, particularly to hypernatremia, may lead to central pontine myelinolysis. Oliguric renal failure may rapidly develop in severe hyponatremia.