Introduction Fluid and electrolyte disturbances are commonly seen in children after acute central nervous system (CNS) injury. Cerebral salt wasting syndrome, syndrome of inappropriate secretion of Anti-Diuretic hormone (SIADH) and central diabetes insipidus (CDI) are frequently observed disorders after acute CNS insults.

Aim This study aimed to assess water and sodium homeostasis in critically ill children who were subjected to acute central nervous system insults.

Methods The study included 31 critically ill children ranging from 1 month to 6 years who were subjected to acute CNS insults such as CNS infections, hypoxic ischaemic events, intracranial haemorrhage and status epilepticus. Serum and urinary sodium and osmolality, as well as sodium balance were measured in the studied subjects at day 1 and day 5 after acute CNS insult. Serum Anti-Diuretic Hormone levels were also measured at Days 1 and 5 From CNS insults.

Results Thirteen (41.9%) of the studied cases did not have any changes in their serum sodium levels after acute central nervous system insult, whereas 8 patients (25.8%) have become hyponatremic, 3 patients of them (9.7%) were diagnosed as cerebral salt wasting syndrome, while 5 patients (16.1%) were hyponatremic due to other causes mainly SIADH. Ten patients (32.3%) have become hypernatremic after acute central nervous system insult, 6 of them (19.4%) were due to confirmed central diabetes insipidus, while the other 4 patients (12.9%) had unconfirmed central diabetes insipidus. Regarding water balance disturbances, all our studied patients with acute central nervous system insult were found to be polyuric with urinary output > 3 cc/kg/hour.

Conclusion We concluded that definite diagnosis of water and sodium disturbances is very important for accurately distinguishing these disease entities from one another, since treatment strategies differ completely for each entity.