Volume 3, Case 15
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
To most effectively appreciate the findings in this case, it is recommended that you review the previous case (Case 14 in Volume 3, Severe Hypernatremia - Salt Poisoning) prior to reviewing this case.
A 3-year old male who is a recent immigrant from Asia is seen in a physician's office following a 4-minute seizure. He appears to be lethargic. Without much of an evaluation, his parents are told to drive him to the hospital for admission. He is seen on the pediatric ward by a first year resident who obtains the following information.
He has been in the U.S. for one month and has not seen a physician in the U.S. until today. He has been having fevers up to 40 degrees for the past two days. Today, he did not feel hot, but his parents describe a 4-minute generalized seizure. Over the past two days his condition has worsened. He is weak and can no longer get up or walk around. He has a mild cough, occasional loose stools, and about three episodes of emesis per day for the past two days. He has not been eating well. His only fluid intake has been three cups of rice soup per day. A friend told the family to spoon feed him a small amount at a time and they have tried to do this.
His past history is significant for "being a little slow". Further questioning reveals that he can only say two words (mother and father) in his native Asian language. His birthweight was 3.5 kg. He was bottle fed, but to date, he cannot feed himself. He must be fed by his parents (even before this illness). He is fed soft table foods. He underwent a language test in his birth country which he did very poorly on. He underwent a hearing test of some type which was reportedly normal. His vision is also in question since at an earlier age, he would bump into walls frequently. However, in the past 9 months, he has been doing this less often. One of his physicians in his birth country felt that he was autistic.
Exam: VS T37.4 (rectal), P120, R25, BP 88/64. Weight 15.5 kg (50th percentile), height 90th percentile. He is lethargic and moaning. His body is well developed and nourished. He has no dysmorphic features. He is not toxic or irritable. There is no respiratory distress evident. His visible perfusion and color are good. Head normocephalic without external signs of head trauma. Pupils 7mm and not reactive to light. His eyes are roughly conjugate, but he does not follow objects. His eyes do not blink with sudden confrontation. Fundi show sharp disc margins. However, the discs are extremely pale, practically resembling a large pit. There is no cup within the disc. The retina is very pale with a sparse paucity of blood vessels. Those blood vessels that are present are very thin. The normal vessels coming through the optic disc are extremely thin. His fundi are easy to view since his pupils are dilated and do not constrict.
His neck, heart, lungs, and abdomen are normal. His facial function is good. He is generally hyporeflexic and hypotonic. Babinski signs are positive bilaterally.
A CBC, chemistry panel, and a CT scan of the head are ordered. A complex patient is currently on the CT scanner and a delay of at least 2 hours is anticipated before our patient can be scanned (this case actually takes place in the early 1980's). The following lab results return before the CT scan is performed:
The first year resident contacts the senior resident and informs the senior resident that this patient has a sodium of 97 with non-reactive pupils. The first year resident is told that these findings are not compatible with life. The senior resident arrives and concurs that the pupils are dilated and non-reactive. He draws another blood sample via a radial artery puncture:
In evaluating a patient with hyponatremia, a urine sodium measurement is very useful in narrowing the differential diagnosis. However, the urine sodium must be obtained while the patient is hyponatremic for it to be useful. Once the patient is normonatremic, the urine sodium value can be anything. In hyponatremic patients, their urine sodium should be low (less than 10 mEq/liter). A high value indicates that the kidneys are inappropriately wasting sodium. Examples of such conditions include SIADH (syndrome of inappropriate antidiuretic hormone), mineralocorticoid deficiency (eg., Addisonian crisis), diuretics (eg., furosemide, thiazides, etc.), and a salt losing nephropathy (in a patient with renal disease). In the rush to correct our patient's hyponatremia, a urine sodium was ordered, however, it was not actually collected until the patient was already receiving sodium supplements.
There was some question as to whether this child was chronically water intoxicated as a result of child abuse. His non-reactive pupils and developmental delays could possibly represent a severe CNS injury sustained any time in the past.
Water intoxication has been described as a syndrome of child abuse if water is forcibly administered to a child, usually as punishment. Once water is forced in the mouth, if the child is too young to spit it out, it must be swallowed. Case reports of forced water intoxication describe children who were forced to drink many glasses of water. Another case described the parents forcing a water hose in the child's mouth. Another case described a child with severe hyponatremia due to water administration and water enemas. The water is often used as a punishment for bed wetting. These cases are often associated with other signs of child abuse such as fractures, bruises, burns, or failure to thrive. However, in the cases described in the literature, these children had sodium values in the 108 to 122 mEq/liter range.
After reviewing the previous case, Case 15 (Severe Hypernatremia - Salt Poisoning), the factors surrounding forcible salt poisoning and forcible water intoxication are very similar with respect to child abuse, however, the opposite extremes of sodium result.
Causes of hyponatremia not associated with deliberate child abuse include infant swimming lessons (infants swallow a lot of water while "swimming"), excessive dilution of infant formula, and drinking large amounts of cold water to help with a toothache. Teenagers and adults have been known to drink large amounts of water prior to urine drug testing to dilute their urine as much as possible to minimize the chance of drug detection.
Further history from our patient's family did not suggest child abuse. In addition to the child's mother, four siblings of the child were present. None of them noted that the child was fed an excessive amount of water.
Questions:
Can you explain his clinical findings ?
In summary, his findings consist of fever, a seizure, hyponatremia, hypokalemia, non-reactive pupils, blindness, optic atrophy, and developmental delays. However, he was able to walk around prior to his current illness.
The CT scan is completed.
View CT scan.
This CT scan shows a 2.5cm cystic partially calcified suprasellar mass which undergoes peripheral enhancement with contrast. This is most likely a craniopharyngioma. Other structures such as the tentorium are also enhancing.
His non-reactive pupils are due to erosion of the optic nerves. His fundoscopic findings are due to severe optic atrophy. It is difficult to believe that the child's family could not tell that he was blind. His motor and developmental delays are now well explained. It is amazing that this child could walk around. It is not surprising that he would bump into the walls since he could not see.
His severe hyponatremia is probably longstanding. Only a child with chronic hyponatremia would be able to tolerate such a low sodium value of 97 mEq/liter. Although this patient probably had long standing panhypopituitarism it is unclear why both his growth and his glucose homeostasis were satisfactory. One would expect that he should have growth hormone deficiency and insufficient adrenal stimulation.
Diabetes insipidus would not account for his hyponatremia since diabetes insipidus should result in hypernatremia. Hypoaldosteronism coupled with SIADH could explain this, but this degree of hyponatremia is so severe that a concomitant element of water intoxication cannot be ruled out.
It is usually taught that hypernatremia should be corrected slowly, while, if symptomatic (seizures, lethargy, etc.), hyponatremia can be corrected quickly. However, if the history suggests that the hyponatremia may be long standing, it may be prudent to correct the hyponatremia slowly (if the patient is not severely symptomatic) to prevent rapid fluid shifts between the intracellular and extracellular compartments that have been accustomed to a low sodium environment. This would be difficult to prove since such severe long standing hyponatremia is very uncommon.
References