Kids With Altered Mental Status: No Diagnosis Is Pretty Common

Finding the Cause of Altered Mental Status in Children

Altered mental status can be a challenging diagnosis to deal with in any setting, including the emergency department (ED), where higher volume and ill patients make focusing on any one patient more difficult. A recent study by Button and colleagues^[1] aimed to identify etiologies of altered mental status in children presenting to the ED and to characterize the yield of diagnostic testing in these patients.

This study was a retrospective review of children treated in 2014 at one pediatric ED. The children, aged 1-17 years, were identified using the institution's electronic health record. Data collected included demographic information (age, gender, race), the presence of complicating medical conditions, family history, clinical data (examination findings; test results, including imaging), the final diagnosis (if made), and an estimation of whether the laboratory or radiologic test results contributed to the diagnosis (the yield of each test type).

Diagnoses were categorized as immediate (those evident at triage) or definite (established after examination and laboratory testing), probable (if the etiology was highly suspected in the ED but not confirmed with test results), or "unknown." Etiologies were further grouped as neurologic, toxicologic, infectious, traumatic, psychiatric, structural, endocrine, metabolic, or "other." Finally, investigators determined how the diagnoses varied by age of the child.

Only 10% of all diagnostic tests were abnormal and contributed to finding a diagnosis.

The study included 336 children, approximately 34% of whom were aged 1-5 years, 28% were aged 6-12 years, and 38% were aged 13-17 years. Boys comprised 58% of the cohort, and there was a reasonable racial and ethnic distribution. Before the index ED visit, 64% had at least one existing diagnosis.

Immediate diagnoses were apparent in 34% of the children. Among the remainder, a definite diagnosis was established in 41% and a probable diagnosis in 41%. That left 40 children, about 12% of the entire group, without a diagnosis.

The presence of an underlying chronic condition did not correlate with the ability to establish a definite diagnosis. About one quarter (24%) of all diagnoses were in the category of neurologic etiologies, followed by toxicologic (21%) and infectious (14%) causes. Age-related differences were apparent, with neurologic causes being the most common reason for a change in mental status for children up to age 12. In contrast, toxicologic reasons for changes in mental status were the most common etiology in teens, accounting for 43% of the diagnoses in those aged 13-17 years.

In terms of diagnostic testing yield, lumbar puncture had the highest yield (42%), but only 11 patients received a lumbar puncture. MRI of the head/neck had a yield of approximately 32%, and head CT had a yield of 19%. Overall, only 10% of all diagnostic tests were abnormal and contributed to finding a diagnosis.

Some of the least helpful tests were liver function tests, serum lactate level, and ultrasound for intussusception, none of which contributed to making a diagnosis in any child. Electrocardiograms had a yield of 3%.

The investigators concluded that neurologic and toxicologic etiologies are the most prevalent among children presenting to the ED with altered mental status, but in a large proportion of such children, no cause can be found for their signs and symptoms during the ED visit.

Viewpoint

Altered mental status in children is a concerning chief complaint, regardless of clinical setting. It is probably worth emphasizing that of all diagnoses made, both immediately and following diagnostic testing, 25%-27% were neurologic, among children of any age. Toxicologic causes were established in 10%-15% of younger children and 43% of adolescents. For all other etiologies, very few age-related differences were found except for infectious causes, which were present in about 21% of the youngest children (aged 1-6 years) compared with 12% of the older children.

Only 10% of all diagnostic tests performed were abnormal and contributed to a diagnosis. And another interesting fact: Despite the low yield, the median number of diagnostic tests per patient was six.

An important take-home message is that practitioners should not be surprised to find that they can't make a diagnosis in about 1 of every 10 children presenting with altered mental status—and almost 1 out of 5 of those whose diagnosis is not immediately obvious.

Being comfortable with that fact is part of the "art of medicine."

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