DEFINITION OF THE COMPLAINT
Altered mental status is a broad, nonspecific term that includes dysfunction of cognition, attention, awareness, or consciousness. Although not a defined disease, altered mental status is a symptom of an underlying disease process. The Glasgow Coma Scale provides a structured system for categorizing a child’s mental status based on eye opening, verbal, and motor response. The simpler AVPU (alert, verbal, pain, unresponsive) provides rapid classification of a child’s mental status. The onset of altered mental status is generally acute, chronic, or progressive and may be obvious or subtle in its presentation. This chapter will focus on the causes of acute altered mental status in children.
Although all disease processes that manifest themselves as an altered mental status are serious, life-threatening disorders must be recognized early and treated appropriately. The brain’s reticulated activating system mediates wakefulness and disruption of these neurons results in an altered mental status. Infection, toxin-mediated, metabolic, and traumatic injury are the most common life-threatening disorders affecting the reticulated activating system. Unfortunately, the presentation of even the life-threatening disorders can be subtle and a high index of suspicion is necessary for proper diagnosis.
COMPLAINT BY CAUSE AND FREQUENCY
Altered mental status does not constitute a diagnosis, but it is a symptom of an underlying disease process that requires a thorough investigation. The causes of altered mental status in childhood vary by age (Table 8-1) and may also be grouped based on the following etiologies (Table 8-2).
TABLE 8-1. Causes of altered mental status in childhood by age.
TABLE 8-2. Causes of altered mental status by etiology.
A thorough history is necessary in any child presenting with an altered mental status. Precipitating factors and associated clinical features provide a useful framework for creating a differential diagnosis. The following questions may help provide clues to the diagnosis:
• Was there a preceding illness or fever?
—Meningitis is a life-threatening cause of altered mental status and efforts should be made to immediately address this possibility. Toxic appearance, fever, and nuchal rigidity should prompt aggressive use of antibiotics pending cerebrospinal fluid (CSF) cultures. Rashes characteristic of varicella, Mycoplasma pneumoniae and Rocky Mountain spotted fever should be explored as possible causes of encephalitis. Shigatoxin release accompanying Shigellagastroenteritis and cerebellitis following varicella and other viral infections may result in an altered mental status.
• Is there a history of ingestion or toxin exposure?
—Drug ingestion of only one tablet can be life threatening to a little toddler. Examples include clonidine, Beta-blockers, and calcium antagonists. Attention should be placed on defining the medications present in the home that the child has the potential to ingest. Furthermore, illness among other family members should prompt concerns of carbon monoxide. It is also important to remember that toxicologic screens do not test for a number of potentially harmful toxins including clonidine, organophosphates, and LSD.
• Is there a history of head trauma?
—Head trauma at any age can present as an altered mental status. It is also important to remember that intracranial injury can present greater than 24 hours after the initial injury. Evidence of increased intracranial pressure, vomiting, severe headache, or focal neurologic examination should prompt emergent neuroimaging to rule out intracranial hemorrhage.