Altered Sensorium Management

Initial Assessment and Intervention

• The American College of Radiology recommends brain imaging when there are focal neurological deficits, suspected intracranial pathology, or no clear metabolic/toxic cause identified, with MRI preferred when available, but CT appropriate for initial rapid assessment, and avoiding routine head CT in patients with clear metabolic causes of altered mental status 1
• Correct electrolyte abnormalities, such as sodium, calcium, or other imbalances, in patients with altered sensorium, as recommended by the American College of Radiology 1
• Perform a neurological assessment, including pupillary response, motor responses, meningeal signs, and focal neurological deficits, as recommended by the American College of Radiology 1
• Assess for altered mental status lasting ≥24 hours with no alternative cause as a major criterion for encephalitis diagnosis, as recommended by the International Encephalitis Consortium 2
• Document fever (≥38°C/100.4°F) and assess for signs of shock and orthostatic changes in patients with fever and altered sensorium 3

Diagnostic Considerations

• Evaluate mental status by assessing level of consciousness, personality changes, and lethargy 2
• Perform a neurological examination to check for focal neurological deficits, meningeal signs (neck stiffness, Kernig's and Brudzinski's signs), seizures, and cranial nerve abnormalities 4
• Note that the specificity of meningeal signs is high, but sensitivity can be as low as 5% 4

• Use the following minor criteria for possible encephalitis, as recommended by the International Encephalitis Consortium:

  Minor Criteria	Description
  Documented fever	≥38°C within 72 hours before/after presentation
  Seizures	Not attributable to pre-existing condition
  New focal neurological findings	-
  CSF WBC count	≥5/mm³
  Abnormal brain imaging	Suggestive of encephalitis
  EEG abnormalities	Consistent with encephalitis

  2

• Conduct essential laboratory tests, including complete blood count, blood cultures, basic metabolic panel, liver function tests, blood glucose, coagulation studies, and malaria testing if travel to endemic area within past year 5
• Obtain a detailed travel history for returning travelers with fever and consider tropical infections based on geographic exposure 5, 6
• The American Geriatrics Society warns against assuming altered sensorium in elderly patients is due to dementia without thorough evaluation 7

Treatment and Management

• Start empiric treatment for encephalitis and meningitis immediately, including acyclovir and appropriate antibiotics, while awaiting diagnostic results, as recommended by the American College of Physicians and other medical societies 3, 8
• Provide critical care, including airway management, fluid resuscitation, seizure management, and management of increased intracranial pressure 3, 8
• Treat probable encephalitis with empiric acyclovir (10 mg/kg IV every 8 hours) started immediately, as recommended by the International Encephalitis Consortium 2
• Consider adding antibacterial coverage if bacterial meningitis cannot be excluded 9
• Use broader antimicrobial coverage in immunocompromised patients due to atypical presentations 9
• Use continuous EEG monitoring for ≥24 hours to detect subclinical seizures, even in the absence of clinical seizures 10
• Do not use prophylactic antiseizure medications in the absence of clinical seizures, but use benzodiazepines (lorazepam 4 mg IV) as first-line treatment if seizures develop 10, 11
• Use levetiracetam (30-50 mg/kg IV) or valproate (20-30 mg/kg IV) as second-line options for seizure management 11
• Use head elevation, mild hyperventilation if needed, and osmotic agents if evidence of cerebral edema to manage increased intracranial pressure 9
• Continue acyclovir for 14-21 days if HSV encephalitis is confirmed 9
• Consider oseltamivir if influenza-associated encephalitis is suspected 12
• Add doxycycline if rickettsial disease is suspected 13
• Add ampicillin if Listeria is a concern, especially in immunocompromised patients 9
• Perform frequent neurological assessments, vital signs monitoring, and watch for signs of clinical seizures or neurological deterioration 9
• Conduct follow-up CSF analysis if initial results are inconclusive, serial EEGs to monitor for development of seizure activity, and renal function tests if on acyclovir (dose adjustment needed for renal impairment) 9
• Monitor patients with suspected encephalitis using frequent neurological assessments, continuous EEG monitoring, and serial CSF analysis 4, 5