What review of systems and initial workup should be performed for a patient presenting with decreased sensorium?

Review of Systems and Initial Workup for Decreased Sensorium

Immediately assess airway patency and intubate if Glasgow Coma Scale ≤8, as this is the highest priority intervention to prevent aspiration and hypoxic brain injury. 1

Immediate Bedside Assessment (First 5 Minutes)

Check fingerstick glucose before any other intervention, as hypoglycemia causes permanent neurological damage if untreated and is rapidly reversible. 1

• Administer thiamine 500mg IV before giving glucose in any patient with malnutrition, alcoholism, or risk factors for deficiency to prevent precipitating Wernicke encephalopathy. 1
• Give IV dextrose immediately after thiamine if hypoglycemia is confirmed. 1
• Administer naloxone if opioid toxicity is suspected based on pinpoint pupils, respiratory depression, or known substance use history. 1

Vital Signs Documentation

Document the following systematically, as each pattern suggests specific etiologies: 1

• Fever suggests infection (meningitis, encephalitis, sepsis)
• Hypotension suggests shock or sepsis
• Hypertension may indicate intracranial pathology or hypertensive encephalopathy
• Abnormal respiratory patterns may indicate brainstem dysfunction or metabolic derangement

Objective Mental Status Quantification

Quantify mental status using Glasgow Coma Scale or FOUR score rather than subjective descriptors like "lethargic" or "confused." 1 This provides reproducible documentation for monitoring progression.

Focused Neurological Examination

Perform a focused neurological examination specifically looking for focal deficits, as these findings substantially increase the likelihood of a structural brain lesion requiring urgent imaging: 1

• Pupillary response and size (pinpoint suggests opioids; dilated suggests anticholinergics)
• Extraocular movements and nystagmus
• Facial symmetry
• Motor strength and tone in all extremities
• Deep tendon reflexes and plantar responses
• Gait assessment if patient is ambulatory
• Downbeating or gaze-evoked nystagmus suggests posterior fossa pathology 2
• Focal weakness, dysarthria, hemiataxia suggest stroke or structural lesion 2

Critical History Elements

Obtain the following from patient, family, or emergency contacts: 1

• Temporal profile: Sudden onset (stroke, trauma) vs. gradual (metabolic, infectious)
• Complete medication list including recent changes, as 20-25% of altered sensorium cases are toxicologic/pharmacologic 1
• Infectious symptoms: Fever, headache, neck stiffness, rash, cough, dysuria
• Recent trauma or falls history, especially in elderly or anticoagulated patients 1
• Substance use history including alcohol, illicit drugs, and over-the-counter medications
• Comorbid conditions: Diabetes, renal failure, liver disease, HIV/AIDS, malignancy 1
• Preceding fluctuating symptoms or prior episodes 2

Initial Laboratory Workup

Order immediately: 1

• Point-of-care glucose (already done at bedside)
• Complete metabolic panel (sodium, calcium, renal function, liver function)
• Complete blood count with differential
• Liver function tests
• Urinalysis
• Toxicology screen (urine and serum)
• Acetaminophen level when substance use is suspected or history is unclear 1
• Arterial blood gas if respiratory abnormalities present
• Thyroid function tests
• Ammonia level if liver disease suspected

Neuroimaging Decision Algorithm

Obtain non-contrast head CT immediately if ANY of the following are present: 1

• Focal neurological deficits
• History of head trauma or falls
• Current anticoagulation use
• Age >60 with unexplained altered mental status
• Severe headache or diplopia 2
• Suspicion of stroke or structural lesion

Consider MRI brain if CT is negative but high clinical suspicion exists for encephalitis, posterior circulation stroke, or inflammatory/autoimmune conditions. 1

Lumbar Puncture Considerations

Perform lumbar puncture when CNS infection is suspected, but only after neuroimaging rules out mass effect or increased intracranial pressure. 1

Send cerebrospinal fluid for: 1

• Cell count with differential
• Protein and glucose
• Gram stain and bacterial culture
• Viral PCR panel if encephalitis is suspected (HSV, VZV, enterovirus)

Empiric Treatment Protocol

Start empiric antibiotics and acyclovir immediately if meningitis or encephalitis cannot be excluded, even before lumbar puncture if there will be any delay in performing it: 1

• Vancomycin plus third-generation cephalosporin (ceftriaxone or cefotaxime) for suspected bacterial meningitis 1
• Add ampicillin if age >50 or immunocompromised (covers Listeria) 1
• Acyclovir 10mg/kg IV every 8 hours for possible herpes simplex encephalitis 1

Critical Pitfalls to Avoid

• Never attribute altered sensorium to psychiatric causes without completing full medical workup, as organic causes are far more common and missing them can be fatal. 1
• Consider multiple concurrent etiologies, especially in elderly patients who may have baseline dementia plus acute infection plus medication effect. 1
• Recognize that infective endocarditis presenting with altered sensorium may be due to intracranial mycotic aneurysm, which has 60% mortality and may present with headache, altered sensorium, or focal deficits before catastrophic rupture. 1
• Do not delay treatment for diagnostic testing when meningitis or encephalitis is suspected—blood cultures and empiric antibiotics should be given immediately. 1

Additional Sensory System Assessment

If patient stabilizes and no acute life-threatening cause is identified, consider: 2

• Hearing assessment with tuning fork testing (Weber and Rinne) to identify sudden sensorineural hearing loss, which may accompany certain neurological conditions 2
• Visual field and acuity testing if patient is cooperative
• Olfactory testing if temporal lobe pathology suspected