What is the initial evaluation and management of an adult with altered sensorium of unknown etiology?

Initial Evaluation and Management of Altered Sensorium in Adults

In an adult presenting with altered sensorium of unknown etiology, immediately assess and secure the airway, ensure adequate oxygenation with 100% oxygen via tight-fitting mask, obtain point-of-care glucose, and perform rapid neurological assessment while simultaneously investigating reversible causes.

Immediate Stabilization (First 5 Minutes)

Airway and Breathing Assessment

• Assess airway patency immediately using basic airway maneuvers (head tilt-chin lift or jaw thrust) as maintaining airway and facilitating breathing are the main priorities during any emergency where breathing is compromised 1.
• Provide 100% oxygen with a tightly fitting mask to optimize body oxygen stores before definitive airway control is possible 2.
• Position the patient appropriately to reduce aspiration risk, particularly if vomiting is present 3.
• Pulse oximetry is a poor indicator of airway compromise; decreasing arterial oxygen saturation is a late sign of impending hypoxemia 2.

Critical Point-of-Care Testing

• Check blood glucose immediately using point-of-care testing to rule out hypoglycemia as a reversible cause 3.
• Monitor oxygen saturation continuously 3.
• Assess neurological status using AVPU scale (Alert, Voice, Pain, Unresponsive) or Glasgow Coma Scale 3.

Pupillary and Vital Signs Assessment

• Check pupillary size and reaction for signs of raised intracranial pressure 3.
• Assess for bradycardia or heart block, which may indicate serious underlying pathology 4.
• Document vital signs looking for fever, hypotension, or other hemodynamic instability 3.

Focused Neurological Examination

Cranial Nerve and Motor Assessment

• Perform detailed sensorimotor examination with attention to eye movements, versions, ductions, saccades, pursuit, and vergence 4.
• Test facial sensation and assess for any focal neurological deficits 4.
• Evaluate for signs of stroke including unilateral weakness (face, arm, leg), speech disturbance, hemibody sensory loss, acute monocular visual loss, binocular diplopia, hemivisual loss, or dysmetria 4.

Specific Red Flags Requiring Urgent Imaging

• Asymmetric neurological findings warrant immediate brain imaging 4.
• Symptoms suggesting posterior circulation involvement (vertigo, diplopia, dysmetria) require urgent vascular imaging 4.
• Pupil-involving third nerve palsy is concerning for compressive lesion, especially posterior communicating artery aneurysm, and requires urgent neuroimaging with MRA or CTA 4.

Essential Laboratory Investigations

Routine Initial Labs

• Complete blood count (hematology) 4.
• Electrolytes including sodium, calcium, and magnesium 3.
• Renal function (creatinine, eGFR) 4.
• Coagulation studies (aPTT, INR) 4.
• Liver function tests based on clinical circumstances 3.

Targeted Additional Testing

• Electrocardiogram (ECG) to assess baseline cardiac rhythm and evidence of cardiac pathology 4.
• Consider serologic testing for infectious diseases (syphilis, Lyme disease) if clinical suspicion exists 4.
• Lumbar puncture if concern for meningitis or encephalitis, particularly with meningismus, excessive drowsiness, or incomplete recovery 3.

Neuroimaging Strategy

First-Line Imaging

• Brain CT without contrast is the initial imaging modality for rapid assessment of hemorrhage, mass effect, or acute stroke 4.
• CT angiography (CTA) from aortic arch to vertex should be performed at the time of brain CT to assess both extracranial and intracranial circulation 4.

Advanced Imaging Indications

• MRI with dedicated sequences is superior to CT for detecting retrocochlear pathology and soft-tissue abnormalities 4.
• MRI with gadolinium and MRA is recommended for pupil-involving third nerve palsy or when compressive lesion is suspected 4.
• High-resolution 3-D T2-weighted images provide submillimeter assessment when inner ear or cranial nerve pathology is suspected 4.

Management of Specific Scenarios

If Seizure Activity Present or Suspected

• Administer lorazepam 0.1 mg/kg IV/IO (maximum 4 mg) slowly at 2 mg/min if seizures are ongoing 3.
• If seizures persist, give levetiracetam 40 mg/kg IV bolus (maximum 2,500 mg) as slow infusion over 5-10 minutes 3.
• Alternatively, phenobarbital 15-20 mg/kg IV loading dose (maximum 1,000 mg) can be used as second-line therapy 3.

If Stroke Suspected

• Patients with motor weakness or speech disturbance within 48 hours are at HIGH risk and require same-day assessment at stroke center 4.
• Extracranial vascular imaging is essential to identify carotid stenosis for possible revascularization 4.

If Intubation Required

• Bag-valve-mask ventilation may be most effective for initial ventilatory support in emergency situations 1.
• Understand that drug-assisted intubation and positive pressure ventilation can cause reduced cardiac output, apnea, and hypoxia 5.
• Each intubation should be anticipated as potentially difficult 1.

Common Pitfalls to Avoid

• Do not rely solely on pulse oximetry as it provides late indication of airway compromise 2.
• Do not assume normal endocrinological or metabolic function in the absence of complaints; altered sensorium may be the presenting sign 4.
• Do not attribute all findings to a single cause without monitoring for progression; for example, parkinsonism attributed to antipsychotic medication requires ongoing assessment 4.
• Do not delay lumbar puncture if CNS infection is suspected, particularly if patient has not returned to baseline within 1 hour 3.
• Do not perform MRI if any concern about ferrous-metallic foreign body exists; CT is required in this scenario 4.

Disposition Criteria

Admission Indicated

• Prolonged altered mental status without return to baseline 3.
• Metabolic abnormalities requiring correction 3.
• Suspected CNS infection 3.
• Stroke or TIA within high-risk timeframe 4.

Discharge Considerations

• Patient has returned to baseline mental status 3.
• Normal neurological examination 3.
• No concerning features identified 3.
• Clear return instructions provided for recurrent symptoms 3.