What is the differential diagnosis and appropriate workup for an elderly male patient with a history of dementia who presents with vomiting and a head injury after a fall, with no reported pain or tenderness?

Differential Diagnosis and Workup for Elderly Male with Dementia, Vomiting, and Head Injury

Immediate Action Required

This patient requires emergent non-contrast head CT imaging based on multiple high-risk criteria: age >64 years, vomiting (occurred three times), and witnessed seizure-like activity with head trauma. 1, 2, 3

Differential Diagnosis

Primary Considerations (Life-Threatening)

• Traumatic intracranial hemorrhage (subdural hematoma, epidural hematoma, subarachnoid hemorrhage, or cerebral contusion) - elderly patients with dementia have increased fall risk and brain atrophy predisposing to subdural bleeds 1
• Seizure with postictal state - the witnessed episode of "tensing up" suggests possible seizure activity, which itself is a high-risk criterion for intracranial injury 1
• Acute stroke - focal neurologic events can present as seizure-like activity in elderly patients 1

Secondary Considerations

• Metabolic encephalopathy precipitating both seizure and vomiting (hypoglycemia, hyponatremia, uremia, hepatic encephalopathy) 4
• Infection (meningitis, encephalitis, or systemic infection with delirium) - can cause altered mental status, vomiting, and seizures 5
• Medication toxicity or withdrawal - particularly relevant in dementia patients who may have medication errors 5
• Intracranial mass lesion (tumor, abscess) - can present with seizures and vomiting 1

Dementia-Related Considerations

• Progression of underlying dementia with superimposed delirium from the traumatic event 4
• Subdural hematoma (acute or chronic) - elderly patients with dementia and brain atrophy are at particularly high risk 1, 6

Required Workup

Imaging (Highest Priority)

Head CT without contrast is mandatory and should be obtained immediately - this patient meets multiple Canadian CT Head Rule high-risk criteria: 1, 2, 3

• Age >64 years (sensitivity 100% for neurosurgical intervention)
• Vomiting more than once (occurred three times total)
• Suspected seizure activity
• Witnessed head trauma with inability to ambulate afterward

The NEXUS Head CT criteria are also met (age ≥65, persistent vomiting, abnormal behavior/alertness), further supporting immediate imaging 1

Laboratory Studies

Immediate labs required: 7, 3

• Complete blood count (assess for infection, anemia)
• Comprehensive metabolic panel (sodium, glucose, renal function, liver function)
• Coagulation studies (PT/INR, aPTT) - critical in elderly patients who may be on anticoagulation 7
• Troponin and ECG (cardiac syncope can mimic seizure)
• Blood glucose (point-of-care immediately)
• Urinalysis and urine culture (UTI common precipitant of delirium in dementia)

Additional labs if clinically indicated: 5

• Ammonia level (if hepatic encephalopathy suspected)
• Thyroid function tests (hypothyroidism can worsen cognition)
• Vitamin B12 and folate (reversible causes of cognitive decline)
• Drug levels if on anticonvulsants or other medications with narrow therapeutic windows

Neurologic Assessment

Document Glasgow Coma Scale score - failure to reach GCS 15 within 2 hours is a high-risk criterion 1

Perform focused neurologic examination looking for: 1, 7

• Focal neurologic deficits (weakness, sensory changes, cranial nerve abnormalities)
• Signs of basilar skull fracture (Battle sign, raccoon eyes, hemotympanum, CSF rhinorrhea/otorrhea)
• Scalp hematoma or evidence of skull fracture
• Pupillary asymmetry or abnormal reactivity
• Neck stiffness (if no contraindication to neck examination)

Additional Interventions

Seizure precautions should be implemented given the witnessed seizure-like activity 1

NPO status until intracranial pathology is ruled out, given recurrent vomiting 3

Continuous monitoring with frequent neurologic checks (every 15-30 minutes initially) 7

Review medication list - specifically assess for anticoagulants (warfarin, DOACs), antiplatelet agents (clopidogrel, aspirin >81mg), or medications that increase fall/seizure risk 7, 3

Critical Decision Points

If CT shows intracranial hemorrhage: 7

• Immediate neurosurgical consultation
• Reverse anticoagulation if applicable
• Admit for serial neurologic examinations
• Maintain mean arterial pressure ≥80 mmHg
• Avoid hypoxemia (maintain SaO2 >90%)

If CT is negative: 7, 3

• Patient may still require admission given seizure activity and recurrent vomiting
• Consider EEG if seizure suspected
• Pursue metabolic/infectious workup
• Provide written discharge instructions if stable for discharge (though admission likely warranted in this case)

Common Pitfalls to Avoid

Do not dismiss vomiting as benign gastroenteritis - vomiting is a validated predictor across all major clinical decision rules for intracranial injury 1, 3

Do not delay CT imaging - elderly patients with dementia and head trauma have significantly elevated risk of intracranial hemorrhage, and this patient has multiple high-risk criteria 1, 2

Do not assume the "seizure" was simply a fall - witnessed tonic activity with head strike requires full seizure and intracranial injury workup 1

Do not overlook anticoagulation status - patients on anticoagulation have 3.9% risk of intracranial hemorrhage versus 1.5% in non-anticoagulated patients and may require admission even with negative CT 7

Do not attribute all symptoms to dementia progression - this acute change requires full evaluation for reversible causes 4, 5