What to order in lab tests and imaging for a patient with dementia after an unwitnessed fall?

Diagnostic Workup for Patients with Dementia After an Unwitnessed Fall

For a patient with dementia who has experienced an unwitnessed fall, a comprehensive neuroimaging evaluation with MRI is essential, along with targeted laboratory tests to identify potential causes of the fall.

Imaging Recommendations

Brain Imaging

• MRI is strongly preferred over CT due to its superior sensitivity for detecting vascular lesions and structural abnormalities 1
• If MRI is performed, the following sequences should be included:
  • 3D T1 volumetric sequence (with coronal reformations for hippocampal assessment)
  • Fluid-attenuated inversion recovery (FLAIR) to detect white matter changes
  • T2 or susceptibility-weighted imaging (SWI) to identify microhemorrhages
  • Diffusion-weighted imaging (DWI) to evaluate for acute infarcts 1, 2
• If CT must be used, obtain non-contrast CT with coronal reformations to assess hippocampal atrophy 1

Other Imaging Considerations

• Look specifically for evidence of:
  • Acute or subacute subdural hematoma
  • Cerebral contusions
  • Recent infarcts that could affect balance or coordination
  • White matter disease burden (using Fazekas scale)
  • Global cortical atrophy (using GCA scale) 1, 2

Laboratory Testing

Essential Tests

• Complete blood count
• Comprehensive metabolic panel (including electrolytes, renal function)
• Thyroid-stimulating hormone (TSH)
• Vitamin B12 level 3
• Hemoglobin A1C (if diabetes suspected)
• Urinalysis (to rule out urinary tract infection)

Additional Tests to Consider

• Medication levels (if on anticonvulsants, sedatives, or other medications with narrow therapeutic windows)
• Cardiac markers if chest pain or dyspnea present
• C-reactive protein if infection suspected 1

Clinical Assessment

Physical Examination

• Vital signs with orthostatic blood pressure measurements (significant predictor of falls in dementia) 4
• Neurological examination focusing on:
  • Focal deficits suggesting stroke
  • Extrapyramidal signs (parkinsonism)
  • Gait and balance assessment (timed gait if possible) 1
• Cardiovascular examination for arrhythmias or murmurs

Cognitive and Functional Assessment

• Brief cognitive assessment to establish current status and compare to baseline
• Assessment of functional abilities to determine impact of fall 1
• Evaluation for delirium using a standardized tool 5

Special Considerations

Fall Risk Factors to Evaluate

• Symptomatic orthostatic hypotension (HR: 2.13) - strongest modifiable predictor of falls in dementia 4
• Depression (assess using Cornell Depression Scale or similar tool) 4
• Autonomic symptoms 4
• Physical activity level (higher levels are protective) 4
• Medication review for drugs that increase fall risk:
  • Psychotropics
  • Antihypertensives
  • Sedatives
  • Anticholinergics

Dementia Subtype Considerations

• Patients with Lewy body disorders have significantly higher fall risk (HR: 3.33) 4
• History of falls in preceding 12 months increases risk of subsequent falls (HR: 2.52) 4

Practical Implementation

1. Order brain MRI with dementia protocol (or CT if MRI contraindicated)
2. Obtain basic laboratory tests (CBC, CMP, TSH, B12, UA)
3. Perform orthostatic vital signs and neurological examination
4. Review medications for fall risk contributors
5. Assess for depression and autonomic symptoms
6. Consider cardiology evaluation if cardiac etiology suspected

This approach prioritizes the detection of acute pathology that may require urgent intervention while also identifying modifiable risk factors to prevent future falls, which is critical for reducing morbidity and mortality in this vulnerable population.