Laboratory and Imaging Workup for New Onset Memory Changes with History of Cervical Fusion
For new onset memory changes, obtain a comprehensive metabolic panel, complete blood count, thyroid function tests (TSH), vitamin B12, homocysteine, ESR, and C-reactive protein to exclude reversible causes of cognitive impairment, and order MRI brain (or CT if contraindicated) to evaluate for structural lesions, vascular disease, and medial temporal lobe atrophy. 1
Essential Laboratory Tests
The following labs are critical to exclude reversible causes of cognitive decline:
- Thyroid function tests (TSH) - hypothyroidism is a treatable cause of cognitive impairment 1
- Vitamin B12 and homocysteine levels - B12 deficiency can present with memory changes 1
- Complete blood count (CBC) - to evaluate for anemia or infection 1
- Comprehensive metabolic panel - to assess electrolytes, renal function, glucose, and hepatic function 1
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) - to screen for inflammatory conditions 1
Vascular Risk Factor Assessment
Evaluate and document the following, as vascular factors impact dementia progression:
- Fasting glucose or HbA1c - diabetes is a modifiable risk factor for cognitive decline 2, 1
- Lipid panel - hyperlipidemia contributes to vascular cognitive impairment 1
- Blood pressure documentation - hypertension accelerates cognitive decline 2, 1
Neuroimaging Requirements
For Memory Changes
MRI brain is the preferred imaging modality (CT only if MRI is contraindicated) to:
- Exclude structural lesions including tumors, hydrocephalus, and hemorrhages 1
- Identify vascular lesions and stroke burden 1
- Assess for medial temporal lobe atrophy, a marker of Alzheimer's disease neurodegeneration 1
- Evaluate for increased signal intensity on T2-weighted imaging, which may indicate spinal cord pathology if cervical imaging is also obtained 3
For History of Cervical Fusion
Given the history of cervical fusion, obtain MRI of the cervical spine (or CT if MRI contraindicated) to:
- Assess fusion status and exclude pseudarthrosis, particularly if the patient has new neurological symptoms 4
- Evaluate for adjacent segment degeneration, which can cause new myelopathic symptoms that may present with cognitive complaints 3
- Rule out spinal cord compression at or adjacent to the fusion site 5
CT cervical spine with 2D reformatted images is more accurate than plain radiographs for assessing fusion status and should be considered if there is concern for hardware failure or pseudarthrosis 4
Additional Cognitive Assessment
Beyond labs and imaging, formal cognitive testing should be performed:
- Use validated instruments such as Montreal Cognitive Assessment (MoCA), Mini-Mental State Examination (MMSE), or Modified MMSE (3MS) to objectify the cognitive deficit 2, 1
- Assess functional status using tools like the Functional Activities Questionnaire (FAQ) to determine if instrumental activities of daily living are impaired 2, 1
- Screen for depression using Geriatric Depression Scale (GDS) or PHQ-9, as depression can mimic or coexist with cognitive impairment 2
Critical Exclusions
Before attributing symptoms to primary neurodegenerative disease, exclude:
- Recent delirium or acute medical illness 1
- Anticholinergic or sedative medication use - review medication list carefully 1
- Untreated sleep apnea - can cause cognitive impairment 1
- History of head trauma - obtain detailed history 1
- Cervical myelopathy - particularly relevant given the fusion history, as myelopathy can present with cognitive slowing 5, 3
Imaging of Thoracic and Lumbar Spine
MRI of the thoracic and lumbar spine is not routinely indicated for new onset memory changes alone. However, if there are accompanying symptoms suggesting myelopathy (gait imbalance, lower extremity weakness, bowel/bladder dysfunction) or if cervical imaging reveals multilevel disease, consider extending imaging caudally 5.