Could a 69-year-old woman with severe non‑verbal dementia, recent falls, prolonged immobility, limb contractures, and markedly elevated creatine kinase and aldolase have myositis rather than traumatic rhabdomyolysis?

Diagnostic Differentiation: Myositis vs. Traumatic Rhabdomyolysis

In this 69-year-old woman with severe dementia, recent falls, prolonged immobility, and markedly elevated CK and aldolase, traumatic rhabdomyolysis from immobility and falls is far more likely than myositis, but the elevated aldolase warrants careful exclusion of inflammatory myopathy before attributing everything to trauma alone.

Key Distinguishing Clinical Features

Weakness Pattern Assessment

• Myositis presents primarily with true proximal muscle weakness (difficulty standing, lifting arms) rather than pain, which is the cardinal distinguishing feature 1
• In contrast, rhabdomyolysis typically presents with severe myalgia, muscle tenderness, and generalized weakness rather than isolated proximal weakness 2
• Given her severe dementia and contractures, assessing for true weakness versus inability to cooperate or move due to pain/contractures is critical 1

The Aldolase Elevation is Concerning

• While CK elevation alone strongly suggests traumatic rhabdomyolysis from falls and immobility 3, the concurrent aldolase elevation raises the possibility of inflammatory myopathy 4
• Aldolase can be selectively elevated in dermatomyositis and other inflammatory myopathies even when CK is proportionally less elevated 4
• However, aldolase is also elevated in rhabdomyolysis, so this finding alone is not diagnostic 5

Immediate Cardiac Assessment Required

Check troponin and ECG immediately to exclude myocarditis, as cardiac involvement would completely change management and require urgent cardiology consultation 1

• Myocarditis with myositis carries high mortality and requires permanent discontinuation of any causative agents 1
• This is the single most important initial test that alters the entire treatment paradigm 1

Clinical Context Strongly Favors Rhabdomyolysis

Multiple Risk Factors Present

• Prolonged immobilization is a well-established cause of severe rhabdomyolysis 3
• Recent falls provide direct traumatic muscle injury 3
• Limb contractures suggest chronic immobility, creating energy supply-demand mismatch in muscles 3
• CK levels in rhabdomyolysis can range from 10,000 to 200,000 or even approach 1 million in severe cases 6

EMG Findings Differ Dramatically

• Rhabdomyolysis typically shows normal EMG or only subtle changes in 74% of cases, with no persistent fibrillation potentials 2
• When abnormal in rhabdomyolysis, changes are subtle and present in only 1-3 proximal muscles 2
• In contrast, myositis shows prominent myopathic motor unit action potentials and muscle fibrillations on EMG 7, 1

Diagnostic Algorithm

Step 1: Exclude Cardiac Involvement

• Obtain troponin and ECG stat 1
• If positive, obtain echocardiogram or cardiac MRI and consult cardiology urgently 1

Step 2: Assess for True Weakness vs. Pain

• Attempt to document if she has proximal symmetric weakness limiting activities (recognizing dementia complicates this) 1
• Pain without weakness favors rhabdomyolysis 7, 2
• True proximal weakness favors myositis 1

Step 3: Skin Examination

• Carefully examine for Gottron's papules, heliotrope rash, V-sign, or shawl sign 8
• Absence of dermatomyositis rash makes inflammatory myopathy less likely 8

Step 4: Additional Laboratory Testing

• Obtain inflammatory markers (ESR, CRP) - these are typically very elevated in myositis 1
• Check AST, ALT, LDH to complete muscle enzyme panel 1
• Consider myositis-specific autoantibodies if clinical suspicion remains 9

Step 5: Advanced Testing if Diagnostic Uncertainty Persists

• EMG is the most useful discriminator: normal or minimally abnormal EMG strongly favors rhabdomyolysis over myositis 2
• MRI of proximal limbs can show inflammatory changes in myositis even with normal enzymes 8
• Muscle biopsy remains gold standard if diagnosis unclear after above workup 1

Management Approach

If Rhabdomyolysis (Most Likely)

• Aggressive hydration to maintain urine output >0.5 mL/kg/hour to prevent myoglobin-induced acute kidney injury 1
• Monitor serum creatinine twice daily 1
• Loop diuretics once euvolemia achieved 3
• Address underlying cause (mobilization, physical therapy as tolerated)

If Myositis Cannot Be Excluded

• Do not initiate corticosteroids empirically without stronger evidence, as this could worsen outcomes if infection or other causes are present
• If CK ≥3x upper limit of normal with documented true weakness and negative cardiac workup, consider prednisone 0.5-1 mg/kg/day 1
• Recheck CK, ESR, CRP weekly 1

Critical Pitfall to Avoid

The combination of dementia, falls, and immobility creates a classic setup for traumatic rhabdomyolysis that can produce extremely high CK levels 6. Do not reflexively diagnose myositis based on elevated muscle enzymes alone without documenting true proximal weakness and excluding the far more common traumatic/immobility-related causes in this clinical context 3, 2.