Is an MRI of the brain with or without contrast (Computerized Tomography) recommended for diagnosing tremor?

MRI of the Brain for Diagnosis of Tremor

MRI of the brain without IV contrast is usually appropriate for the initial imaging evaluation of patients with tremor, particularly when structural lesions or neurodegenerative changes are suspected. 1

Types of Tremor and Diagnostic Approach

Tremor is an involuntary, rhythmic, oscillatory movement of a body part that can be classified based on:

1. Activation condition:

   • Resting tremor (occurs when body part is relaxed)
   • Action tremor (occurs with voluntary muscle contraction)
     • Postural tremor
     • Kinetic tremor
     • Intention tremor

2. Common causes:

   • Enhanced physiologic tremor
   • Essential tremor
   • Parkinsonian tremor
   • Cerebellar tremor
   • Dystonic tremor
   • Drug-induced tremor

Imaging Recommendations

MRI Brain Without Contrast

• First-line imaging modality for evaluating tremor when structural or neurodegenerative causes are suspected 1
• Particularly valuable for detecting:
  • Structural lesions in the basal ganglia or cerebellum
  • Neurodegenerative changes
  • Iron deposition in the substantia nigra (in Parkinson's disease)
  • Cerebellar atrophy (in essential tremor or cerebellar disorders)

When to Add Contrast

• Contrast is typically not needed for the evaluation of most tremor syndromes 1
• Consider adding contrast only when:
  • Inflammatory conditions are suspected
  • Neoplastic causes are being considered
  • Infectious processes are in the differential diagnosis

Specific Imaging Findings by Tremor Type

Parkinsonian Tremor

• MRI may show:
  • Increased susceptibility in the substantia nigra
  • Thinning of the pars compacta
  • Diffuse blurring of borders between substantia nigra and red nucleus 1
  • Decreased magnetization transfer ratio and functional anisotropy within substantia nigra nuclei

Essential Tremor

• MRI findings may include:
  • Cerebellar atrophy
  • Volumetric changes in the thalamus 2
  • Often normal in early stages

Cerebellar Tremor

• MRI is crucial for evaluating:
  • Cerebellar atrophy
  • Demyelinating lesions
  • Vascular lesions
  • Structural abnormalities of the cerebellum 1

Advanced Imaging Considerations

Functional Neuroimaging

• I-123 ioflupane SPECT/CT (DaTscan) may be valuable for differentiating:
  • Parkinsonian syndromes from essential tremor
  • Drug-induced tremor from neurodegenerative causes 1
• A normal DaTscan essentially excludes Parkinsonian syndromes

When Standard MRI is Normal

• Consider advanced MRI techniques:
  • Susceptibility-weighted imaging (may show "swallow tail" sign in PD)
  • Diffusion tensor imaging
  • 7-T MRI (when available) has shown promise in differentiating healthy subjects from PD patients 1

Clinical Pitfalls and Caveats

• Imaging may be normal in early disease stages, particularly in essential tremor and early Parkinson's disease
• Structural imaging alone cannot definitively diagnose the cause of tremor - clinical correlation is essential
• Psychogenic tremor has no specific imaging findings - diagnosis is clinical
• Drug-induced tremor typically has normal imaging - medication review is crucial
• Enhanced physiologic tremor has normal imaging - clinical history (caffeine, anxiety, medications) is key

Algorithmic Approach to Imaging in Tremor

1. Initial evaluation: If tremor is the only symptom and no red flags, MRI brain without contrast
2. If parkinsonian features: MRI brain without contrast; consider DaTscan if diagnosis uncertain
3. If cerebellar signs: MRI brain without contrast; consider MRI with contrast if inflammatory/neoplastic cause suspected
4. If focal/unilateral tremor: MRI brain without contrast to rule out structural lesion
5. If normal imaging but high clinical suspicion: Consider advanced imaging techniques or functional imaging

MRI brain without contrast provides the best balance of diagnostic yield and patient safety for the initial evaluation of tremor when imaging is clinically indicated 1.