USMLE Prep - Medical Reference Library

Brain Metastases - SRS Versus Whole Brain Selection

System: Radiation Oncology • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

For limited brain metastases favor stereotactic radiosurgery; reserve whole brain for diffuse disease or leptomeningeal spread and consider hippocampal avoidance.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

For Brain Metastases Srs Vs Whole Brain Selection, frame the differential by acuity and pathophysiology, then align diagnostics to the leading hypotheses. Prioritize stabilization while obtaining high‑yield studies such as CBC (Baseline hematology), BMP (Electrolytes/renal). Incorporate bedside imaging and targeted labs to define severity and identify complications; synthesize results with clinical trajectory to refine the working diagnosis and disposition needs.


Treatment Strategy & Disposition

Initiate disease‑directed therapy alongside supportive care, titrating to objective response. Pharmacologic options commonly include Analgesia/Antipyretics. Use validated frameworks (e.g., Typical Selection Clues) to guide escalation and site of care. Address precipitating factors, de‑escalate empiric therapies with data, and arrange follow‑up for monitoring and risk‑factor modification; admit patients with instability, high risk of deterioration, or needs for close monitoring.


Epidemiology / Risk Factors

  • Risk factors vary by condition and patient profile

Investigations

TestRole / RationaleTypical FindingsNotes
CBCBaseline hematologyAbnormal counts
BMPElectrolytes/renalDerangements

Typical Selection Clues

ScenarioApproach
1 to 4 small lesionsSRS
Numerous lesions or leptomeningealWhole brain
Large symptomatic lesionSurgery then SRS or radiation

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Dexamethasone (IV/PO)GlucocorticoidHoursReduce vasogenic edemaHyperglycemia
Levetiracetam (selected)SV2A modulationHoursSeizure prophylaxis/treatmentSomnolence

Prognosis / Complications

  • Prognosis depends on severity, comorbidities, and timeliness of care

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

Notes

Check prior cranial radiation. Discuss risks of radionecrosis and steroid use with SRS.


References

  1. ASTRO brain metastases guideline — Link
  2. NCCN Central Nervous System Cancers — Link