Anesthesia for Neurovascular Procedures

Pre-Op Neuro Check - Brainy Blueprint

• Objective: Baseline neuro status, risk identification, surgical optimization.
• BRAINY Assessment (📌):
  • Baseline: GCS (e.g., < 8), focal deficits, pupils.
  • Review Imaging: CT/MRI/Angio for lesion, edema, shift.
  • Airway & C-spine: Assess difficulty, instability.
  • ICP Signs: Headache, N/V, papilledema. Note Cushing's Triad (HTN, bradycardia, irregular respirations).
  • Necessary Labs: Coags (PT/INR, aPTT), electrolytes, glucose.
  • Your Meds: Antiplatelets (Aspirin hold 5-7 days), anticoagulants, anticonvulsants.

⭐ Cushing's triad (hypertension, bradycardia, irregular respirations) is a late, critical sign of markedly ↑ICP_._

Intra-Op Watchtower - Neuro-Guardians

Core Goals: Maintain CPP, ↓CMRO2, neuroprotection, surgical access, rapid emergence.

Key Monitoring:

• Standard ASA + IBP (A-line).
• Neuro-Specific:
  • EEG: Ischemia/seizures. Burst suppression: 1-5 bursts/min.
  • Evoked Potentials (EPs):
    • SSEP: Dorsal column. Alarm: ↓50% amplitude, ↑10% latency.
    • MEP: Corticospinal tract. Alarm: ↓>50-80% amplitude. (NMB caution)
    • BAEP: Brainstem.
  • NIRS (Cerebral Oximetry): rSO2. Alarm: ↓20-25% baseline or <50-55%.
  • TCD: Blood flow velocities.

Management Pearls:

• MAP targets: Procedure-specific (e.g., controlled hypotension).
• Ventilation: Normocapnia (PaCO2 35-40 mmHg).
• Brain relaxation: Mannitol ($0.25-1 \text{ g/kg}$), HTS.
• Temperature: Avoid hyperthermia.

⭐ During temporary aneurysm clipping, a >50% drop in SSEP/MEP amplitude warns of ischemia, may need clip adjustment.

Anesthesia Arsenal - Brain's Best Friends

• Goal: ↓ICP, ↓CMRO₂, maintain CPP, optimize surgical field.
• Induction:
  • Propofol: ↓CMRO₂/ICP/MAP. ICP dose: 1-2 mg/kg.
  • Etomidate: Stable hemodynamics, ↓CMRO₂/ICP. Risk: adrenal suppression.
  • Thiopental: Potent ↓CMRO₂/ICP.
• Maintenance - Inhalational:
  • Isoflurane, Sevoflurane: ↓CMRO₂. Keep <1 MAC (risk ↑CBF/ICP).
  • N₂O: Generally avoid (↑CBF, pneumocephalus).
• Opioids:
  • Remifentanil, Fentanyl: ↓CMRO₂. Minimal direct CBF/ICP effects.
• Muscle Relaxants:
  • Non-depolarizing (e.g., Vecuronium): Preferred.
  • Succinylcholine: Transient ↑ICP; consider defasciculation.
• ICP Management Adjuncts:
  • Lidocaine IV: 1.5 mg/kg (pre-intubation).
  • Mannitol: 0.25-1 g/kg. Hypertonic Saline (HTS).

⭐ Propofol is favored in neuroanesthesia: it reduces CMRO₂, CBF, and ICP, while preserving cerebrovascular CO₂ reactivity.

Vascular Hotspots - Procedure Playbook

• Universal: Maintain CPP (60-70 mmHg), brain relaxation, smooth emergence. IABP, neuromonitoring.
• Pharmacology: TIVA (Propofol/Remifentanil). Avoid N₂O, Ketamine (if ↑ICP).

⭐ During temporary aneurysm clipping, induced hypotension or brief adenosine-induced asystole can facilitate clip placement.

High‑Yield Points - ⚡ Biggest Takeaways

• Optimize Cerebral Perfusion Pressure (CPP), typically 60-80 mmHg, avoiding hypotension.
• Induced hypotension is a key strategy for aneurysm surgery to minimize bleeding.
• Rapid, smooth emergence is vital for immediate neurological assessment.
• Aggressively manage Intracranial Pressure (ICP), targeting <20 mmHg.
• Utilize neuromonitoring (e.g., SSEP, MEP, EEG) to detect ischemia early.
• Maintain normoglycemia and normothermia for optimal neuroprotection.
• Thrombectomy anesthesia: balance between GA and MAC based on patient stability.