Neurological Complications

CNS Complications: Stroke & Seizures - Brainy Blues

• Perioperative Stroke:
  • Incidence: 0.1-1%; ↑ risk in cardiac, neuro, major vascular surgery.
  • Types: Ischemic (~80%; e.g., hypotension, embolism); Hemorrhagic (e.g., HTN, anticoagulation).
  • Risk Factors: Age >65, prior stroke, HTN, DM, AF.
  • Prevention: Maintain MAP ±20% baseline; avoid severe hypocapnia; glycemic control.
  • Mgmt: ABCs, neuro consult, imaging, specific therapy.
• Perioperative Seizures:
  • Causes: Hypoxia, hypoglycemia, electrolytes (Na↓, Ca↓, Mg↓), drugs (LA toxicity, meperidine, tramadol), withdrawal, epilepsy.
  • Mgmt:
    • ABCs, 100% O2.
    • Terminate: Benzodiazepines (IV lorazepam 0.1 mg/kg).
    • Second-line: Phenytoin, levetiracetam.
    • Treat cause.

  ⭐ Perioperative strokes are predominantly ischemic, often linked to intraoperative hypotension or embolic events.

Cognition & Awareness - Mind Matters

• Postoperative Cognitive Dysfunction (POCD):
  • Subtle, persistent decline in cognitive functions (memory, concentration) post-surgery.
  • Risk factors: Age >60 years, pre-existing cognitive impairment, major surgery (especially cardiac), longer anaesthesia duration.
  • Prevention: Multimodal approach; optimize baseline health, consider regional techniques, effective pain management.
• Postoperative Delirium:
  • Acute, fluctuating disturbance in attention, awareness, and cognition.
  • Risk factors: Elderly, polypharmacy (benzodiazepines, anticholinergics), infection, metabolic disturbances, ICU stay.
  • Assessment: Confusion Assessment Method (CAM).
  • Management: Treat underlying cause, supportive care, reorientation, environmental modifications.
• Awareness with Recall (AWR):
  • Explicit recall of intraoperative events. Incidence: 0.1-0.2%.
  • Higher risk: Cardiac surgery, trauma, C-sections, TIVA, inadequate anaesthetic depth, muscle relaxant use.
  • Prevention: Depth of anaesthesia monitoring (e.g., BIS target 40-60), end-tidal anaesthetic concentration (ETAC) monitoring.
  • 📌 Mnemonic AWARE: Anaesthesia depth inadequate, Woman (higher risk), Anaesthetic delivery issues, Relaxants used, Emergency surgery/trauma.

⭐ BIS monitoring with a target range of 40-60 is a key strategy to minimize the risk of Awareness with Recall during general anaesthesia.

Spinal Cord & PNS Injuries - Nerve Knots

• Neuraxial Catheter Knotting:
  • A rare complication involving epidural or spinal catheters.
  • Risk factors: excessive insertion length (e.g., > 5 cm beyond needle tip for epidural; > 2-3 cm for spinal), coiling of catheter, significant patient movement.
  • Clinical signs: difficulty with injection or aspiration, unusual resistance during catheter removal, new-onset paresthesia.
  • Management: gentle, steady traction; altering patient position; injecting saline to distend space; fluoroscopic guidance for removal. Surgical intervention is rarely required.
  • Prevention: limit catheter insertion depth to minimum effective length, secure catheter properly.
• Focal Nerve Lesions (Perceived as "Knots"):
  • Etiology: direct trauma from needle, sustained compression (e.g., improper patient positioning), hematoma formation, excessive nerve stretch.
  • Commonly affected nerves: ulnar nerve (at elbow), brachial plexus, common peroneal nerve (at fibular head), sciatic nerve.
  • Symptoms: localized pain, paresthesia, numbness, or motor weakness corresponding to the affected nerve's distribution.
  • Prevention: meticulous anesthetic technique, careful patient positioning with adequate padding, avoiding extreme joint positions, regular checks.

⭐ Ulnar neuropathy is the most frequently reported perioperative peripheral nerve injury, typically resulting from compression or stretch of the nerve at the elbow.

Prevention & Management - Safe Signals

• Prevention Strategies:
  • Pre-anesthetic: Detailed neuro Hx, risk stratification (elderly, DM, PVD, prior neuro deficit).
  • Positioning: Careful padding, limit extreme positions, avoid nerve compression/stretch (brachial plexus, ulnar, common peroneal).
  • Physiological: Maintain normotension (MAP >65-70 mmHg), normoxia, normocapnia, euglycemia, normothermia.
  • Regional: Ultrasound guidance, low injection pressure, incremental dosing, avoid neurotoxic additives.
• Intraoperative Monitoring (Safe Signals):
  • Standard ASA monitors. Consider arterial line for beat-to-beat BP.
  • Advanced (high-risk): IONM (SSEP, MEPs, BAEPs, EMG) to detect early compromise.
• Post-operative Management Protocol:

⭐ During regional anesthesia, if patient reports sharp pain or paresthesia on injection ("electric shock"), withdraw needle immediately to prevent intraneural injection. (📌 Mnemonic: Stop Pain Alerts Nerve = SPAN)

High‑Yield Points - ⚡ Biggest Takeaways

• POCD & delirium are frequent post-op, especially in elderly patients.
• Perioperative stroke risk factors: hypotension, hypoxia, major cardiac/carotid surgery.
• Seizures can be due to LA toxicity, hypoxia, hypoglycemia, or specific drugs.
• Awareness with recall: Higher risk with TIVA, muscle relaxants, difficult intubation.
• Ulnar nerve is the most common peripheral nerve injury from malpositioning.
• Spinal epidural hematoma/abscess: Rare but critical causes of post-neuraxial cord injury.