Headache After Spinal Anaesthesia: Pathophysiology and Treatment Options
Spinal anaesthesia is a widely used regional anaesthetic technique due to its efficacy, safety, and cost-effectiveness. However, post-dural puncture headache (PDPH) is a well-recognized complication following this procedure. This article explores the pathophysiology of PDPH, associated risk factors, and available treatment options.
Pathophysiology of PDPH
PDPH typically results from a dural puncture that allows cerebrospinal fluid (CSF) to leak from the subarachnoid space. This leakage leads to decreased intracranial pressure and compensatory cerebral vasodilation, both of which contribute to headache.
Key Mechanisms:
- CSF Leak and Intracranial Hypotension: The loss of CSF volume results in downward traction on pain-sensitive intracranial structures.
- Cerebral Vasodilation: In response to reduced CSF pressure, compensatory vasodilation occurs to maintain cranial blood flow, contributing to headache.
- Stretching of Meningeal Fibers: Intracranial hypotension may stretch pain-sensitive dura mater fibers, causing pain.
Risk Factors:
- Needle Size and Type: Larger gauge needles and cutting-tip needles increase the risk of dural tears.
- Patient Factors: Young age, female gender, and low BMI are associated with a higher incidence of PDPH.
- Procedure-Related Factors: Multiple puncture attempts, midline puncture site, and prolonged surgery are contributing factors.
Clinical Features
PDPH typically presents within 48 hours after dural puncture, though onset may be delayed. The hallmark symptoms include:
- Location: Frontal or occipital headache, often bilateral.
- Quality: Throbbing or pressure-like pain.
- Positional Nature: Worsens in the upright position and improves when lying down.
- Associated Symptoms: Nausea, vomiting, neck stiffness, dizziness, tinnitus, or photophobia.
Treatment Options
Effective management of PDPH aims to restore normal CSF dynamics and alleviate symptoms. Treatment strategies can be categorized into conservative, pharmacological, and invasive options.
1. Conservative Measures
- Bed Rest: Reduces CSF leakage by minimizing positional changes.
- Hydration: Encourages CSF production.
- Caffeine: Administered orally or intravenously, caffeine acts as a cerebral vasoconstrictor, relieving headache.
2. Pharmacological Interventions
- Analgesics: Paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) can provide symptom relief.
- Theophylline: A xanthine derivative that helps in CSF pressure stabilization.
- Epidural Saline or Dextran Injection: Bolus injections of saline can counteract the pressure drop temporarily.
3. Invasive Procedures
- Epidural Blood Patch (EBP): Considered the gold standard for PDPH treatment, EBP involves injecting autologous blood into the epidural space to seal the dural defect and stop CSF leakage.
- Effectiveness: Relief is achieved in 90% of cases within 24 hours.
- Timing: Performed when conservative measures fail or in severe cases.
- Sphenopalatine Ganglion Block: Emerging as a minimally invasive technique to manage PDPH.
- Surgical Repair: Rarely required, reserved for persistent CSF leaks that do not respond to other treatments.
Prevention Strategies
Minimizing the risk of PDPH is crucial and can be achieved through:
- Needle Selection: Use of smaller gauge, pencil-point needles (e.g., Whitacre or Sprotte).
- Optimal Technique: Ensuring a single, atraumatic dural puncture and proper needle alignment.
- Hydration and Monitoring: Ensuring adequate preoperative hydration and postoperative observation.
Conclusion
PDPH is a manageable complication of spinal anaesthesia with well-defined treatment strategies ranging from conservative to invasive options. Preventive measures, including the use of atraumatic needles and precise technique, are pivotal in reducing its incidence. Further research into minimally invasive interventions, such as sphenopalatine ganglion blocks, offers hope for improving PDPH management.
