Before Surgery Evaluation:

• Diagnosis:

  • MRI (brain and cervical spine, 90–95% of cases): Confirms tonsillar herniation (>5 mm), assesses syringomyelia or hydrocephalus.

  • Cine MRI (20–30%): Evaluates CSF flow dynamics at the foramen magnum to confirm obstruction.

  • Neurological Exam: Assesses symptoms (e.g., gait, reflexes, sensory deficits, cranial nerve function like swallowing or gag reflex).

  • Blood Tests: Checks coagulation (e.g., INR, platelets), hemoglobin, and infection markers to ensure surgical fitness.

• Preparation:

  • Medications: Pain relief for headaches (e.g., ibuprofen, paracetamol); steroids (e.g., dexamethasone) rarely used unless hydrocephalus present.

  • Fasting: 6–8 hours before general anesthesia.

  • Consent: Includes risks like CSF leak, infection, or neurological injury.

• Multidisciplinary Team: Involves neurosurgeon, anesthesiologist, neurologist (for pre/post-op assessment), and physiotherapist (if motor deficits present).

Surgical Techniques:

1. Posterior Fossa Decompression (Suboccipital Craniectomy, 80–90%):

   • Performed under general anesthesia, lasting 2–4 hours.

   • Process:

     • Patient positioned prone (face down) with head secured in a Mayfield clamp.

     • A midline incision (5–8 cm) is made from the base of the skull to the upper neck.

     • A small portion of the suboccipital bone (~3×3 cm) is removed to widen the foramen magnum.

     • The posterior arch of C1 vertebra (laminectomy) may be removed (50–60% of cases) to create additional space.

     • Dura (brain covering) is opened (durotomy) to inspect cerebellar tonsils and relieve compression.

     • In some cases, tonsils are gently shrunk (resection or electrocautery, 20–30%) to improve CSF flow.

     • A dural patch (synthetic or patient’s pericranium) is sewn in to expand the dura (duraplasty, 70–80% of cases).

     • Incision closed in layers with sutures; no hardware (e.g., plates) typically needed.

   • Tools: Surgical microscope, intraoperative ultrasound, neuromonitoring (to track brainstem/spinal cord function).

2. Additional Procedures (10–20%):

   • Syrinx Shunt: For persistent or large syringomyelia (rare, <5%; decompression often resolves syrinx).

   • Ventriculoperitoneal Shunt: For hydrocephalus (5–10%) to drain excess CSF.

3. Intraoperative Considerations:

   • Intraoperative ultrasound: Confirms CSF flow restoration.

   • Neuromonitoring: Tracks brainstem and spinal cord function to avoid injury (e.g., motor, sensory, or cranial nerve deficits).

   • Blood loss: Minimal (100–300 mL); transfusion rarely needed.

After Surgery:

• Monitoring: ICU for 1–2 days to watch for brain swelling, bleeding, or CSF leaks; then general ward.

• Hospital Stay: 3–7 days; longer (7–10 days) for complications (e.g., CSF leak, meningitis).

• Care:

  • Pain management: IV analgesics (e.g., morphine, tramadol) for 1–2 days, then oral (e.g., ibuprofen, paracetamol).

  • Antibiotics (e.g., cefazolin): 1–3 days to prevent infection.

  • Head elevation (30 degrees): Reduces CSF leak risk for 1–2 weeks.

  • Neurological checks: For signs of worsening (e.g., weakness, swallowing difficulty).

• Instructions:

  • Avoid straining (e.g., coughing, sneezing, heavy lifting >5 kg) for 6–8 weeks to prevent CSF leak.

  • Keep incision dry for 7–10 days; sutures/staples removed at 10–14 days.

  • Follow-up MRI at 3–6 months to assess CSF flow and syrinx resolution.