A 2-year-old girl with cerebral palsy presents with severe spasticity affecting her lower limbs, limiting her mobility and causing pain. Physiotherapy and oral baclofen have provided inadequate relief. What is the drug of choice for intrathecal administration in this case?

Explanation

## Intrathecal Baclofen in Cerebral Palsy Spasticity ### Clinical Context Cerebral palsy is the most common motor disorder in children, and spasticity is a major comorbidity affecting quality of life and function. When oral antispasticity agents fail to provide adequate relief, **intrathecal baclofen (ITB)** via pump infusion is the gold-standard intervention. ### Drug of Choice: Baclofen (Intrathecal) **Key Point:** Baclofen is a GABA~B~ receptor agonist that acts at the spinal cord level to reduce excitatory neurotransmitter release. When delivered intrathecally, it achieves high local concentrations with minimal systemic side effects—the defining advantage over oral formulations. ### Why Intrathecal Baclofen is Preferred | Aspect | Intrathecal Baclofen | Oral Baclofen | Dantrolene | Tizanidine | |--------|----------------------|---------------|-----------|----------| | **Efficacy in severe spasticity** | ✓ Excellent (80–90% reduction) | ✗ Limited in severe cases | ✗ Moderate | ✗ Moderate | | **Route for refractory cases** | ✓ Yes (pump infusion) | ✗ Systemic only | ✗ Systemic only | ✗ Systemic only | | **Mechanism** | GABA~B~ agonist (spinal) | GABA~B~ agonist (spinal + CNS) | Direct muscle relaxant | α~2~-adrenergic agonist | | **CNS side effects** | ✓ Minimal (local delivery) | ✗ Significant (sedation, weakness) | ✗ Hepatotoxicity risk | ✗ Hypotension, sedation | | **Pediatric evidence** | ✓ Gold-standard in CP | ✓ First-line oral agent | ✗ Limited pediatric use | ✗ Second-line | | **Reversibility** | ✓ Yes (pump can be stopped) | ✓ Yes | ✗ Irreversible effects | ✓ Yes | **Clinical Pearl:** Intrathecal baclofen is particularly effective in cerebral palsy because: - It bypasses the blood-brain barrier, achieving 600–1000 times higher spinal cord concentrations than oral dosing - It reduces spasticity without causing generalized weakness or sedation - It improves function, reduces pain, and facilitates rehabilitation - It is reversible: if complications occur, the pump can be stopped or removed **High-Yield:** The **intrathecal pump** (programmable or fixed-rate) is implanted surgically, with the catheter tip placed in the lumbar subarachnoid space. This is the **gold-standard intervention** for severe, refractory spasticity in cerebral palsy when conservative measures fail. ### Indications for Intrathecal Baclofen in Pediatric CP 1. Severe spasticity refractory to oral agents and physiotherapy 2. Spasticity limiting mobility, causing pain, or interfering with care 3. Age ≥4 years (though used in younger children in specialized centers) 4. Adequate cognitive function or caregiver support for pump management ### Dosing and Monitoring - **Initial bolus test:** 50 μg intrathecal dose to confirm efficacy and tolerability - **Maintenance:** Programmable pumps allow dose titration (typical range 200–1200 μg/day) - **Monitoring:** Regular follow-up for pump function, catheter patency, and tolerance development