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# Lennox-Gastaut Syndrome (LGS)
## Overview
LGS is a severe form of childhood-onset epilepsy characterized by multiple seizure types (typically tonic, atonic, and atypical absence), characteristic slow spike-and-wave EEG patterns, and cognitive impairment. Management focus is on seizure reduction and quality of life.
## Primary Indications
Approved adjunctive therapies for seizures associated with LGS:
* Clobazam
* Rufinamide
* Topiramate
* Lamotrigine
* Felbamate
* Cannabidiol (CBD)
* Fenfluramine (newly indicated for LGS-associated seizures)
## Adult Dosing
* **Clobazam:** Start 5-10 mg/day; titrate to 20 mg/day (max 40 mg/day).
* **Rufinamide:** Start 400-800 mg/day; titrate to 3200 mg/day.
* **Topiramate:** Start 25-50 mg/day; titrate to 200-400 mg/day in two divided doses.
* **Cannabidiol:** Start 5 mg/kg BID; target 10 mg/kg BID.
* **Fenfluramine:** Start 0.2 mg/kg BID; target 0.35 mg/kg BID (max 26 mg/day).
## Pediatric Dosing
* **Clobazam:** (≥2 years) Weight-based titration. <30 kg: Start 5 mg/day; max 20 mg/day. ≥30 kg: Start 10 mg/day; max 40 mg/day.
* **Rufinamide:** (≥1 year) Start 10 mg/kg/day; titrate by 10 mg/kg increments to max 45 mg/kg/day (or 3200 mg/day, whichever is less).
* **Topiramate:** (≥2 years) Starting dose 1–3 mg/kg/day; titrate to 5–9 mg/kg/day in two divided doses.
* **Cannabidiol:** (≥1 year) Same as adults (10 mg/kg BID).
* **Felbamate:** (2-14 years) Not generally recommended; use only if refractory to all alternatives.
## Dose Adjustments
* **Renal:** Topiramate/Rufinamide require reduction in severe impairment (CrCl <30 mL/min).
* **Hepatic:** Clobazam and Cannabidiol require significant reduction in Child-Pugh class B or C.
* **Titration:** Most anti-seizure medications (ASMs) require slow titration to prevent skin rashes (Lamotrigine) or neurotoxicity.
## Contraindications
* **Felbamate:** History of aplastic anemia or hepatic failure.
* **Topiramate:** Significant history of nephrolithiasis or metabolic acidosis (e.g., on ketogenic diet).
* **Cannabidiol:** Hypersensitivity to cannabinoids.
## Adverse Effects
* **Clobazam:** Somnolence, drooling, respiratory depression.
* **Rufinamide:** Shortened QT interval (do not use in FHH syndrome).
* **Topiramate:** Cognitive slowing ("dopamax"), weight loss, nephrolithiasis, paresthesia.
* **Cannabidiol:** Somnolence, decreased appetite, elevated transaminases.
* **Felbamate:** Aplastic anemia, hepatotoxicity (requires frequent CBC/LFT monitoring).
## Key Drug Interactions
* **Clobazam:** Potentiates CNS depression with other sedative-hypnotics. CBD increases Clobazam levels via CYP2C19 inhibition.
* **Topiramate:** May decrease levels of oral contraceptives.
* **Valproate:** Significantly increases serum levels of Lamotrigine and Clobazam active metabolites.
## Monitoring
* **Baseline:** CBC with differential (if Felbamate), LFTs (for CBD, Felbamate, Valproate), EKG (if Rufinamide is used).
* **Ongoing:** Routine assessment for suicidality (all ASMs), LFTs, weight, and seizure frequency diaries.
## Clinical Pearls
* **Ketogenic Diet:** Highly effective in LGS and often considered early in treatment.
* **Titration:** "Start low, go slow" is critical to minimize cognitive and behavioral side effects in pediatric populations.
* **Polypharmacy:** LGS is often refractory; combinations (e.g., Clobazam + Valproate) are common but increase risk of adverse effects.
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**Disclaimer:** This information is for educational purposes and does not replace professional clinical judgment. Always verify current prescribing information, institutional protocols, and patient-specific factors before administration.
