Please check your internet connection and try again.
# Lennox-Gastaut Syndrome (LGS)
## Overview
LGS is a severe form of childhood-onset epilepsy characterized by multiple seizure types (tonic, atonic, absence), slow spike-and-wave EEG patterns, and intellectual impairment. Treatment is often polytherapeutic and rarely leads to seizure freedom.
## Primary Indications
Adjunctive treatment for seizures associated with LGS in patients ≥1 year of age. Common agents include Clobazam, Rufinamide, Topiramate, Valproate, Lamotrigine, and Cannabidiol.
## Adult Dosing
* **Clobazam:** Start 5-10 mg/day; titrate weekly to 20-40 mg/day in divided doses.
* **Rufinamide:** Start 400-800 mg/day; titrate by 400-800 mg every 2 days to maximum 3,200 mg/day (divided).
* **Cannabidiol:** 10-20 mg/kg/day divided twice daily.
* **Topiramate:** 5-9 mg/kg/day (varies by weight); usually titrated slowly to 400 mg/day.
## Pediatric Dosing
* **Clobazam (≥2 yrs):** Weight-based; <30 kg start 5 mg/day, target 20 mg/day; ≥30 kg start 10 mg/day, target 40 mg/day.
* **Rufinamide (≥1 yr):** Start 10 mg/kg/day; titrate by 10 mg/kg increments every 2 days to max 45 mg/kg/day or 3,200 mg/day.
* **Cannabidiol (≥1 yr):** 5 mg/kg BID (10 mg/kg/day), titrate to 10 mg/kg BID (20 mg/kg/day) after 1 week.
* **Lamotrigine:** Requires very slow titration to mitigate SJS risk; follows specific cross-taper schedules based on concomitant valproate usage.
## Dose Adjustments
* **Renal/Hepatic:** Most anti-seizure medications (ASMs) require reduced starting doses and slower titration in hepatic impairment. Rufinamide is contraindicated in severe hepatic impairment.
* **Drug-Drug Interactions:** Valproate significantly increases lamotrigine and clobazam levels; doses must be reduced accordingly.
## Contraindications
* **Rufinamide:** Short QT syndrome.
* **Topiramate/Zonisamide:** History of nephrolithiasis or metabolic acidosis.
* **General:** Hypersensitivity to specific drug classes.
## Adverse Effects
* **CNS:** Somnolence, dizziness, ataxia, cognitive impairment, irritability.
* **Systemic:** Weight loss (topiramate/felbamate), weight gain (valproate), nephrolithiasis, metabolic acidosis, and skin rash (lamotrigine - monitor for SJS).
* **Cannabidiol:** Elevated transaminases (ALT/AST).
## Key Drug Interactions
* **Enzyme Inducers (Phenytoin/Carbamazepine):** Increase clearance of most ASMs, potentially requiring higher doses.
* **Valproate:** Potent inhibitor of UGT enzymes; significantly increases clobazam and lamotrigine concentrations.
* **Cannabidiol:** Increases levels of clobazam's active metabolite (N-desmethylclobazam), often necessitating a dose reduction of clobazam.
## Monitoring
* **Baseline/Routine:** CBC, LFTs, and electrolytes (bicarbonate).
* **Clinical:** Seizure frequency charts; monitor for signs of mood instability or suicidality.
* **Theophylline/Caffeine:** Monitor levels if using stiripentol, as it inhibits several CYP450 pathways.
## Clinical Pearls
* **Protocol Dependency:** Dosing protocols vary by institution; specific titration schedules for Lamotrigine and Topiramate must be strictly followed to minimize titration-related adverse events.
* **Polytherapy:** LGS is notoriously refractory; the addition of a third or fourth agent often yields diminishing returns vs. increased toxicity.
* **Cannabidiol:** FDA-approved synthetic CBD carries a risk of liver injury; monitor LFTs at baseline, and at 1, 3, and 6 months.
***
**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols vary. Always verify current prescribing information, black box warnings, and patient-specific contraindications via official manufacturer literature or institutional guidelines before administration.
