DEE's: Recognising Dravet Syndrome and  Lennox-Gastaut Syndrome

What is a DEE?

Developmental and epileptic encephalopathy (DEE) is a group of severe epilepsies that begin in infancy or childhood, characterized by frequent, drug-resistant seizures and significant developmental delays. The condition often leads to intellectual disabilities and other developmental issues due to both the underlying cause and the impact of the seizures themselves. Early diagnosis and treatment are crucial for improving long-term outcomes.^1,2

Diagnosing LGS

More accurate & earlier identification of LGS

Diagnosing LGS remains a significant challenge due to its varied clinical presentation and evolving symptoms. Even with established criteria, delayed or missed diagnoses are common.

To support clinicians, an international panel of epilepsy experts has developed a practical, easy-to-use checklist, which was sponsored by UCB, based on the International League Against Epilepsy (ILAE) criteria.

This checklist is designed to help both specialists and non-specialists identify LGS earlier and more accurately.

_{This is a supportive checklist and not to be used in isolation to make a diagnosis, individual clinical judgement must be applied. This checklist was presented as a poster (IEC, Lisbon, 2025), and is currently undergoing peer-review for publication. This checklist was sponsored by UCB.}

FIND THE CHECKLIST HERE

Recognising: Dravet Syndrome (DS)

Associated with drug-resistant seizures and multiple co-morbidities which impacts patient and families quality of life (QoL)^4,5

Misdiagnosis is frequent, an estimated 20% underdiagnosis in children & 60% in adults⁶

How to recognise DS:

Download Infographic

Convulsive seizures^4,7

Hemiclonic, Tonic, Clonic, Tonic-atonic, Generalised tonic-clonic, Focal with clearly observable motor signs

SCN1A mutation⁷

In 80-85% of patients

Cormorbidities and development⁴

Neurodevelopmental abnormalities, Impairment in motor control, Behavioural abnormalities, Neurodevelopmental delay

Age of onset⁷

Higher incidence of onset within the first year of life

NICE & HSE recommendation of the use of Fintepla

Fintepla^® (fenfluramine) is indicated for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome as an add-on therapy to other antiepileptic medicines for patients 2 years of age and older.¹³

Recognising: Lennox-Gastaut syndrome (LGS)

Download Infographic

Approximately 1-2% of all persons with epilepsy⁸

Diagnosis takes on average 12.3 months following first seizure⁸

Usually begins between 18 months and 8 years, peak age 3-5 years⁸

How to recognise DS:

Multiple types of drug-resistant seizures with onset prior to 18 years (one of which must include tonic seizures)^8,10-12

Diffuse slow spike-and-wave (<3Hz) and generalised paroxysmal fast activity on EEG⁸

Cognitive and often behavioural impairments, which may not be present at seizure onset^11,12

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Listen to Mike Taylor and guest speakers on Let's Talk about Dravet Syndrome discussing: The facts about DS, Neurodevelopmental impact of Dravet syndrome and lots more!

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Fintepla^®▼ (fenfluramine) is indicated for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome as an add-on therapy to other antiepileptic medicines for patients 2 years of age and older.¹

Rystiggo^®▼ (rozanolixizumab) is indicated as an add-on to standard therapy for the treatment of generalised myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibody positive.

Rystiggo currently not reimbursed on the NHS in Scotland.

Zilbrysq^®▼ (zilucoplan) is indicated as an add-on to standard therapy for the treatment of generalised myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive.

Abbreviations:

SUDEP, Sudden unexpected death in epilepsy; DS, Dravet syndrome; LGS, Lennox-Gastaut syndrome; GTCS, Generalised tonic-clonic seizures; ASM, Antiseizure medication; CI, Confidence interval; EAP, Early Access Programme.

References:

1. Lagae L, Sullivan J, Knupp K, et al. FAiRE DS Study Group. Lancet. 2019;394(10216):2243-54.

2. Epilepsy Foundation https://www.epilepsy.com/what-is-epilepsy/syndromes/developmental-and-epileptic-encephalopathy#What-is-developmental-and-epileptic-encephalopathy-(DEE)?. Accessed September 2025

3. Specchio N, Arzimanoglou A, Auvin S, et al. IEC 2025 poster. A checklist to support the diagnosis of Lennox-Gastaut syndrome. 2025

4. Lagae L, Irwin J, Gibson E, et al. Seizure. 2019;65:72-9.

5. Wirrell EC, Hood V, Knupp KG, et al. Epilepsia. 2022;63(7):1761–77.

6. Gil-Nagel A, Sanchez-Carpintero R, San Antonio V, et al. Rev Neurol. 2019;68(2):75–81.

7. Zuberi SM, Wirrell E, Yozawitz E, et al. Epilepsia. 2022;63(6);1349-97.

8. Specchio N, Wirrell EC, Scheffer IE, et al. Epilepsia. 2022;63:1398–442.

9. Strzelczyk A. 2024. EEC. Poster.

10. Cross JH, Auvin S, Falip M, et al. Front Neurol. 2017;8:505.

11. Reaven NL, Funk SE, Montouris GD, et al. Epilepsy Behav. 2018;88:66–73.

12. Knupp KG, Scheffer IE, Ceulemans B, et al. JAMA Neurol. 2022;79(6):554–64.

13. Fintepla^® Summary of Product Characteristics.