Issue 1

Frustrations With the LGS Diagnosis

by Christina SanInocencio

Christina is the Founder and President of the LGS Foundation. Her brother was diagnosed with LGS when he was 3. Christina brings her knowledge of LGS and experience of watching her own brother transition from childhood to adolescence and adulthood. Christina is a paid consultant of Eisai Inc.

About 4 years ago, I received a phone call from a mother whose 19-year-old daughter had just received the diagnosis of Lennox-Gastaut syndrome. For this mother, learning the name of the condition that had caused her daughter 18 years of uncontrolled seizures was bittersweet. At first, she was frightened. What does this diagnosis mean? Why have I not heard of it before? What will my daughter's future hold?

But shortly after, she expressed relief, not something you'd expect when you are given a diagnosis of a rare and potentially catastrophic condition. This mother realized that there were many benefits to finally knowing her daughter has LGS. She and her daughter were now part of a community of people whom they could learn from and bond with. For the first time, the mother felt like she fit in with people who knew exactly what she was going through. She now had an abundance of resources and information available to her through organizations like the LGS Foundation.

But the question she and many other LGS parents ask themselves is, "Why did it take so long to get the diagnosis of LGS?"

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Although the diagnosis shouldn't be difficult if the strict criteria are used, it may take time for a patient to present with all clinical and EEG characteristics.

Clinical presentation

The onset of Lennox-Gastaut syndrome usually occurs before age 8.1 The first clinical signs of LGS can begin with one or more seizure types,2 including:

  • Atonic — Known as drop attacks1 because they cause head nods, loss of posture, and sagging at the knees2
  • Tonic — Also known as drop attacks,1 and characterized by muscle tightening (this can happen to a specific set of muscles, or most muscle groups at once), eyes rolling back, and pupil dilation. Doctors won't diagnose LGS if a child doesn't have this type of seizure1
  • Tonic-clonic — In the first phase of this type of seizure, the stiffening associated with tonic seizures occurs. It then gradually changes to the clonic phase, in which the muscles quickly switch between contraction and relaxation3
  • Atypical absence — This seizure is usually characterized by staring, pauses in activity, and a lack of response2

In addition, children with LGS may also experience clonic,3 myoclonic,2 and partial seizures.4

Some patients may also have nonconvulsive status epilepticus (prolonged seizures whose symptoms are confusion or abnormal behavior instead of physical symptoms).1 Although 20% to 30% of children with LGS develop normally prior to the onset of symptoms, cognitive impairment (the inability to remember things, learn new things, concentrate, or make simple decisions) will likely appear during the evolution of LGS.5


The diagnosis

After seizures begin, doctors may try to treat each seizure type with a specific medication before making the diagnosis of LGS. This results in a trial and error process to find the best combination of medications with the fewest side effects. This process can take a long time. It can be very frustrating for the patients and their caregivers.

In addition, physicians will look for a number of signs. These include a history of infantile spasms or an underlying brain condition. During the evaluation, the physician may order brain imaging and genetic or metabolic testing.

Unlike some rare diseases, LGS is not identifiable by simple genetic tests or one single symptom. Therefore, physicians need to make the diagnosis based on a combination of clinical and EEG results. The classic LGS diagnostic criteria consist of 3 features:

  • multiple seizure types
  • cognitive impairment or developmental delays
  • a slow spike-wave EEG pattern5

However, there is some debate by clinicians about whether the criteria for diagnosing LGS are too broad or too strict and if the term LGS may be overused to describe severe, childhood-onset epilepsies that are hard to diagnose.1

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What parents can do

LGS is a complicated syndrome with many causes and outcomes. Although the diagnosis shouldn’t be difficult if the strict criteria are used, it may take time for a patient to present with all clinical and EEG characteristics. This will slow the diagnosis. It is your responsibility, and well within your right, to find out all the information you can. That may include seeking a second opinion from a different doctor. You can also visit a Level 4 epilepsy center for help. A Level 4 epilepsy center offers thorough care for people with LGS and epilepsy. Services include a complete evaluation of your child’s condition as well as extensive medical, psychological, and neuropsychologic care.6 To find an epilepsy center near you, visit


  • 1. Arzimanoglou A, French J, Blume WT, et al. Lennox-Gastaut syndrome: a consensus approach on diagnosis, assessment, management, and trial methodology. Lancet Neurol. 2009;8:82-93.
  • 2. Crumrine PK. Lennox-Gastaut syndrome. J Child Neurol. 2002;17(suppl 1):S70-75.
  • 3. Benbadis SR. Epileptic seizures and syndromes. Neurol Clin. 2001;19(2):251-270.
  • 4. Shafer PO, Kiriakopoulos E, Sirven JI. LGS: characteristics. Epilepsy Foundation Web site. Updated November 2014. Accessed November 27, 2019.
  • 5. Guidelines for epilepsy centers. National Association of Epilepsy Centers Web site. Published January 12, 2010. Accessed October 21, 2019.