Landau-Kleffner Syndrome (LKS)

By Dovy Paukstys, Founder, Komori Care

This article is educational and is not medical advice. It does not diagnose, treat, prevent, or cure any condition. Komori is not a medical device, is not FDA-cleared, does not detect seizures, and is not intended for people with epilepsy. Talk with a neurologist or epileptologist about personal medical decisions. Households living with epilepsy should use clinically validated seizure-detection devices as directed by their care team.

A kid who was talking stops understanding speech. People say hearing. People say autism. People say stubborn.

Sometimes the sleep EEG is the actual story.

I'm not a neurologist. I don't have epilepsy. I read the ILAE SWAS pages and GARD so this hub uses the current name stack. Landau-Kleffner. Acquired epileptic aphasia. A subtype of EE-SWAS.

What LKS is

GARD: a rare childhood nervous-system disorder. Repeated seizures and a sudden or gradual inability to understand or express language. Aphasia. Diagnosis is clinical features plus an EEG with specific seizure activity.

ILAE does not keep LKS as a standalone top-level syndrome anymore. They folded it into developmental and/or epileptic encephalopathy with spike-wave activation in sleep. DEE-SWAS / EE-SWAS.

Landau-Kleffner is the subtype where the regression is mostly language. Acquired auditory agnosia. The child can hear. Speech stops making sense.

EE-SWAS if development was typical before the drop. DEE-SWAS if there was already impairment, then more loss when the sleep spikes arrived.

Old names this replaced: epileptic encephalopathy with continuous spike-wave in sleep. Atypical childhood epilepsy with centrotemporal spikes. Pseudo-Lennox. Atypical benign partial epilepsy. ILAE put those in one spectrum. Self-limited epilepsy with centrotemporal spikes sits on the milder end. A kid can slide from one to the other.

When it shows up

ILAE's SWAS syndrome: seizure onset 2 to 12 years, peak 4 to 5. Both sexes. History, head size, exam, and development may be typical or may already show a cause.

About 1 to 2 years after seizure onset, cognitive, behavioral, psychiatric, or motor regression or plateau. Language and communication. Orientation. Attention. Social interaction. Impairments are typically severe. Some improvement later. Residual deficits stay.

Seizures and the sleep EEG pattern usually quiet around puberty.

GARD, via Orphanet, says symptoms may start in childhood, age band 2 to 11. Aphasia is listed as very frequent.

Alerts on ILAE's table: onset at 1 to 2 years. Exclusion: under 1 or over 12. Tonic seizures from sleep are an alert (think LGS). Epileptic spasms are exclusionary.

The EEG is a sleep test

You cannot diagnose this without a sleep EEG. ILAE says that twice.

Mandatory: slow 1.5 to 2 Hz spike-wave in non-REM sleep. Abnormalities markedly activated in sleep. Overnight may be required. A nap in clinic can miss it.

Background can be normal or slow, depending on cause. Sleep architecture gets hard to read because the spikes eat it.

Alerts that smell like LGS: generalized paroxysmal fast activity in sleep, or generalized slow spike-wave both awake and asleep.

MRI is not required to name the syndrome. Often done anyway to look for a cause.

Regression should line up in time with the sleep EEG change. Weeks, ILAE says. If the kid was already losing language and the EEG later happens to look busy, that is not automatically SWAS. They warn against over-diagnosis.

Seizures are not the main show

Some children have obvious seizures. Some don't, or not many. GARD still lists repeated seizures as part of the classic picture. ILAE's SWAS table does not require a particular waking seizure type. The required piece is the sleep activation plus the regression.

When seizures happen they can be focal, absence-like, or atonic. I'm not going to invent a percentage I didn't fetch from these pages.

The language loss is the part families notice. Auditory agnosia looks like deafness. It isn't, on a hearing test. That's why kids bounce through audiology first. Fine. Then someone has to order a sleep EEG.

Causes

GARD: complicated, varies. Some cases may be autoimmune. Some kids have a GRIN2A variant. That gene helps build a protein that sends signals between neurons. Wrong signals can hit language and can hit seizure threshold. Not everyone with a GRIN2A change gets LKS. Other unknown genes and environment likely sit in the mix.

GARD also tags inheritance, when it's the gene, as autosomal dominant. One copy can be enough. 50 percent chance of passing that copy. Having the copy is not a promise of LKS.

CureGRIN and GRIN2B Foundation show up on GARD's organization list. Resource links. Not a diagnosis.

Course

ILAE: spike-wave activation in sleep remits by mid-adolescence. Seizures usually do too. Language and cognition can recover some. Residual deficits are expected, not rare.

I'm not going to quote a "most kids talk again" percent I did not fetch. The fetched pages say improvement happens and leftovers stay. A speech-language pathologist and an epileptologist measure that in one child.

Treatment, no protocol

Medicines. Sometimes steroids or other immune therapy when a clinician thinks inflammation is in the story. Speech therapy. Educational support. I'm not dosing any of it.

GARD's practical point: rare diseases take too long to name. Epileptologist plus, if genetics is on the table, a geneticist. Children's hospital if the local workup stalls.

Households living with epilepsy should use clinically validated seizure-detection devices as directed by their care team. A baby monitor does not diagnose electrical status in sleep. A wellness gadget does not restore language and does not prevent SUDEP.

Nearby things that are not LKS

Autism with language delay: the sleep EEG does not suddenly explode in step with a language crash.

Self-limited centrotemporal epilepsy: spikes can increase in sleep without cognitive regression. ILAE keeps that distinction.

LGS: slow spike-wave awake and asleep, sleep fast activity, tonic seizures. Different syndrome. Different outlook.

For gene-named DEEs that can include speech regression, see Rare Epilepsy Long Tail.

FAQ

What is Landau-Kleffner syndrome?

A rare childhood epileptic encephalopathy. Language comprehension and speech fall off, suddenly or slowly. GARD calls that aphasia. ILAE treats LKS as the language-first subtype of EE-SWAS. Sleep EEG is required.

Does every child with LKS have obvious seizures?

No. GARD includes repeated seizures in the classic description. ILAE's SWAS diagnosis hangs on sleep spike-wave activation plus timed regression, not on a daily convulsion. Some kids seize. Some mostly lose language.

Is this the same as CSWS or ESES?

Those are older EEG labels for near-continuous spike-wave in slow sleep. ILAE rolled that picture, and LKS, into DEE-SWAS / EE-SWAS. Same neighborhood. LKS is the one where language is the main loss.

Who diagnoses LKS?

A physician. Pediatric neurologist or epileptologist. Sleep EEG required. Hearing tests often come first and can be normal. No app reads this off a late-talker video.

Sources

• ILAE / epilepsydiagnosis.org, DEE-SWAS / EE-SWAS overview: https://www.epilepsydiagnosis.org/syndrome/ee-csws-overview.html
• ILAE / epilepsydiagnosis.org, DEE-SWAS diagnostic criteria: https://www.epilepsydiagnosis.org/syndrome/ee-csws-diagcriteria.html
• ILAE / epilepsydiagnosis.org, DEE-SWAS EEG: https://www.epilepsydiagnosis.org/syndrome/ee-csws-eeg.html
• ILAE / epilepsydiagnosis.org, Encephalopathy: https://www.epilepsydiagnosis.org/encephalopathy.html
• GARD / NIH, Landau-Kleffner syndrome: https://rarediseases.info.nih.gov/diseases/6855/landau-kleffner-syndrome
• NINDS, Epilepsy and Seizures: https://www.ninds.nih.gov/health-information/disorders/epilepsy-and-seizures
• Scheffer et al., ILAE classification of the epilepsies, Epilepsia (2017): https://www.ilae.org/files/dmfile/ClassificationOfEpilepsies_Scheffer_et_al-2017-Epilepsia.pdf