Landau-Kleffner Syndrome
Landau-Kleffner Syndrome (LKS) is a rare, acquired epileptic encephalopathy of childhood. The ILAE classifies it under the broader category of Epileptic Encephalopathies, highlighting that the epileptic activity itself contributes to a progressive cognitive decline beyond what would be expected from the underlying etiology.
Presentation and Clinical Features
Age of Onset: LKS typically begins in previously healthy children between the ages of 3 and 8 years.
Core Feature: Acquired Aphasia: The hallmark of LKS is the subacute onset of aphasia, which is a loss of the ability to understand and express language. The child, who previously had normal language development, progressively or suddenly loses the ability to comprehend spoken words (verbal auditory agnosia). This can be mistaken for hearing loss or autism spectrum disorder. However, unlike autism, the language regression is often the primary and most striking feature.
Seizures: Seizures are a common but not mandatory feature. When present, they are often infrequent and typically occur during sleep. They can be focal motor, atypical absence, or atonic. The seizures usually resolve with age, but the aphasia often persists.
Other Symptoms: Behavioral disturbances, such as hyperactivity and attention deficits, are also common.
Investigations
EEG: The EEG is the most critical diagnostic tool. It shows a striking pattern of near-continuous epileptiform activity, known as Electrical Status Epilepticus in Sleep (ESES), which is also referred to as Continuous Spike-and-Wave during Sleep (CSWS). This activity is bilateral, often prominent over the temporal regions, and is a key driver of the aphasia. The ESES pattern is often missed on a brief waking EEG. A prolonged sleep-deprived EEG or a 24-hour ambulatory EEG is essential for diagnosis.
Neuroimaging: An MRI of the brain is typically normal. It is performed to rule out a structural cause for the aphasia.
Management and Prognosis
Treatment Goal: The primary goal of treatment is to suppress the continuous epileptiform discharges during sleep, as this is thought to be the cause of the language regression. Seizure control alone is not sufficient.
First-Line Medications:
Corticosteroids (e.g., prednisone, methylprednisolone) and high-dose benzodiazepines (e.g., clobazam) are often the most effective treatments for suppressing ESES.
Valproate, Levetiracetam, and Ethosuximide are also used.
Medications to Avoid: Carbamazepine, Phenytoin, and Phenobarbital can worsen the EEG and clinical picture and should be avoided.
Surgical Intervention: For patients who fail to respond to medication, specialized surgical procedures, such as multiple subpial transections, may be considered at tertiary epilepsy centers. This involves making a series of cuts in the cerebral cortex to disrupt the horizontal spread of epileptiform activity without damaging key language functions.
Prognosis: While the seizures and EEG abnormalities generally resolve by adolescence, the language and cognitive deficits often persist to varying degrees. Early diagnosis and treatment are crucial for improving the long-term prognosis for language recovery. Multidisciplinary support from speech therapists, neuropsychologists, and special education professionals is vital.