Landau Kleffner syndrome is characterized by subacute onset of acquired aphasia in a child with normal previous development and cognition. Seizures may not occur in all cases, and when present are infrequent and self-limiting. However, there is a high risk of significant residual language impairment.
NOTE Self-limiting refers to there being a high likelihood of seizures spontaneously remitting at a predictable age.
NOTE Landau Kleffner syndrome is considered an 'epileptic encephalopathy'. This term denotes the concept that the epileptic activity itself might directly contribute additional cognitive and behavioral impairments over those expected from the underlying etiology alone, and that suppression of epileptic activity might minimize this additional impairment.
NOTE Childhood epilepsy with centrotemporal spikes, atypical childhood epilepsy with centrotemporal spikes, epileptic encephalopathy with continuous spike-and-wave during sleep and Landau Kleffner syndrome are syndromes that have in common certain EEG features, with variable severity of focal seizures and neurocognitive impairment. They may be considered as a spectrum, an individual child may transition from one of these syndromes to another over time.
Landau Kleffner syndrome is characterized by subacute onset of progressive aphasia in a child with previous age-appropriate language development. The syndrome has onset between the ages of 2 and 8 years (peak 5 to 7 years), or rarely later. The initial presentation may be with progressive aphasia (40%), seizures or both. Both sexes are affected. The aphasia occurs as a consequence of an acquired verbal auditory agnosia. Children become progressively unable to comprehend spoken word, cease to understand when spoken to and to respond verbally. The diagnosis is typically delayed as children are thought to have acquired deafness, autistic regression or mutism. Antecedent and birth history is normal. Neurological examination and head size are normal. Behavioral (e.g. attention deficit hyperactivity disorder, aggression), psychiatric and cognitive disturbances are commonly observed in addition to language impairment. Language impairment typically fluctuates. Seizures and EEG abnormality resolve with age in most cases, however residual language impairment is seen in the majority (>80%) and may be severe (especially if onset is earlier).
CAUTION Children who have not developed language before onset of seizures should generally not be considered for this syndrome.
CAUTION Children with autism may show language regression, however this typically occurs earlier (< 2 years), prior language development is typically abnormal and regression in language is not compensated for by non-verbal communication.