Acquired epileptic aphasia (AEA) typically develops in healthy children who acutely or progressively lose receptive and expressive language ability coincident with the appearance of paroxysmal electroencephalographic (EEG) changes. In 1957, Landau and Kleffner initially described acquired epileptic aphasia and subsequently reluctantly agreed to the attachment of their names to the syndrome. In this article, acquired epileptic aphasia is used as a synonym for Landau-Kleffner syndrome (LKS).
In most cases described in detail, a clearly normal period of motor and language development occurs before acquired epileptic aphasia symptoms appear. However, in the last 2-3 decades, several reported cases have been difficult to classify, because the patients' presenting symptoms appear to have been variants of those originally described. In one case, expressive language deteriorated instead of receptive language, whereas in another case, a brief period of normal language development (single words) was followed by language regression with abnormal EEG findings.
Acquired epileptic aphasia must be differentiated from autism with minimal language regression, especially when it is associated with isolated EEG abnormalities. Many current researchers classify acquired epileptic aphasia as part of the syndrome of electrical status epilepticus of sleep (ESES), which is also known as continuous spike and wave of slow-wave sleep (CSWS) as initially described by Patry et al 1971. 
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Whether seizures and epileptiform discharges cause language dysfunction in acquired epileptic aphasia (AEA) is disputed. Aphasia and electroencephalographic (EEG) abnormalities might have a common cause (eg, a left temporal brain astrocytoma or head injury). Some authors speculate that reinforcement of synaptogenesis mediates the neurologic deficits in acquired epileptic aphasia and that epileptiform discharges during a critical period of synaptic reinforcement or pruning in turn mediate the reinforcement of synaptogenesis.
Concrete substantiation of this hypothesis is the existence of poor speech in patients who are affected early and whose condition does not respond to anticonvulsant measures. Other patients with acquired epileptic aphasia appear to have worsened language skills during periods of increased epileptiform activity. However, some reports describe no correlation between EEG abnormality and language dysfunction.
Most cases of acquired epileptic aphasia are spontaneous, although familial clustering has been reported. Descriptions of monozygotic twins include cases in which acquired epileptic aphasia affects only one sibling, cases in which this condition affects both siblings, and cases in which it affects one twin and developmental dysphasia affects the other.  These cases cast serious doubt on the role of epilepsy in speech dysfunction.
Most cases of acquired epileptic aphasia (AEA) do not have a well-defined cause. However, a few cases of secondary acquired epileptic aphasia have been described. 
Low-grade brain tumors,  closed-head injury, neurocysticercosis,  and demyelinating disease [6, 7] have been associated with the clinical picture of acquired epileptic aphasia. Central nervous system (CNS) vasculitis may also be associated with this condition. One case of otherwise typical acquired epileptic aphasia has been described in association with mitochondrial respiratory chain complex I deficiency.  Bilateral perisylvian polymicrogyria may also present with new onset of speech disturbance after a 2-year period of normal language and electroencephalographic (EEG) findings typical of acquired epileptic aphasia.  Other diagnostic considerations might be warranted when evaluated a case of suspected acquired epileptic aphasia.
Population-based epidemiologic data related to acquired epileptic aphasia (AEA) in the United States are limited. The Children's Hospital and Medical Center (Seattle, Wash) treats 1-2 new cases of acquired epileptic aphasia each year.
Globally, more than 200 cases have been described in the literature. Between 1957 and 1980, 81 cases of acquired epileptic aphasia were reported; more than 100 cases are documented every 10 years. Detailed numbers are difficult to report, because patients may be repeated in various series, as switching professional care is common due to the patient's and family's frustration with aggressive treatment that does not improve the patient's speech. An urban Israeli pediatric neurology clinic reported a 0.2% rate of acquired epileptic aphasia.
The first study of AEA in Japan concluded that the incidence in children aged 5-14 years was about 1 in a million; the prevalence of AEA in children aged 5-19 and under medical care was 1 in about 300,000-410,000. 
In affected children, aphasia usually appears at age 4-7 years, and there is a slight male predominance (male-to-female ratio, 1.7:1). However, symptom onset has been described in patients as young as 18 months and in those as old as 13 years. This discussion excludes the congenital cases with typical electroencephalographic (EEG) patterns and little or no language development; in such cases, the precise age of onset can never be determined.
In the early descriptions of the syndrome, language dysfunction was not recognized in the early acquisition phase in the first 18 months of life. In the last 2 decades, scrutiny of the language development has revealed some minor abnormalities. Soprano et al found signs of developmental dysphasia in 9 of 12 cases,  and Robinson et al reported language delay in 4 of 18 cases. 
Long-term outcome studies of patients with acquired epileptic aphasia (AEA) are limited by the lack of uniformity in diagnostic criteria. About half the patients have some fluctuation in aphasia, and the fluctuations usually occur over several months. On occasion, aphasia may worsen for as long as 7 years after the disease onset.
Worsened outcome has been noted in patients with an onset of language regression before age 5 years. Morrell found that symptoms persisting for longer than 1 year are predictive of poor language recovery,  and Robinson et al found that poor language recovery was correlated with electrical status epilepticus of sleep (ESES) for longer than 36 months.  Impaired short-term memory was universal on long-term follow-up of all of their patients with acquired epileptic aphasia. 
Short-term remissions pose a challenge in evaluating responses to various therapeutic modalities. One should be mindful that fluctuations are not unusual on the course of this disease. Both the clinical course and the electroencephalographic (EEG) changes may get worse, better, and even return to the baseline.  In many studies, these fluctuations did not always occur simultaneously (see History under the Clinical section for the explanation).
Lower rates of good outcomes have been reported, ranging from 14% to 50%, with a combined rate of 28.6% (see Table 1, below). Duran et al completed a transversal study of 7 patients (all males, aged 8-27 y) with Landau-Kleffner syndrome (acquired epileptic aphasia).  On long-term follow-up, most patients did not experience total epilepsy remission and language disturbances persisted. One patient had a normal quality of life and 6 patients reported agnosia/aphasia to be their biggest difficulty. 
Beaumanoir analyzed cases with follow-up of more than 10 years, which included those published in peer-reviewed journals and those from other sources, such as a doctoral thesis reported before 1992. 
Table 1. Long-Term Follow-up of Acquired Epileptic Aphasia (Open Table in a new window)
|Study||Number of Patients||Mean Follow-up, y||Number of Patients with Normal or Mild Language Problems|
|Soprano et al  (1994)||12||8||3|
|Mantovani and Landau  (1980)||9||22||6|
|Paquier  (1992)||6||8.1||3|
|Rossi  (1999)||11||9.7||2|
|Robinson et al  (2001)||18||5.6||3|
|Duran et al  (2009)||7||9.5||1|
Patients with acquired epileptic aphasia (AEA) have special educational needs. Teaching them sign language when they are aphasic may be helpful in maintaining a useful communication channel. Learning sign language does not prevent or delay the recovery of aphasia. These patients may be able to read and write; therefore, these skills should be used for teaching whenever doing so is possible.
It is important to educate patients and their parents regarding acquired epileptic aphasia and realistic outcomes. A potential cause of litigation in acquired epileptic aphasia is the high parental expectations for a complete and quick recovery of language and speech functions. These unrealistic expectations often come from information in the lay press and from television shows that mention isolated miracle cures in cases of acquired epileptic aphasia after treatment with steroids or other measures. These cases do not represent the usual course of most children with this condition but make up good cases for television or newspaper stories.
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