science

Landau–Kleffner syndrome

Landau–Kleffner syndrome is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Landau–Kleffner syndrome rather than just read about it. In short: Landau–Kleffner syndrome (LKS), also called infantile acquired aphasia, acquired epileptic aphasia, or aphasia with convulsive disorder, is a rare neurological syndrome that develops during childhood. It is named after William Landau and Frank Kleffner, who characterized it in 1957 with a diagnosis of six children.

Key takeaways

Landau–Kleffner syndrome belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Landau–Kleffner syndrome to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Landau–Kleffner syndrome from memory before moving on to harder problems.

Reference excerpt

Landau–Kleffner syndrome (LKS), also called infantile acquired aphasia, acquired epileptic aphasia, or aphasia with convulsive disorder, is a rare neurological syndrome that develops during childhood. It is named after William Landau and Frank Kleffner, who characterized it in 1957 with a diagnosis of six children.

Signs and symptoms Landau–Kleffner syndrome is characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electroencephalogram (EEG). LKS affects the parts of the brain that control comprehension and speech (Broca's area and Wernicke's area). The disorder usually occurs in children between the ages of 2 and 5 years. There appears to be a male dominance in the diagnosis of the syndrome (ratio of 1.7:1, men to women). Typically, children with LKS develop normally, but then lose their language skills. While many affected individuals have clinical seizures, some only have electrographic seizures, including electrographic status epilepticus of sleep (ESES). The first indication of the language problem is usually auditory verbal agnosia. This is demonstrated in patients in multiple ways including the inability to recognize familiar noises and the impairment of the ability to lateralize or localize sound. In addition, receptive language is often critically impaired, however in some patients, impairment in expressive language is the most profound. In a study of 77 cases of Landau–Kleffner syndrome, 6 were found to have this type of aphasia. Because this syndrome appears during such a critical period of language acquisition in a child's life, speech production may be affected just as severely as language comprehension. The onset of LKS is typically between 18 months and 13 years, the most predominant time of emergence being between 3 and 7 years. Generally, earlier manifestation of the disease correlates with poorer language recovery, and with the appearance of night seizures that last for longer than 36 months. LKS has a wide range of symptom differences and lacks a uniformity in diagnostic criteria between cases, and many studies don't include follow-ups on the patients, so no other relationships between symptoms and recovery have been made known. Language deterioration in patients typically occurs over a period of weeks or months. However, acute onset of the condition has also been reported as well as episodic aphasia. Seizures, especially during the night, are a heavily weighted indicator of LKS. The prevalence of clinical seizures in acquired epileptic aphasia (LKS) is 70–85%. In one third of patients, only a single episode of a seizure was recorded. The seizures typically appear between the ages of 4 and 10 and disappear before adulthood (around the age of 15). Often, behavioral and neuropsychologic disturbances accompany the progression of LKS. Behavioral issues are seen in as many as 78% of all cases. Hyperactivity and a decreased attention span are observed in as many as 80% of patients as well as rage, aggression, and anxiety. These behavior patterns are considered secondary to the language impairment in LKS. Impaired short-term memory is a feature recorded in long-standing cases of acquired epileptic aphasia.

Cause Most cases of LKS do not have a known cause. Occasionally, the condition may be induced secondary to other diagnoses, such as low-grade brain tumors, closed-head injuries, neurocysticercosis, and demyelinating disease. Central nervous system vasculitis may be associated with this condition as well.

Diagnosis The syndrome can be difficult to diagnose and may be misdiagnosed as autism, pervasive developmental disorder, hearing impairment, learning disability, auditory processing disorder, attention deficit hyperactivity disorder (ADHD), intellectual disability, childhood schizophrenia, or emotional/behavioral problems. An EEG (electroencephalogram) test is imperative to a diagnosis. Many cases of patients exhibiting LKS will show abnormal electrical brain activity in both the right and left hemispheres of the brain; this is exhibited frequently during sleep. Even though an abnormal EEG reading is common in LKS patients, a relationship has not been identified between EEG abnormalities and the presence and intensity of language problems. In many cases however, abnormalities in the EEG test has preceded language deterioration and improvement in the EEG tracing has preceded language improvement (this occurs in about half of all affected children). Many factors inhibit the reliability of the EEG data: neurologic deficits do not closely follow the maximal EEG changes in time. The most effective way of confirming LKS is by obtaining overnight sleep EEGs, including EEGs in all stages of sleep. Many conditions like demyelination and brain tumors can be ruled out by using magnetic resonance imaging (MRI). In LKS, fluorodeoxyglucose (FDG) and positron emission tomography (PET) scanning can show decreased metabolism in one or both temporal lobes – hypermetabolism has been seen in patients with acquired epileptic aphasia.

Differential diagnosis The table below demonstrates the extensive and differential diagnosis of acquired epileptic aphasia along with Cognitive and Behavioral Regression:

Note: EEG = electroencephalographic; ESES = electrical status epilepticus of sleep; RL = receptive language; S = sociability

Continuous spike and wave of slow-wave sleep (>85% of slow-wave sleep).

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Landau–Kleffner syndrome

Start with the simplest possible case. Write down what Landau–Kleffner syndrome claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Landau–Kleffner syndrome before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Landau–Kleffner syndrome ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Landau–Kleffner syndrome

In research: Landau–Kleffner syndrome appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Landau–Kleffner syndrome in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Landau–Kleffner syndrome is common in secondary-school and first-year university syllabi. It links to neighbouring topics Epilepsy types, Specific developmental disorders, Syndromes, so understanding it makes those chapters shorter.
In everyday life: Look for Landau–Kleffner syndrome outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Landau–Kleffner syndrome in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Landau–Kleffner syndrome means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Landau–Kleffner syndrome out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Landau–Kleffner syndrome in simple terms?

Why does Landau–Kleffner syndrome matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Landau–Kleffner syndrome?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Landau–Kleffner syndrome.