Clinics in Developmental Medicine: The Epilepsy-Aphasia Spectrum From Landau-Kleffner Syndrome to Rolandic Epilepsy by Thierry Deonna & Eliane Roulet-Perez

Author:Thierry Deonna & Eliane Roulet-Perez
Language: eng
Format: epub
Publisher: Mac Keith Press
Published: 2016-07-15T00:00:00+00:00

10

PHYSIOPATHOLOGY OF SPEECH, LANGUAGE AND OTHER PROLONGED EPILEPTIC DYSFUNCTION IN LANDAU–KLEFFNER SYNDROME, EPILEPSY WITH CONTINUOUS SPIKE WAVES DURING SLEEP AND RELATED SYNDROMES

Introduction

The effects of a focal epileptic activity originating in a cortical region or in a particular set of neurons that are part of a cognitive network (i.e. interacting neural circuits supporting a cognitive function) will depend on the consequences of the bioelectrical changes (excitation/inhibition) it induces locally and more remotely by propagation via established short- and long-distance connections (cf. Chapter 11 ). Impact on cognition can be limited when the concerned network underpins a localized and modular skill (e.g. visual or auditory perception and graphomotor skill) or more pervasive when the affected circuits are the substrate of more complex and widely distributed processes (attention and memory consolidation) (see Fig 10.1 ). In addition to the epilepsy-induced dysfunction that can be circumscribed, one has to take into account the downstream effect of the loss of a given function on those depending on it, which can be considerable. This is best illustrated by verbal auditory agnosia in which a localized dysfunction in the auditory cortices will interfere not only with the patients’ speech comprehension but also its expression by interrupting the auditory feedback from his own production.

While the variable dynamics of the installation and course of the aphasia in LKS can readily be accepted as an argument in favour of its epileptic origin, the absence of immediate correlation with the electroencephalogram (EEG) findings and the long-term sequelae are often taken against it.

Table 10.1 summarizes the dynamics of evolution observed in patients diagnosed with LKS from the first symptoms and through the course of the disease until the final stage. This is essentially its natural course, although therapy can modify it for the better or the worse. It is noteworthy that the same child can have episodes of acute, subacute or slow onset and recovery, with variable degree of severity at different periods.

TABLE 10.1

Dynamics of language deficit in Landau-Kleffner syndrome

Acute versus insidious slow onset

Acute onset then slow aggravation (or reverse)

Rapid versus slow recovery

No recovery

Monophasic versus relapsing – remitting course

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