title: Evidence for normal letter-sound integration, but altered language pathways in a case of recovered Landau-Kleffner Syndrome.
abstract: Landau-Kleffner Syndrome (LKS) is a rare form of acquired aphasia in children, characterized by epileptic discharges, which occur mostly during sleep. After normal speech and language development, aphasia develops between the ages of 3-7 years in a period ranging from days to months. The epileptic discharges usually disappear after reaching adulthood, but language outcomes are usually poor if no treatment focused on restoration of (non-) verbal communication is given. Patients often appear deaf-mute, but sign language, as part of the treatment, may lead to recovery of communication. The neural mechanisms underlying poor language outcomes in LKS are not yet understood. In this detailed functional MRI study of a recovered LKS patient - that is, a patient no longer suffering from epileptic discharges, audiovisual multi-sensory processing was investigated, since LKS patients are often proficient in reading, but not in speech perception. In the recovered LKS patient a large difference in the neural activation to auditory stimuli was found in the left versus the right auditory cortex, which cannot be attributed to hearing loss. Compared to healthy proficient readers investigated earlier with the same fMRI experiment, the patient demonstrated normal letter-sound integration in the superior temporal gyrus as demonstrated by the multi-sensory interaction index, indicating intact STG function. Diffusion Tensor Imaging (DTI) based fiber tracking in the LKS patient showed fibers originating from Heschl's gyrus that seem to be left-right inverted with respect to HG fiber pattern described in the literature for healthy controls. In the patient, in both hemispheres we found arcuate fibers projecting from (homologues of) Broca's to Wernicke's areas, and a lack of fibers from arcuate left inferior parietal and sylvian areas reported in healthy subjects. We observed short arcuate segments in the right hemisphere. Although speculative, our results suggest intact temporal lobe processing but an altered temporal to frontal connectivity. The altered connectivity might explain observed short-term verbal memory problems, disturbed (speech) sound-motor interaction and online feedback of speech and might be one of the neuronal factors underlying LKS.
authors.affiliation: Maastricht University, Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Oxfordlaan 55, 6229 EV Maastricht, Netherlands; Brain Innovation BV, Research & Development, Oxfordlaan 55, 6229 EV Maastricht, Netherlands. Electronic address: pim.pullens@uantwerpen.be.
authors.forename: Pim
authors.initials: P
authors.lastname: Pullens
authors.affiliation: Royal Dutch Kentalis, School Mariëlla, Theerestraat 42, 5271 GD Sint Michielsgestel, Netherlands.
authors.forename: Will
authors.initials: W
authors.lastname: Pullens
authors.affiliation: Maastricht University, Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Oxfordlaan 55, 6229 EV Maastricht, Netherlands.
authors.forename: Vera
authors.initials: V
authors.lastname: Blau
authors.affiliation: Maastricht University, Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Oxfordlaan 55, 6229 EV Maastricht, Netherlands.
authors.forename: Bettina
authors.initials: B
authors.lastname: Sorger
authors.affiliation: Maastricht University, Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Oxfordlaan 55, 6229 EV Maastricht, Netherlands.
authors.forename: Bernadette M
authors.initials: BM
authors.lastname: Jansma
authors.affiliation: Maastricht University, Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Oxfordlaan 55, 6229 EV Maastricht, Netherlands; Brain Innovation BV, Research & Development, Oxfordlaan 55, 6229 EV Maastricht, Netherlands.
authors.forename: Rainer
authors.initials: R
authors.lastname: Goebel
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology*; D032882:Comprehension / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018887:Landau-Kleffner Syndrome / Q000503:physiopathology* / Q000628:therapy; D008279:Magnetic Resonance Imaging; D009415:Nerve Net / Q000503:physiopathology; D010700:Phonetics; D012660:Semantics
keywords: Arcuate fasciculus; Audiovisual; Auditory cortex; DTI; Landau–Kleffner Syndrome; Multisensory integration; fMRI