title: Apraxic agraphia following thalamic damage: Three new cases.
abstract: Apraxic agraphia (AA) is a so-called peripheral writing disorder following disruption of the skilled movement plans of writing while the central processes that subserve spelling are intact. It has been observed in a variety of etiologically heterogeneous neurological disorders typically associated with lesions located in the language dominant parietal and frontal region. The condition is characterized by a hesitant, incomplete, imprecise or even illegible graphomotor output. Letter formation cannot be attributed to sensorimotor, extrapyramidal or cerebellar dysfunction affecting the writing limb. Detailed clinical, neurocognitive, neurolinguistic and (functional) neuroimaging characteristics of three unique cases are reported that developed AA following a thalamic stroke. In marked contrast to impaired handwriting, non-handwriting skills, such as oral spelling, were hardly impaired. Quantified Tc-99m ECD SPECT consistently showed a decreased perfusion in the anatomoclinically suspected prefrontal regions. The findings suggest crucial involvement of the anterior (and medial) portion of the left thalamus within the neural network subserving the graphomotor system. Functional neuroimaging findings seem to indicate that AA after focal thalamic damage represents a diaschisis phenomenon.
authors.affiliation: Clinical and Experimental Neurolinguistics, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium; Cepos, Rehabilitation Centre, Rooienberg 21, B-2570 Duffel, Belgium.
authors.forename: Dorien
authors.initials: D
authors.lastname: Vandenborre
authors.affiliation: Clinical and Experimental Neurolinguistics, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
authors.forename: Kim
authors.initials: K
authors.lastname: van Dun
authors.affiliation: Department of Neurology & Memory Clinic, ZNA Middelheim General Hospital, Lindendreef 1, B-2020 Antwerp, Belgium; Reference Center for Biological Markers of Dementia (BIODEM), Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp (UA), Universiteitsplein 1, BE-2610 Antwerp, Belgium.
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Engelborghs
authors.affiliation: Clinical and Experimental Neurolinguistics, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium; Department of Neurology & Memory Clinic, ZNA Middelheim General Hospital, Lindendreef 1, B-2020 Antwerp, Belgium. Electronic address: peter.marien5@telenet.be.
authors.forename: Peter
authors.initials: P
authors.lastname: Mariën
mesh_terms: D000368:Aged; D000381:Agraphia / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D002544:Cerebral Infarction / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D006236:Handwriting; D006801:Humans; D007802:Language; D008297:Male; D059906:Neuroimaging; D013788:Thalamus / Q000473:pathology* / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon
keywords: Apraxic agraphia; Thalamic stroke