Haukur Hjaltason

Torsin A haplotype predisposes to idiopathic dystonia

Previous work has suggested that in many neurological diseases genetic variability in the loci predisposing subjects to autosomal dominant disease contributes to the risk of sporadic disease. Here, using a population‐based sample of dystonia cases, we show an association with the torsin A haplotype and sporadic idiopathic dystonia. Ann Neurol 2005;57:765–767

Damage to Left Anterior Temporal Cortex Predicts Impairment of Complex Syntactic Processing: A Lesion-Symptom Mapping Study

Sentence processing problems form a common consequence of left‐hemisphere brain injury, in some patients to such an extent that their pattern of language performance is characterized as “agrammatic”. However, the location of left‐hemisphere damage that causes such problems remains controversial. It has been suggested that the critical site for syntactic processing is Brocas area of the frontal cortex or, alternatively, that a more widely distributed network is responsible for syntactic processing. The aim of this study was to identify brain regions that are required for successful sentence processing. Voxel‐based lesion‐symptom mapping (VLSM) was used to identify brain regions where injury predicted impaired sentence processing in 50 native speakers of Icelandic with left‐hemisphere stroke. Sentence processing was assessed by having individuals identify which picture corresponded to a verbally presented sentence. The VLSM analysis revealed that impaired sentence processing was best predicted by damage to a large left‐hemisphere temporo‐parieto‐occipital area. This is likely due to the multimodal nature of the sentence processing task, which involves auditory and visual analysis, as well as lexical and syntactic processing. Specifically impaired processing of noncanonical sentence types, when compared with canonical sentence processing, was associated with damage to the left‐hemisphere anterior superior and middle temporal gyri and the temporal pole. Anterior temporal cortex, therefore, appears to play a crucial role in syntactic processing, and patients with brain damage to this area are more likely to present with receptive agrammatism than patients in which anterior temporal cortex is spared. Hum Brain Mapp 34:2715–2723, 2013.

Prevalence study of primary dystonia in Iceland

In Iceland, the crude prevalence for all types of primary dystonia was 37.1/105 (confidence interval, 30.4–44.9). Focal dystonia had the highest prevalence (31.2/105), followed by segmental (3.1/105), multifocal (2.4/105) and generalized dystonia (0.3/105). Cervical dystonia was the most common focal dystonia (11.5/105), followed by limb dystonia (8.0/105), laryngeal dystonia (5.9/105), blepharospasm (3.1/105), and oromandibular dystonia (2.8/105). The male:female ratio for all patients was 1:1.9 (P = 0.0007), and females outnumbered males in all subtypes except oromandibular dystonia. Mean age of onset for all patients was 42.7 years (range, 3–82 years). This prevalence of primary dystonia is higher than in most reported studies, possibly because of more complete ascertainment but the relative frequencies of dystonia subtypes is similar.

Repetition of distractor sets improves visual search performance in hemispatial neglect.

Priming from repeated distractor sets, or search context, in conjunctive visual search was examined in four patients with hemispatial neglect. In the first experiment overall context was either changed or repeated while the target was always the same to control for any modulatory effect of target priming. Considerable priming was seen from repeated context. In the second experiment the context was either repeated on the left side, on the right side, on both sides, or the context was new. Priming from repeated context was found to arise from the left visual field, as well as the right visual field, as well as when overall context was repeated. Brief masked displays were used in experiment 3, the results again showing strong priming from repeated overall context. The results of the three experiments suggest that visual grouping, or perceptual organization, of distractor sets is relatively intact in the affected hemifield of parietal neglect patients. Furthermore, repetition of context may even temporarily ameliorate neglect symptoms in search. These findings are consistent with claims that grouping is distinct from attentional processing and that it operates at lower levels of the perceptual hierarchy.

Retinal oximetry is affected in multiple sclerosis

Structural and physiological abnormalities have been reported in the retina in patients with multiple sclerosis (MS). Retinal oximetry has recently detected changes in retinal oxygen metabolism in Alzheimer′s disease and mild cognitive impairment. Our goal was to determine whether oxygen saturation in retinal blood vessels of patients with patients is different from that of a healthy population.

“Getting the Left Right” The Experience of Hemispatial Neglect After Stroke

We used a phenomenological approach to gain insight into the experiences of self, other, and world in patients with hemispatial neglect within the first month following stroke. Comprehensive descriptions of circumstances were conjoined with open-ended interviews of 12 participants. The neglect experience was captured in the overarching theme, “getting the left right,” which encompasses the two subthemes of (a) surreal awareness of the left and (b) emergence of a different world. Patients had unclear perceptions of their own body and surroundings, their attention was brittle, and they encountered bewildering reactions from other people. They simultaneously pursued the ineffable neglected space and searched for coherence. The vulnerability, loss, and conflicting perceptions that patients with neglect face should be acknowledged and alleviation sought. Facilitating methods should provide additional opportunities for patients to communicate their experiences. We underscore the importance of readjusting the current approaches of neglect and emphasizing meaningfulness in professional guidance.