Damage to the Upper Portion of Area 19 and the Deep White Matter in the Left Inferior Parietal Lobe, Including the Superior Longitudinal Fasciculus, Results in Alexia with Agraphia

Abstract

Analysis of lesions and symptoms in patients with brain tumors combined with information from diffusion tensor imaging provides direct evidence of the anatomical localization of brain function. Using these methods, we evaluated 8 patients who underwent surgery for metastatic brain tumors located in the left occipital lobes between 2007 and 2009. Preoperatively, 4 patients (cases 1–4) had alexia with agraphia while the other 4 patients (cases 5–8) did not. Tractography for the superior longitudinal fasciculus (SLF) was performed before surgery in case 1. The common brain tumors in cases 1–4 were located in the upper portion of area 19, and peritumor edema in that area resulted in compromise of the deep white matter of the inferior parietal lobe (IPL). The SLF was compressed and disrupted in the white matter of the IPL near the upper portion of area 19 in case 1. In cases 5–8, the brain tumors were not located in the upper portion of area 19. These results suggest that damage to the upper portion of area 19 and to the white matter in the left IPL, including the SLF, resulted in alexia with agraphia.

Tracing superior longitudinal fasciculus connectivity in the human brain using high resolution diffusion tensor tractography

“…Better knowledge of detailed connectivity of the SLF combined with correlational functional studies could contribute to a better understanding and mapping of the human language network (Makris et al 2005; Catani and Jones 2005; Frey et al 2008; Makris et al 2009). The current descriptions of the SLF fiber bundles provide basic anatomical information as the first step toward unraveling the detailed pathophysiology of the SLF including the SLF TP-SPL and MdLF-SPL in developmental disorders such autism (Fletcher et al 2010; Poustka et al 2012), schizophrenia (de Weijer et al 2011), dyslexia (Ben-Shachar et al 2007; Frye et al 2010; Frye et al 2011; Vandermosten et al 2012), and acquired language or speech disorders (Catani et al 2003; Catani and ffytche et al 2005; Catani and Mesulam 2008; Breier et al 2008; Shinoura et al 2010; Turken and Dronkers 2011; Glasser and Rilling 2008; Fernández-Miranda et al 2008). …”

The Left Superior Longitudinal Fasciculus within the Primary Sensory Area of Inferior Parietal Lobe Plays a Role in Dysgraphia of Kana Omission within Sentences

“…The SLF is a probably candidate for such a tract, because it connects the temporal lobe and occipital lobe with the frontal lobe via the parietal lobe [6]. Indeed, lesions associated with dysgraphia seem to be related to dorsal systems, such as the dorsolateral frontal lobe, centrum semiovale or angular gyrus [1,17,18], and the main nerve tract in the dorsal system is the SLF [19]. Therefore, damage to the SLF in the IPL might disrupt transmission of word images from the posterior inferior temporal lobe to the parietal or frontal lobe, resulting in dysgraphia [20].…”

“…The left SLF may mediate other functions in addition to writing. Indeed, the left SLF is mainly associated with language-related function, including reading, and speed of lexical decision or cognitive processing [19,[24][25][26][27]. All these language-related functions may be associated with writing, since these functions can improve with writing.…”

Quantification of white matter fibre pathways disruption in frontal transcortical approach to the lateral ventricle or the interventricular foramen in diffusion tensor tractography

“…Memory deficits occur after the damage of nucleus caudatus or thalamocortical fibres [20]. Alexia, agraphia or spatial neglect are another complications of transcortical approach caused by an interruption of subcortical SLF [44,45].…”