A pure case of Gerstmann syndrome with a subangular lesion

Abstract

The four symptoms composing Gerstmann's syndrome were postulated to result from a common cognitive denominator (Grundstörung) by Gerstmann himself. He suggested that it is a disorder of the body schema restricted to the hand and fingers. The existence of a Grundstörung has since been contested. Here we suggest that a common psychoneurological factor does exist, but should be related to transformations of mental images rather than to the body schema. A patient (H.P.) was studied, who presented the four symptoms of Gerstmann's syndrome in the absence of any other neuropsychological disorders. MRI showed a focal ischaemic lesion, situated subcortically in the inferior part of the left angular gyrus and reaching the superior posterior region of T1. The cortical layers were spared and the lesion was seen to extend to the callosal fibres. On the basis of an extensive cognitive investigation, language, praxis, memory and intelligence disorders were excluded. The four remaining symptoms (finger agnosia, agraphia, right-left disorientation and dyscalculia) were investigated thoroughly with the aim of determining any characteristics that they might share. Detailed analyses of the tetrad showed that the impairment was consistently attributable to disorders of a spatial nature. Furthermore, cognitive tests necessitating mental rotation were equally shown to be impaired, confirming the essentially visuospatial origin of the disturbance. In the light of this report, the common cognitive denominator is hypothesized to be an impairment in mental manipulation of images and not in body schema.

Three Parietal Circuits for Number Processing

“…The lesions that cause acalculia of the Gerstmann's type are typically centred in the depth of the left intraparietal sulcus (Mayer, Martory, Pegna, Landis, Delavelle, & Annoni, 1999;Takayama, Sugishita, Akiguchi, & Kimura, 1994). This is compatible with the above brain-imaging results showing intraparietal activation during various numerical manipulation tasks independently of language.…”

“…Inter-individual variability in the boundaries between cortical territories as well as in the branching patterns of this artery would explain that the different elements of Gerstmann's syndrome can be dissociated (Benton, 1961(Benton, , 1992. Note that this interpretation implies that, contrary to a frequent speculation, Gerstmann's syndrome does not result from a homogeneous impairment to a single representation that would somehow intermingle fingers, numbers, and space (Butterworth, 1999;Gerstmann, 1940;Mayer et al, 1999). Rather, the syndrome may represent a happenstance conjunction of distinct, but dissociable, deficits that frequently co-occur due to a common vascularisation, and that are only loosely connected at the functional level due to the overarching spatial and sensorimotor functions of the parietal lobe.…”

Does lateral parietal cortex support episodic memory?

“…Traditionally, lateral posterior parietal cortex (including BAs 39, 40, and the posterior part of area 7) is thought to support planning and control of movement, as well as perception of, and attention to, spatial information (for influential models, see Corbetta & Shulman, 2002;Milner & Goodale, 1995;Mishkin, Ungerleider, & Macko, 1983;Nobre et al, 2001;Posner & Peterson, 1990), multisensory integration (Xing & Andersen, 2000) and construction (Critchley, 1953;Luria, 1973). For example, damage to posterior parietal cortex can limit awareness of the outside world, an object, or even of one's own body, so that only the contralesional half is consciously perceived (i.e., neglect; for theories, see Bisiach & Vallar, 1998;Dankert & Ferber, 2006;Driver & Vuilleumier, 2001;Karnath et al, 2001;Mayer et al, 1999;Rafal, 1997), and can impair the ability to detect multiple objects simultaneously (especially when they are in opposite hemifields; i.e., simultanagnosia; Balint, 1909Balint, /1995Rafal, 2002). Current models have proposed subdivisions of the posterior parietal region along functional lines.…”

The role of vision in the development of finger–number interactions: Finger-counting and finger-montring in blind children

“…These studies found that similar parietal networks (i.e., the angular gyrus) were activated when participants were submitted to tasks involving either finger movement control or number processing (Pesenti, Thioux, Seron, & De Volder, 2000;Piazza, Mechelli, Butterworth, & Price, 2002;Pinel, Piazza, Le Bihan, & Dehaene, 2004;Zago et al, 2001). Accordingly, the capacity to execute tasks requiring access to finger representations and numerical judgments was found to be disrupted after an acquired lesion (Gerstmann, 1930;Mayer et al, 1999) or a transient lesion (via repetitive transcranial magnetic stimulation [rTMS]) of the left angular gyrus (Rusconi, Walsh, & Butterworth, 2005).…”