Deficits of memory, executive functioning and attention following infarction in the thalamus; a study of 22 cases with localised lesions
Introduction
Studies of patients with thalamic damage show that the thalamus plays a role in several aspects of cognition. Of these, memory has always received the greatest attention due to striking cases of diencephalic amnesia, i.e. severe memory loss due to thalamic damage (Bogousslavsky et al., 1988, Bogousslavsky et al., 1988; Castaigne et al., 1981; Ghidoni, Pattacini, Galimberti, & Aguzzoli, 1989; Graff-Radford, Damasio, Eslinger, Yamada, & Damasio, 1985; Neau & Bogousslavsky, 1996; Partlow, Del Carpio-O’Donovan, Melanson, & Peters, 1992; Rousseaux, 1994, Rousseaux et al., 1986; Stuss, Guberman, Nelson, & Larochelle, 1988; Wallesch, Kornhuber, Kunz, & Brunner, 1983). This memory deficit depends on damage to the medial and anterior portions of the thalamus (Graff-Radford, Tranel, Van Hoesen, & Brandt, 1990; Von Cramon, Hebel, & Schuri, 1985); more precisely, the anterograde amnesia, reminiscent of that seen following hippocampal damage, in cases with thalamic damage appears to follow lesions of the anterior thalamic nuclei or their afferent white matter bundle, the mammillo-thalamic tract (Gentillini, De Renzi, & Crisi, 1987; Van Der Werf, Witter, Uijlings, & Jolles, 2000). Severe deficits in executive functioning and attention have also been noted in thalamic patients, but it remains unclear which structures are involved (Bogousslavsky et al., 1988, Bogousslavsky et al., 1988; Fukatsu, Fujii, Yamadori, Nagasawa, & Sakurai, 1997; McGilchrist, Goldstein, Jadresic, & Fenwick, 1993; Miller, Cummings, McIntyre, Ebers, & Grode, 1986; Pepin & Auray-Pepin, 1993; Sandson, Daffner, Carvalho, & Mesulam, 1991; Van Der Werf et al., 1999).
We here present a study of 22 cases of thalamic infarction, tested with a fixed battery of tests to allow comparison between cases. The selection of tests aimed to measure different aspects of memory, attention and executive functioning. We obtained MRI scans from each patient and plotted the lesion sites both in standard stereotactic space and in an atlas of the thalamus. This allowed us on the one hand to perform an analysis of the overlap of infarctions in groups of patients with similar symptoms and on the other hand, we were able to describe the location of the regions of interest in terms of nuclei and white matter tracts affected. We controlled for infarctions in subcortical areas and white matter tracts surrounding the thalamus, hippocampal atrophy and sulcal widening, factors that would confound structure–function relationships within the thalamus (De Groot et al., 2000; Houx, Vreeling, & Jolles, 1991; Scheltens et al., 1992, Visser et al., 1999). Similarly, we controlled for deficits of basal cognitive abilities, such as vigilance and understanding. In doing so, we aimed to provide more information on which thalamic structures are involved in executive functioning and attention, and to confirm previously established structure–function relationships for memory (Van Der Werf et al., 2000).
Section snippets
Methods
Neurologists from four academic centres in The Netherlands participated to recruit patients with thalamic stroke from neurology clinics, rehabilitation clinics, academic hospitals and community hospitals. In the course of 4 years, 22 patients were included.
In all patients, the diagnosis of thalamic infarction was made with the aid of structural brain images; in most cases, high-resolution MR images were obtained with a 1.5 T machine using both T1- and T2-weighted images. In case 11, no MR
Thalamic lesions
Of the 22 patients studied, 15 had unilateral lesions and 7 had lesions falling in the thalamus of both hemispheres. The latter type of infarction was more or less symmetrical in three cases, but four cases had lesions that were larger on one side or in different locations on each side. Table 3 lists the nuclei affected and Fig. 2 illustrates the location, size and shape of the lesions.
Recurring patterns occurred in the distribution of lesions: eight patients showed an elongated lesion in the
Discussion
We aimed to find relationships between thalamic structures and memory, executive functions and attention. We performed a lesion-overlap and subtraction study in stereotactic space to investigate associations between thalamic structures and cognitive functions across our group of subjects, followed by a case-wise analysis of the pattern of deficits in each subject. A clear relationship between a specific kind of memory disorder, i.e. the amnesic syndrome, and structural damage to the MTT was
Acknowledgments
This study was supported by a grant from The Netherlands Organisation for Scientific Research (NWO), Grant Number 970-10-012. The help of Drs. W.J.H.J. Smeets and H.J. Groenewegen for lesion localisation and of Drs. Barkhof, Boiten, Gonera, Haaxma and Weerts for referral of patients is gratefully acknowledged.
References (66)
- et al.
Neural systems engaged by planning: A PET study of the Tower of London task
Neuropsychologia
(1996) - et al.
Physiological activation of a cortical network during performance of the Wisconsin Card Sorting Test: A positron emission tomography study
Neuropsychologia
(1995) - et al.
Pesticide exposure and risk of mild cognitive dysfunction
Lancet
(2000) - et al.
A new parcellation of the human thalamus on the basis of histochemical staining
Brain Research Reviews
(1989) - et al.
Rigorous health screening reduces age effect on memory scanning task
Brain and Cognition
(1991) - et al.
Tapping, talking and the thalamus: Possible influence of the intralaminar nuclei on basal ganglia function
Neuropsychologia
(1997) - et al.
Long-term postoperative cognitive dysfunction in the elderly ISPOCD1 study. ISPOCD investigators. International study of post-operative cognitive dysfunction
Lancet
(1998) - et al.
Bilan de l’amnesie des infarctus thalamiques restreints—6 cas
Cortex
(1986) - et al.
A semiquantative rating scale for the assessment of signal hyperintensities on magnetic resonance imaging
Journal of the Neurological Sciences
(1993) - et al.
The neuropsychology of paramedian thalamic infarction
Brain and Cognition
(1988)