MRI extrahippocampal volumes and visual memory: Correlations independent of MRI hippocampal volumes in temporal lobe epilepsy patients

Abstract

Limbic system atrophy and memory dysfunction are common in patients with temporal lobe epilepsy (TLE). However, the relationship between extrahippocampal limbic structures and memory functioning within TLE has received little attention. The present study examined associations of MRI volumetric measurements of the mammillary body, fornix, amygdala, and hippocampus to measures of episodic verbal and visual memory. The Logical Memory and Visual Reproduction subtests from the Wechsler Memory Scale were administered to 47 unilateral TLE patients (25 right, 22 left). Normalized right and left MRI volumes were determined for each patient by cursor tracing 1.5 mm slices from 3D-MRI. Significant associations were found between left hippocampal volume and the immediate, delayed, and percent retention scores of the Logical Memory Test; between the left mammillary body volume and the Logical Memory Test delayed and percent retention scores; immediate Visual Reproduction performance was significantly related to the right and left amygdala volumes, and right mammillary body volume; only the right amygdala and right mammillary body volume were associated with the delayed Visual Reproduction trial. However, neither right nor left hippocampal volumes were related to visual memory performance. Multiple limbic system structural volumes were independently associated with verbal and nonverbal memory performance. Results suggest that visual memory, as measured by the Visual Reproduction Test, may be uniquely associated with extrahippocampal volumes in patients with TLE. (JINS, 1999, 5, 540-548.)

The use of neuroimaging to study behavior in patients with epilepsy

“…Initial studies focused exclusively on hippocampal volumes and their relationship to memory dysfunction in temporal lobe epilepsy (TLE) ((1-3), for a review, see (4)). These studies demonstrated a consistent relationship between reductions in left hippocampal volume, or hippocampal asymmetries, and impairments in verbal learning and memory, in TLE patients who were left-hemisphere dominant for language (1,2,(5)(6)(7)(8)(9). More importantly, these studies established that patients without left hippocampal volume loss were at greatest risk for postoperative memory decline (7).…”

“…The association between right hippocampal volumes and nonverbal learning and memory is tenuous, but has been reported in a few studies (7,10,11). In addition, there are data to support the role of other medial temporal lobe structures in verbal and visual memory, including the amygdala (8,12), mammillary bodies (8), and perirhinal cortex (9,13). In fact, there is some evidence that right amygdala volume is a stronger predictor of visual memory than right hippocampal volume (8,12).…”

“…In addition, there are data to support the role of other medial temporal lobe structures in verbal and visual memory, including the amygdala (8,12), mammillary bodies (8), and perirhinal cortex (9,13). In fact, there is some evidence that right amygdala volume is a stronger predictor of visual memory than right hippocampal volume (8,12). Undoubtedly, volumetric MRI has been important in validating the role of the hippocampus and other medial temporal lobe structures in learning and memory, and in determining which patients are at greatest risk for memory decline following temporal lobectomy.…”

The Frequency and Extent of Mammillary Body Atrophy Associated with Surgical Removal of a Colloid Cyst

“…Although the present study used a 1.0-mm-volume scan for comparison purposes, previous MR imaging studies of the mammillary bodies have used a variety of section thicknesses (1.0 mm, 31 1.1 mm, 28 1.5 mm, 29,30,32, and 3.0 mm 26,27 ). Other differences included the use of a 3T imaging system because previous MR imagingϪbased measurements of mammillary body volume have used 1.5T systems.…”

“…[27][28][29][30][31][32] An additional MR imaging sequence was used to acquire intracranial volume data for normalizing the data for differences in head size across patients and controls. This sequence was a T2-weighted intracranial volume scan; parameters were TR, 3000 ms; TE, 102 ms; FA, 150°; 3-mm section thickness; 10-mm section gap; acquisition time, 2 minutes.…”