Memory Dysfunction and Caudate Stroke
To the Editor:
We read with great interest the recent article by Kumral et al1 on caudate vascular lesions and functional outcome. We agree with the authors that it is indeed important to take into account behavioral abnormalities after subcortical stroke. However, we would like to comment on the authors’ suggestion of the role of the caudate nucleus in the integration of verbal and visual memory, especially on the interpretation and the conclusion drawn from the neuropsychological test results.
Verbal memory function was assessed by means of the Rey Auditory Verbal Learning Test (AVLT), originally developed by Rey.2 This widely used task consists of a list of 15 words that has to be remembered in 5 consecutive learning trials. After each presentation, the patient is prompted to recall as many words as he or she can remember from that list, thus providing information on immediate recall and verbal learning.
To determine whether a patient is verbally amnesic, Kumral et al used a cutoff score of ≤9 on the first of 5 trials. This seems rather arbitrary, because the normal performance of healthy subjects runs from 5.8 to 7.8 words on this first trial of the AVLT.3 4 In addition, we recommend against use of only the initial trial to assess verbal amnesia, as this gives only an indication of immediate recall or supraspan learning. For example, patients with cerebral damage may perform equal to healthy subjects on the first trial, but the impairment presents particularly on the consecutive trials.4 Moreover, others5 have suggested that memory impairment after caudate infarction might be the result of a retrieval problem. This can be studied effectively with use of the recognition list of the AVLT, the results of which were not reported.
Unfortunately, no essential information is provided about the administration and scoring procedure of Form F of the Benton Visual Retention Test (BVRT). As this form is to the best of our knowledge not part of the standard BVRT, which consists of 5 parallel forms (A, B, C, D, and E), we cannot comment on the reported findings on visual memory.
In summary, the AVLT is a widely used neuropsychological test for the assessment of verbal memory function. However, when a cutoff is used to determine memory dysfunction, a score of 9 or lower on the initial trial is too high and results in too many false-positives. Because verbal memory is not a unitary concept, the scoring of consecutive learning trials and delayed and recognition test performance yields the most valid and reliable test results. Cognitive research that focuses on the role of the caudate nucleus in memory function is extremely important, but the conclusions of Kumral et al1 inferred from the neuropsychological findings are somewhat overstated.
- Copyright © 1999 by American Heart Association
Kumral E, Evyapan D, Balkir K. Acute caudate vascular lesions. Stroke. 1999;30:100–108.
Rey A. L’examen clinique en psychologie. Paris, France: Presses Universitaires de France; 1964.
Van Zandvoort MJE, Kappelle LJ, Algra A, De Haan EHF. Decreased capacity for mental effort after single supratentorial lacunar infarct may affect performance in everyday life. J Neurol Neurosurg Psychiatry. 1998;65:697–702.
Lezak MD, ed. Neuropsychological Assessment. 3rd. ed. Oxford, UK: Oxford University Press; 1995.
We thank Drs Kessels, van Zandvoort, de Haan, and Kappelle for their interest in our work on the clinical profiles and behavioral abnormalities of acute caudate stroke. It is well known that the caudate nuclei have a primary role in behavioral and cognitive functions, in processing information, and probably in conceptually integrating information.R1 R2 Although the role of caudate nuclei in mnemonic functions is not well established, Bokura and RobinsonR3 observed that lesions in caudate nuclei led to chronic cognitive decline, which was assessed at follow-up by the Mini-Mental State Examination. In a previous study by Mendez et al,R4 patients with caudate lesions showed impaired immediate and delayed recall memory scores on a word list learning test (California Verbal Learning Test) and had poor recall of a complex figure drawing on a visual learning test (Rey Complex Figure Test). The Rey AVLT is a brief, easily administered test that assess immediate memory span, new learning, and recognition memory. It consists of 5 presentations with recall of a 15-word list, 1 presentation of a second 15-word list, and a sixth recall trial.R5 Retention may be examined after 30 minutes, and hours or days later. Trial I may be considered an indication of immediate recall; on average, our normal older adults (65 to 80 years) may recall 8±2 words. In our study, we measured only immediate verbal recall. We agree that other subtests are also necessary to measure long-term learning and retrieval efficiency. In our study, we used Form F of the BVRT to assess immediate visual recall and recognition.R6 Form F is an additional form that is available to test the subject’s visual recognition and recall. This form consists of 15 stimulus cards, each exposed for 10 seconds, and corresponding 4-choice response card. We used a cutoff score of ≤9 on this form. In our study, we only analyzed immediate verbal and visual recall, which are parts of memory function. Memory function has many aspects, including acquisition, retention, and retrieval. Future studies will further clarify the abilities of learning, holding, and storing information in relation to caudate subnuclei.
Caplan LR, Schmahmann JD, Kase CS, Feldmann E, Baquis G, Greenberg JP, Gorelick PB, Helgason C, Hier DB. Caudate infarcts. Arch Neurol. 1990;47:133–143.
Bokura H, Robinson RG. Long-term cognitive impairment associated with caudate stroke. Stroke. 1997;28:970–975.
Mendez MF, Adams NL, Lewandowsky K. Neurobehavioral changes associated with caudate lesions. Neurology. 1989;39:349–354.
Rey A. L’examen clinique en psychologie. Paris, France. Presses Universitaires de France; 1964.
Benton AL. Revised Visual Retention Test. 4th ed. San Antonio, Tex: The Psychological Corporation; 1974.