Background and purpose: Although sensory deficits caused by stroke have been reported occasionally, dysfunction of discriminative sensation has seldom been studied in patients with unilateral stroke. The frequency and modality of bilaterally impaired discriminative sensation also remain to be clarified.
Methods: With the use of specifically designed methods, we tested discriminative sensations including texture discrimination, two-point discrimination, stereognosis, point localization, and position sense in 67 patients with acute unilateral stroke. The locations of the lesions were identified with the use of CT and/or MRI. Thirty-two age- and sex-matched healthy subjects were used as a control.
Results: Impaired discriminative sensation was common in patients with unilateral stroke (detected in 57 of the 67 patients) regardless of lesion location except for patients with lateral medullary infarction. Discriminative sensation remained intact in only 3 of 25 patients who were initially diagnosed as having pure motor stroke on the basis of conventional sensory tests. Point localization and stereognosis were bilaterally impaired in 17 of 39 patients and 7 of 38 patients, respectively, regardless of the laterality of the lesion. Dysfunction of other sensory modalities was observed exclusively on the side contralateral to the lesion.
Conclusions: Discriminative sensory disturbances, which often occur bilaterally in some modalities, are common in patients with unilateral stroke even in those with intact sensory function on routine examination. The subtle disturbances of this sensation may explain, at least in part, the clumsiness of the patients that is not readily explained by conventional neurological tests.