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In this report,I describe 30 patients presenting with RASS secondary to minor stroke.Computed tomographic scan and/or magnetic resonance imaging identified lesions in the lateral thalamus in 11,midbrain in 2,pontine tegmentum in 8,capsulo-corona radiata in 5,and frontoparietal subcortical- cortical areas in 4 patients.The patterns of RASS were cheiro-oral in 10, cheiro-oral-pedal in 8,cheiro-pedal in 4,restricted to palm and/or fingers in 7,and periotal-pedal in 1.Dominant involvement of upper lip,thumb,and index finger was frequent,especially in patients with thalamic and thalamocortical lesions.In patients with cortical-subcortical lesions, cheiro-oral or restricted finger involvements were observed,while the foot was spared.In patients with pontine lesions,bilateral RASS was occasionally observed,and the pattern of preponderant involvement of the first two digits was not apparent.These patterns of RASS generally agree with the previously observed sensory topography of monkeys,and they support anatomic proximity of sensory fibers from acral parts of the body. However,other mechanisms such as differential vulnerability of generation of paresthesia in different body parts of a low-threshold concept based on disproportionately large representing areas for the acral parts of the body in the human sensory system may also be required to explain some of the clinical observations. |
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