Restricted acral sensory syndrome following minor stroke. Further observation with special reference to differential severity of symptoms among individual digits.

Abstract

Restricted acral sensory syndrome (RASS) after minor stroke most often manifests as a cheiro-oral syndrome. However, recent studies have described more varied patterns of RASS and also have reported that the degree of sensory symptoms may vary among individual digits. Until recently, however, there have been no reports in which sufficient numbers of patients were studied with detailed information on the symptomatic severity among individual digits. 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 or 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.