Stroke and restricted sensory syndromes

[Vascular syndromes of the thalamus]

The thalamus comprises numerous nuclei that can be grouped into five major functional domains: (1) the reticular and intralaminar nuclei influence arousal and nociception, (2) sensory nuclei handle afferent pathways, (3) the effector nuclei are involved in motor function and language, (4) associative nuclei participate in higher cognitive functions and (5) limbic nuclei influence mood and motivation. The thalamic nuclei are mainly supplied by the following four cerebral arteries: paramedian artery, anterior thalamoperforating artery, thalamogeniculate artery and posterior choroidal artery (lateral branches). Occlusions of these arteries affect the thalamic nuclei to varying degrees and produce partly characteristic and partly overlapping deficits. This article describes the clinical pictures.

Bilateral perioral sensory symptom after unilateral stroke: does it have a localizing value?

Bilateral perioral sensory dysfunction due to unilateral cerebral lesion is rare, and has been thought to be caused by midline brainstem lesions. Six patients are described herewith, with bilateral perioral sensory symptoms due to unilateral strokes that do not involve the mid-brainstem region. Brain-computed tomographic scan and magnetic resonance imaging demonstrated unilateral cerebral strokes in the thalamus, posterior limb of the internal capsule, basal ganglia, fronto-parietal cortex and the insular-frontal subcortical area. This observation suggests that bilateral perioral sensory symptoms do not have a localizing value. Possible pathogenetic mechanisms for this sign are discussed.

Restricted nonacral sensory syndrome

BACKGROUND

Restricted sensory symptoms due to stroke most often occur at distal parts of the body, manifesting as cheiro-oral or cheiro-oral-pedal syndrome. Sensory symptoms restricted to proximal body parts have rarely been recognized.

CASE DESCRIPTIONS

I describe four patients presenting with restricted sensory disturbances at the proximal parts of the body. The sensory symptoms were restricted to discrete areas of the contralateral proximal arm, shoulder, trunk, and upper thigh. The face and the distal parts of the extremities were largely spared. On MRI, three patients had a small thalamic infarction and one had a putaminal infarction.

CONCLUSIONS

Strategically located minor strokes can produce restricted sensory syndromes at discrete areas of nonacral parts of the body. These observations highlight the diverse patterns of restricted sensory syndromes after unilateral stroke and support the theory of somatotopic-anatomic proximity of certain parts of the body in the human sensory pathway.

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

BACKGROUND

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.

SUMMARY OF REVIEW

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.

CONCLUSIONS

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.