MEDizzy - A 73-year-old man suffers from an acute infarction leading

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COGNITIVE AND BEHAVIORAL NEUROLOGY

A 73-year-old man suffers from an acute infarction leading to right arm and leg hemianesthesia. Three months later he presents to the outpatient clinic with severe right-sided hyperesthesia and allodynia. Which of the following is the most likely explanation for this man’s symptoms?

ExplanationDamage to the posterolateral thalamus gives rise to Dejerine– Roussy syndrome, or thalamic pain syndrome, which is characterized by initial contralateral hemianesthesia followed weeks later by pain, hyperesthesia, and allodynia. A similar delayed central pain syndrome can occur with a lesion to the medial lemniscus, dorsal columns, or with lesions to the parietal operculum (the latter is also termed pseudothalamic syndrome). The spinothalamic tract projects to the ventral posterolateral nucleus of the thalamus, which in turn projects to the secondary somatosensory cortex (area SII). A lesion to the primary somatosensory cortex (area SI) would lead to contralateral loss of sensation to touch, joint position sense, and vibration, but would spare pain and temperature sensation, and would not cause a delayed pain syndrome.