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RESEARCH PRODUCT

Chapter 15 Pain and itch in Wallenberg's syndrome: anatomical–functional correlations

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Publisher Summary The Wallenberg syndrome or dorso-lateral medullary infarction is the most common vascular syndrome of the medulla oblongata. Its clinical features include an ipsilateral Horner's syndrome, an ipsilateral limb ataxia, and mostly an ipsilateral but sometimes also a contralateral or bilateral decrease of pain and temperature sensibility of the face. Patients with Wallenberg's syndrome and with morphological (lesion) or functional (ipsilateral sensory deficit and delayed late blink reflex responses) show evidence of damage to the trigeminal tract and nucleus with sparing of the nucleus caudalis would develop facial pain. The trigeminal trophic syndrome (TTS), a very rare complication of Wallenberg's syndrome, can occur with and without central poststroke pain (CPSP). In these patients, itch is the predominant complaint causing facial ulcerations maintained by picking and scratching. Ongoing itch is a matter of not only neural injury but also missing inhibition. The intensity and duration of scratching provoked by itch are reduced with the onset of pain. The lack of pain sensibility in most patients with itch following TTS may result in this kind of missing inhibition. TTS patients often, but not always, suffer from diseases leading to a reduction of central inhibitory mechanisms, such as dementia or bipolar depression.