title: Somatosensory symptoms and signs and conditioned pain modulation in chronic post-stroke shoulder pain.
abstract: Persistent shoulder pain is a common complication after stroke. Its etiology and underlying mechanisms are not well understood and treatment is generally unsatisfactory. The objective of this study was to assess the role of central sensitization and disinhibition in chronic stroke patients with chronic PSSP (n = 19), pain-free stroke patients (n = 29), and healthy controls (n = 23). Positive and negative somatosensory symptoms and signs were assessed using clinical examination and electrical and mechanical quantitative sensory testing (QST). Conditioned pain modulation (CPM) was assessed by comparing QST thresholds before and after applying a cold pressor test. Sensory abnormalities were more frequently observed and more severe in patients with PSSP, including positive signs such as allodynia at the affected side and generalized hyperalgesia at the unaffected side. CPM was similar in stroke patients and healthy controls. This study showed that chronic PSSP was associated with several positive and negative somatosensory signs, implicating a role for central sensitization and possibly for disinhibition. Since the causal relationship remains unclear, and may be related to either neuroplasticity induced by ongoing nociception as well as to the neuropathic brain lesion, prospective studies are warranted.
  
  
  CONCLUSIONS
  The assessment of somatosensory symptoms and signs and endogenous pain modulation demonstrated a role for central sensitization and possibly for disinhibition in chronic PSSP. Prevention and treatment of PSSP could benefit from a more detailed analysis of both peripheral and central pain mechanisms.
authors.affiliation: Biomedical Signals & Systems, MIRA institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands. meyke.roosink@gmail.com
authors.forename: Meyke
authors.initials: M
authors.lastname: Roosink
authors.forename: Gerbert J
authors.initials: GJ
authors.lastname: Renzenbrink
authors.forename: Jan R
authors.initials: JR
authors.lastname: Buitenweg
authors.forename: Robert T M
authors.initials: RT
authors.lastname: van Dongen
authors.forename: Alexander C H
authors.initials: AC
authors.lastname: Geurts
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Ijzerman
mesh_terms: D000328:Adult; D002908:Chronic Disease; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000502:physiology*; D012782:Shoulder / Q000503:physiopathology*; D020069:Shoulder Pain / Q000209:etiology* / Q000503:physiopathology*; D020521:Stroke / Q000150:complications*