Multimodal and widespread somatosensory abnormalities in persistent shoulder pain in the first 6 months after stroke: an exploratory study.

Objective: To explore the role of multimodal and widespread somatosensory abnormalities in the development of persistent poststroke shoulder pain (pPSSP) in the first 6 months after stroke.

Design: Prospective inception cohort study.

Setting: Stroke units of 2 teaching hospitals.

Participants: The data of a strict selection of patients (N=31) with a clinical diagnosis of stroke were analyzed.

Interventions: Not applicable.

Main Outcome Measures: The development of pPSSP within the first 6 months after stroke. Bilateral sensation and pain thresholds at 3 (t1) and 6 (t2) months, and conditioned pain modulation (CPM) at 3 months after stroke. Clinical examination within 2 weeks after stroke (t0), at t1, and at t2.

Results: pPSSP (n=9) was associated with increased sensation and pain threshold ratios at the affected side (t1, t2), and with reduced cold pain tolerance at the unaffected side (t1). CPM was not different from patients without pPSSP (n=22). Notably, in patients with pPSSP reporting increased sensation on clinical examination, multiple body sites across multiple stimulus modalities were involved, and increased sensation persisted from t1 to t2.

Conclusions: pPSSP in the first 6 months after stroke was associated with somatosensory loss to both innocuous and noxious stimuli (affected side). In addition, pPSSP was associated with sensitization to cold pain (unaffected side) and with widespread sensitization to multimodal innocuous stimuli (affected side). The results support the notion that central somatosensory sensitization could play an important role in the development of pPSSP, the maintenance of pPSSP, or both.