Background & Aims
Rotator cuff tear (RCT) frequently leads to shoulder pain and dysfunction in middle-aged and elderly patients. Although its clinical course varies from asymptomatic to highly symptomatic, mechanisms underlying refractory motion pain and nocturnal pain have not been fully elucidated. Recent studies have suggested that increased blood flow in the rotator interval (RI) and axillary pouch (AP) is possibly related to pain in patients with frozen shoulder, drawing attention to the role of local hemodynamics in shoulder pain mechanisms. In this study, we focused on the hemodynamics of different shoulder structures in patients with RCT and investigated their relationship to pain intensity.
Methods
54 RCT patients (Mean age: 64[42-83]) with full-thickness supraspinatus tendon tears undergoing arthroscopic repair were included. The intensity of motion and nocturnal shoulder pain was evaluated using a 100mm visual analog scale (VAS). Dynamic MRI was performed for 3 minutes, and time-intensity-curve analysis was conducted to assess hemodynamics of the remnant tendon stump, surrounding bursa, RI, AP, and deltoid muscle (control) within a 20mm2 ROI. Peak enhancement ratio (PER, reflecting blood flow volume) and enhancement slope (ESL, reflecting blood flow velocity) were calculated. Correlations of PER / ESL in each structure (divided by the data of deltoid muscle for normalization) with the pain VAS were evaluated. Additionally, whether demographic data (age, sex, duration of pain, size of RCT, range of motion) and chronic-pain-associated questionnaires (pain catastrophizing scale, hospital anxiety, depression scale, and central sensitization inventory) contributed to shoulder pain.
Results
Motion and nocturnal shoulder pain VAS was 69 [58-81] (Median [interquartile range]) mm and 63 [31-79] mm. The values of PER/ESL in each structure were 0.04 [0.03-0.10] / 0.20 [0.10-0.51] in the tendon stump, 5.62 [3.59-7.24] / 5.10 [3.60-8.63] in the surrounded bursa, 5.95 [3.63-8.25] / 6.00[3.88-8.38] in the RI, 5.64 [3.38-7.84] / 5.91[3.20-9.00] in the AP, and 0.27 [0.22-0.32] / 1.13[0.91-1.66] in the deltoid muscle. The PER and ESL showed significantly higher in the bursa, RI, and AP than in the deltoid muscle, whereas it presented markedly lower in the tendon stump (P < 0.01). The motion pain VAS was positively correlated with PER (r=0.529 and 0.360, P<0.01) and ESL (r=0.473 and 0.382, P<0.01) in the bursa and AP respectively, while the nocturnal pain VAS was negatively correlated with PER (r=-0.324, P<0.05) and ESL (r=-0.272, P<0.05) in the tendon stump. Neither demographic data nor chronic pain-associated questionnaires were associated with the motion and nocturnal pain VAS.
Conclusions
In this study, abundant hemodynamic activity within the bursa and AP exhibited severe motion pain, which reflected focal inflammation probably due to subacromial impingement in the bursa and secondary glenohumeral synovitis. In contrast, diminished vascular perfusion at the tendon stump was significantly associated with severe nocturnal pain, suggesting that ischemic conditions of the torn tendon play a substantial role in the etiology. Although larger investigation with multivariate analysis is warranted, these hemodynamic alterations in the affected shoulder predominantly contributed to pain intensity rather than patients’ demographic data and chronic pain-associated questionnaires.
References
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Presenting Author
Toru Morimoto
Poster Authors
Topics
- Specific Pain Conditions/Pain in Specific Populations: Acute Pain and Nociceptive Pain