Investigation of the Effect of Central Sensitization Symptom Severity on Steroid Injection Results in Shoulder Pain

The aim of this study was to investigate the effect of the presence and severity of pre-treatment central sensitization on the results of subacromial/ intra-articular shoulder injection in patients with rotator cuff lesion/subacromial impingement. The hypothesis of the study is that the treatment response will decrease in patients with pre-injection central sensitization.

There are many studies investigating the frequency of central sensitization in various shoulder pathologies. However, the effect of this condition, which is likely to be associated with chronic pain in these patients, on treatment response is unknown. The effect on the results of shoulder injection, one of the most common procedures in physical therapy practice, will be investigated.

Shoulder pain is one of the most common musculoskeletal complaints and its prevalence varies between 7-26%. Although some of the patients with shoulder pain show complete recovery, pain persists in some of them. One of the most common sources of pain in these patients is subacromial impingement syndrome (SIS) leading to rotator cuff pathology. The multifactorial nature of pain in these patients makes the treatment of SIS difficult.

Central sensitization (CS) has been reported as one of the factors associated with persistence of pain in patients with shoulder pain in different etiologies, especially in the SIS. CS can be summarized as an increase in the response of neurons located in the central nervous system to subthreshold stimuli and is the source of chronic pain in many diseases. A decrease in the pressure pain threshold was observed in the painful shoulder of 58 patients with experimental pain response in the shoulder.

In a meta-analysis of patients with shoulder pain, a decrease in pressure pain threshold was found in 29-77% of patients, while SS was found in 11-24% of patients. The authors emphasized the significant correlation of CS with poor treatment response. There is increasing evidence that CS negatively affects various pain treatment responses, including surgery. Considering the frequency of CS in patients with shoulder pain, it is likely to have a negative impact on treatment response in these patients as well. One of the most common treatments for SIS is subacromial/ intra-articular shoulder injection. Although several factors have been identified in the prediction of shoulder injection outcomes, the effect of pain sensitization on these procedures is not yet known.

This study was designed as a prospective single-center study. Patients aged 18-65 years with rotator cuff lesions lasting more than three months and presenting to our physical medicine and rehabilitation outpatient clinic will be included. Patients who have received medical treatment as part of routine practice and have not had an adequate response will be evaluated before and after injection. Injection preference will be determined according to the patient primary complaint and lesion and will be administered into the subacromial space or into the shoulder joint. There is no additional interventional procedure due to the study. Patients will be divided into 2 groups with and without central sensitization. A total of 18 patients were planned for each group. The study will be conducted between March 2023 and June 2024.

Within the scope of the study, age, gender, body mass index, marital status, education level and occupation of the participants will be recorded as demographic data. Clinical evaluation includes pain duration, treatments received, pain intensity (numeric pain scale 0-10), disease-related MRI/USG findings and the following evaluations.

All patients will be evaluated before injection, 1 week, 1 and 3 months after injection. Within the scope of evaluation, Central Sensitization Scale, Quick DASH, SF-36 and Hospital Anxiety and Depression questionnaire, pressure pain threshold, goniometric shoulder range of motion measurement, hand grip strength (with Jamar hydraulic hand dynamometer), numeric pain scale (no pain: 0- unbearable pain: 10) and pain intensity will be recorded at each visit.

Data analysis will be performed by using the Statistical Package for the Social Sciences (SPSS, version 23.0, IBM Corp., Armonk, NY, USA).

Eligibility Criteria:
Inclusion Criteria:

* Clinically and radiographically confirmed rotator cuff pathology
* Being between the ages of 18-65
* Non-response to medical treatment
* Being literate
* To agree to participate in the study

Exclusion Criteria:

* History of shoulder trauma and previous shoulder surgery
* Injection in the shoulder area in the last 3 months
* History of active cancer, systemic inflammatory disease and infection
* Pregnancy
* Under 18 and over 65 years of age
* Illiteracy
* Refusal to participate in the study