The role of the peripheral and central nervous systems in rotator cuff disease

Abstract

Rotator cuff (RC) disease is an extremely common condition associated with shoulder pain, reduced functional capacities and impaired quality of life. It primarily involves alterations in tendon health and mechanical properties that can ultimately lead to tendon failure. RC tendon tears induce progressive muscular changes that negatively impact surgical reparability of the RC tendons and clinical outcomes. At the same time, a significant base of clinical data suggests a relatively weak relationship between RC integrity and clinical presentation, emphasizing the multifactorial aspects of RC disease. This review aims to summarize the potential contribution of peripheral, spinal and supraspinal neural factors that may: (i) exacerbate structural and functional muscle changes induced by tendon tear, (ii) compromise the reversal of these changes during surgery and rehabilitation, (iii) contribute to pain generation and persistence of pain, iv) impair shoulder function through reduced proprioception, kinematics and muscle recruitment, and iv) help to explain interindividual differences and response to treatment. Given the current clinical and scientific interest in peripheral nerve injury in the context of RC disease and surgery, we carefully reviewed this body of literature with a particular emphasis for suprascapular neuropathy that has generated a large number of studies in the past decade. Within this process, we highlight the gaps in current knowledge and suggest research avenues for scientists and clinicians.

Prevalence and Risk Factors of Neuropathic Pain in Patients with a Rotator Cuff Tear

“…The peripheral neural lesions trigger pathologic activity and sensitization processes in peripheral nociceptors that is peripheral sensitization, leading to neuropathic pain such as spontaneous burning pain, static mechanical, and heat hyperalgesia (22). This peripheral sensitization occurs in patients with rotator cuff disease, which releases a variety of substances that sensitize nociceptors by decreasing their activation threshold in the shoulder because RC disease is associated with local tissue damage and inflammation within the RC and surrounding structures (12). The spontaneous activity of nociceptors in turn induces secondary changes in the central sensory processing, leading to spinal cord hyperexcitability, which generates dynamic and punctate mechanical allodynia (22).…”

“…Fabis and Bgucki (10) reported that 33 (34%) of 97 patients with a rotator cuff tear (RCT) had radiating pain, which disappeared completely in 26 cases, partially in six, and persisted in one after an intra-articular lidocaine injection. Bachasson et al (12) reviewed a large number of neural structures and mechanisms that contribute to pain and shoulder dysfunction in patients with a RCT. They revealed that the neural factor around the shoulder may contribute to pain generation and persistence of pain in the patients with a RCT.…”

The role of mechanobiology in progression of rotator cuff muscle atrophy and degeneration

“…Mechanical unloading is potentially compounded by pain‐induced diminution of voluntary muscle contraction. Suprascapular nerve dysfunction may also impact muscle remodeling, though the prevalence of neuropathy in RC tears appears to be limited . As the muscle retracts, muscle fibers shorten via serial sarcomere subtraction and the muscle becomes fibrotic (discussed in further detail below).…”

The effects of rotator cuff tear on shoulder proprioception

“…Expanding our knowledge, research is moving on the effects that this musculoskeletal disease causes on peripheral, spinal, and central neural factors, especially in the field of proprioception [13]. The latter is not a new concept; in 1906, Charles Sherrington coined this term considering it as Bour perception of joint movement and positioning in space in the absence of visual feedback^ [14].…”