Cryoneurolysis as a Drug Free Novel Treatment for Knee and Shoulder Pain Impairing Inpatient Neurological Rehabilitation

Hemiplegic shoulder pain (HSP) is the most common pain disorder after stroke and one of the four most common complications. The estimated incidence ranges from of 30%-70%. HSP is associated with reductions in function, interference with rehabilitation efforts , and a reduced quality of life .Onset of HSP is rapid, occurring as soon as a week after stroke in 17% of patients.While ubiquitous, the management of HSP represents a complex treatment pathway that has insufficient evidence supporting one particular treatment.

The pain associated with HSP may be due to heterogeneous causes. In the acute setting, decreased ROM in the shoulder may represent several processes including the early onset of spasticity, capsular pattern stiffness, glenohumeral pathology, or a component of complex regional pain syndrome (CRPS). Effective management of the HSP with decreased ROM requires assessment of each possible contributor. The suprascapular nerve provides up to 70% of the sensory fibers to the shoulder. Targeting the suprascapular nerve to reduce pain from stroke has been study with both nerve blocks and radiofrequency ablation. Cryoneurolysis to treat shoulder pain has also been proposed in recent years.

The lack of early recognition and treatment of HSP can lead to worsening limb function, increased pain, and may impair the rehabilitation and recovery process Early intervention may reduce the risk and onset of contracture, which can lead to significant impairments and a reduced quality of life. The incidence of developing at least one contracture in stroke patients within six months of their stroke is estimated at 52%.Contractures are a source of pain and limited ROM, and limit function while stretching has not been shown to be clinically effective. Patients with contractures and limited volitional control of their shoulder muscles, can experience maceration, skin dehiscence, impaired hygiene, and difficulty dressing, thus more invasive surgery may be required.

Knee osteoarthritis is ubiquitous in the aging population. Many stroke patients may have been pre-stroke poor candidates for a total knee arthroplasty due to medical frailty. Participants recovering from stroke, with pre-existing arthritis perceived that their arthritis "held them back" from an expected stroke recovery trajectory.In this study; "This slowed stroke recovery was attributed to daily pain, frustration, mobility limitations, and the required extra coping due to arthritis. As a result, comorbid arthritis increased the complexity of stroke recovery and rehabilitation."

This group has been global pioneers in the use of cryoneurolysis to treat spasticity.The process first involves isolating the nerves with ultrasound guidance and e-stimulation for motor nerves. A diagnostic nerve block is then performed to assess if spasticity is reduced, and range of motion and ease of movement occurs, as well as pain reduction. After a successful nerve block the patient then goes on to have cryoneurolysis which is performed using a small 1.2 to 1.3 mm diameter cryoprobe that is inserted percutaneously to targeted peripheral nerves. It has an established history over more than fifty years for lasting pain relief from months to years, when used for sensory nerves. Cryoneurolysis is possible due to the process of throttling a gas through an orifice from high to low pressure resulting in a rapid expansion of the gas and a drop in temperature, known as the Joule-Thomson effect. The rapid cooling generates an ice ball or oval between 3.5 and 18 mm that is formed at the tip of the with compressed CO2 or N2O at temperatures typically between -60 to -88° C. The ball or oval creates a targeted zone of axon and myelin disruption. This results in loss of axon continuity due to Wallerian degeneration of the targeted nerve extending outward from the lesion over a limited distance. However, the basal lamina, epineurium and perineurium of the targeted nerve remain intact and serve as a conduit or tube for neural regeneration.