Evaluation of Percutaneous Cryoneurotomy Compared to Surgical Open Neurotomy for the Management of Equinovarus Foot Deformity in Patients With Refractory Lower Limb Spasticity After Stroke

Stroke, arising from cerebral vascular hemorrhage or ischemia, represents a major health-care problem affecting more than 140,000 persons in France every year. One of the major concerns after stroke is impairment of the pyramidal tract and parapyramidal fibers, resulting in upper motor neuron syndrome and spasticity. Up to 20% to 40% of stroke survivors develop spasticity, which dramatically impacts health status, pain, functional capacity, and ultimately, quality of life. Spastic equinovarus foot (SEF) is the most common deformity due to lower limb spasticity and is defined as a combination of an abnormal plantar-flexion, inversion and adduction of the foot. Consequently, SEF severely impairs walking capability and mobility, impacting daily life activities and restricting social participation. In addition to therapeutical physical rehabilitation programs, two main treatments can be proposed. First, SEF can be initially treated with focal botulinum toxin injections that for reducing spasticity. However, botulinum toxin injections are effective for only a limited period of time, and iterative reinjections are required. Second, permanent treatment of spasticity can be achieved by surgical neurotomy. This procedure, variably combined with muscle and tendon lengthening in the event of associated retractions, can be considered as the long-term radical and effective gold standard, but at the price of surgical invasiveness and complications.

A recent alternative allowing for both permanent treatment and a minimally invasive approach has been introduced: "percutaneous cryoneurotomy". While this approach has provided promising results, as shown in multiple case reports, its efficacy has yet to be determined in a randomized control study.

CryoNeurotomy (CN) was first performed and developed in daily practice for the upper limb. Through a mentoring process, a feasibility study was performed on cadavers and transposed the technique to human procedures in a pilot study. The results from the first patients, with a 90-day follow-up period, are promising, with decreased spasticity and significantly increased walking capabilities. Major potential advantages of percutaneous CN compared to surgical neurotomy were identified, such as minimal skin incision, faster procedure, far less invasiveness of muscle tissue and adjacent neuro-vascular structures, particularly a decreased risk of post-operative sensory loss or neuropathic pain, no need for general anesthesia (local anesthesia) and possible performance on an outpatient basis. By enlarging Physical Medicine and Rehabilitation (PMR) therapeutical armamentarium, percutaneous CN could represent a new compromise between botulinum toxin iterative injections and radical surgery, in terms of invasiveness \& complications/long-term benefit ratio on spasticity and function.

The CRYOSTROKE study was designed:

* to compare the efficacy and safety of percutaneous CN versus surgical neurotomy on spasticity, 90 days after intervention, in post-stroke patients presenting with spastic equinovarus foot and, * to ensure that potential clinical effect/safety remain stable within time, with a 12-month follow-up.

• Mean absolute change in functional disability assessed using the Barthel Index (BI). [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in passive ankle dorsal flexion with knee flexed (90°) and extended (180°) movement spasticity assessed by the Modified Ashworth Scale (MAS) [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in muscle's response to stretch applied at given velocities assessed by the Tardieu Scale and the Modified Tardieu Scale (MTS) [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in maximal ankle range of motion (in degrees) assessed with a goniometer in slow and rapid movement [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in the Medical Research Council (MRC) scale of muscle strength of the impaired foot. [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in time in seconds to complete the 10-meter walking test [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in the distance in meters covered in the 6-min walking test [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Physical activity intensities: Mean absolute change in the rate of high, moderate, light activities bet [Time frame: Between baseline and 90, 180 and 365-day follow-ups for a period of 7 days before each visit]
• Physical activity intensities: mean absolute change in number of steps measured with accelerometer (ActiGraph GT9X) [Time frame: Physical activity intensities: mean absolute change in number of steps measured with accelerometer (ActiGraph GT9X)]
• Mean absolute change in pain surface using a digital mapping tool converting pain drawings to cm² [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in pain intensity and interference using the Brief Pain Inventory (BPI) questionnaire [Time frame: Between baseline and 90, 180 and 365-day follow-ups]
• Mean absolute change in quality of life: EuroQol 5 Dimensions 5 Levels (EQ-5D-5L) questionnaire [Time frame: Between baseline and 90, 180 and 365-day follow-ups]