Medical Student The University of British Columbia
Objectives Multiple Sclerosis (MS) is identified as a global health concern that impacts nearly 3 million people worldwide. Widespread physical disability for MS patients is common, with one of the most disabling symptoms being spasticity, which is experienced in up to 90% of patients. The primary treatments for MS to date have targeted disease progression, with less research focused on interventions targeting symptoms, such as pain and spasticity. The purpose of this study is to address the current research gaps within symptom management by examining the effects of cryoneurolysis to the tibial nerve to treat spasticity in patients with Multiple Sclerosis. Design This study is a retrospective chart review for 20 patients with Multiple Sclerosis. The assessments measured include: the maximum passive range of motion (ROM) and tone based on the Modified Ashworth Scale (MAS). Ankle dorsiflexion was measured when the knee was both flexed and extended. Baseline measurements were taken before the procedure and follow-up measurements were completed up to 1.5 years post-cryo. Results Ultimately, the MAS for dorsiflexion with the knee flexed and extended showed spasticity to be significantly reduced at the first three follow-ups relative to baseline, p< 0.05. Significant increases in range of motion were also found for dorsiflexion under both conditions, with the greatest increase in V1 being 35 degrees, p< 0.05. The longest-standing improvements in tone and range of motion lasted 1.5 years post-cryoneurolysis. Conclusions This study suggests that cryoneurolysis can be an effective treatment for lower limb spasticity in patients with Multiple Sclerosis through reducing tone and increasing the range of motion for dorsiflexion when the knee is flexed and extended. Further studies are required to examine a variety of nerves to assess the clinical scope of cryoneurolysis treatment.
Introduction/
Objectives:
Multiple Sclerosis (MS) is identified as a “global health concern” that impacts nearly 3 million people worldwide. MS is a chronic autoimmune disorder that targets the central nervous system and is characterized by demyelination, neuroinflammation and axonal damage. Individuals with MS have a vast array of symptoms such as spasticity, muscle weakness, neuropathic pain and cognitive dysfunction. One of the most disabling symptoms is spasticity, which is experienced in up to 90% of patients. Spasticity is a condition that results in muscle stiffness and involuntary contractions that can worsen pain and enhance functional impairments and psychological stress.
Cryoneurolysis is a novel procedure that is minimally invasive and functions to treat focal spasticity and associated pain. The procedure uses ultrasound guidance and a 16-gauge angiocatheter to allow the cryoprobe, which is cooled to a temperature range of -60°C to -88°C, to generate an ice ball from interstitial fluid surrounding a peripheral nerve. This process causes secondary axonotmesis, where the epineurium and perineurium remain intact and ultimately, this provides a pathway for the damaged axon to regenerate. Research has shown that the effects of cryoneurolysis on pain and spasticity can last from months to years.
This study is a retrospective chart review evaluating the effects of cryoneurolysis to treat ankle spasticity in 20 patients with Multiple Sclerosis. For all patients, cryoneurolysis to the tibial nerve was performed with the goals of treatment being to reduce tone based on the Modified Ashworth Scale (MAS) and improve the maximum passive range of motion (V1) through the use of a goniometer. This study aims to demonstrate cryoneurolysis as an effective treatment to manage lower limb spasticity in patients with MS.
Methods:
Study
Design:
This study is a retrospective chart review and follows the Case Reports (CARE) guidelines and reports the required information accordingly. Institutional research ethics approval from the local research ethics board was collected [H23-00533]. The patient's medical charts were reviewed to collect all data regarding cryoneurolysis and any assessments before and after the procedure.
Interventional Procedure:
Once the patients were assessed for spasticity in their lower limbs, a diagnostic motor nerve block (DNB) was first performed to the tibial nerve or its branches for each patient to help predict the effectiveness of cryoneurolysis. This DNB is ultrasound guided and consists of 1 cc of 2% lidocaine to the motor nerve trunk or the intramuscular motor branches to the gastrocnemius or soleus muscle. Patients were informed that cryoneurolysis could be a treatment option if there was improved pain and range of motion. The 20 patients then consented to cryoneurolysis and received the treatment to the same targets as their DNBs.
Data Review:
For each patient in the study, baseline measurements were taken prior to receiving cryoneurolysis. The baseline measurements for ankle dorsiflexion were documented including: the maximum passive range of motion (PROM; V1) when the knee was extended and flexed, angle of catch with fast movement V3, based on the Modified Tardieu Scale, along with spasticity severity based on the modified Ashworth scale (MAS) when the knee was flexed and extended. Follow-up measurements were then documented up to a maximum of 1.5 years post procedure for each patient. All patients had a minimum of two follow-up measurements and a maximum of nine.
Results:
At the first, second, and third follow-up, there were significant reductions in tone relative to baseline for dorsiflexion when the knee was flexed and extended based on the MAS, p< 0.05. For V1 with the knee extended, significant increases were noted at the first and third follow-ups relative to baseline, p< 0.05. For V1 with the knee flexed, a significant increase was noted at the third follow up relative to baseline, p< 0.05. The largest increase in V1 was 35 degrees. The longest-standing improvements in tone and range of motion lasted 1.5 years post-cryoneurolysis.
Discussion:
This paper studied the effects of cryoneurolysis to the tibial nerve to treat ankle spasticity in patients with Multiple Sclerosis. While there have been studies examining the effects of cryo in patients with MS, this is the largest sample size documented to date (n=20) and the only one to focus solely on the tibial nerve.
The current interventions for treating spasticity include baclofen, diazepam, tizanidine and botulinum toxin injections (BoNT). However, these treatment options have been shown to have various adverse side effects and low satisfaction rates among patients. In addition, a recent study has shown that the price of a single patient with MS receiving BoNT injections was 10 times the price of cryoneurolysis for a single year of treatment. In addition to the cost savings with cryoneurolysis, the effects have been shown to last longer than that of BoNT injections with a recent study including patients with MS, having improvements in range of motion and tone lasting up to 12 months post-procedure.
Furthermore, the effects from this study show improvements in ankle spasticity lasting up to 1.5 years post-cryoneurolysis. It is also important to note that the patients included in our study had a variation of Multiple Sclerosis, including relapsing and remitting and primary progressive MS. A number of patients in the study also experienced an advancement in their disease to the secondary progressive form of MS. Disease progression and MS flares, which are seen in 85% of patients, results in unpredictability when examining the effects of cryoneurolysis. The progressive nature and exacerbations may explain some of the variable findings from the study in terms of range of motion improvements. However, the overall results of our study still showed that regardless of the form of MS a patient has, cryoneurolysis can be effective at treating lower limb spasticity as seen through a statistically significant improvement in tone being documented.
Conclusion:
This study shows that cryoneurolysis can be an effective treatment for ankle spasticity in patients with Multiple Sclerosis through reducing tone and increasing the range of motion for dorsiflexion when the knee is flexed and extended. Further studies are required to examine a variety of nerves to assess the scope of cryoneurolysis treatment.
