Cryoneurotomy to Reduce Spasticity and Improve Range of Motion in Spastic Flexed Elbow: A Visual Vignette.

Abstract

The flexed-elbow pattern of spasticity causes pain and reduced function and greater caregiver burden.1 Genet et al.1 reported the brachialis as the dominant muscle limiting extension. The musculocutaneous nerve (MSCN)–innervated brachialis and biceps brachii as well as the radial nerve–innervated brachioradialis are all implicated.1 Refractory spasticity after rehabilitation and chemodenervation with botulinum toxin type A may require selective surgical or neurolytic interventions to improve outcomes. The diagnostic anesthetic nerve block (DNB) has been used to assist in the evaluation of a muscle’s contribution to spasticity.1 The DNB can differentiate between spasticity and contracture and predict the outcome of surgical neurotomy. It was proposed in 2019 that cryoneurotomy is a safe percutaneous treatment for refractory spasticity.2 Long used in the anesthetic literature, cryoneurotomy is a mini-invasive technique that introduces a hand-held cryoprobe to a peripheral nerve and using the expansion of gas at the cannula tip to create an ice ball, which disrupts the nerve structure, causing axonotmesis. The distal fibers undergo Wallerian degeneration while the basal lamina and endoneurium are preserved, providing a scaffold for regeneration. A hallmark of the procedure is the lack of neuritis or neuroma formation.3 This retrospective chart review identified 11 adult patients with a flexed-elbow spasticity who had previously undergone a screening DNB then a subsequent cryoneurotomy from February 1, 2018, to February 28, 2020, in one clinic (Table 1). All patients had spasticity of at least grade 2 on the Modified Ashworth Scale (MAS), improvement in elbow range of motion, and/or reduction in spasticity after DNB to the MSCN ± radial nerve. All had previously been treated with botulinum toxin type A for their flexed-elbow spasticity with nine of our patients with ongoing botulinum toxin type A at a relatively high average dose of 444 U, with 231 U in the upper extremity. Images were hosted on a secure cloud server. This study was approved by the local institutional ethics board, with patient consent to participate. TABLE 1 - Patient demographics (N = 11) Age at first DNB, mean (SD), yr 53 (15) Sex, female/male, n 4/7 Etiology of spasticity, n Spinal cord injury 2 Stroke (hemorrhagic/ischemic) 7 (4/3) Multiple sclerosis 1 Traumatic brain injury 1 Affected side, right/left, n 4 / 7 Disease onset to first DNB, mean (SD), yr 9 (5) Our video presentation provides an illustration of the interventional techniques, the reduction in spasticity, and increased range of motion over a mean follow-up of 12.5 mos. Each patient was screened with a DNB to the brachialis branch of the MSCN and three patients with additional radial nerve blocks to the brachioradialis. The MSCN and radial nerves were localized with ultrasound guidance. A small bore, Teflon-coated hypodermic needle was inserted. Needle placement was confirmed with ultrasound guidance and electrical stimulation at less than 1 mA causing brachialis or brachioradialis contraction. One millilitre of 2% lidocaine was injected around the target nerve. A positive response was determined by a reduction in MAS, an improvement in passive ± active range of motion, no adverse outcomes, and no loss of function, on DNB. All patients in this study had positive DNB results and went on to cryoneurotomy of the MSCN with three additional to the radial nerve branch to the brachioradialis with the technique described by Winston et al.2 Documenting outcomes in spasticity remain a challenge for research. Our vignette illustrates the changed range of motion and spasticity.