Article Text
Abstract
Severe, persistent neuropathic pain after surgery and trauma occurs as frequent as 10–50%.1,2 The pain is typically due to cutaneous neuropathy, which is due to injury of skin nerves.
Cryoneurolysis can be used to treat cutaneous neuropathy3 : A double-barrel needle is inserted until the needle tip touches the target nerve. A few-mm-wide ice-ball is generated and interrupts the nerve fibers. The needle tip is cooled down to minus 60–80°C when using carbondioxide (CO2). The cryoprobe is a ‘closed circuit’.4
Cryoneurolysis with CO2 interrupts the axons and their myelin sheaths but leaves the connective tissue skeleton of the nerve intact securing normal neural regeneration.5 This relieves the neuropathic pain for 4–12 months.5,6 Cryoneurolysis with CO2 never reach temperature lower than minus 78 degrees Celcius as this is the boiling point of the gas. Thus, the nerve is safe-quarded against irreversible destruction, which occurs when the freezing exceeds minus 100 degrees Celcius.6
No serious or persistent adverse effects have been reported even after repeated cryoneurolysis.9,10 Clinical cryoneurolysis studies have been carried out on various cutaneous nerves. Most of these studies present data of pain relief with cryoneurolysis of cutaneous nerves – but the results are heterogenous and flawed by high incidences of failure of pain relief.
The causes of failure are: (a) Lack of knowledge about specific cutaneous nerves and cutaneous nerve territories; (b) lack of direct visual ultrasonographic identification of true target nerve; (c) inaccuracy of needle tip placement exactly adjacent to the target nerve; (d) a very small diameter of the ice-ball capable of generating freezing below -20 degrees Celcius.
Conclusion In summary, persistent painful cutaneous neuropathy is frequent after surgery and trauma. However, the applicability of cryoneurolysis with CO2 is limited by a range of technical problems.
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