Cryolesioning or cryoneurolysis
One of the methods that can be used to provide longterm interruption of nerves carrying pain is the use of cold. Various names have been used for this, including cryoablation, cryoneurolysis or cryolesioning. The instrument used for this is termed a cryoprobe.
Cryoneurolysis involves freezing a nerve, in order to interrupt its ability to transmit pain signals to the brain, and thus provide pain relief. While cryolesioning can be applied to various organs and tissues and is used in a variety of medical specialties, for pain it is primarily used to treat peripheral nerves. A wide range of nerves can be treated, including abdominal cutaneous and other nerve entrapments, occipital nerves and potentially the intercostal nerves in the chest wall.
How does cryoneurolysis work?
The cryoprobe is shaped like a long thin needle, which has channels through which nitrous oxide or another gas is passed under pressure towards its tipe where it expands in a closed compartment. The expansion of the gas causes its temperature to reduce, and with continued gas flow the temperature at the tip of the probe drops to around -70 degrees centrigrade. This freezes the nerve fibre and the ice crystals formed disrupt the nerve, or may interfere with the blood supply into the nerve via tiny vessels called the vasi nervorum. When this happens the pain nerve fibre (neuron) dies back to its cell body next to the spinal cord, although generally the nerve will regrow over time. This regrowth process cannot practically be prevented.
How is cryoneurolysis done?
The procedure is done in the operating room under local anesthetic. A special needle is inserted towards the nerve. Prior to lesioning, sensory and motor nerve testing may be performed to identify the nerve and confirm probe placement. Once the nerve is identified with a nerve stimulation test, the nerve is treated by decreasing the temperature surrounding the nerve to -70 C. The cooling of these nerves interrupts the pain messages before they are sent to the brain where the pain is actually perceived.
How long does the pain relief typically last?
Unfortunately pain relief from this procedure can last from six to twelve months or longer. This is because the nerve damage from the Cryoablation is typically only temporary. These nerves will regrow over time, and the time frame for this varies, as every individual patient is unique in their healing process.
Is it safe?
As with any medical procedure, there may be some risks although due to the fact that only fine probes are used for this procedure, the risks for bruising, bleeding and infection are low. Some patients may experience a short-term flare up of pain following this procedure. Other risks, although rare, include, but are not limited to, no effect on pain, increased pain and permanent nerve injury. Depending on which part of the body the nerve is, there may be other potential risks which will be discussed when obtaining consent for the procedure.
an article on cryoneurolysis, although written for doctors, may be useful.
A very detailed article can be accessed here.
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Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 19/02/2016