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Cryoanalgesia, that is, the use of low temperatures to provide
analgesia, is a pain management technique that can be applied to
a variety of painful situations. From the topical application of
ice to a sprained ankle or cryoneurolysis of an intercostal nerve
for postoperative pain control in a post-thoracotomy patient to
cryoneurolysis of the trigeminal nerve for trigeminal neuralgia, cryoanalgesia
has a multitude of uses. This chapter focuses on the application
of cryoanalgesia for acute and chronic pain management.
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Historical Perspectives
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The first account of the use of cryoanalgesia for pain control
was recorded by Hippocrates (460–377 bc). He described
the use of ice and snow packs to prevent pain from surgery.1 An
11th century Anglo-Saxon monk, Avicenna of Persia (980–1070),
and Severino of Naples (1580–1656) also recognized the
use of cold as preemptive analgesia for surgery.1,2 Other
historical recorders who recognized the value of cryoanalgesia include
Napoleon’s surgeon general, Baron Larre (1812), Dr James
Arnott (1851), and Richardson (1866).1,2
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Recently, Irvine Cooper and his colleagues (1961) developed the
first prototype of a cryoprobe that could be used for analgesia.1,3 It
utilized the principle of phase change using liquid nitrogen to
produce a temperature of –196°C. Several years later in 1967, Amoils
developed a smaller cryoprobe that employed the Joule-Thompson principle
and used carbon dioxide or nitrous oxide to produce temperatures
to –50°C.4) Present cryoprobes
use either of these two principles to produce a temperature of at
least –70°C.
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Cryoneurolysis involves using cold to induce nerve injury, thus
providing analgesia. The exact cellular mechanism of nerve injury
is not known. Theories include ischemic necrosis, physical destruction
by large cellular ice crystals, damage to proteins, minimal cell
volume, production of autoantibodies, and membrane rupture caused
by rapid water loss.5 Cryolesioning causes a second-degree
nerve injury as classified by Sunderland. A second-degree injury
involves degeneration of the axon and myelin sheaths (wallerian
degeneration) from the site of freezing distally to the nerve’s
termination.6 The minimum temperature required
is 20°C or lower.5 The endoneurium, perineurium,
and ectoneurium remain intact, thus regeneration is possible. The
return of normal sensory and motor activity depends primarily on
two factors: the rate of axonal regrowth (average of 1 to 2 mm per
day) and the distance of the cryolesion from the end organ, although
nerve conduction velocity remains only reduced to an average of
35 days.1,7,8
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The success of a cryolesion depends on several factors: the rate
of freezing and thawing, the temperature attained by the tissue
in proximity to the cryoprobe, and the size of the cryolesion.7 Evans
and Gill et al showed that repeat freeze-and-thaw cycles enlarged
the size of the cryolesion, improving the success of the block.5,9 Freeze
cycles are typically 1.5 to 3 minutes with ...