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Methylprednisolone shortens the effects of bupivacaine on sensory nerve fibers in vivo
Author(s) -
Johansson A.
Publication year - 1996
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1996.tb04494.x
Subject(s) - bupivacaine , medicine , anesthesia , methylprednisolone , sciatic nerve , nerve fiber , local anesthetic , nerve block , nociception , reflex , anatomy , receptor
Perineural administration of corticosteroids is frequently applied in the treatment of a variety of chronic pain conditions. Methylprednisolone selectively inhibits the transmission of nerve impulses in C‐fibers whereas A‐fiber activity is unaffected. In the present study the effect of a mixture of 0.05 ml of methyprednisolone (40 mg/ml) and 0.05 ml of bupivacaine (5 mg/ml) was compared to that of 0.05 ml bupivacaine (5 mg/ml) using a plantar nerve block model in the rat. The conduction of impulses in electrically stimulated A‐fibers of the plantar nerve was monitored by a bipolar volley recording from the sciatic nerve. Impulse conduction in electrically stimulated C‐fibers was studied through a C‐fiber evoked segmental flexion reflex. The function of both the A‐fibers and the C‐fibers exposed to the methylprednisolone‐bupivacaine mixture showed a less profound block with signs of earlier recovery than those exposed to plain bupivacaine. The A‐fibers recovered somewhat faster than the C‐fibers. It is postulated that methylprednisolone adjuvant to bupivacaine affects the intra‐axonal uptake of bupivacaine in C‐fibers but not in A‐fibers by some unknown mechanism. The effect seems to be longer lasting in C‐fibers than in A‐fibers.