Floor plan - 2013 Annual Meeting - American Association for Hand ...

ASPN POSTER PRESENTATIONS
Increase of Neuronal Sprouting and Migration Using 780mn Laser Phototherapy
Institution where the work was prepared: Tel Aviv Medical Center, Tel Aviv University and NVR Lab., Tel Aviv, Ness
Ziona, Israel
Shimon Rochkind, MD1; Dalia El-Ani, PhD2; Tami Hayun, MA2; Zvi Nevo, PhD3; Abraham Shahar, PhD2; (1)Tel-Aviv
Medical Center, Tel-Aviv University, (2)NVR Labs, (3)Tel Aviv University
PURPOSE:
The present study focuses on the effect of 780 nm laser irradiation on the growth of embryonic rat brain cultures embedded in neurogel
(cross-linked hyaluronic acid with adhesive molecule laminin). Neuronal cells attached to microcarriers (MCs) were laser treated, and
their growth in stationary cultures was detected.
METHODS:
Whole brains were dissected from rat embryos. Cells were seeded directly in neurogel on DE-53 positively charged cylindrical MCs. After 14 days
of suspension, the formed floating cell-MC aggregates were sub-cultured in neurogel. Single cell-MC aggregates were either irradiated with nearinfrared
780 nm laser beam for 1, 3, 4 or 7 min, or cultured without irradiation. Laser powers were 10, 30, 50, 110, 160, 200 and 250 mW.
RESULTS:
780 nm laser irradiation accelerated migration and fiber sprouting of neuronal cells aggregates. The irradiated cultures contained a
higher number of large neurons than the controls. Significant differences in cell size were obtained following 1 min irradiation of 50mW.
Neurons in the irradiated cultures developed a dense branched interconnected network of neuronal fibers.
CONCLUSION:
780 nm laser treatment of embryonic rat brain cultures embedded in neurogel and attached to positively charged cylindrical MCs, stimulated
migration and fiber sprouting of neuronal cells aggregates and, therefore, can be considered as potential therapy for neuronal injury.
Ropivacaine-Induced Nerve Injection Injury in the Rodent Model
Institution where the work was prepared: Washington University School of Medicine, St Louis, MO, USA
Elizabeth L. Whitlock, BA; Arash Moradzadeh, MD; Michael J. Brenner; Daniel A. Hunter; Susan E. Mackinnon;
Washington University School of Medicine
BACKGROUND/HYPOTHESIS:
Ropivacaine is a long-acting local anesthetic which has gained recognition for its reduced potential for CNS and cardiac toxicity as compared
to racemic bupivacaine. Because of its milder toxicity profile, ropivacaine is indicated when a large quantity of local anesthetic is
given, such as in major peripheral nerve block. Iatrogenic intraneural administration of certain local anesthetics has been associated
with severe nerve damage. Because ropivacaine is injected in high concentrations for peripheral nerve blockade, we undertook the
present study to investigate histologic changes induced by ropivacaine injection into rat sciatic nerve.
METHODS:
Forty-five adult male Lewis rats were randomly distributed to 9 groups, 5 animals per group. Fifty microliters of normal saline, 10% phenol
or 0.75% ropivacaine was administered by intrafascicular injection, extrafascicular injection, or as a drip in close proximity to the sciatic
nerve. At a two-week endpoint, animals were sacrificed and the sciatic nerve at the injection site was evaluated with light
microscopy, histomorphometry and electron microscopy.
RESULTS:
Injection with saline was associated with mild intraneural edema and no significant damage to nerve fibers. Injection with phenol resulted
in severe demyelination and axonal degeneration. Intrafascicular injection of ropivacaine resulted in a wedge-shaped region of
demyelination with relative sparing of axons, bordered by a region of normally-myelinated axons in a background of edematous
endoneurium. The area most distant from the administration site was uninjured. Extrafascicular injection and ropivacaine drip were both
associated with damage to the perineurium, with an area of local demyelination surrounded by edematous endoneurium. Nerve tissue
distant to the site of ropivacaine contact was uninjured. Extrafascicular injection resulted in more significant damage than ropivacaine
drip, but less than intrafascicular injection as shown with quantitative histomorphometry.
CONCLUSION:
Unlike bupivacaine, from which it is derived, ropivacaine is associated with marked nerve damage when injected into or dripped in close
proximity to a nerve. Because extrafascicular and drip injury were associated with similar, although milder, histological damage than
intrafascicular injection, we suggest that extrafascicular injection or extraneural drip of ropivacaine is associated first with disruption of
the perineurium, permitting the anesthetic to enter and damage the nerve fibers themselves. These results suggest that great care
should be taken when administering large volumes of concentrated ropivacaine near a nerve, since injury may occur even without
mechanical damage to the nerve itself.
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