Effects of hypertonic dextrose injections in the rabbit carpal tunnel.
OBJECTIVE
This study investigated the effects of different doses of hypertonic dextrose injection on the carpal tunnel subsynovial connective tissue (SSCT) and median nerve in a rabbit model.


METHODS
Thirty-eight New Zealand white rabbits weighing 4.0-4.5 kg were used. One forepaw carpal tunnel was randomly injected with one of five different treatments: saline-single injection; saline-two injections 1 week apart; 10% dextrose-single injection; 20% dextrose-single injection; or 10% dextrose-two injections 1 week apart. Animals were sacrificed at 12 weeks after the initial injection and were evaluated by electrophysiology (EP), SSCT mechanical testing and histology.


RESULTS
There were significant increases in the energy absorption of the SSCT in the 10% dextrose-double injection group compared to the saline injection groups. SSCT stiffness was also significantly increased in the 10% dextrose-double injection group compared to the other groups. There was a significant increase in the thickness of the SSCT in the 10% dextrose-double injection group compared to the saline-single injection group and a significant decrease in the nerve short-long diameter ratio in the 10% dextrose-double injection group compared to the saline-single injection group. There were no changes in EP among the groups.


CONCLUSIONS
SSCT fibrosis is present for up to 12 weeks after dextrose injection; multiple injections have bigger effects, including what appears to be a secondary change in nerve flattening. This model may be useful to study the effects of external fibrosis on nerve morphology and physiology, such as occurs clinically in carpal tunnel syndrome.
Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, Minnesota 55905, USA.
Yuichi
Y
Yoshii
Chunfeng
C
Zhao
James D
JD
Schmelzer
Phillip A
PA
Low
Kai-Nan
KN
An
Peter C
PC
Amadio
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002349:Carpal Tunnel Syndrome / Q000139:chemically induced* / Q000473:pathology* / Q000503:physiopathology; D002350:Carpus, Animal / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D003238:Connective Tissue / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D004195:Disease Models, Animal; D005355:Fibrosis; D005947:Glucose / Q000633:toxicity*; D006982:Hypertonic Solutions / Q000633:toxicity*; D007270:Injections, Intra-Articular; D008475:Median Nerve / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D011817:Rabbits; D013583:Synovial Membrane / Q000187:drug effects / Q000473:pathology
D006982:Hypertonic Solutions; D005947:Glucose
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