Histologic effect of doxycycline sclerotherapy on rat femoral nerve

This study stems from an encounter with a phrenic nerve paralysis in a patient following doxycycline sclerotherapy for treatment of chylous fistula. The purpose of this study is to identify possible histologic evidence of doxycycline-induced nerve injury. The femoral nerves of CD rats were used as the in vivo animal model. The nerves were exposed to varying concentrations doxycycline and normal saline was the control. The nerves were studied at several time intervals using two different staining techniques. The results suggest that topical doxycycline induces tissue reactions which are different from normal saline. These reactions include stimulation of a local giant cell inflammatory reaction and disruption of the myelin sheath. Despite the fact that this study does not give physiologic evidence of neurotoxicity, the histologic results suggest that topical doxycycline may cause nerve damage directly or indirectly. We conclude that doxycycline should not be used for sclerotherapy where unprotected nerves are exposed to the agent until further physiologic tests are performed to prove its safety.