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

The Mechanisms of Axonal Sprouting With End-to-Side Neurorrhaphy
Institution where the work was prepared: Washington University in St Louis, St Louis, MO, USA
Ayato Hayashi, MD, PhD; Daniel A. Hunter, RA; Alice Y. Tong, MS; David H. Kawamura, MD; Arash Moradzadeh, MD;
Sami H. Tuffaha, BA; Christina B. Kenney, MD; Janina Luciano, BS; Thomas H. Tung, MD; Susan E. Mackinnon, MD;
Terence M. Myckatyn, MD; Washington University in St. Louis
BACKGROUND:
Nerve injuries are usually reconstructed by end-to-end neurorrhaphy. However, end-to-side neurorrhaphy is an alternative procedure
that may be used in certain situations. Since the reintroduction of this technique in 1992, significant controversy remains regarding how
end-to-side neurorrhaphy results in axonal sprouting and whether it provides any functional benefit. To investigate these issues, we used
transgenic mice with fluorescently-labeled axons to visualize this process.
METHODS:
We used transgenic mice in which a few motor axons (Thy1-GFPS) or all axons, including sensory, (Thy1-YFP16) were labeled with GFP
or YFP. Animals were randomized into three groups: 1) end-to-side neurorrhaphy was performed by opening an epineurial window with
partial neurectomy, 2) the nerve graft was wrapped around the donor nerve to keep the donor nerve completely uninjured while endto-side
coaptation was achieved, and 3) chronic compression to the donor nerve was applied by wrapping the proximal donor nerve
with a tight fitting silicon tube. All animals were evaluated using a fluorescent live imaging system at multiple time points to monitor
for regenerating axons. At a 3 or 5 month endpoint, the site of anastomosis was harvested and evaluated with immunohistochemistry,
confocal whole mount imaging, histomorphometry, and western blot. In addition, the functional connections of the regenerating axons
were characterized with muscle end plate staining and an evaluation of cutaneous innervation.
RESULTS:
With partial neurectomy, abundant regenerating axons were seen projecting from the stump of the injured donor nerve into the graft at
early time points. The non-injury model using thy1-GFPS mice showed no motor axonal regeneration throughout the experiment.
However, YFP16 mice showed new axons projecting into the graft at late time points. The compression injury group using thy1-GFPS mice
also showed regenerating motor axons at late time points, appearently due to induction of collateral sprouting from the donor nerve.
CONCLUSION:
Our results demonstrate that some type of injury, such as compression or epineurotomy, is required to trigger motor axonal regeneration
through an end-to-side neurorrhaphy. In contrast, sensory axonal regeneration can take place with end-to-side neurorrhaphy without
any injury to the donor nerve as evidenced by the different results seen with the YFP16 and thy1-GFPS mice. This study represents
a novel model for studying end-to-side neurorrhaphy over time and provides further insights into the mechanism by which axonal
regeneration occurs in this setting.
Comparison of Psychosocial Outcomes of Patients with Neuropathic Conditions Treated With
and Without Surgery
Institution where the work was prepared: Hand and Microsurgery Center of El Paso, El Paso, TX, USA
Jose Monsivais, MD; Hand & Microsurgery Center; Kris Robinson, PhD, FNP; University of Texas at El Paso
PURPOSE:
To evaluate psychosocial outcome after surgical and non-surgical treatment of neuropathies and nerve injuries in chronic pain patients.
METHODS:
Archival review of records from 91 patients (1995-2005). Inclusion criteria included nerve dysfunction and pain >3 months. Diagnosis was
established by history, P/ E, sensory/motor evaluation, electrodiagnostics and imaging. Surgical candidates were determined by severity
of sensory -motor abnormalities and had no evidence of uncontrolled depression/psychological distress. Pain was not used as an
indicator for any form of treatment. Surgical procedures included nerve decompressions, reconstruction, neurolysis, and excision of
neuromas. Medical treatment included analgesics, adjuvants, and neuroleptic medications. Psychological reports included psychological
diagnosis, results of Oswestry Pain Questionnaire, GAF, and PSS. Statistician conducted correlational analysis using SAS statistical
program. A sample size of 85 is required to detect a medium effect size with alpha set at .05 and power of .80.
RESULTS:
The majority of patients returned to work and reported lower levels of pain ~5 years after onset of nerve injury/ condition. No differences
were noted between groups on a variety of measures including pain level (p=.2), litigation status (p>.5), and return to work
(p>.05). The majority of individuals expected total relief of pain with surgical treatment.
CONCLUSION:
With psychosocial assessment, support, and adequate pain treatment, no difference was detected in psychosocial outcomes between those
patients receiving surgical and non ñsurgical treatment. Patients' expectations of surgery are unrealistic and must be addressed prior to treatment.
113