Shin, Alexander Y.

Abstract Myopericytomas belong to a benign group of tumors consisting of perivascular myopericytes or pericytes with a characteristic myoid differentiation pattern. The tumor is histologically and radiographically heterogenous, similar to superficial myofibromas. We report on a case of a myopericytoma arising in the hypothenar eminence of a 58-year-old man with a history of over 15 years of ulnar-sided and midcarpal wrist pain. Decision was made to excise the mass after it had increased in size by over 50 % over a 10-year period. Excision of the mass led to remarkable relief of his symptoms in the hypothenar as well as midcarpal regions. Consideration of this rare perivascular tumor should be included in patients with slow-growing benign appearing masses within the subcutaneous tissues of the hand.

The purpose of this study was to evaluate the effect of wrapping bioabsorbable nerve conduit around primary suture repair on motor nerve regeneration in a rat model. Forty rats were randomly divided into two experimental groups according to the type of repair of the rat sciatic nerve: group I had primary suture repair; group II had primary suture repair and bioabsorbable collagen nerve conduit (NeuraGen® 1.5 mm, Integra LifeSciences Corp., Plainsboro, NJ) wrapped around the repair. At 12 weeks, no significant differences in the percentage of recovery between the two groups were observed with respect to compound muscle action potentials, isometric muscle force, and muscle weight (P = 0.816, P = 0.698, P = 0.861, respectively). Histomorphometric analysis as compared to the non‐operative sites was also not significantly different between the two groups in terms of number of myelinated axons, myelinated fiber area, and nerve fiber density (P = 0.368, P = 0.968, P = 0.071, respectively). Perineural scar tissue formation was greater in primary suture repair group (0.36 ± 0.15) than in primary repair plus conduit wrapping group (0.17 ± 0.08). This difference was statistically significant (P < 0.001). Wrapping bioabsorbable nerve conduit around primary nerve repair can decrease perineural scar tissue formation. Although the scar‐decreasing effect of bioabsorbable nerve wrap does not translate into better motor nerve recovery in this study, it might have an effect on the functional outcome in humans where scar formation is much more evident than in rats. © 2014 Wiley Periodicals, Inc. Microsurgery 34:562–567, 2014.

Object Choline acetyltransferase (ChAT) is an enzyme synthesized within the body of a motor neuron whose role is to form the neurotransmitter acetylcholine. Quantification of ChAT levels in motor or mixed nerves has been proposed to provide information regarding the viability of a proximal nerve stump for motor neurotization following brachial plexus injury. To do so requires information regarding normal ChAT levels and those in injured nerves, as well as the correlation of ChAT level determined at surgery with eventual motor recovery. The purpose of this study was to determine ChAT activity in the normal and injured sciatic/peroneal nerve in a rat model, evaluate the correlation between ChAT and motor recovery, find the relationship between ChAT activity and isometric muscle force, and elucidate the parallel between ChAT activity and acetylcholinesterase (AChE) activity. Methods Sixty animals were divided into 3 groups. The sciatic nerves in Group 1 were transected without repair. Nerves in Group 2 were transected and repaired. Nerves in Group 3 sustained a crush injury followed by transection and reconstruction. All animals were allowed 12 weeks of recovery followed by evaluation of ChAT levels in the peroneal nerve, correlated with measures of maximal isometric tibialis anterior muscle force and muscle weight (the operated side normalized to the control side). Karnovsky AChE staining of peroneal nerve segments was also compared with radiochemical assay of ChAT activity in the same nerve. Results A significant difference in the tibialis anterior isometric tetanic force and the tibialis anterior muscle weight index (TAMI) was noted between Group 1 and Groups 2 and 3 (p < 0.0001); no significant difference was found comparing Group 2 with Group 3. The correlation between the force measurement and the TAMI was 0.382. Both AChE measurement and ChAT activity demonstrated significantly fewer fibers in the operated nerve compared with the contralateral nerve. Intergroup variability could also be illustrated using these tests. The correlation coefficient between the isometric tetanic force measurement and the ChAT analysis in Groups 1 and 2 was 0.468. The correlation for the AChE staining and the isometric tetanic force measurement was 0.111. The correlation between the TAMI and the ChAT levels was 0.773. The correlation between the TAMI and the AChE-stained fibers was 0.640. Correlating AChE staining to the ChAT analysis produced a correlation of 0.712. Conclusions The great variability in all groups and weak correlations to the functional muscle assessments and the ChAT radiochemical assay made this technique an unreliable method of determining motor nerve viability.

The purpose of this study is to evaluate the rate of union after four-corner arthrodesis with a locking, dorsal circular plate comprised of polyether-ether-ketone. A retrospective review was conducted of all patients who underwent four-corner arthrodesis with a locking, dorsal circular plate at our institution from January 2005 to May 2009. The primary outcome measure was radiographic and clinical union. During the study period, 26 consecutive wrists underwent four-corner arthrodesis with a locking, dorsal circular plate. Twenty-three wrists were included. The mean clinical follow-up was 16 months (range 3–37). Union was achieved in 22 of 23 wrists at a mean time of 3 months (range 1–12). There was one partial union that underwent successful revision arthrodesis. In summary, four-corner fusion with a polyether-ether-ketone locking, dorsal circular plate results in high union rates. The use of a radiolucent plate allows for more accurate assessment of union with the biomechanical advantages of a fixed angle construct.

Object Patients with brachial plexus injury (BPI) present with a combination of motor weakness/paralysis, sensory deficits, and pain. Brachial plexus injury is generally not believed to be associated with headaches. However, CSF leaks may be associated with CSF volume–depletion (low-pressure) headaches and can occur in BPI secondary to nerve root avulsion. Only a few cases of headaches associated with BPI have been reported. It is unknown if headaches in patients with BPI occur so rarely, or if they are just unrecognized by physicians and/or patients in which the focus of attention is the affected limb. The aim of this study was to determine the prevalence of CSF volume–depletion headaches in patients with BPI. Methods All adult patients presenting at the Mayo brachial plexus clinic with traumatic BPI were asked to complete a questionnaire addressing the presence and quality of headaches following their injury. The patients' clinical, injury, and imaging characteristics were subsequently reviewed. Results Between December 2008 and July 2010, 145 patients completed the questionnaire. Twenty-two patients reported new onset headaches occurring after their BPI. Eight of these patients experienced positional headaches, suggestive of CSF volume depletion. One of the patients with orthostatic headaches was excluded because the headaches immediately followed a lumbar puncture for a myelogram. Six of the other 7 patients with positional headaches had a clear preganglionic BPI. The available imaging studies in these 6 patients revealed evidence of CSF leaks: pseudomeningoceles (n = 5), CSF tracking into soft tissues (n = 3), CSF tracking into the intraspinal compartment (n = 3), CSF tracking into the pleural space (n = 2), and low-positioned cerebellar tonsils (n = 2). Conclusions In this retrospective study, 15.2% of patients (22 of 145 patients) with traumatic BPI suffered from a new-onset headache. Seven of these patients (4.8%) experienced postural headaches clearly suggestive of CSF volume depletion likely secondary to a CSF leak associated with the BPI, whereas the other 15 patients (10.3%) suffered headaches that may have represented a variant of CSF depletion headaches without a postural characteristic or a headache from another cause. These data suggest that CSF volume–depletion headaches occur in a significant proportion of patients with BPI and have been underrecognized and underreported.

Introduction Proximal row carpectomy (PRC) is a popular procedure for the treatment of wrist arthritis; however, the long-term clinical outcomes of this procedure are not well-characterized. The purpose of this study was to evaluate long-term results with PRC and to identify factors that may improve clinical outcomes. Methods A retrospective study was performed on all patients who underwent proximal row carpectomy between January 1967 and January 1992. Medical records and available radiographs were reviewed. The Disabilities of the Arm, Shoulder and Hand, and Patient Rated Wrist Exam, as well as hand motion diagrams were sent to all surviving patients. The contralateral extremity was used as a control. Data was analyzed using multivariant analysis and a Student's t test. Results Eighty-one patients underwent PRC. Average age at the time of surgery was 41 years. Average follow-up was 19.8 years. Sixty-one patients responded to the questionnaires. On final follow-up, wrist motion and grip strength were not significantly different from preoperative values. Radiographic follow-up beyond 2 years revealed joint narrowing and arthritic changes within the radiocapitate joint. Forty-six patients (74%) were not satisfied with the results of their surgery due to persistent pain or inability to return to previous occupational activities. Fifty-two patients required daily pain medication for wrist pain. Twelve patients had undergone a wrist arthrodesis. Conclusions Post-operative motion and grip strength values following PRC appear to remain stable over time. Surgical failure rates with conversion to wrist fusion occurred early within the post-operative follow-up. Many patients continued to complain of pain requiring daily medication and were unable to return to manual labor type jobs. The results of this study suggest that long-term patient satisfaction following PRC can be poor and the surgeon may wish to consider alternative treatment options for younger patients and those with high-demand jobs.