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Thomas J. Wilson, R. Shane Tubbs and Lynda J. S. Yang

OBJECTIVE

The authors hypothesized that when the anatomical variant of an anconeus epitrochlearis is present, the risk of developing cubital tunnel syndrome would be reduced by replacing the normal roof of the cubital tunnel (Osborne's ligament) with a more forgiving muscular structure, the anconeus epitrochlearis. The authors further hypothesized that when the presence of an anconeus epitrochlearis contributes to ulnar neuropathy, it would be secondary to muscular hypertrophy, thereby making it more likely to occur in the dominant arm. Therefore, the goal of the present study was to evaluate these hypotheses.

METHODS

This retrospective cohort study was performed by reviewing the records of all adult patients who underwent operative intervention for cubital tunnel syndrome between 2005 and 2014 as the experimental group and all asymptomatic patients in the medical literature who were part of a series reporting the prevalence of an anconeus epitrochlearis as the control group. The primary outcome of interest was the presence of an anconeus epitrochlearis in asymptomatic individuals versus patients with cubital tunnel syndrome.

RESULTS

During the study period, 168 patients underwent decompression of the ulnar nerve for cubital tunnel syndrome, and an anconeus epitrochlearis was found at surgery in 9 (5.4%) patients. The control group consisted of 634 asymptomatic patients from the medical literature, and an anconeus epitrochlearis was present in 98 (15.5%) of these patients. An anconeus epitrochlearis was present significantly less frequently in the symptomatic patients than in asymptomatic individuals (p < 0.001). Among patients undergoing surgical decompression, an anconeus epitrochlearis was associated with symptoms in the dominant arm (p = 0.037).

CONCLUSIONS

The authors found that an anconeus epitrochlearis was present significantly less often in patients with cubital tunnel syndrome than in asymptomatic controls. The mechanism of protection may be that this muscle decreases the rigidity of the entrance into the cubital tunnel. When an anconeus epitrochlearis does contribute to cubital tunnel syndrome, it is significantly more likely to occur in the dominant arm, possibly due to repetitive use and hypertrophy of the anconeus epitrochlearis. The presence of an anconeus epitrochlearis may be protective against the development of cubital tunnel syndrome, although this is a preliminary finding.

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Kate W. C. Chang, Denise Justice, Kevin C. Chung and Lynda J. S. Yang

Object

Neonatal brachial plexus palsy (NBPP) affects 0.4–2.6 newborns per 1000 live births in the US. Many infants recover spontaneously, but for those without spontaneous recovery, nerve and/or secondary musculoskeletal reconstruction can restore function to the affected arm. This condition not only manifests in a paretic/paralyzed arm, but also affects the overall health and psychosocial condition of the children and their parents. Currently, measurement instruments for NBPP focus primarily on physical ability, with limited information regarding the effect of the disablement on activities of daily living and the child's psychosocial well-being. It is also difficult to assess and compare overall treatment efficacy among medical (conservative) or surgical management strategies without consistent use of evaluation instruments. The purpose of this study is to review the reported measurement evaluation methods for NBPP in an attempt to provide recommendations for future measurement usage and development.

Methods

The authors systematically reviewed the literature published between January 1980 and February 2012 using multiple databases to search the keywords “brachial plexus” and “obstetric” or “pediatrics” or “neonatal” or “congenital.” Original articles with primary patient outcomes were included in the data summary. Four types of evaluation methods (classification, diagnostics, physical assessment, and functional outcome) were distinguished among treatment management groups. Descriptive statistics and 1-way ANOVA were applied to compare the data summaries among specific groups.

Results

Of 2836 articles initially identified, 307 were included in the analysis, with 198 articles (9646 patients) reporting results after surgical treatment, 70 articles (4434 patients) reporting results after medical treatment, and 39 articles (4247 patients) reporting results after combined surgical and medical treatment. Among medical practitioners who treat NBPP, there was equivalence in usage of classification, diagnostic, and physical assessment tools (that focused on the Body Function and Structures measure of the International Classification of Functioning, Disability, and Health [ICF]). However, there was discordance in the functional outcome measures that focus on ICF levels of Activity and Participation. Of the 126 reported evaluation methods, only a few (the Active Movement Scale, Toronto Scale Score, Mallet Scale, Assisting Hand Assessment, and Pediatric Outcomes Data Collection Instrument) are specifically validated for evaluating the NBPP population.

Conclusions

In this review, the authors demonstrate disparities in the use of NBPP evaluation instruments in the current literature. Additionally, valid and reliable evaluation instruments specifically for the NBPP population are significantly lacking, manifesting in difficulties with evaluating the overall impact and effectiveness of clinical treatments in a consistent and comparative manner, extending across the various subspecialties that are involved in the treatment of patients with NBPP. The authors suggest that all ICF domains should be considered, and future efforts should include consideration of spontaneous (not practitioner-elicited) use of the affected arm in activities of daily living with attention to the psychosocial impact of the disablement.

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Mark A. Mahan, Wilson Z. Ray, Lynda J. S. Yang and Robert J. Spinner

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Brandon W. Smith, Nicholas J. Chulski, Ann A. Little, Kate W. C. Chang and Lynda J. S. Yang

OBJECTIVE

Neonatal brachial plexus palsy (NBPP) continues to be a problematic occurrence impacting approximately 1.5 per 1000 live births in the United States, with 10%–40% of these infants experiencing permanent disability. These children lose elbow flexion, and one surgical option for recovering it is the Oberlin transfer. Published data support the use of the ulnar nerve fascicle that innervates the flexor carpi ulnaris as the donor nerve in adults, but no analogous published data exist for infants. This study investigated the association of ulnar nerve fascicle choice with functional elbow flexion outcome in NBPP.

METHODS

The authors conducted a retrospective study of 13 cases in which infants underwent ulnar to musculocutaneous nerve transfer for NBPP at a single institution. They collected data on patient demographics, clinical characteristics, active range of motion (AROM), and intraoperative neuromonitoring (IONM) (using 4 ulnar nerve index muscles). Standard statistical analysis compared pre- and postoperative motor function improvement between specific fascicle transfer (1–2 muscles for either wrist flexion or hand intrinsics) and nonspecific fascicle transfer (> 2 muscles for wrist flexion and hand intrinsics) groups.

RESULTS

The patients’ average age at initial clinic visit was 2.9 months, and their average age at surgical intervention was 7.4 months. All NBPPs were unilateral; the majority of patients were female (61%), were Caucasian (69%), had right-sided NBPP (61%), and had Narakas grade I or II injuries (54%). IONM recordings for the fascicular dissection revealed a donor fascicle with nonspecific innervation in 6 (46%) infants and specific innervation in the remaining 7 (54%) patients. At 6-month follow-up, the AROM improvement in elbow flexion in adduction was 38° in the specific fascicle transfer group versus 36° in the nonspecific fascicle transfer group, with no statistically significant difference (p = 0.93).

CONCLUSIONS

Both specific and nonspecific fascicle transfers led to functional recovery, but that the composition of the donor fascicle had no impact on early outcomes. In young infants, ulnar nerve fascicular dissection places the ulnar nerve at risk for iatrogenic damage. The data from this study suggest that the use of any motor fascicle, specific or nonspecific, produces similar results and that the Oberlin transfer can be performed with less intrafascicular dissection, less time of surgical exposure, and less potential for donor site morbidity.

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Thomas J. Wilson, Jacob R. Joseph, Jonathan R. Dillman, Amer Heider and Lynda J. S. Yang

Patients presenting with enlarging fibrofatty masses in the extremities pose an interesting dilemma to clinicians, as the differential diagnosis in such cases ranges from benign to malignant, and from lesions optimally managed operatively to those managed nonoperatively. The differential diagnosis includes benign lipoma, liposarcoma, lipoblastoma, and fibrolipomatous hamartoma (lipomatosis) of the nerves. The authors present the case of a 14-year-old girl with an enlarging fibrofatty mass of the forearm, initially thought, based on diagnostic imaging, to be a fibrolipomatous hamartoma of the median nerve, but found to be a lipoblastoma without direct nerve involvement based on histopathological examination of the operative specimen. This case serves to illustrate the diagnostic predicament that can exist with such masses. The authors advocate the need to establish a tissue diagnosis while having a contingency plan for each of the diagnostic possibilities because the management of each lesion is markedly different. In this report, the authors consider the differential diagnosis of fibrofatty masses of the extremities that the peripheral nerve surgeon may encounter, and they highlight the significant differences in management strategies for each possible diagnosis.

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Thomas J. Wilson, Kate W. C. Chang, Suneet P. Chauhan and Lynda J. S. Yang

OBJECTIVE

Neonatal brachial plexus palsy (NBPP) occurs due to the stretching of the nerves of the brachial plexus before, during, or after delivery. NBPP can resolve spontaneously or become persistent. To determine if nerve surgery is indicated, predicting recovery is necessary but difficult. Historical attempts explored the association of recovery with only clinical and electrodiagnostic examinations. However, no data exist regarding the neonatal and peripartum factors associated with NBPP persistence.

METHODS

This retrospective cohort study involved all NBPP patients at the University of Michigan between 2005 and 2015. Peripartum and neonatal factors were assessed for their association with persistent NBPP at 1 year, as defined as the presence of musculoskeletal contractures or an active range of motion that deviated from normal by > 10° (shoulder, elbow, hand, and finger ranges of motion were recorded). Standard statistical methods were used.

RESULTS

Of 382 children with NBPP, 85% had persistent NBPP at 1 year. A wide range of neonatal and peripartum factors was explored. We found that cephalic presentation, induction or augmentation of labor, birth weight > 9 lbs, and the presence of Horner syndrome all significantly increased the odds of persistence at 1 year, while cesarean delivery and Narakas Grade I to II injury significantly reduced the odds of persistence.

CONCLUSIONS

Peripartum/neonatal factors were identified that significantly altered the odds of having persistent NBPP at 1 year. Combining these peripartum/neonatal factors with previously published clinical examination findings associated with persistence should allow the development of a prediction algorithm. The implementation of this algorithm may allow the earlier recognition of those cases likely to persist and thus enable earlier intervention, which may improve surgical outcomes.

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John A. Cowan Jr., Garni Barkhoudarian, Lynda J. S. Yang and B. Gregory Thompson

✓ The authors present a case in which a posterior communicating artery (PCoA) infundibulum progressed into an aneurysm in a patient with Alagille syndrome (arteriohepatic dysplasia). The 3-mm PCoA infundibulum had been noted on angiography studies obtained 5 years earlier, prior to clip occlusion of a basilar tip aneurysm. Recently, the patient presented to the emergency department with the sudden onset of headache and decreased mental status. A computerized tomography scan of the head with three-dimensional angiography revealed no gross subarachnoid hemorrhage, but did demonstrate a 5-mm PCoA aneurysm. Lumbar puncture demonstrated xanthochromia and a large quantity of red blood cells. The patient underwent open surgery for aneurysm clip occlusion and obtained a good recovery.

This case illustrates the small but growing number of examples of infundibulum progression. It also indicates the need for a close follow up in patients with congenital abnormalities that may pose an increased risk for what has traditionally been considered a benign lesion.

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Aqueel Pabaney, Shawn L. Hervey-Jumper, Joseph Domino, Cormac O. Maher and Lynda J. S. Yang

Neuropathic pain is rare in children, and few reports provide adequate guidelines for treatment. The authors describe the successful treatment of tardy neuropathic pain via macrovascular decompression in a 15-year-old boy who presented with progressive pain 11 years following trauma to the upper extremity that had required surgical repair of the brachial artery. Examination revealed mild chronic median and ulnar motor neuropathy as well as recent progressive lancinating pain and a Tinel sign at the prior scar. A soft tissue mass in the neurovascular bundle at the site of previous injury was noted on MRI. Surgical exploration demonstrated an altered anatomical relationship of the previously repaired brachial artery and the median nerve, resulting in pulsatile compression of the median nerve by the brachial artery. Neurolysis and decompression of the median nerve with physical separation from the brachial artery resulted in immediate pain relief.

This is the first report of macrovascular decompression of a major peripheral nerve with complete symptom resolution. Noninvasive imaging together with a thorough history and physical examination can support identification of this potential etiology of peripheral neuralgic pain. Recognition and treatment of this uncommon problem may yield improved outcomes for children with neuropathic pain.

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Brandon W. Smith, Kate W. C. Chang, Lynda J. S. Yang and Mary Catherine Spires

OBJECTIVE

The incorporation of ancillary testing in the preoperative setting for patients with neonatal brachial plexus palsy (NBPP) remains controversial, but the recommendation for early nerve reconstruction when a baby has a preganglionic lesion at the lower nerve roots is generally accepted. At some specialty centers, nerve surgeons use preoperative electrodiagnostic testing (EDX) and imaging to aid in lesion localization and the preoperative planning of the nerve reconstruction. EDX and imaging have been evaluated for their abilities to detect pre- and postganglionic lesions, but their accuracies have never been compared directly in the same set of patients. The aim of the present study was to evaluate the accuracy of imaging and EDX in an NBPP population.

METHODS

A retrospective review was conducted of 54 patients with operative NBPP seen between 2007 and 2017. The patients underwent EDX and imaging: EDX was performed, and the results were reviewed by board-certified electrodiagnosticians, and imaging was reviewed by board-certified neuroradiologists. The gold standard was considered to be the findings at surgical exploration. Descriptive and analytical statistics were utilized to compare the accuracies of imaging and EDX.

RESULTS

The mean age at surgery was 6.94 mos (± 4 mos). Fifteen patients (28%) were Narakas grade I–II, and 39 (72%) were Narakas grade III–IV. For all nerve roots, the overall accuracy of detecting preganglionic lesions was 74% for EDX and 69% for imaging. The overall sensitivity of detecting preganglionic lesions by EDX was 31%, but the specificity was 90%. The overall sensitivity of detecting preganglionic lesions by imaging was 66%, and the overall specificity was 70%. However, at C8, EDX was 37.5% sensitive and 87.5% specific, whereas imaging was 67.7% sensitive but only 29.4% specific.

CONCLUSIONS

EDX outperformed imaging with regard to specificity and accuracy of identifying preganglionic injuries. This finding is especially relevant in the lower nerve roots, given that lower plexus preganglionic lesions are an accepted indication for early intervention.

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Lynda J. S. Yang, Vishal C. Gala and John E. McGillicuddy

✓Lower-extremity pain and paresthesia have multiple origins. Early recognition of the symptoms of peripheral nerve entrapment leads to timely treatment and avoids the cost of unnecessary studies. The authors report on a case of superficial peroneal nerve syndrome resulting from nerve herniation through a fascial defect, which was responsive to surgical treatment.

This 22-year-old man presented with pain and paresthesias over the lateral aspect of the right calf and the dorsum of the foot without motor weakness. Exercise led to the formation of a tender bulge approximately 12 cm above the lateral malleolus. Percussion of this site worsened his symptoms. Radiography and electromyography studies were nondiagnostic. The patient underwent surgical decompression that involved division of the fascia overlying the nerve and neurolysis of the superficial peroneal nerve. The operation resulted in symptom-free relief.

Superficial peroneal nerve syndrome is an entrapment neuropathy that results from mechanical compression of the nerve at or near the point where the nerve pierces the fascia to travel within the subcutaneous tissue. Surgical decompression of the mechanical entrapment usually provides relief from pain and paresthesia.