Pediatric ulnar mononeuropathy: report of 21 electromyography-documented cases and review of the literature

Peripheral Nerve Compression Syndromes in Children

Nontraumatic neuropathies of the upper limb are rare in children. In this paper, we present the latest updates in this field and also critically review the diagnosis and treatment of nerve compression syndromes in children. This review describes the most common manifestations including idiopathic carpal tunnel syndrome (CTS), CTS occurring as a component of lysosomal storage diseases (mucopolysaccharidosis) and hereditary neuropathies, ulnar nerve neuropathy, and atraumatic radial nerve neuropathies.

Utility and practice of electrodiagnostic testing in the pediatric population: An AANEM consensus statement

Nerve conduction studies and needle electromyography, collectively known as electrodiagnostic (EDX) studies, have been available for pediatric patients for decades, but the accessibility of this diagnostic modality and the approach to testing vary significantly depending on the physician and institution. The maturation of molecular diagnostic approaches and other diagnostic technologies such as neuromuscular ultrasound indicate that an analysis of current needs and practices for EDX studies in the pediatric population is warranted. The American Association of Neuromuscular & Electrodiagnostic Medicine convened a consensus panel to perform literature searches, share collective experiences, and develop a consensus statement. The panel found that electrodiagnostic studies continue to have high utility for the diagnosis of numerous childhood neuromuscular disorders, and that standardized approaches along with the use of high-quality reference values are important to maximize the diagnostic yield of these tests in infants, children, and adolescents.

Peripheral nerve injuries in the pediatric population: a review of the literature. Part II: entrapment neuropathies

INTRODUCTION

Entrapment neuropathies are infrequent in children, and therefore remain unrecognized. The incidence of radial, median, and cubital mononeuropathies are all similar. Despite the rarity of such cases, extensive, albeit scattered, literature has accumulated concerning entrapment neuropathies in children.

OBJECTIVE

To the literature concerning entrapment neuropathies in children.

METHODS

A systematic review of the existing literature has been made.

RESULTS

The management of chronic pediatric pain is very important in such patients to prevent youths from experiencing prolonged absences from school, sports, or other productive activities, and limit the psychological burden of chronic disease. Nonsurgical treatment of both cubital and carpal tunnel syndromes has been disappointing in pediatric patients, with only limited success; and, to date, there is no clear explanation for the outcome differences generated by nonsurgical management between adults and youths. Simple decompression of the ulnar nerve at the elbow also has much higher rates of failure in children than in adults.

CONCLUSIONS

The presence of an entrapment neuropathy (specially carpal tunnel syndrome) in a pediatric-age patient should alert medical care providers to the potential of some underlying genetic condition or syndrome.

Peripheral nerve injuries in the pediatric population: a review of the literature. Part I: traumatic nerve injuries

OBJECTIVE

This article reviews the clinical results that can be obtained after repair of a traumatic peripheral nerve injury in the pediatric population.

METHODS

A systematic review of the published literature has been made.

RESULTS

Functional outcome after major nerve injuries is sometimes disappointing in adults. However, children have been reported to experience much better functional results after nerve repair than adults. Moreover, recovery generally is faster in children. The superior capacity of children's central nervous system to adapt to external or internal environmental changes (neural plasticity) and the shorter recovery distance from the axon repair site to the target muscle are claimed to be crucial determinants of their favorable outcomes. Moreover, even in the pediatric population, it has been demonstrated that functional results are better the younger the patient is, including better clinical results in those injured in early childhood (< 6 years old) than in those injured in adolescence. Other favorable prognostic factors include the type of nerve injury (with complete transections doing less well than crush injuries) and the timing of surgery (with better outcomes after early repairs).

CONCLUSIONS

All efforts should be done to repair in a timely and adequate fashion traumatic peripheral nerve injuries in children, as the results are good.

Surgical Treatment of Cubital Tunnel in Pediatric Athletes

Background Cubital tunnel syndrome is the second most common upper extremity peripheral nerve entrapment syndrome. In particular, cubital tunnel has been documented occasionally in young, throwing athletes. Materials and Methods Billing databases were searched for patients undergoing surgical decompression of the ulnar nerve at the elbow, who were age 18 or younger at the time of surgery. Charts were reviewed and patients were included if they had an isolated mononeuropathy consistent with cubital tunnel syndrome and were symptomatic. Data on age of onset, duration of symptoms, Dellon classification, nerve subluxation, provocative testing results, nerve conductions, and exacerbating activities were abstracted. Patients were contacted for a postsurgical follow-up questionnaire. Results Seven patients were identified. The average age was 16, and duration of symptoms was 7 months. All seven patients had normal electrodiagnostic studies and had failed a course of conservative treatment. All were satisfied with surgery and felt improvement. One stopped playing their sport, and three had mild symptoms with varied activities. Conclusion Although uncommon, pediatric cubital tunnel syndrome does occur. Surgical release improves symptoms and return to activities. Nevertheless, some degree of symptoms often persists. Electrodiagnostic studies may be negative in many patients with an otherwise consistent history and examination. Level of Evidence This is a level IV therapeutic study.

Electrophysiologic features of ulnar neuropathy in childhood and adolescence

OBJECTIVE

To analyze patterns of nerve injury in pediatric ulnar neuropathy (PUN).

METHODS

Retrospective analysis of 49 children with PUN.

RESULTS

Sensory loss in digit V was the prevailing complaint (89%). Predominant localization was at the elbow (55%). Diminished ulnar SNAP was the most common abnormality (71%) with median axon loss estimate (MAXE) of 62%. Dorsal ulnar cutaneous (DUC) sensory nerve action potential (SNAP) was reduced in 55% with MAXE of 43%. Abductor digiti minimi (ADM) and first dorsal interosseous (FDI) compound muscle action potential (CMAP) were reduced half of the time, with MAXE of 30% and 28% respectively. There was high correlation between ulnar sensory MAXE and ADM MAXE (r=0.76, p<0.0001), FDI MAXE (r=0.81, p<0.0001) and DUC MAXE (r=0.60, p=0.0048). Neurogenic changes were seen in the ADM, FDI, flexor carpi ulnaris (FCU) and flexor digitorum profundus IV (FDP IV) in 79%, 77%, 25% and 35% respectively. Pathophysiology was demyelinating in 27%, axonal in 59% and mixed in 14%.

CONCLUSIONS

In proximal axonal lesions, sensory fibers to digit V and motor fibers to distal muscles are predominantly affected, whereas in demyelinating lesions, slowing occurs twice as frequently as conduction block.

SIGNIFICANCE

There is frequent axonal and fascicular injury in PUN.

Ulnar mononeuropathy associated with eosinophilia

A boy aged 4.5 years presented with isolated left ulnar nerve motor neuropathy and moderate eosinophilia. There was no evidence of parasitic infection. He was commenced on empirical diethylcarbamazine citrate and albendazole. Improvement occurred 6 days later with complete recovery by 2 weeks. It is presumed that he had a parasitic infection.

Surgical anatomy of the Guyon canal in children

OBJECT

The anatomy of the Guyon canal is crucial for open and endoscopic surgeries for ulnar canal syndrome at the wrist level. It is also of interest for surgical treatment of carpal canal syndromes. Whereas the Guyon canal is largely described in adults, no studies exist in children. In the present study, the authors examined the Guyon canal in children.

METHODS

Sectional anatomy was used. Thirty-two formalin-fixed cadavers (64 sides) were examined (age range 2-11 years). The hands were transversely cut into 2-3-mm-thick slices. Slices were placed in embedding medium, and transverse sections (10 μm thick) were stained with histological methods and photographed under a light microscope.

RESULTS

The roof of the Guyon canal was attached to the flexor retinaculum laterally to the hamulus of the hamate bone. Thus, the radial boundary of the Guyon canal was lateral to the hamulus, which became part of the floor of the Guyon canal. An ulnar neurovascular bundle was found directly volar to the hamulus in 93.8% of the cases and slightly medial to the hamulus (to the ulnar side) in 6.2% of the cases. Proximally, the ulnar artery and nerve were sustained by the flexor retinaculum in direct apposition to the carpal canal.

CONCLUSIONS

In children, the Guyon canal displays an anatomical particularity regarding the topography of the ulnar artery and nerve that may be of relevance for intraoperative orientation and endoscopic navigation to avoid lesions to the ulnar nerve and artery in carpal and Guyon canal syndromes.

MRI in unexplained mononeuropathy

Four young patients with severe unexplained progressive mononeuropathy are described. None had a history of known trauma to the affected limb. In addition to the standard neurologic examination and electrophysiologic studies (nerve conduction studies and electromyography), all underwent neuroimaging of the involved extremity. In three patients, magnetic resonance imaging revealed intrinsic abnormalities of the appropriate nerve. The pattern or absence of magnetic resonance imaging changes directly influenced decisions about surgical exploration of the nerve in all four patients. With the advent of more sophisticated technology, magnetic resonance neurography has become a potent diagnostic tool in the evaluation of disorders of peripheral nerve and muscle.

Pediatric radial mononeuropathies: a clinical and electromyographic study of sixteen children with review of the literature

Sixteen pediatric radial mononeuropathies were seen among 2077 electromyograms performed in the electromyography laboratory at The Children's Hospital, Boston, during 16.5 years, 1979-1995. Eight (50%) of these radial neuropathies, including 2 in newborns with apparent prenatal onset, were atraumatic, primarily related to compression in 6 and entrapment in 2. The other 8 (50%) were traumatic related to fractures or lacerations. Electromyography documented the radial neuropathy to be localized to the proximal main radial nerve trunk in 2 (13%), distal main radial nerve trunk in 9 (56%), and posterior interosseous nerve in 5 (31%) children. Significant improvement was noted in 13 of the 16 radial neuropathies--within 6-12 weeks for demyelinating lesions and up to 17 months for axonal injuries. Rarely, a child with a chronic progressive radial neuropathy or a postfracture radial neuropathy that does not improve in 3 months may require exploration.