Determining the utility of minimum F-wave latency alterations in the electrodiagnosis of ulnar neuropathy at the elbow / Determinação da utilidade das alterações mínimas da latência da onda F no eletrodiagnóstico da neuropatia ulnar do cotovelo

ABSTRACT Background: Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy. There is little information about the application of F-wave studies for evaluation of UNE. Objective: The aim of this study was to evaluate the diagnostic value of minimum F-wave (F-min) latency alterations by comparing this with nerve conduction analyses in UNE-suspected patients. Methods: Ninety-four UNE-suspected patients were admitted to this study. Sensory and motor nerve conduction and F-wave analyses on the median and ulnar nerves were performed on both upper extremities. Results: A total of 188 upper extremities of 94 patients were examined. Their mean age was 41.4±12.9 years, and 69 patients were female (73.4%). The mean ulnar-nerve across-elbow motor conduction velocity (MCV) in the affected arms was significantly slower than the velocity in healthy arms. The mean ulnar-nerve F-min latencies were significantly longer in the affected arms. Fifty-one patients were electrophysiologically diagnosed as presenting UNE (54.2%). Significantly slower mean ulnar-nerve across-elbow MCV, longer mean ulnar-nerve F-min latency and longer distal onset latency were detected in UNE-positive arms. Lastly, patients who were symptomatic but had normal nerve conduction were evaluated separately. Only the mean ulnar F-min latency was significantly longer in this group, compared with the healthy arms. Conclusion: Our study confirmed the utility of F-min latency measurements in the electrodiagnosis of UNE. F-wave latency differences can help in making an early diagnosis to provide better treatment options.

RESUMO Introdução: A neuropatia ulnar do cotovelo (NUC) é a segunda neuropatia por encarceramento mais comum. Existem poucas informações sobre a aplicação dos estudos da onda F para avaliação da NUC. Objetivo: O objetivo deste estudo foi avaliar o valor diagnóstico das alterações mínimas de latência da onda F (F-min), comparando-as com análises de condução nervosa em pacientes com suspeita de NUC. Métodos: Noventa e quatro pacientes com suspeita de NUC foram admitidos neste estudo. A condução nervosa sensitiva e motora e as análises da onda F nos nervos mediano e ulnar foram realizadas em ambas as extremidades superiores. Resultados: Um total de 188 membros superiores de 94 pacientes foi examinado. A média de idade foi 41,4±12,9 anos e 69 pacientes eram do sexo feminino (73,4%). A velocidade de condução motora média do nervo ulnar através do cotovelo (VCM) nos braços afetados foi significativamente mais lenta do que a velocidade em braços saudáveis. As latências médias F-min do nervo ulnar foram significativamente mais longas nos braços afetados. Cinquenta e um pacientes foram diagnosticados eletrofisiologicamente como apresentando NUC (54,2%). Pacientes com presença de NUC tiveram, de forma significativa, detecção de VCM mais lenta no nervo ulnar ao nível do cotovelo, presença de latência mais longa da onda F-mínima no nervo ulnar, bem como latência de início distal mais longa. Por fim, os pacientes sintomáticos, e com condução nervosa normal, foram avaliados separadamente. Apenas a latência da onda F mínima média do nervo ulnar foi significativamente maior neste grupo, em comparação com os braços saudáveis. Conclusão: Nosso estudo confirmou a utilidade das medidas de latência da onda F-mínima no eletrodiagnóstico da NUC. As diferenças de latência da onda F podem ajudar a fazer um diagnóstico precoce para fornecer melhores opções de tratamento.

Extensor indicis proprius transfer for the abducted small finger

PURPOSE: Persistent abduction of the small finger has usually been treated by transfer of the extensor digiti minimi muscle. However, anatomic variations of the extensor system may limit the potential for a successful extensor digiti minimi transfer. Therefore, we evaluated the outcomes of an alternative reconstruction method for the abducted small finger using an extensor indicis proprius (EIP) transfer. METHODS: We performed 8 EIP transfers in 8 patients with persistent, flexible abduction posturing of the small finger. The primary etiology of the deformity was incomplete motor reinnervation after surgeries for ulnar neuropathy in 6 patients, rupture of the third palmar interosseous musculotendinous unit in 1 patient, and intrinsic muscle fibrosis in 1 patient. The EIP was elongated by splitting the tendinous portion and was transferred to the distal and radial part of the extensor hood. Surgical outcomes were assessed by comparing preoperative and postoperative active adduction and abduction motion of the 2 ulnar digits. RESULTS: At the mean follow-up of 23 months, the average adduction angle improved from 19 degrees to 1 degrees postoperatively. In terms of active finger motion, 6 patients showed excellent results, 1 good, and 1 fair, without loss of flexion and extension. No patient had an extension lag or complained of functional deficits of the donor index finger. There was not adverse change to digital function or range of motion for the middle and ring fingers that are crossed by the EIP. CONCLUSIONS: Extensor indicis proprius transfer can be a reliable option for correction of abduction deformity of the small finger, maintaining active abduction and full flexion and extension. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Avaliação da neurólise ulnar na neuropatia hansênica / Assessment of ulnar neurolysis in leprous neuropathy

Os autores avaliam os resultados de 35 procedimentos de descompressão cirúrgica do nervo ulnar realizados em 28 pacientes hansênicos. Os parâmetros utilizados incluíram a escala analógica visual, a escala comportamental, a avaliação da força muscular, a estesiometria e a avaliação do efeito do procedimento no que tange à diminuição da corticoterapia no pós-operatório. Observou-se resolução imediata da dor após a realização da cirurgia, melhora da força muscular em metade dos pacientes, melhora da sensibilidade em metade dos pacientes. A diminuição da dosagem da prednisona após a cirurgia foi constante e significativa após a operação.

In this study, the authors assess the results of 35 surgical ulnar nerve decompression procedures performed on 28 leprous patients. The parameters employed included the visual analogue scale, the behavioral scale, the muscle strength evaluation, the esthesiometry and the evaluation of the effect of the procedure on decreasing postoperative corticoid therapy doses. Early resolution of pain was seen after surgery, muscle strength increased in half of the patients, sensitivity increased in half of the patients, with ongoing and significant decrease of prednisone doses after surgery.

Neuropatías por Atrapamiento / Entrapment neuropathies

Nerve entrapment and compression produce a pathology known as mononeuropathy, which consists in the isolated affectation of a peripheral nerve due to mechanical forces that act on themselves for a prolonged period. Neuropathies by entrapment affect diverse nerves along its path. The most frequent points of entrapment are – in the upper limbs – the path along the carpal tunnel for the median nerve, and the cubital channel at the level of the elbow for the cubital nerve. Diagnosis of these pathologies is based fundamentally on clinical and electrodiagnostic studies. Each one of the phases of the nerve entrapment lesion has its classification in the neurophysiological study, starting with a focal slowing of conduction (due to focal demyelinization), followed by a blocked nerve conduction and temporal dispersion through the compression site and, in later stages, the electromyography shows signs of denervation of the distal muscles (axonal damage).

Ulnar nerve palsy due to axillary crutch.

A young lady with residual polio, using axillary crutch since early childhood, presented with tingling, numbness and weakness in ulnar nerve distribution of five months duration. Ulnar motor conduction study revealed proximal conduction block near the axilla, at the point of pressure by the crutch while walking. Distal ulnar sensory conduction studies were normal but proximal ulnar sensory conduction studies showed absence of Erb's point potential. These findings suggested the presence of conduction block in sensory fibers as well. Proper use and change of axillary crutch resulted in clinical recovery and resolution of motor and sensory conduction block.

Dorsal cutaneous branch of ulnar nerve: an appraisal on the anatomy, injuries and application of conduction velocity studies in diagnosis

Classical textbooks and recent publications about the anatomy of the dorsal cutaneous branch of the ulnar nerve are revisited and correlated with methods of measurement of its conduction velocity, in order to evaluate the indications and limitations of the procedure. Etiology and pathogenesis of isolated lesions of this nerve branch are discussed