Doble compresión del nervio mediano en el brazo. Revisión crítica de la bibliografía. [Double compression syndrome of the median nerve in the arm]

La compresión mecánica de un nervio periférico en dos sitios diferentes a lo largo de su trayecto se define como síndrome de doble compresión. Esta enfermedad se basa en la teoría de la mayor susceptibilidad que tendría un nervio a nivel distal cuando este también se encuentra comprimido, en forma asintomática, a nivel proximal, debido a una alteración en el flujo axonal. Si bien la descompresión del túnel carpiano es una cirugía con resultados previsibles, hay pacientes operados por síndrome de túnel carpiano que no mejoran después de una cirugía, como cabría esperar. Si se excluye de este análisis a las comorbilidades, como diabetes, casos avanzados con atrofia muscular o descompresiones insuficientes, muchos de estos fracasos terapéuticos podrían estar fundamentados por el escaso diagnóstico de un segundo sitio de compresión concomitante. No obstante, existe gran controversia alrededor del síndrome de doble compresión que involucran no solo a su existencia, sino también a su incidencia y fisiopatología. El objetivo de esta publicación es presentar una revisión bibliográfica crítica del síndrome de doble compresión centrada en el compromiso del nervio mediano tanto en la muñeca como en el codo. AbstractThe mechanical compression of a peripheral nerve at two different sites is defined as double compression syndrome. This concept is based on the theory of the higher susceptibility that a nerve would present at a distal level when it is also compressed asymptomatically at a more proximal site. While carpal tunnel release is a surgery with predictable results, there are patients undergoing carpal tunnel decompression who do not have the expected improvement after surgery. Excluding from this analysis comorbidities such as diabetes, advanced cases with thenar atrophy, or incomplete decompressions, many of these therapeutic failures could be explained on the sub diagnosis of a second concomitant compression site. Despite this, there exists a big controversy around the double compression syndrome involving not only its existence but also its incidence and pathophysiology. Our objective is to perform a critical literature review of the double compression syndrome focused on the entrapment of the median nerve in the wrist and elbow.

A Tablet-Based App for Carpal Tunnel Syndrome Screening: Diagnostic Case-Control Study

Background Carpal tunnel syndrome (CTS), the most common neuropathy, is caused by a compression of the median nerve in the carpal tunnel and is related to aging. The initial symptom is numbness and pain of the median nerve distributed in the hand area, while thenar muscle atrophy occurs in advanced stages. This atrophy causes failure of thumb motion and results in clumsiness; even after surgery, thenar atrophy does not recover for an extended period. Medical examination and electrophysiological testing are useful to diagnose CTS; however, visits to the doctor tend to be delayed because patients neglect the symptom of numbness in the hand. To avoid thenar atrophy-related clumsiness, early detection of CTS is important. Objective To establish a CTS screening system without medical examination, we have developed a tablet-based CTS detection system, focusing on movement of the thumb in CTS patients; we examined the accuracy of this screening system. Methods A total of 22 female CTS patients, involving 29 hands, and 11 female non-CTS participants were recruited. The diagnosis of CTS was made by hand surgeons based on electrophysiological testing. We developed an iPad-based app that recorded the speed and timing of thumb movements while playing a short game. A support vector machine (SVM) learning algorithm was then used by comparing the thumb movements in each direction among CTS and non-CTS groups with leave-one-out cross-validation; with this, we conducted screening for CTS in real time. Results The maximum speed of thumb movements between CTS and non-CTS groups in each direction did not show any statistically significant difference. The CTS group showed significantly slower average thumb movement speed in the 3 and 6 o’clock directions (P=.03 and P=.005, respectively). The CTS group also took a significantly longer time to reach the points in the 2, 3, 4, 5, 6, 8, 9, and 11 o’clock directions (P<.05). Cross-validation revealed that 27 of 29 CTS hands (93%) were classified as having CTS, while 2 of 29 CTS hands (7%) did not have CTS. CTS and non-CTS were classified with 93% sensitivity and 73% specificity. Conclusions Our newly developed app could classify disturbance of thumb opposition movement and could be useful as a screening test for CTS patients. Outside of the clinic, this app might be able to detect middle-to-severe-stage CTS and prompt these patients to visit a hand surgery specialist; this may also lead to medical cost-savings.

A Tablet-Based App for Carpal Tunnel Syndrome Screening: Diagnostic Case-Control Study (Preprint)

BACKGROUND Carpal tunnel syndrome (CTS), the most common neuropathy, is caused by a compression of the median nerve in the carpal tunnel and is related to aging. The initial symptom is numbness and pain of the median nerve distributed in the hand area, while thenar muscle atrophy occurs in advanced stages. This atrophy causes failure of thumb motion and results in clumsiness; even after surgery, thenar atrophy does not recover for an extended period. Medical examination and electrophysiological testing are useful to diagnose CTS; however, visits to the doctor tend to be delayed because patients neglect the symptom of numbness in the hand. To avoid thenar atrophy-related clumsiness, early detection of CTS is important. OBJECTIVE To establish a CTS screening system without medical examination, we have developed a tablet-based CTS detection system, focusing on movement of the thumb in CTS patients; we examined the accuracy of this screening system. METHODS A total of 22 female CTS patients, involving 29 hands, and 11 female non-CTS participants were recruited. The diagnosis of CTS was made by hand surgeons based on electrophysiological testing. We developed an iPad-based app that recorded the speed and timing of thumb movements while playing a short game. A support vector machine (SVM) learning algorithm was then used by comparing the thumb movements in each direction among CTS and non-CTS groups with leave-one-out cross-validation; with this, we conducted screening for CTS in real time. RESULTS The maximum speed of thumb movements between CTS and non-CTS groups in each direction did not show any statistically significant difference. The CTS group showed significantly slower average thumb movement speed in the 3 and 6 o’clock directions (P=.03 and P=.005, respectively). The CTS group also took a significantly longer time to reach the points in the 2, 3, 4, 5, 6, 8, 9, and 11 o’clock directions (P<.05). Cross-validation revealed that 27 of 29 CTS hands (93%) were classified as having CTS, while 2 of 29 CTS hands (7%) did not have CTS. CTS and non-CTS were classified with 93% sensitivity and 73% specificity. CONCLUSIONS Our newly developed app could classify disturbance of thumb opposition movement and could be useful as a screening test for CTS patients. Outside of the clinic, this app might be able to detect middle-to-severe-stage CTS and prompt these patients to visit a hand surgery specialist; this may also lead to medical cost-savings.

Report of a New Case With Pentasomy X and Novel Clinical Findings

Pentasomy X is an extremely rare sex chromosome abnormality, a condition that only affects females, in which three more X chromosomes are added to the normally present two chromosomes in females. We investigated the novel clinical findings in a 1-year-old female baby with pentasomy X, and determined the parental origins of the X chromosomes. Our case had thenar atrophy, postnatal growth deficiency, developmental delay, mongoloid slant, microcephaly, ear anomalies, micrognathia and congenital heart disease. A conventional cytogenetic technique was applied for the diagnosis of the polysomy X, and quantitative fluorescent polymerase chain reaction (QF-PCR) using 11 inherited short tandem repeat (STR) alleles specific to the chromosome X for the determination of parental origin of X chromosomes. A cytogenetic evaluation revealed that the karyotype of the infant was 49,XXXXX. Comparison of the infant’s features with previously reported cases indicated a clinically recognizable specific pattern of malformations referred to as the pentasomy X syndrome. However, to the best of our know-ledge, this is the first report of thenar atrophy in a patient with 49,XXXXX. The molecular analysis suggested that four X chromosomes of the infant originated from the mother as a result of the non disjunction events in meiosis I and meiosis II. We here state that the clinical manifestations seen in our case were consistent with those described previously in patients with pentasomy X. The degree of early hypotonia constitutes an important early prognostic feature in this syndrome. The pathogenesis of pentasomy X is not clear at present, but it is thought to be caused by successive maternal non disjunctions.

Evaluation of the scratch collapse test for the diagnosis of carpal tunnel syndrome

This prospective study measured and compared the diagnostic performance characteristics of various clinical signs and physical examination manoeuvres for carpal tunnel syndrome (CTS), including the scratch collapse test. Eighty-eight adult patients that were prescribed electrophysiological testing to diagnose CTS were enrolled in the study. Attending surgeons documented symptoms and results of standard clinical manoeuvres. The scratch collapse test had a sensitivity of 31%, which was significantly lower than the sensitivity of Phalen’s test (67%), Durkan’s test (77%), Tinel’s test (43%), CTS-6 lax (88%), and CTS-6 stringent (54%). The scratch test had a specificity of 61%, which was significantly lower than the specificity of thenar atrophy (96%) and significantly higher than the specificity of Durkan’s test (18%) and CTS-6 lax (13%). The sensitivity of the scratch collapse test was not superior to other clinical signs and physical examination manoeuvers for CTS, and the specificity of the scratch collapse test was superior to that of Durkan’s test and CTS-6 lax. Further studies should seek to limit the influence of a patient’s clinical presentation on scratch test performance and assess the scratch test’s inter-rater reliability.