Extensor digitorum brevis manus: A case of fourth-compartment syndrome

Abstract

The presence of an extensor digitorum brevis manus represents a variation of the normal anatomy of the fourth extensor compartment of the wrist. It usually presents as a swelling on the dorsum of the wrist and is often inaccurately diagnosed. An awareness of its existence and of its characteristic appearance on diagnostic imaging studies is the basis for diagnosis. Symptomatic cases require division of the extensor retinaculum or excision of the muscle, depending on subtype, while asymptomatic cases require no intervention.Key Words: Anomalous extensors; Extensor digitorum brevis manus; EDBM; Fourth-compartment syndrome Un muscle extenseur commun court des doigts : Un syndrome de la quatrième loge La présence d'un muscle extenseur commun court des doigts représente une variation de l'anatomie normale de la loge du quatrième extenseur du poignet. D'ordinaire, cette manifestation prend la forme d'un oedème du dos du poignet. Elle est souvent mal diagnostiquée. La prise de conscience de son existence et de son apparence caractéristique à la visualisation diagnostique constitue le fondement du diagnostic. En présence de cas symptomatiques, il faut diviser le ligament annulaire ou exciser le muscle, selon le sous-type, tandis que les cas asymptomatiques n'exigent aucune intervention.T he vast majority of variations of the extensor tendons of the hand are asymptomatic throughout life, but their importance in hand surgery has been documented (1-4). The variations are often found incidentally at the time of surgery and at the time of diagnostic imaging (5). On occasion they may be associated with dorsal wrist pain, but a direct correlation is often difficult in the presence of other pathology, such as a ganglion or synovitis (6-9).First described by Albinus in 1734, as "muscles extensor brevis digiti indicis vel medii" (1), the existence of this anomalous muscle was questioned owing to its infrequent clinical presentation. Various anatomical descriptions persisted, but in 1866 Macalister (10) coined the term 'extensor digitorum brevis manus' (EDBM). The first clinical correlate was reported in 1926 (11). Since then, over 100 articles have been published on the topic leading to the development of two separate classifications. With incidences reported to be between 1% and 9% (11-16), the occurrence of this muscle should not surprise the anatomist or hand surgeon. In light of the high incidence and the lack of symptomatic case reports, the majority of EDBM cases must remain asymptomatic.A case of EDBM in association with an intraosseous ganglion of the lunate as a cause of fourth-compartment syndrome is reported. A review of the literature and current imaging techniques are presented to underline the clinical implications of this anomalous extensor muscle. CASE PRESENTATIONA 36-year-old, right-hand dominant woman was referred with left wrist pain after falling on her outstretched hand. The initial swelling and pain was managed with physiotherapy. However, the pain persisted over the central dorsal aspect of the wrist and s...

Radial nerve compression: anatomical perspective and clinical consequences

“…It can be palpated as a mass located on the posterior wrist, which can cause pain when the fingers are strenuously extended against resistance or during wrist extension with the palm pushed against a flat surface. In MRI, the muscle can be seen as a homogenous mass along the extensors' tendons [74]. Typically, the extensor digitorum brevis manus takes its origin at the posterior side of the wrist: at the wrist joint capsule, the distal end of the radius, or the posterior metacarpal surface; or from the radiocarpal ligament.…”

Extensor digitorum brevis manus bilateral

“…El EDBM se trata de una variante de los músculos extensores de la muñeca que puede ser causa de dolor crónico de muñeca. Puede ser unilateral, no habiendo diferencias en la incidencia entre la mano derecha o izquierda, o bilateral, como en este caso, lo que ocurre aproximadamente un tercio de las veces (1,2,4,5) .…”

“…Se localiza en el cuarto compartimento del retináculo extensor (6,7) . Aunque hay variantes, suele surgir de los ligamentos radiocarpianos posteriores y distalmente es habitual que se una al extensor indicis proprius (EIP) (1,2,5) . No es infrecuente que, en presencia del EDBM, esté ausente el EIP, siendo el EDBM el único extensor del dedo índice y así compensando la falta del EIP (2) .…”

“…En cuanto a la sintomatología, dada la relativa alta incidencia de aparición de esta variante anatómica y el escaso reporte de series de casos de pacientes sintomáticos, hace suponer que la mayoría de EDBM deben cursar sin síntomas asociados (3)(4)(5) . La clínica de masa dolorosa, presente en nuestro paciente, se relaciona con el llamado "síndrome del cuarto compartimento".…”

“…La clínica de masa dolorosa, presente en nuestro paciente, se relaciona con el llamado "síndrome del cuarto compartimento". Se produce por un aumento de la presión, por tratarse de un músculo adicional en este compartimento o por la inflamación e hipertrofia del mismo, lo que puede comprimir directa o indirectamente el nervio interóseo posterior (1)(2)(3)5,8) . Por ello, los síntomas son más frecuentes en personas que realicen movimientos repetitivos de la muñeca y en la mano dominante, ya que aumenta el flujo sanguíneo y genera un edema muscular que aumenta la presión (2)(3)(4)8) .…”