Extensor digitorum brevis manus associated with a dorsal wrist ganglion: a review of five cases

Finger abduction as a novel function of the extensor digitorum brevis manus muscle

A 25-year-old female presented with a chronic scapho-lunate ligament injury with development of carpal instability requiring reconstruction. During a standard dorsal longitudinal mid-line approach to the carpus, an extensor digitorum brevis manus (EDBM) muscle was found taking its origin from the dorsal wrist capsule overlying the lunate with innervation from the posterior interosseous nerve (PIN). Electrical stimulation of the muscle belly demonstrated abduction of the middle finger. The EDBM is a rare anatomical variant of the extensor compartment of the wrist and may be encountered during surgical approaches. Where possible these variant muscles should be carefully dissected off underlying structures, preserved and repaired at the conclusion of a procedure to ensure no perceived functional deficit to the patient. We present a case of a previously undescribed EDBM muscle function of pure finger abduction with no extension and a surgical technique of preserving its origin. We propose that the middle finger variant of the EDBM should be re-named the extensor digitorum brevis medius to reflect our findings.

Extensor Digitorum Brevis Manus: A Comprehensive Review of this Variant Muscle of the Dorsal Hand

The extensor digitorum brevis manus (EDBM) is a variant muscle located on the dorsum of the hand. This variant of the fourth compartment has often eluded preoperative diagnosis and led to unnecessary repeat visits to the operating room owing to its lack of notoriety. As a result, we aim to review the literature concerning the EDBM with respect to its embryology, comparative anatomy and variants, and clinical significance in an attempt to increase awareness and help in preoperative diagnosis and management. A total of 21 articles were reviewed. The results show that the EDBM often goes underdiagnosed and is frequently discovered incidentally in the operating room or in cadaveric dissections. There are multiple variations of the EDBM that, in certain instances, dictate the correct method of management. While there has been a reversal of opinions on which technique is the most popular at relieving symptoms caused by the EDBM, current arguments stand for retinacular release only when the EDBM serves as a sole extensor for one of the indices. In other instances where this is not the case, surgical excision of the EDBM proved to be the most effective at relieving symptoms.

Dorsal Wrist Ganglion Associated with Extensor Digitorum Brevis Manus: Case Report and Review of the Literature

Aberrant accessory muscles are rare entities in the hand. The extensor digitorum brevis manus (EDBM) muscle is amongst them and may be seen in association with dorsal ganglion cysts. Distinguishing an EDBM muscle is relevant in the diagnostic consideration of a dorsal ganglion in order to facilitate and guide its proper treatment. To date, there have been only few reports of an EDBM in association with a dorsal ganglion cyst. We report our experience with an incidental intraoperative finding of an intramuscular EDBM dorsal ganglion cyst and follow with a literature review and guide to management.

The prevalence of extensor digitorum brevis manus and its variants in humans: a systematic review and meta-analysis

Extensor digitorum brevis manus (EDBM) is a rare variant extensor muscle of the dorsum of the hand, which constitutes a diagnostic challenge in clinical practice. The aims of the review are to provide a better estimate of the frequency of EDBM and its association with variables such as ancestry, gender, laterality and side. Twenty-six studies met the inclusion criteria. The pooled rates of the meta-analyses yielded the following values: (a) an overall crude cadaveric prevalence of 4%, (b) an overall true cadaveric prevalence of 2.5%, (c) a true cadaveric prevalence of 2.6 % in European ancestry, (d) a true cadaveric prevalence of 2.3% in Asian ancestry (2.07% in Japanese and 4.2% in Indian), (e) a bilateral occurrence in 26.3%. Non-significant association was found between EDBM presence and ancestry, gender or side. The EDBM muscle was inserted on the index in 77% of cases and on the long finger in the remaining 23%. This is the first evidence-based anatomical review, which addresses the frequency of EDBM in humans.

Treatment of extensor digitorum brevis manus myalgia with botulinum toxin

Extensor digitorum brevis manus (EDBM) muscles are accessory dorsal hand muscles that are present in 1%-3% of the population. These muscles are not commonly symptomatic, but they can occasionally cause pain and discomfort and may be misdiagnosed as tenosynovitis or a ganglion cyst. In this case, we describe an appropriate workup of dorsal hand masses and myalgia that are suspected to be related to EDBM muscles. The patient's symptoms were controlled with injections of botulinum toxin into the EDMB muscle belly, which allowed the patient to be relatively pain free for a considerable amount of time and avoid surgery.

Extensor digitorum brevis manus muscle in association with a metacarpal boss

Awareness of the existence of accessory muscles in the hand, such as the extensor digitorum brevis manus (EDBM) muscle, is important when making a differential diagnosis and considering the treatment of mass lesions with similar appearances. Cases of EDBM with associated dorsal wrist ganglion have been reported in earlier published reports. This report describes an unusual case of the EDBM muscle in association with carpometacarpal (CMC) boss. To the best of the authors' knowledge this has not been previously reported.

An unusual morphological variant of the extensor digitorum brevis manus in an Indian male cadaver

The extensor digitorum brevis manus is a supernumerary muscle of the dorsum of hand and is a relatively rare finding during dissection. Only 2-3% of the cases are found world wide. Here we report the case of extensor digitorum brevis manus in an approximately 65-year-old Indian male cadaver. This report discusses the variant anatomy, morphology, review of literature and clinical implications of this muscle. We believe that it is of importance to report the observation of this muscle as the variation reported herein should be of interest to clinicians, surgeons and anatomists for academic purposes.

Incidence of extensor digitorum brevis manus muscle

The extensor digitorum brevis manus, a supernumerary muscle in the fourth extensor compartment of the dorsum of the wrist, is a relatively rare anomalous muscle. Extensor digitorum brevis should be included in the differential diagnosis of soft tissue masses on the dorsal aspect of the hand as it may mimic cystic, neoplastic, inflammatory, and infectious masses arising in the dorsum of the wrist. Seventy-two upper limbs of male and female cadavers were dissected and examined to study the pattern of extensor tendons of the index finger. In the present study, we observed three cases (4.2%) of the extensor digitorum brevis manus on the left side. In one cadaver (0.72%), there was an additional tendon arising from the extensor indices which was inserted to the radial side of the dorsal digital expansion of the index finger. The extensor digitorum brevis manus muscle (EDBM), an anatomic variant of the extensor muscle of the dorsum of the hand, is found in approximately 2% to 3% of the population. This variation is, therefore, clinically and surgically relevant because the EDBM may be the only muscle responsible for the independent extension of the second digit. The aim of the present study is to report the incidences of this muscle thereby creating awareness of its existence and of its characteristic appearance to surgeons.

A case of bilateral extensor digitorum brevis manus

We report a case of symptomatic dorsal mass in a 72-year-old man, with onset of pain during daily life efforts. On the other side, the dominant hand, a similar mass without any impairment was present. Before surgery, the mass on the left nondominant wrist was diagnosed by ultrasound as synovial ganglion: during excision, a muscular belly was found and sent to isthological evaluation, confirming the existence of an alive aberrant muscular tissue, named Extensor Digitorum Brevis Manus. Being reported in literature as occasionally bilateral, we decided to perform, 3 months later, an MRI in the contralateral asymptomatic wrist: it was possible to reveal the presence of a similar but asymptomatic mass.

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

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.

Extensor digitorum brevis manus: anatomical, radiological and clinical relevance. A review

The extensor digitorum brevis manus (EDBM) is a supernumerary muscle in the dorsum of the hand frequently misdiagnosed as a dorsal wrist ganglion, exostosis, tendon sheath cyst or synovitis. Its presence in a living subject, confirmed by magnetic resonance imaging (MRI), is presented together with a review of the hitherto reported cases and the results of an anatomical study on 128 adult human cadavers (59 males and 69 females). The EDBM was found in three (2.3%) of the 128 cadavers. It occurred in two (3.4%) of the 59 male cadavers (one bilateral and one unilateral on the right side) and in one (1.5%) of the 69 female cadavers (unilateral on the left side). Consequently, the EDBM was found in four (1.6%) of the 256 upper limbs. It originated from the dorsal wrist capsule within the compartment deep to the extensor retinaculum for the extensor digitorum and inserted into the extensor hood of the index finger in one case and into that of the middle finger in three cases. In both hands of the living subject, the origin was similar but the insertion was into the index and middle fingers. In all cases, it was innervated by the posterior interosseous nerve and its blood supply was provided by the posterior interosseous artery.