Double Crush Syndrome of the Median Nerve: A Literature Review

Double crush syndrome (DCS) is defined as the compressive involvement of the same peripheral nerve in different segments.When this syndrome affects the median nerve, a proximal compression of a spinal nerve that will constitute this structure (often the spinal nerve at the C6 vertebra) is usually noted at the cervical spine level as a herniated disc and as a distal compression at the level of the carpal tunnel. Epidemiological data on median nerve compromise by DCS are still very scarce in the medical literature. The diagnosis can be inferred by symptoms and signs occurring proximally and distally in the arm, as well as by alterations revealed by upper limb electromyography and neuroimaging studies, such as magnetic resonance imaging (MRI) of the cervical spine. Nowadays, information on which compressed neuroanatomical point should be initially addressed still depends on further studies. Limited data infer that these patients, when submitted to surgical treatment in only one of the median nerve compression points, evolve with worse functional outcomes than the surgically-treated group with carpal tunnel syndrome without DCS.

A study of anatomical variations of median nerve formation and its relation to the arteries in the axilla and arm / Estudio de las variaciones anatómicas en la formación del nervio mediano y su relación con las arterias de la axila y el brazo

Variations of the peripheral nerve formation, communication and distribution are clinically important because such knowledge can be used for proper planning of surgeries and evaluating effects of nerve injuries and clinical imaging. Median nerve is known to have several such variations. However studies done on median nerve in Sri Lankan subjects are spars. The objective of this study was to find out anatomical variations of the median nerve with regards to its variations in roots and relations to the arteries in the axilla and arm. The study was done using 98 upper limbs of 49 formalin fixed cadavers. They were dissected and anatomy of the median nerve formations was studied focusing its variations of the roots and relation to the arteries. Anatomical variations of MN formation were observed in 33 (33.67 %) upper limbs with 4 bilateral and 25 unilateral variations. These variations were classified broadly in to two groups, variations of roots (15.3 %) and variation of arterial relations (18.37 %). There were three types of numerical variations (9.18 %) and three types of morphological variations (6.12 %) of roots. The median nerve was found to form in relation to the 2nd part of the axillary artery in 6.12 %, abnormal relation to the 3rd part of the axillary artery in 2.04 %, normal relation to the 3rd part of the axillary artery in 81.63 %, and brachial artery in 10.2 % of the specimens. The current study highlights the presence of different anatomical variations at median nerve formation with regards to its roots and arterial relations and describes three rare forms of anomalies which were not found on literature survey.

Las variaciones de la comunicación, formación y distribución del nervio periférico son clínicamente importantes para la planificación adecuada de las cirugías y para evaluar los efectos de las lesiones nerviosas y la imagen clínica. En el nervio mediano se han observado varias de estas variaciones. Sin embargo, son escasos los estudios realizados del nervio mediano en sujetos de Sri Lanka. El objetivo de este estudio fue conocer las variaciones anatómicas del nervio mediano con respecto a sus raíces y las relaciones con las arterias axilar y braquial. El estudio se realizó utilizando 98 miembros superiores de 49 cadáveres fijados con formalina. Se disecó y se estudió la anatomía de las formaciones de los nervios medianos, enfocando sus variaciones a nivel de las raíces y las relaciones con las arterias. Se observaron variaciones anatómicas de la formación de nervio mediano en 33 miembros superiores (33,67 %) con 4 variaciones bilaterales y 25 unilaterales. Estas variaciones se clasificaron ampliamente en dos grupos, variaciones de raíces (15,3 %) y variación de las relaciones arteriales (18,37 %). Existen tres tipos de variaciones numéricas (9,18 %) y tres tipos de variaciones morfológicas (6,12 %) de las raíces. Se encontró que el nervio mediano se formaba en relación con la 2 parte de la arteria axilar en el 6,12 %, relación anormal con la 3 parte de la arteria axilar en 2,04 %, relación normal con la 3 parte de la arteria axilar en el 81 ,63 % y braquial en el 10,2 % de los especímenes. El presente estudio señala la presencia de diferentes variaciones anatómicas en la formación del nervio mediano con respecto a sus raíces y relaciones arteriales y describe tres anomalías raras que no se encontraron en la investigación bibliográfica.

Sonographic Findings of the Bifid Median Nerve and Persistent Median Artery in Carpal Tunnel: A Preliminary Study in Chinese Individuals

OBJECTIVE: The aim of this study was to investigate the prevalence of anatomic variations of the bifid median nerve, persistent median artery and persistent median vein in Chinese individuals and their relationship with carpal tunnel syndrome. METHODS: One hundred and sixty median nerves were examined using ultrasonography and colour Doppler ultrasonography. The location, shape, and size of the bifid median nerve, persistent median artery and persistent median vein were recorded. The cross-sectional area of the bifid median nerve (two trunks) was measured at the level of the pisiform. RESULTS: Among the 160 wrists examined, a bifid median nerve was observed in 15 (9.4%) wrists, and a persistent median artery was observed in 12 (7.5%) wrists. These two variations either coexisted or were observed independently, and the probability of coexistence (6.3%) was higher than the probability of existing independently (bifid median nerve only 3.1%, persistent median artery only 1.3%). The cross-sectional area of the radial trunk was greater than (13 in 15, 86.7%) the cross-sectional area of the ulnaris trunk. Persistent median vein was observed in 9 wrists (5.6%). CONCLUSIONS: The persistent median artery and bifid median nerve tend to coexist, and the persistent median vein sometimes runs parallel to the persistent median artery. Their positional relationship in carpal tunnel is uncertain, and thus, preoperative ultrasound is necessary. These three variations do not present any additional risk for the development of carpal tunnel syndrome.

Incidence of unusual formation of the median nerve in Thai-Northeast embalmed cadavers / Incidencia de la formación inusual del nervio mediano en cadáveres embalsamados del noreste de Tailandia

This study aimed to investigate the incidence of unusual formation of the median nerve in Thai cadavers. Two hundred and ninety-two upper limbs were dissected and observed. The results showed that 5 out of 292 (1.71 %) arms had unusual splitting of median nerve that supplied the flexor arm muscles. Concomitantly, the musculocutaneous nerve was absent. In 4 out of 5 variant arms (80 % or 1.37 % of total upper limbs), each median nerve was unusually formed by 3 roots; the first and second roots were from lateral cord and the third one from medial cord. The union of the second lateral and medial roots to become a median nerve distantly extended in the arm. The second lateral roots gave off small muscular branches to the upper part of flexor arm muscles. Knowledge of such anatomical variations is helpful for surgeons in performing of brachial plexus surgery.

Este estudio tuvo como objetivo investigar la incidencia en la formación inusual del nervio mediano en cadáveres tailandeses. Se disecaron y observaron 292 miembros superiores. En 5 casos (1,71 %) se presentó una división inusual del nervio mediano que suministraba los nervios para los músculos flexores del brazo. Concomitantemente, el nervio musculocutáneo estaba ausente. En 4 de los 5 casos (80 % o 1,37 % del total de los miembros superiores), cada nervio mediano se formó por 3 raíces; la primera y segunda raíces procedían del fascículo lateral y la tercera del fascículo medial. La unión de la segundas raíces lateral y medial formaban el nervio mediano distalmente en el brazo. Las segundas raíces laterales daban pequeños ramos musculares a la parte superior de los músculos flexores del brazo. El conocimiento de tales variaciones anatómicas es útil para los cirujanos en la realización de la cirugía del plexo braquial.

Bilateral triad of persistent median artery, a bifid median nerve and high origin of its palmar cutaneous branch: a case report and clinical implications / Tríada bilateral correspondiente a arteria mediana persistente, nervio mediano bífido y origen alto de la rama cutánea palmar: reporte de caso e implicancias clínicas

We report the association of a persistent median artery, a bifid median nerve with a rare very high origin palmar cutaneous branch, presenting bilaterally in the upper limb of a 75-year-old female cadaver. The persistent median nerve with a bifid median nerve has been reported in patients presenting with carpal tunnel syndrome. Reports of this neurovascular anomaly occurring in association with a high origin palmar cutaneous branch however, are few. This subset of patients is at risk of inadvertent nerve transection during forearm and wrist surgery. Pre-operative magnetic resonance imaging (MRI) and high resolution sonography (HRS) can be used to screen this triad. MRI can reveal if the patient's disability is associated with a persistent median nerve, a bifid median nerve. HRS can help identify a palmar cutaneous branch of the median nerve that arises in an unexpected high forearm location. Such knowledge will help surgeons in selecting the most appropriate surgical procedure, and help avoid inadvertent injury to cutaneous nerves arising in unexpected locations. In patients presenting with a bilateral carpal tunnel syndrome, hand surgeons should consider very high on the list of differential diagnosis a persistent median artery with a concomitant bifid median nerve, with a high suspicion of a possible bilateral occurrence of a bilaterally high arising palmar cutaneous branch of the median nerve.

En este estudio se presenta la disposición bilateral de una arteria mediana persistente, un nervio mediano bífido con ramo cutáneo palmar de origen alto, en los miembros superiores de un cadáver de sexo femenino de 75 años de edad. Clínicamente se asocia la presencia del nervio mediano bífido en pacientes con síndrome de túnel carpiano. Sin embargo, son escasos los informes de esta anomalía neurovascular en asociación con un ramo cutáneo palmar del nervio mediano de origen alto. Este subconjunto de pacientes podría sufrir de transección del nervio durante la cirugía de antebrazo y de la muñeca. Se recomienda utilizar la imagen preoperatoria de resonancia magnética (RM) y sonografía de alta resolución (SAR) para detectar esta tríada. La RM puede revelar si la discapacidad del paciente se asocia con un nervio mediano persistente, un nervio mediano bífido. SAR puede ayudar a identificar un ramo cutáneo palmar del nervio mediano que surge en una situación alta del antebrazo en forma inesperada. Tal conocimiento ayudará a los cirujanos en la selección del procedimiento quirúrgico más apropiado, y a evitar una lesión inadvertida de nervios cutáneos que surgen en lugares inesperados. En los pacientes que presentan un síndrome del túnel carpiano bilateral, los cirujanos de mano deben considerar como prioridad en la lista de diagnóstico diferencial una arteria mediana persistente con un nervio mediano bífido concomitante, con una alta sospecha de una posible aparición bilateral de un ramo cutáneo palmar bilateral alto que surja del nervio mediano.

Coupled multiple musculo-neurovascular variations in same upper limb: a case report and clinical significances / Múltiples variaciones músculo-neurovasculares conectados en el mismo miembro superior: reporte de un caso y significados clínicos

Variants of the median nerve, extra forearm flexor muscles heads are relationships of the persistent median artery (PMA) that have been extensively reported. We report the findings of a PMA (diam. 3.25 mm), a pierced median nerve, and accessory heads of the flexor digitorum profundus (FDP) and flexor policis longus (FPL) muscles coexisting with a brachioradial artery (BRA) (diam.1.8mm) in the left upper limb of a 65 year-old male cadaver. The median nerve provided a ring for the passage of the PMA about the junction of the proximal and middle thirds of the forearm. Both accessory muscles were placed anterior to the ulnar artery, with the brachioradial artery coursing superficially in the brachium and antebrachium. The notable diameter of the PMA may be etiological in the causation of a carpal tunnel syndrome, while the hypoplastic BRA may pose some challenges inits selection as good conduit for catheterization and other surgical interventions like CABG in the upper limb. Additional clinical interest include the possible reduction in blood supply to the hand from the compressive effect of the 2 accessory muscles on the ulnar artery and possible inadvertent drug injection due to the superficial placement of the brachioradial artery close to veins.

Variantes del nervio mediano y cabezas adicionales de los músculos flexores del antebrazo, se relacionan con la arteria mediana persistente (AMP). Presentamos los resultados de una AMP (diámetro 3,25 mm), un nervio mediano pinzado y cabezas accesorias de los músculos flexor profundo de los dedos (FPD) y flexor largo del pulgar (FLP) que coexisten con una arteria braquiorradial (ABR) (diámetro 1,8 mm) en el miembro superior izquierdo de un cadáver de sexo masculino de 65 años. El nervio mediano proporciona un anillo para el paso de la AMP sobre la unión de los tercios proximal y medio del antebrazo. Ambos músculos accesorios se colocaron por delante de la arteria ulnar, con la arteria braquiorradial ubicada superficialmente en el brazo y en el antebrazo. El diámetro notable de la AMP puede ser la causa del síndrome del túnel carpiano, mientras que la ABR hipoplásica puede plantear algunos desafíos en su selección como buen conducto para la cateterización y otras intervenciones quirúrgicas como la cirugía de revascularización coronaria a partir del miembro superior. De interés clínico se considera la posible reducción en el suministro de sangre debido a la compresión de los 2 músculos accesorios a la arteria ulnar y la posible inyección fallida de drogas debido a la ubicación superficial de la arteria braquiorradial, cercana a las venas.

Absence of musculocutaneous nerve associated with variations of distribution patterns of the median nerve / Ausencia del nervio musculocutáneo asociada con variaciones de los patrones de distribución del nervio mediano

Variations in the brachial plexus and the distribution patterns of its branches are not uncommon. A communicating branch, which is the most frequent variation, often arises from musculocutaneous nerve to median nerve. However, the branches arising from lateral cord of the brachial plexus and median nerve instead of musculocutaneous nerve are very rare. Detailed description of the abnormalities is important for surgical procedures. Our case study reports the musculocutaneous nerve was absent, a branch from the medial cord innervated the coracobrachialis muscle and two branches from the median nerve innervated the biceps and brachialis muscles, respectively. Moreover, the median nerve gave off the lateral antebrachial cutaneous nerve. This report provides evidence of such possible anatomical variations to surgeons, anesthetists and neurologists during clinical practice.

Las variaciones en el plexo braquial y los patrones de distribución de sus ramos no son infrecuentes. Un ramo comunicante, que es la variante más frecuente, a menudo surge desde el nervio musculocutáneo al nervio mediano. Sin embargo, los ramos que surgen del fascículo lateral del plexo braquial y nervio mediano en vez de nervio musculocutáneo son muy raros. La descripción detallada de las anomalías es importante para procedimientos quirúrgicos. En nuestro caso el nervio musculocutáneo estaba ausente, un ramo del fascículo medial inervó el músculo coracobraquial y dos ramos del nervio mediano inervaron los músculos bíceps y braquial, respectivamente. Por otra parte, el nervio mediano originó al nervio cutáneo antebraquial lateral. Este informe proporciona evidencia de algunas variaciones anatómicas útiles para cirujanos, anestesistas y neurólogos durante la práctica clínica.

Incidences and clinical implications of communications between musculocutaneous nerve and median nerve in the arm: a cadaveric study / Incidencias e implicaciones clínicas de las comunicaciones entre el nervio musculocutáneo y nervio mediano en el brazo: un estudio cadavérico

OBJECTIVES: Variations such as communications between the median nerve and musculocutaneous nerve or in their abnormal branching pattern constitute a major concern in clinical and surgical field. Knowledge of these variations not only provides the clinician with a proper interpretation of the case, but also minimizes the complication in surgical approaches in this region. METHOD: We examined 50 isolated upper limbs to investigate the possible incidences of various types of communications between these two neighbouring peripheral nerves. RESULT: Twenty-eight per cent of limbs were found to have communication between these two nerves. When categorized according to Venieratos and Anagnostopoulou's classification method, 11 out of 14 cases (79%) showed type I communications, two out of 14 (14%) showed type II and the remaining one (7%) showed type III communication pattern. CONCLUSION: Prior knowledge of communications between these two neighbouring nerves, both in terms oftheir incidences and pattern ofcommunications, may be ofconsiderable significance to neurologists and orthopaedic surgeons in dealing with nerve entrapment syndromes in the upper limb of patients.

OBEJTIVOS: Las variaciones tales como las comunicaciones entre el nervio mediano y el nervio musculocutáneo o en su patrón de ramificación anormal constituyen un interés principal en el campo clínico y quirúrgico. El conocimiento de estas variaciones no sólo proporciona una interpretación adecuada del caso clínico, sino que también minimiza la complicación en abordajes quirúrgicos en esta región. MÉTODO: Se analizaron 50 miembros superiores aislados para investigar las posibles incidencias de diversos tipos de comunicaciones entre estos dos nervios periféricos vecinos. RESULTADO: Se halló que el veintiocho por ciento de los miembros tenía comunicación entre estos dos nervios. Cuando fueron categorizados según el método de clasificación de Venieratos y Anagnostopoulou, 11 de 14 casos (79%) mostró comunicaciones de tipo I, dos de 14 (14%) mostraron el tipo II, y el restante (7%) mostró un patrón de comunicación de tipo III. CONCLUSIÓN: El conocimiento previo de las comunicaciones entre estos dos nervios vecinos, en términos tanto de sus incidencias como patrones de comunicación, puede ser de una importancia considerable para los neurólogos y ortopédicos a la hora de tratar con el síndrome del atrapamiento del nervio en la extremidad superior de los pacientes.

Neuro-Vascular Variation in Axilla.

A variation in the branching pattern of third part of axillary artery was observed in the right upper limb of an adult male cadaver during routine dissection. The axillary artery gave a large abnormal arterial trunk. This trunk branched into anterior circumflex humeral, subscapular and profunda brachii artery. Subscapular trunk further divided into posterior circumflex humeral and circumflex scapular artery. There was abnormal formation of median nerve by two roots, anterior to abnormal arterial trunk. Medial root of median nerve was present behind axillary artery. Ulnar nerve was also formed around the abnormal trunk by medial and lateral roots. This abnormality might cause neurovascular compression in the upper limb like compression of abnormal arterial trunk by two roots of median nerve and compression of medial root of median nerve by axillary artery.

Comunicación bilateral de los nervios músculocutáneo y mediano: aspectos morfológicos e importancia clínica / Bilateral communications of the musculocutaneous and median nerves, morphological aspects and clinical significance

Las comunicaciones entre los ramos terminales de plexo braquial son frecuentes y tienen importancia en la evaluación de traumatismos y procedimientos quirúrgicos de las regiones axilar y braquial. En este artículo presentamos un caso en el que durante la disección de rutina del miembro superior, se observó la presencia de comunicaciones bilaterales entre los nervios musculocutáneo y mediano. Los ramos comunicantes fueron descritos en su trayecto, relaciones y morfometría y se discutió acerca de la prevalencia e importancia clínica de estas comunicaciones.

Communication of the musculocutaneous and median nerves of the brachial plexus is common and is important in the evaluation of trauma and surgical procedures in axillary and brachial regions. This paper presents a case in which during a routine dissection of upper limb the presence of bilateral communication between musculocutaneous and medium nerves was observed. Trajectory of communicating branches was described, relation and morphometry was discussed with regard to prevalence and clinical significance of these communications.

Arteria mediana persistente (AMP) bilateral de gran calibre en sujeto asintomático / High-caliber persistent bilateral median artery in asymptomatic

Se describe hallazgo en hombre de 22 años, asintomático, sano, de Arteria Mediana Persistente (AMP) bilateral de gran calibre asociada a un nervio median bífido (NMB) en una de las muñecas. La arteria mediana puede persistir hasta la adultez, acompañando al nervio por el túnel carpiano. Es una variante frecuente, suele ser bilateral y se asocia usualmente a NMB. La presencia de AMP puede asociarse a STC agudo secundario a trombosis y a STC crónicos por conflicto espacial. Sorprende el carácter asintomático de nuestro paciente a pesar del gran calibre de sus AMP. Sugerimos realizar, previo a cirugía o infiltración por STC, una ultrasonografía para adaptar tratamiento y evitar complicaciones.

We describe two high-caliber persistent median arteries (MPA) in an asymptomatic 22 year old healthy man, one of them between a bifid median nerve (BMN). The median artery may persist into adulthood, accompanying the median nerve through the carpal tunnel. It is a frequent anatomic variant, usually bilateral, regularly associated to BMN. The presence of MPA may be associated with acute carpal tunnel syndrome (CTS) secondary to thrombosis and chronic CTS probably due to spatial conflict. In this case, calls attention the lack of symptomatology despite the great size of MPA. We suggest performing prior to any surgery or infiltration of corticosteroids for CTS, an ultrasonographic study to avoid surgical complications.

Martin-Gruber anastomoses in the forearm with an anomalous course: a case report and review of literature

To report an anomalous communication of the median nerve with the ulnar nerve in the right upper limb of formalin-fixed adult male cadaver and compare it to those reported in similar studies that were retrieved after a wide review of the literature. During a routine cadaveric dissection of a formalin-fixed cadaver in our laboratory, we encountered a neuro-anatomical variation. The forearm was exposed and carefully dissected and examined for any further anatomical variations. The Martin-Gruber branch originated from the median nerve close to the cubital fossa approximately at the junction between the upper one fourth and the lower three fourth of the forearm. The nerve which was related lateral to the ulnar artery then descended downwards deep to the ulnar artery and emerged on its medial border before it communicated with the ulnar nerve. The anastomoses between median and ulnar nerves are clinically relevant. By identifying the existence of different types of anastomoses, mistakes in the diagnosis of peripheral nerve lesions or compression neuropathies in the forearm can be avoided

Entrapment of the median nerves and brachial arteries in the lower arms bilaterally and additional origin of biceps brachii muscle: case report / Compresión bilateral del nervio mediano y de la arteria braquial en la parte distal del brazo y origen adicional del músculo bíceps braquial: reporte de caso

Neuro-vascular entrapments associated with variations observed in the origins of muscles in the arm are not uncommon. Though additional heads of biceps brachii muscle and extra fibres of brachialis muscles have been demonstrated earlier, bilateral additional heads of the biceps are rarely seen, especially with entrapment of the median nerve and the brachial arteries in both the arms. The present study reports conspicuous heads of the biceps brachii originating extensively from the medial inter-muscular septum, sharing its origin with the brachialis muscle. The extra origins of the muscle formed long musculo-aponeurotic tunnels. The tunnels measured eight centimeters in length extending from the lower arm to the cubital-fossa. Both the median nerve and the brachial arteries passed through the tunnel. The lower aspect of the left tunnel exhibited origins of fibres belonging to the superficial flexors of the forearm. The neuro-vascular structures did not give any branches in the tunnel. Awareness of such variations can aid clinicians in diagnosing and treating such neuropathies and vascular compromise.

No es infrecuente observar atrapamientos neuro-vasculares asociados con variaciones en el origen de los músculos del brazo. A pesar de haberse observado cabezas adicionales del músculo bíceps braquial y fibras extra del músculo braquial raramente estas cabezas adicionales bilaterales han sido causantes de la compresión del nervio mediano y de la arteria braquial. En este trabajo presentamos las cabezas del músculo bíceps braquial originándose en gran parte en el tabique intermuscular medial compartiendo su origen con el músculo braquial. Los orígenes adicionales del músculo forman largos túneles músculo fasciales. Los túneles miden 8 cm de longitud, y se extienden desde la parte inferior del brazo hasta la fosa cubital. Tanto el nervio mediano como la arteria braquial pasan por el túnel. La parte inferior del túnel izquierdo dio origen a fibras pertenecientes al músculo flexor superficial del antebrazo. Las estructuras neurovasculares no otorgaron colaterales en el túnel. El conocimiento de estas variaciones puede ayudar a los clínicos en el diagnóstico y el tratamiento de neuropatías y compromiso vascular.

Course pattern of the muscular branch of the median nerve in Sri Lankans hand / Curso del patrón del ramo muscular del nervio mediano de la mano en sri lankenses

Transligamentous variant of the recurrent motor branch is having a higher risk of getting damage during both endoscopic and open carpal tunnel releases. The incidence of the transligamentous variant is about 7 percent to 80 percent world wide. This wide variation of the incidence could be due to the failure of identification of the distal edge of the flexor retinaculum from the obliquely oriented fascia that runs from the distal edge. We used two criteria to identify the distal edge; the abrupt change in the thickness of the flexor retinaculum and its colour change in cross section. The incidence of transligamentous variant is rare and the reported high incidence could be due to an error in identification of the distal edge of the flexor retinaculum as shown by Kosin (1998).

Las variantes transligamentosas del ramo motor recurrente tienen un mayor riesgo de recibir daños durante la endoscopía y liberación abierta del túnel carpiano. La incidencia de la variante transligamentosa es de, aproximadamente, 7 a 80 por ciento en todo el mundo. Esta amplia variación de la incidencia podría deberse a la falla en la identificación del borde distal del retináculo flexor de la fascia de orientación oblicua que va desde el borde distal. Hemos utilizado dos criterios para identificar el borde distal, el brusco cambio en el grosor del retináculo flexor y su cambio de color en la sección transversal. La incidencia de la variante transligamentosa fue rara y el informe de la alta incidencia podría deberse a un error en la identificación del borde distal del retináculo flexor, como lo demuestra Kosin (1998).

Absence of the musculocutaneous nerve: a rare anatomical variation with possible clinical-surgical implications / Ausência do nervo musculocutâneo: uma rara variação anatômica com possíveis implicações clínico-cirúrgicas

CONTEXT: The musculocutaneous nerve is one of the terminal branches of the lateral fasciculus of the brachial plexus, and is responsible for innervation of the flexor musculature of the elbow and for skin sensitivity on the lateral surface of the forearm. Its absence has been described previously, but its real prevalence is unknown. CASE REPORT: A case of absence of the musculocutaneous nerve that was observed during the dissection of the right arm of a male cadaver is described. The area of innervation was supplied by the median nerve. From this, three branches emerged: one to the coracobrachialis muscle, another to the biceps brachii muscle and the third to the brachialis muscle. This last branch continued as a lateral antebrachial cutaneous nerve. This is an anatomical variation that has clinical-surgical implications, considering that injury to the median nerve in this case would have caused unexpected paralysis of the flexor musculature of the elbow and hypoesthesia of the lateral surface of the forearm.

CONTEXTO: O nervo musculocutâneo é um dos ramos terminais do fascículo lateral do plexo braquial, sendo responsável pela inervação da musculatura flexora do cotovelo e pela sensibilidade cutânea da face lateral do antebraço. Sua ausência já foi descrita previamente, mas a sua real prevalência é desconhecida. RELATO DE CASO: Este é um relato de caso da ausência do nervo musculocutâneo observada durante a dissecção do membro superior direito de um cadáver do sexo masculino, sendo o seu território de inervação suprido pelo nervo mediano. Deste emergiam três ramos, um para o músculo coracobraquial, outro para o músculo bíceps braquial e o terceiro para o músculo braquial. Este último ramo continuava-se como nervo cutâneo lateral do antebraço. Trata-se de variação anatômica que tem implicações clínico-cirúrgicas, já que a lesão do nervo mediano, neste caso, acarretaria inesperada paralisia da musculatura flexora do cotovelo e hipoestesia da face lateral do antebraço.

Variant structures potent to compress the median nerve in the arm

The most commonly known nerve compression syndrome is carpal tunnel syndrome, in which the median nerve is compressed at the wrist. Along with the pathological processes, some of the anatomically variant structures can also compress the nerves and often leads to confusion in the diagnosis and treatment if one is unaware of such possible anatomical variants. Here, we present a case of possible median nerve compression by an additional belly of coracobrachialis and a fascial sheet from the brachialis, and we also discuss the other possible structures that can compress the median nerve

Síndrome do túnel do carpo: estudo de 330 punhos em 173 pacientes / Carpal tunnel syndrome: analysis of 330 hands in 173 patients

Neste trabalho foram estudados 330 punhos, em 173 pacientes, com síndrome do túnel carpiano (STC). Houve uma prevalência, quase exclusiva, do sexo feminino, apenas 2,4 por cento dos pacientes eram homens. Dos pacientes 59 por cento encomtravam-se entre a 5ª e a 6ª décadas de vida. Em 47 por cento dos casos o punho mais severamente acometido era o do membro dominante. Hipotrofia da regiäo tenar foi observada em apenas 4,6 por cento dos casos. Considerando individualmente, cada punho acometido pela STC 35 por cento a 66 por cento apresentaram positividade nas provas de Tinel e Phalen, respectivamente. Como fatores predisponentes associados encontramos: artrite (14,5por cento), diabetes mellitus (9,2por cento), hipotiroidismo (7,5por cento), gravidez (5,2por cento) e acromegalia (1,2por cento)