Bilateral ulnar nerve entrapment by the M. anconeus epitrochlearis. A case report and literature review

Abstract

Ulnar neuropathy at the elbow is the second most common entrapment neuropathy. Ulnar nerve entrapment has several causes. A case report is presented with the presence of the M. anconeus epitrochlearis at both sides. The patient contacted our department with chronic, diffuse bilateral elbow pain irradiating into both forearms. She experienced typical nocturnal paresthesias involving digit IV and V of both hands. Tinel's sign was present just proximal to the medial epicondyle. A bilateral ulnar nerve entrapment was clinically suspected. An electromyographic (EMG) investigation revealed slowing of the motor conduction velocity in the ulnar nerve across the elbow. An ultrasound and MRI investigation demonstrated the presence of an anomalous muscle, called the M. anconeus epitrochlearis, at both sides. Treatment consisted of bilateral surgical excision of the muscle and retinacular release, followed by physical therapy. The outcome was favourable.

Síndrome del túnel cubital causado por el músculo anconeus epitrochlearis. Reporte de un caso. [Cubital tunnel syndrome caused by anconeus epitrochlearis muscle. Case Report]

“…Luego, en el brazo, atraviesa el tabique intermuscular medial y desciende por el lado interno del músculo tríceps para ingresar en el túnel cubital. [1][2][3] La neuropatía compresiva del nervio cubital es la segunda patología compresiva de nervios periféricos más frecuente luego del síndrome del túnel carpiano.…”

“…6 También se lo conoce como ancóneo accesorio y músculo epitrocleo-cubital. 1,9 Su función en el codo humano es incierta. Dada su inserción entre la epitróclea y el olécranon, el músculo aberrante podría tener…”

“…El mayor aporte a la literatura proviene de reportes de casos aislados. 1,5,6,12,15 Una de las series más grandes es la de Masear y cols. 16 con 5 casos de neuropatía cubital asociados a anconeus epitrochlearis y tratados mediante resección y descompresión sin transposición.…”

Hypotheses for ongoing evolution of muscles of the upper extremity

“…As over 70% of the human population does not even have this muscle(27), one can see that the muscle must not be necessary in humans and may be indicative of a late evolutionary process. Indeed, presence of an AE may not only be unnecessary, but may cause problems such as ulnar neuropathy, cubital tunnel syndrome and elbow pain(28, 29). It is therefore important for clinicians to be aware of the potential presence of the AE [Figure 2], as it may potentially be a contributing factor to patients presenting with elbow pain or neuropathy.…”

High‐resolution ultrasound in ulnar neuropathy at the elbow: A prospective study

“…3 UN at the elbow occurs most commonly due to mechanical forces that produce traction or ischemia of the ulnar nerve. Entrapment may also occur from soft-tissue structures such as tumors or ganglion cysts, bony abnormalities such as bone spurs, subluxation of the ulnar nerve over the medial epicondyle with elbow flexion, anatomical variants like an anconeus epitrochlearis muscle or abnormal insertion of the triceps muscle, 4 repeated traumas, 5,6 forceful work, 7 or smoking. 8 Electrodiagnostic techniques to evaluate ulnar neuropathy were first described by Simpson in 1956.…”