Pseudo-Anterior Interosseous Nerve Syndrome by Multiple Intramuscular Injection

Abstract

Blind intramuscular injection might cause severe neurovascular injury if it would be performed with insufficient knowledge of anatomy around the injection area. We report a case of pseudo-anterior interosseous syndrome caused by multiple intramuscular steroid injections around the antecubital area. The patient had weakness of the 1st to 3rd digits flexion with typical OK sign. Muscle atrophy was noted on the proximal medial forearm, and sensation was intact. The electrophysiologic studies showed anterior interosseous nerve compromise, accompanying with injury of the other muscles innervated by the median nerve proximal to anterior interosseous nerve. Magnetic resonance imaging of the left proximal forearm revealed abnormally increased signal intensity of the pronator teres, flexor carpi radialis, proximal portion of flexor digitorum superficialis, and flexor digitorum profundus innervated by the median nerve on the T2-weighted images. This case shows the importance of knowledge about anatomic structures in considering intramuscular injection.

The Median Nerve at the Carpal Tunnel … and Elsewhere

“…It originates from the radial side (60% of cases) or from the posterior side (40%) of the MN [10]. The anterior interosseous branch comes from a posterior fascicle of the MN which can be isolated from the brachial plexus.…”

“…The anterior interosseous nerve syndrome is rare (representing less than 1% of all the entrapment syndromes of the upper limb) [10]. …”

“…Nerves can be entraped by tendinous or muscular variations (including an accessory head of the flexor pollicis longus also known as Gantzer muscle), bicipital bursa, vascular abnormalities or Volkmann’s ischaemic contractures [1012]. …”

Sonography of the Pronator Teres: Normal and Pathologic Appearances

“…As a result, the patient becomes unable to perform the “OK” gesture with the thumb and index finger . Other causes of proximal compression of the median nerve must be eliminated, such as a pseudoaneurysm of the axillary or brachial artery, a dialysis fistula, postpuncture hematoma in an anticoagulated patient, musculotendinous trauma, anatomic variations (bone, ligament, vascular, or muscular), inadequate position during a surgical intervention, tourniquet syndrome, or a conflict with orthopedic material (Figures and ) . If the symptoms persist for greater than 6 months, despite adequate conservative treatment, surgery may be requested but unfortunately followed by limited results, usually due to frequent postoperative adhesions …”

“…postpuncture hematoma in an anticoagulated patient, musculotendinous trauma, anatomic variations (bone, ligament, vascular, or muscular), inadequate position during a surgical intervention, tourniquet syndrome, or a conflict with orthopedic material (Figures 18 and 19). 15,32,33 If the symptoms persist for greater than 6 months, despite adequate conservative treatment, surgery may be requested but unfortunately followed by limited results, usually due to frequent postoperative adhesions. 4…”