TITLE:
Potential Compressive Sites of the Anterior Interosseous Nerve in the Proximal Forearm: An Anatomic Study
AUTHORS:
Laurent Mathieu, Eric R. Simms, Frédéric Rongiéras, Eric J. Voiglio, Christophe Oberlin
KEYWORDS:
Anterior Interosseous Nerve; Anatomy; Compression; Paralysis; Neurolysis
JOURNAL NAME:
Open Journal of Orthopedics,
Vol.2 No.4,
December
31,
2012
ABSTRACT:
Background: The etiology and treatment of spontaneous paralysis variants of anterior
interosseous nerve (AIN) syndrome remains controversial. Variation and
multiple sites of potential compression complicate the successful performance of neurolysis. This
anatomic study of the AIN and sites of potential compression in the proximal
forearm facilitates critical steps involved in neurolytic
procedures and management. Methods: Upper
extremities of twelve cadavers were examined to evaluate potential sites of AIN
compression in the proximal forearm. Potential sites of musculoaponeurotic compression
were evaluated, including: lacertus
fibrosus; inferior fibrous arch of the humeral head of the pronator teres (PT) muscle; inferior
fibrous arch of the ulnar head of the PT muscle; fibrous arch in the flexor digitorum superficialis (FDS)
muscle; Gantzer’s muscle; and vascular structures near the AIN and median nerve. Results: The AIN arose at a mean
distance of 54.5 mm
distal to the elbow from the posterior (n = 9)
or ulnar side (n = 3) of the median nerve. Relative positions of AIN branches
were variable. A fibrous arch was found between the lacertus fibrosus and the PT in two cases. Nine
cadavers had two fibrous arches in the PT and FDS, and three cadavers had
one arch. An accessory head in the FDS was found to be a risk of AIN compression. Gantzer’s muscle was present in six
cases, crossing the AIN superficially. Two potentially compressive vascular
arches were identified. Conclusions: Our observations confirm that
multiple musculoaponeurotic and/or vascular structures can contribute to AIN
compression in the proximal forearm. Understanding the complex anatomic
relationships of this nerve is crucial to improving outcomes of neurolysis in
cases of non-regressive AIN paralysis.