gms | German Medical Science

Objectives/Interrogation: Anterior interosseous nerve (AIN) palsy is a purely motor neuropathy that comprises less than 1% of all upper extremity nerve palsies. The AIN innervates three muscles in the forearm: flexor pollicis longus (FPL), pronator quadratus (PQ), and the radial half of flexor digitorum profundus (FDP).

AIN compression is classically treated under general anesthesia with open surgical release of the median nerve through a long incision above and below the elbow. More recently, Hagert has published good success sectioning the Lacerates Fibrosus (LF) with a less invasive wide awake approach though a 3 cm incision at the elbow crease in a cohort of patient suffering of AIN compression without palsy.

We present 2 cases report of a AIN palsy, treated with minimally invasive ultrasound guided wide awake release of lacertus compression of the proximal median nerve at the elbow with return of function on the operating table.

Methods: 2 patients (30 year old female and a 26 year old male) presented to the outpatient clinic complaining of a 4 months history of complete palsy in the FPL and index FDP for the male and a unique palsy of the FPL tendon for the female.

He was found to have a positive scratch collapse test over the median nerve at the elbow. There was no sensory deficit in the median nerve distribution.

Electrodiagnostic studies supported the diagnosis of a compression neuropathy affecting the AIN at the elbow. An ultrasound examination showed no extrinsic tumor or vascular/nervous abnormalities but the dynamic compression of the median nerve between the pronator teres and the LF. The MRI of the wrist showed a denervation of the FPL and the PQ muscles.

The patients underwent wide awake surgical decompression of the median nerve using a technique similar to the technique described by Hagert. We used a 1 cm transverse skin incision 5 mm distal to the anterior elbow crease to cut the LF with a polycarbonate knife.

Results and Conclusions: We performed an intraoperative total active movement examination, and found the index distal interphalangeal joint and the interphalangeal joint of the thumb were able to immediately actively flex against resistance, compared to no movement preoperatively.

The wide awake ultrasound guided AIN release technique allowed intraoperative active motor examination confirming immediate return of strength of muscle groups involved in AIN palsy.