Selective anterior interosseous nerve conduction study: Coaxial needle versus surface electrode recordings

Area of Science:

• Neuroscience
• Clinical Electrophysiology
• Neurology

Background:

• The anterior interosseous nerve (AIN) is a motor nerve branch of the median nerve.
• Diagnosing isolated AIN lesions can be challenging due to potential overlap with median nerve stimulation.
• Accurate electrodiagnostic assessment is crucial for identifying specific nerve pathologies.

Purpose of the Study:

• To compare the selectivity of different nerve conduction study (NCS) methods for recording anterior interosseous nerve (AIN) motor action potentials (MAPs).
• To determine the optimal technique for diagnosing isolated AIN lesions.

Main Methods:

• Stimulation of the AIN and median nerve at the elbow.
• Recording of AIN motor action potentials (MAPs) using a coaxial needle electrode in the pronator quadratus (PQ) muscle.
• Recording of AIN motor action potentials (MAPs) using surface electrodes on the PQ muscle.
• Assessment of 22 healthy controls and 4 patients with suspected AIN palsy.

Main Results:

• Needle electrode recording in the PQ showed normal distal motor latency (DML) and significantly reduced MAP amplitude in patients compared to controls.
• Surface electrode recording on the PQ revealed no substantial changes in DML or compound MAP (CMAP) amplitude in patients.
• An additional surface electrode method on the flexor pollicis longus was also assessed in two patients.

Conclusions:

• Recording with a coaxial needle electrode inserted into the pronator quadratus muscle is the most selective method for AIN nerve conduction studies.
• This technique allows for specific diagnosis of isolated AIN lesions that might be overlooked with other methods.