Related Experiment Video
Updated: Apr 23, 2026

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies
Published on: January 11, 2019
Ulnar nerve compression at the wrist: diagnostic role of palmar stimulation
Fikret Aysal1, Belgin Mutluay, Aysun Soysal
1*Department of Neurology, Bakirkoy Research and Training Hospital for Psychiatry, Neurology and Neurosurgery, Istanbul, Turkey; and †Department of Neurology, Istanbul University, Istanbul, Turkey.
Objective:
Electrophysiological diagnosis of ulnar nerve entrapment at the wrist is sometimes difficult. The aim was to evaluate the diagnostic role of ulnar nerve stimulation above and below the Guyon channel in ulnar nerve entrapment at the wrist.
Methods:
Supramaximal ulnar nerve stimulation at the wrist and palm, in addition to the standard nerve conduction studies, in 10 patients with ulnar nerve entrapment at the wrist and 40 controls.
Results:
Motor latencies to the first dorsal interosseous muscle with wrist stimulation were prolonged unilaterally in six and bilaterally in four patients. Palmar stimulation showed partial conduction blocks on the more symptomatic side in all. In two bilateral cases, there were 28.8% and 44.3% amplitude loss on the less symptomatic side. Motor responses elicited with palm stimulation were also found to have prolonged latencies and decreased amplitudes.
Conclusions:
Stimulation of the deep branch of the ulnar nerve can expand the information about ulnar nerve entrapment at the wrist by providing evidence about its nature, prognosis, precise localization, and distal extent.
Related Concept Videos
Spinal Nerves: Plexus I
The Cervical Plexus
The cervical plexus, formed by the anterior rami of the first four...
Bones of the Upper Limb: Ulna
Assessment of the Cardiovascular System III: Palpation
Jugular Venous Pressure (JVP) Measurement
Position the patient at a thirty- to forty-five-degree angle or in a semi-fowler's position. Look for the highest point of pulsation in the internal jugular vein and measure the vertical distance to the angle of Loius or sternal angle. A normal JVP is 3-4 cm above...
Assessment of radial pulse
The radial pulse, located at the wrist, is often the preferred site for assessing peripheral pulse because of its accessibility and dependability. The process of determining the radial pulse involves several steps:
Muscles of the Forearm that Move the Hand and Fingers
Anterior Compartment
The anterior compartment muscles originate from the humerus. They primarily function as flexors and are also known as flexor muscles. They typically insert on the carpals, metacarpals, and phalanges. The superficial layer includes the flexor carpi...
Arteries of the Upper Limbs

