The analysis of spontaneous activity is the first part of the needle electromyography (EMG) examination of every muscle. The presence of abnormal spontaneous activity on EMG is of key importance and yields several important pieces of information. First, the distribution…
Upper Extremity Median Nerve Abductor Pollicis Brevis (APB) ( Fig. 13.1A,B ) Innervation Median nerve, medial cord, lower trunk, C8–T1 Needle Insertion Insert the needle tangentially into the lateral thenar eminence, just lateral to the mid-point of the first metacarpal.…
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Tibial Motor Study ( Fig. 11.1 ) Recording Site Abductor hallucis brevis (AHB) muscle: G1 placed 1 cm proximal and 1 cm inferior to the navicular prominence G2 placed over the metatarsal-phalangeal joint of the great toe Stimulation Sites Medial…
Median Motor Study ( Fig. 10.1 ) Recording Site Abductor pollicis brevis (APB) muscle (lateral thenar eminence): G1 placed over the muscle belly G2 placed over the first metacarpal-phalangeal joint Stimulation Sites Wrist: Slightly lateral to the mid-wrist between the…
For every electrodiagnostic (EDX) test performed, one needs to decide if the study is normal or abnormal. That determination often needs to be made in real time as the testing progresses, so that the study can be modified based on…
Understanding and recognizing artifacts and technical factors play a central role in every nerve conduction and electromyography (EMG) study ( Box 8.1 ). The value of the information gained during an electrodiagnostic (EDX) study relies on two important and complementary…
Although peripheral nerve anatomy is more or less similar among individuals, in a sizable minority, there are some significant anatomic variations. These are known as anomalous innervations. Several of these anomalous innervations of peripheral nerve are commonly seen in the…
The use of repetitive nerve stimulation (RNS) dates to the late 1800s, when Jolly made visual observations of muscle movement that occurred after nerve stimulation. Although his initial studies were done with submaximal stimuli and mechanical rather than electrical measurements…
Few routine electrophysiologic tests are available to evaluate the cranial nerves and their proximal segments other than visual and brainstem-evoked potentials. However, cranial nerves V (trigeminal) and VII (facial), along with their connections in the pons and medulla, can be…