Pictorial Guide to Nerve Conduction Techniques

Henry L. Lew

Su-Ju Tsai

Abbreviations for the electrode placement are as follows:

E1	Placement of the active electrode
E2	Placement of the reference electrode
G	Placement of the ground electrode
S	• Cathode	Placement of the cathode for stimulation
	• Anode	Relation of stimulator anode to the cathode

Cranial Nerves

Table 9-1 Cranial Nerve VII to Nasalis (Fig. 9-1)

Figure 9-1 • Cranial nerve VII Electrode placement E1 Over nasalis (lateral side of midnose) E2 Over contralateral nasalis G On the cheek or chin S Postauricular stimulation—behind the lower ear, below the mastoid process and behind the neck of the mandible Normal values   Mean ± SD Normal limit Onset latency (1) 3.5 ± 0.4 ms ≤4.2 ms Amplitude (2)   ≥1 mV Note: Alternate recording sites from other facial muscles as needed to evaluate specific branches of CN VII.

Table 9-2 Blink Reflex (Fig. 9-2)

Figure 9-2 • Blink reflex Electrode placement E1 Over bilateral orbicularis oculi muscle, lower lateral portion E2 Medial inferior orbit G Chin S Cathode At the supraorbital notch Anode Superiorly Normal values (3) (n = 83)   Mean ± SD (Normal limit) Side-to-side difference (Normal limit) R1 latency 10.5 ± 0.8 ms (≤13.0 ms) 0.3 ± 0.9 ms (≤1.2 ms) Ipsilateral R2 latency 30.5 ± 3.4 ms (≤41.0 ms) 1.0 ± 3.4 ms (≤4.4 ms) Contralateral R2 latency 30.5 ± 4.4 ms (≤44.0 ms)   Note: Amplitudes are variable.

Table 9-3 Cranial Nerve XI to Trapezius (Fig. 9-3)
Figure 9-3 • Cranial nerve XI Electrode placement E1 Over the upper trapezius, midway between C7 spinous process and acromion. E2 On acromion G Medial clavicle S Cathode At the posterior edge of the sternocleidomastoid muscle Anode Superiorly Normal values (4,5) (n = 30)   Mean ± SD Normal limit Onset latency 2.2 ± 0.4 ms ≤ 3.0 ms Peak amplitude 3.9 ± 1.6 mV ≥ 1.0 mV

Upper Body

Upper Body: Motor Nerves

Table 9-4 Phrenic Nerve (Fig. 9-4)
Figure 9-4 • Phrenic nerve Electrode placement E1 On the xiphoid process E2 On the costal margin, at anterior axillary line G Medial sternum S Cathode 3 cm above the clavicle, along the posterior border of the sternocleidomastoid muscle Anode Superiorly Normal values (6) (n = 50)   Mean ± SD Normal limit Onset latency 6.3 ± 0.8 ms ≤8.6 ms Amplitude 597 ± 139 μV ≥400 μV

Table 9-5A Long Thoracic Nerve-1 to Serratus Anterior (Fig. 9-5A)

Figure 9-5 • A. Long thoracic nerve Electrode placement (7) (Fig. 9-5A) E1 Self-adhesive, 8.0 × 0.5-cm, ring-type electrode—cranial end at nipple level (5 cm distal to the bipolar stimulator) in line with the bipolar stimulator contact points and the anterior superior iliac spine E2 Self-adhesive surface electrode over the seventh rib distal to the pectoralis muscle G Over the ipsilateral latissimus dorsi S In the axilla just anterior to the midaxillary line Normal values (7) (n = 15, self-adhesive ring-type electrode recording)   Side Mean ± SD Normal limit Onset latency Right 2.3 ± 0.5 ms ≤3.5 ms Left 2.3 ± 0.4 ms ≤3.2 ms Side-to-side difference 0.3 ± 0.2 ms ≤0.6 ms Amplitude Right 3.8 ± 1.9 mV ≥1.6 mV Left 3.9 ± 1.9 mV ≥1.2 mV Side-to-side difference 0.6 ± 0.6 mV ≤2 mV

Table 9-5B Long Thoracic Nerve-2 to Serratus Anterior (Fig. 9-5B)

Figure 9-5 • B. Long thoracic nerve Electrode placement E1 A needle electrode is placed into the digitation of the serratus anterior muscle over the fifth rib, along the midaxillary line. E2 Two cm distal to the E1 (no need if a concentric needle electrode is used for E1) G Over the 12th rib level at the anterior axillary line S Cathode Slightly above the upper margin of the clavicle lateral to the clavicular head of the sternocleidomastoid muscle Anode Superomedially Normal values (8) (n = 16, concentric needle recording) Age (years) Onset latency Mean ± SD Normal limit 20–35 3.6 ± 0.3 ms ≤4.2 ms 36–50 3.8 ± 0.4 ms ≤4.4 ms 51–65 4.0 ± 0.4 ms ≤4.8 ms

Table 9-6 Axillary Nerve to Deltoid (Fig. 9-6)
Figure 9-6 • Axillary nerve Electrode placement E1 Midway between acromion and deltoid tubercle E2 At deltoid tubercle G Between the stimulating point and active electrode S Cathode Supraclavicular fossa Anode Superomedially Normal values (9) (n = 62)   Mean ± SD Normal limit Onset latency 3.9 ± 0.5 ms ≤5.0 ms Note: No information on amplitude is available (9).

Table 9-7 Musculocutaneous Nerve to Biceps (Fig. 9-7)
Figure 9-7 • Musculocutaneous nerve Electrode placement E1 Midpoint of the biceps brachii muscle belly E2 Distal biceps tendon G Over the acromion S Cathode Supraclavicular fossa Anode Superomedially Normal values (9) (n = 62)   Mean ± SD Normal limit Onset latency 4.5 ± 0.6 ms ≤5.7 ms Note: No information on amplitude is available (9).

Table 9-8 Suprascapular Nerve (Fig. 9-8)

Figure 9-8 • Suprascapular nerve Electrode placement E1 A concentric recording needle (E2 = reference/outer cannular of needle) Supraspinatus: Insert the needle just above the scapular spine at the midpoint. Advance the needle in a downward and forward direction until the needle touches the scapula, then withdraw it 2–3 mm. Infraspinatus: Insert the needle 3 cm below the scapular spine and 3 cm lateral to the medial border of the scapula. G Over the posterolateral shoulder S Cathode Supraclavicular fossa Anode Superomedially Normal values (9) (n = 62) Onset latency Mean ± SD Normal limit Supraspinatus recording 2.7 ± 0.5 ms ≤3.7 ms Infraspinatus recording 3.3 ± 0.5 ms ≤4.2 ms Note: No information on amplitude is available (9).

Table 9-9 Thoracodorsal Nerve to Latissimus Dorsi (Fig. 9-9)

Figure 9-9 • Thoracodorsal nerve Electrode placement (10) E1 Supine position with the arm abducted to 90 degrees. E1 is on the posterior axillary line at the intersection of the line horizontally drawn from the inferior angle of the scapula. E2 On the posterior axillary line distal to E1 G On the chest wall, between E1 and S1 S1 Cathode In the axilla toward the lateral margin of the scapula Anode Superior S2 Cathode Erb’s point Anode Superior Normal values (10) (n = 30)     Mean ± SD Range Axilla (S1) Onset latency 1.9 ± 0.4 ms ≤2.7 ms Amplitude, right 4.1 ± 1.8 mV ≥1.4 mV Erb’s point (S2) Onset latency 3.6 ± 0.4 ms ≤4.5 ms Amplitude 6.0 ± 2.0 mV ≥2.0 mV

Table 9-10 Median Nerve to the Abductor Pollicis Brevis (Fig. 9-10)

Figure 9-10 • Median nerve to the abductor pollicis brevis Electrode placement E1 Midline between the first metacarpophalangeal joint and the first carpometacarpal joint E2 Distal to E1 on the first metacarpophalangeal joint G On the dorsum of the hand S Cathode S1: 8 cm proximal to the E1, measured first to the midpoint of the distal wrist crease and then on the line between the tendons of the flexor carpi radialis and the palmaris longus S2: On the antecubital crease, at the medial border of the biceps brachii tendon Anode Proximal Normal values (11,12) (n = 47)   Mean ± SD Normal limit Onset latency 3.7 ± 0.3 ms ≤4.3 ms Amplitude 13.2 ± 5.0 mV ≥5.0 mV Nerve conduction velocity 56.7 ± 3.8 m/s ≥50 m/s Normal values (13) (n = 243)   Mean ± SD Normal limit Onset latency 3.7 ± 0.5 ms ≤4.7 ms Amplitude 10.2 ± 3.6 mV ≥3.0 mV Nerve conduction velocity 57 ± 5 m/s ≥47 m/s

Table 9-11 Median Nerve (Anterior Interosseous Branch) to the Pronator Quadratus (Fig. 9-11)

Figure 9-11 • Median nerve (anterior interosseous branch) to the pronator quadratus Electrode placement E1 Centrally over the dorsum of the forearm, 3 cm proximal to the ulnar styloid E2 On the medial dorsum of the wrist over the ulnar styloid process G On the dorsal forearm, between the E1 and stimulating electrodes S Cathode On the antecubital crease, at the medial border of the biceps brachii tendon Anode Proximally Normal values (14) (n = 52)   Right Left Onset latency 3.6 ± 0.4 ms 3.5 ± 0.4 ms Onset to peak amplitude 3.1 ± 0.8 mV 3.1 ± 0.8 mV

Table 9-12 Radial Nerve to the Extensor Digitorum (Fig. 9-12)

Figure 9-12 • Radial nerve to the extensor digitorum Electrode placement E1 Proximal third from the antecubital crease (S1), over the belly of the extensor digitorum E2 On the medial dorsum of the wrist over the ulnar styloid process G Between the E1 and the S1 S Cathode S1: In the antecubital fossa just lateral to the biceps tendon as the tendon crosses the flexor crease S2: In the axilla between the coracobrachialis and the long head of the triceps Anode Proximally Normal values (15) (n = 30)   Mean ± SD Normal limit Onset latency 2.6 ± 0.4 ms ≤3.5 ms Amplitude 11.2 ± 3.5 mV ≥4.3 mV Conduction velocity 68 ± 7.0 m/s ≥54 m/s

Table 9-13 Radial Nerve to the Extensor Indicis Proprius (Fig. 9-13)

Figure 9-13 • Radial nerve—to the extensor indicis proprius Electrode placement (16) E1 Concentric needle electrode into the extensor indicis proprius, at the distal third of the dorsal forearm and on the dorsum of the ulna (E2 = outer cannula of needle) G Between E1 and S1, on the dorsum of the forearm S Cathode S1: In pronation of the forearm; 4 cm proximal to the needle insertion site, radial border of the extensor carpi ulnaris muscle S2: In pronation of the forearm; 5 cm proximal to the lateral epicondyle, lateral border of the triceps brachii muscle S3: Erb Point Anode Proximally Normal values (n = 49)   Mean ± SD Normal limit Distal latency (17) 2.4 ± 0.5 ms ≤2.9 ms Conduction velocity (16)     S1-S2 61.6 ± 5.9 m/s ≥50 m/s S2-S3 72.0 ± 6.3 m/s ≥60 m/s

Table 9-14 Ulnar Nerve to the Abductor Digiti Minimi (ADM) (Fig. 9-14)

Figure 9-14 • Ulnar nerve—to the abductor digiti minimi Electrode placement E1 On the border of the palm and dorsum of the hand, halfway between the wrist crease and the base of the little finger E2 Distal to the fifth metacarpophalangeal joint G On the dorsum of the hand or between the stimulating and recording electrodes S Cathode The arm is in a 45 degrees abducted and externally rotated position with the elbow moderately flexed to 90–135 degrees (18). S1: 2 cm proximal to the E1, along the radial border of the tendon of the flexor carpi ulnaris S2: 2 cm distal to the ulnar groove at the elbow S3: 10 cm proximal to the S2, measured in a curve along the ulnar groove to a point between triceps and brachialis S4: 10 cm proximal to S3 in the axilla Anode Proximally Normal values (n = 31)   Mean ± SD Normal limit Onset latency (18) 3.2 ± 0.5 ms ≤4.2 ms Amplitude 6.14 ± 1.90 mV ≥2.3 mV Nerve conduction velocity (18,19,20)     S1-S2 61.8 ± 5.0 m/s ≥53 m/s S2-S3 62.7 ± 5.5 m/s ≥52 m/s S3-S4 62.8 ± 6.0 m/s ≥51 m/s Normal values (21) (n = 248)   Mean ± SD Normal limit Distal latency (21) 3.0 ± 0.3 ms ≤3.6 ms Amplitude, peak to peak (21) 11.6 ± 2.1 mV ≥7.4 mV Conduction velocity (21)     S1-S2 61 ± 5 m/s ≥51 m/s S2-S3 61 ± 9 m/s ≥43 m/s S3-S4 61 ± 7 m/s ≥47 m/s

Table 9-15 Ulnar Nerve to the First Dorsal Interosseous (Fig. 9-15)

Figure 9-15 • Ulnar nerve—to the first dorsal interosseous Electrode placement E1 On the dorsum of the hand, the first web space, 1 cm radial to the midpoint of the second metacarpal bone E2 Over the first metacarpophalangeal joint G Between E1 and S1 S Cathode At the ulnar wrist crease, along the radial border of the tendon of the flexor carpi ulnaris Anode Proximally Normal values (22) (n = 373)   Onset latency Amplitude Age (years) Mean Limit Mean Limit <20 3.3 ms ≤4.2 ms 15 mV ≥8 mV 20–29 3.4 ms ≤4.1 ms 14 mV ≥8 mV 30–39 3.3 ms ≤4.4 ms 15 mV ≥6 mV 40–49 3.2 ms ≤4.2 ms 13 mV ≥6 mV 50–59 3.4 ms ≤4.4 ms 13 mV ≥6 mV 60–69 3.6 ms ≤4.5 ms 12 mV ≥7 mV >70 3.6 ms ≤4.2 ms 12 mV ≥8 mV Note: No summarized values are available (22). Mean side-to-side difference, FDI = 0.2 ms (0.0–1.3); ipsilateral difference, FDI – ADM = 0.9 ms (0.2–2.0) (22).

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