Ann Rehabil Med.  2019 Feb;43(1):74-80. 10.5535/arm.2019.43.1.74.

Could Ultrasound-Guided Stimulation of Sural Nerve Affect Nerve Conduction Study?

• Choi H
• Chung SY
• Kang S
• Son SH
• Yoon JS

• KMID: 2440954
• DOI: http://doi.org/10.5535/arm.2019.43.1.74

Abstract

OBJECTIVE
To determine anatomical variation of the sural nerve (SN) by ultrasonography (US) and compare sensory nerve action potential (SNAP) of the SN obtained by a control method to that obtained with adjusted method using US.
METHODS
Eighty legs of 40 healthy volunteers were enrolled. The location and formation of SN were investigated through US. Two methods of nerve conduction study (NCS) were then performed. In the control method, the cathode was placed 14 cm proximal to the lateral malleolus and the greatest SNAP amplitude was obtained by moving the cathode medially or laterally from just lateral to the calf-mid line. In adjusted NCS, the exact SN union site was stimulated in type 1. In other SN types, the stimulation was done directly over the nerve and the distance from the lateral malleolus was set to be 14 cm.
RESULTS
It was found that 73.8% of the SNs were type 1, 22.5% were direct continuation of MSCN (type 2), and 3.8% were MSCN and LSCN without communicating (type 4). However, type 3 was not found. The union point in type 1 SN was 12.6±2.5 cm proximal to the lateral malleolus and 1.4±0.7 cm lateral to the calf-midline. After stimulation adjustment, SNAP amplitude in type 1 SN was significantly increased (20.7±5.5 μV vs. 27.1±6.7 μV).
CONCLUSION
Anatomical variation of SN and its location were verified by US. US provides additional information for conducting sural NCS and helps obtain more accurate results.

Keyword

Sural nerve; Nerve conduction study; Ultrasonography

MeSH Terms

Action Potentials
Electrodes
Healthy Volunteers
Leg
Methods
Neural Conduction*
Sural Nerve*
Ultrasonography

Figure

• 

  Fig. 1. Types of sural nerve formation: type 1, classical pattern (union of MSCN and LSCN); type 2, extending from MSCN alone; type 3, extending from LSCN alone; type 4, MSCN and LSCN are separate and running parallel to each other down to the ankle. SCN, sciatic nerve; CPN, common peroneal nerve; TN, tibial nerve; MSCN, medial sural cutaneous nerve; LSCN, lateral sural cutaneous nerve; SN, sural nerve.

• 

  Fig. 2. Sural nerve conduction study with adjusted stimulation location and ultrasonography of a transverse view of sural nerve. (A) Traced upwardly from B level where MSCN and LSCN are just about to divide. (B) Level of ankle. MSCN, medial sural cutaneous nerve; LSCN, lateral sural cutaneous nerve; V, small saphenous vein; E1, active electrode; E2, reference electrode.

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