Nerve conduction study of the superficial peroneal sensory distal branches in koreans

Abstract

Objective: To perform nerve conduction studies of the four branches of the superficial peroneal nerves to determine normal values and anatomic variations in Koreans.

Method: Antidromic sensory nerve conduction studies of the four distal branches were performed on 70 healthy subjects (100 feet). We applied electrical stimulation at the midpoint of medial and lateral malleoli for the medial dorsal cutaneous nerve (MDCN), and at the lateral 1/4 point between the medial and lateral malleoli for the 2 branches of the intermediate dorsal cutaneous nerve (IDCN).

Results: Reference values (mean±SD) of the onset/ peak latency (ms)/ sensory action potential amplitude (µV) for the two branches of the MDCN and for the first branch of the IDCN were 2.2±0.3/2.9±0.3/9.2±3.1, 2.2±0.3/2.8±0.3/9.1±3.0 and 2.3±0.4/2.9±0.3/8.5±2.8, respectively. For the second IDCN branch, the reference values were 2.3±0.4/3.0±0.4/7.1±2.6 but anomalous sural innervation was also found. Three types of IDCN innervations to the fourth interdigital web space were detected. In type I, the fourth interdigital webspace was innervated solely by the IDCN, whereas in type II, it was innervated by both the IDCN and distal sural nerve. In type III, it was solely innervated by the distal sural nerve.

Conclusion: The results of this study show the reference values of the distal sensory branches of the superficial peroneal nerve, and provide information on the variant innervations to the fourth interdigital web space.

Keywords: Innervations; Reference values; Sensory nerve; Superficial peroneal; Variant.

Fig. 1

(A) Anatomical courses of the medial and intermediate dorsal cutaneous nerves. (B) Placement of the recording electrodes and stimulator for recording the sensory action potential from the two branches of the MDCN and IDCN of the superficial peroneal nerve, as suggested by Oh. (Sm: stimulating electrode of MDCN, SI: stimulating electrode of IDCN, BR1: recording electrode of first branch of MDCN, BR2: recording electrode of second branch of MDCN, BR3: recording electrode of first branch of IDCN, BR4: recording electrode of second branch of IDCN).

Fig. 2

The three proposed innervation types of the distal branches for the superficial peroneal nerve and their corresponding sensory nerve action potential waveforms recorded with Medelec Select (A): type 1, typical innervation type, (A'): all SNAPs are obtained in all four branches. (B): type 2, dual innervations type from the IDCN and sural nerve, (B'): SNAP amplitudes for BR4 are small and an additional potential (BR4S) is detected with sural nerve stimulation. (C): type 3, sole sural nerve innervation type, (C'): BR4 SNAP is not evoked with IDCN stimulation but a SNAP is recorded with sural nerve stimulation. (N: nerve, BR: branch, BR1, BR2: 1^st and 2^nd branches of MDCN, BR3, BR4: 1^st and 2^nd branches of IDCN, BR4S: variation of BR4 with sural innervation, MDCN: Medial dorsal cutaneous nerve, IDCN: Intermediate dorsal cutaneous nerve, SNAP: sensory nerve action potential).

Fig. 3

BR4S antidromic and orthodromic SNAP waveforms recorded with Medelec Select (A): Stimulation with antidromic method, (A'): BR4S SNAP evoked with the antidromic method. (B): Stimulation with the orthodromic method, (B'): BR4s SNAP evoked with the orthodromic method. (BR4: 2^nd branch of IDCN, BR4S: variation of BR4 with sural innervation, SNAP: sensory nerve action potential).