Superficial peroneal nerve (SPN) sensory studies are quite helpful in distinguishing L5 radiculopathies from more distal lesions. The sensory nerve action potential of SPN should be preserved in L5 radiculopathies, while in sacral plexopathies, sciatic neuropathies, polyneuropathies it is expected to be either low in amplitude or absent. The most commonly used method for SPN sensory studies is the antidromic method, with recording from dorsum of the foot or at the ankle at the level of lateral malleolus, stimulating 10-14 cm proximally. Some problems maybe encountered during the recording. Responses may be unelicitable bilaterally in >5% of "normal" people of any age group; sometimes difficult to obtain due to motor artefact, and of low amplitude after middle age. We worked on a more proximal method for obtaining the SPN sensory nerve action potential. The active recording electrode was placed 2 cm medially and 7 cm proximally from the lateral malleolus and the nerve was stimulated 10 cm proximally from the recording site. We compared this method with the conventional technique in 20 healthy adults. Introduction The superficial peroneal nerve (SPN) is derived from the L-5 root, branching off the common peroneal nerve below the fibular head. It divides into two branches at the lower leg; the medial dorsal cutaneous nerve and the intermediate dorsal cutaneous nerve. The intermediate dorsal cutaneous branch has a higher amplitude therefore most methods involve studying this branch with a recording point at the level of the ankle (1). The SPN is very useful in distinguishing L5 radiculopathies from more distal lesions, since the responses are usually normal with the former and either absent or abnormal with the latter such as sacral plexopathies, sciatic neuropathies or polyneuropathies. We report a new proximal method (method 2) for obtaining sensory nerve conduction velocities in the superficial peroneal nerve and compared the results with the classical method defined by Jabre in 1981 (method 1) (2). Materials And Methods The study group consisted of 20 healthy volunteers aged between 18-60. All subjects gave their informed consent prior to the study. Individuals with a diagnosis of diabetes mellitus, endocrine disorders or any other disease capable of causing polyneuropathy, a family history of inherited neuropathies or occupational/environmental history of heavy metal exposure, history of lumbar or cervical radiculopathy as well as using medications which could cause polyneuropathy were excluded. A neurologic examination was done by the same neurologist. Only the right side was studied in 3, and only the left side was studied in 1 subject, the rest subjects were studied bilaterally Therefore the SPN was studied with 2 different antidromic methods on 36 extremities. For the classical method defined by Jabre the active side of the bar recording electrode was placed at the level of the ankle one fingerbreadth medial to the lateral malleolus and the nerve was stimulated with a bipolar percutaneous stimulator at a point 12 cm proximal to the active recording electrode from the anterior edge of the fibula (2). For the proximal method the active recording electrode was placed 2 cm medially and 7 cm proximally from the lateral malleolus and the nerve was stimulated 10 cm proximally from the recording site. All SNAP's were recorded using 0.1 ms stimulus duration. Filter settings were 2 20 Hz and 2 kHz. The ground electrode was placed between the recording electrode and the stimulator for all studies. The room temparature was kept at at least 22 C. Conventional methods for the measurement of nerve conduction were employed. The latencies were measured from the onset of the action potential and the amplitudes were measured peak to peak. Sensory nerve conduction velocities were calculated from the onset latencies. Statistical Analysis: Mean values and standard deviations were determined for each measured nerve conduction parameter. The dif
展开▼
