Antidromic sensory nerve conduction studies of medial and lateral plantar nerves in normals

Department of Physical Medicine and Rehabilitation, Wayne State University, Detroit.
Electromyography and clinical neurophysiology 01/1993; 33(5):289-94.
Source: PubMed


A reliable sensory nerve conduction study for the most distal lower extremities is needed in routine clinical electromyography. This paper reports a study of 150 medial and lateral plantar nerves in the foot in normals. An antidromic technique was used with stimulation at the ankle and recording from the small and large toes. Recordable responses were obtained in 149 instances. Conduction velocity in the medial branch distal to the tarsal tunnel was 40.5 +/- 4.0 m/sec and significantly slower than conduction in the lateral branch by 4.3 m/sec. The amplitude of the evoked response from the big toe was 3.46 +/- 2.2 microV and significantly larger than that in the small toe by 1.34 microV. Evoked response amplitude in the medial branch was greater in younger subjects.

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    • "Tibial sensory conduction values also need to be evaluated in patients with possible tarsal tunnel syndrome complaints [13,20]. Updated normative values have been published for both antidromic [21,22] and orthodromic medial and lateral plantar sensory techniques [23,24]. There are, however, few well controlled studies using adequate sample sizes to establish normative data for tibial sensory nerve conduction values. "
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    ABSTRACT: Standard tibial motor nerve conduction measures are established with recording from the abductor hallucis. This technique is often technically challenging and clinicians have difficulty interpreting the information particularly in the short segment needed to assess focal tibial nerve entrapment at the medial ankle as occurs in posterior tarsal tunnel syndrome. The flexor hallucis brevis (FHB) has been described as an alternative site for recording tibial nerve function in those with posterior tarsal tunnel syndrome. Normative data has not been established for this technique. This pilot study describes the technique in detail. In addition we provide reference values for medial and lateral plantar orthodromic sensory measures and assessed intrarater reliability for all measures. Eighty healthy female participants took part, and 39 returned for serial testing at 4 time points. Mean values ± SD were recorded for nerve conduction measures, and coefficient of variation as well as intraclass correlation coefficients (ICC) were calculated. Motor latency, amplitude and velocity values for the FHB were 4.1 ± 0.9 msec, 8.0 ± 3.0 mV and 45.6 ± 3.4 m/s, respectively. Sensory latencies, amplitudes, and velocities, respectively, were 2.8 ± 0.3 msec, 26.7 ± 10.1 μV, and 41.4 ± 3.5 m/s for the medial plantar nerve and 3.2 ± 0.5 msec, 13.3 ± 4.7 μV, and 44.3 ± 4.0 msec for the lateral plantar nerve. All values demonstrated significant ICC values (P ≤ 0.007). Motor recording from the FHB provides technically clear waveforms that allow for an improved ability to assess tibial nerve function in the short segments used to assess tarsal tunnel syndrome. The reported means will begin to establish normal values for this technique.
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