Antidromic sensory nerve conduction studies of medial and lateral plantar nerves in normals.
ABSTRACT 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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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.Journal of Foot and Ankle Research 05/2011; 4(1):14. DOI:10.1186/1757-1146-4-14 · 1.83 Impact Factor
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ABSTRACT: The authors report clinical and electrophysiological findings in 59 patients with tarsal tunnel syndrome (TTS) and follow-up in 23 of them. The entrapment was prevalent in females; was bilateral in 6 patients and involved medial plantar in 7 and lateral plantar nerves in two cases. Eleven presented with other nerve entrapment syndromes or focal mononeuropathies, due to hereditary neuropathy with liability to pressure palsy or systemic diseases. The other 48 subjects had TTS without any other related entrapment syndromes: 23 were idiopathic cases, 13 had a history of local trauma, 3 had systemic diseases and the others had external or intrinsic compressions. The most frequent symptoms were paraesthesia or dysaesthesia (86% of feet) and pain (55%). Hypoaesthesia of the sole and weakness of toe flexion were evident in 74% and 22% of feet, respectively. Absence of sensory action potential or slowing of sensory conduction velocity (SCV) of the plantar nerves were present in 77% of feet; significant differences of SCV between affected and unaffected plantar nerves and/or between distal sural and plantar nerves were evident in 14%. Abnormalities of plantar SCV were therefore absent in only 9% of feet. Distal motor latency was delayed in 55% and electromyography showed neurogenic changes in 45% of sole muscles. Five cases (6 feet) underwent surgery with excellent or good results in 5, 4 of them also showing improvement in distal conduction of the plantar nerves. Nine were treated with local steroid injections, with good results shown in 6 patients. Nine other patients who did not receive any therapy showed a disappearance of symptoms or good outcome in 6 cases. The subjects with poor therapeutic results had S1 radiculopathy or systemic diseases. The authors underline that patients with connective tissue diseases should not be treated by surgical decompression because they may have subclinical neuropathy. Some subjects with idiopathic or trauma-induced TTS recover spontaneously. Surgical release should be limited to cases with space-occupying lesions and when conservative treatments fail.Electroencephalography and Clinical Neurophysiology 11/1998; 109(5):418-25. DOI:10.1016/S0924-980X(98)00039-3
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ABSTRACT: A technique of testing sensory nerve conduction of the dorsal sural nerve in the foot was used in 38 normal subjects and 70 patients with peripheral neuropathies. The normal dorsal sural sensory nerve action potential (SNAP) had a mean amplitude of 8.9 microV (range 5-15 microV), mean latency to negative peak of 4.0 ms (range 3.2-4.7 ms), and mean conduction velocity of 34.8 m/s (range 30-44 m/s). Optimal placement of the recording electrodes to obtain a maximal nerve action potential was proximal to digits 4 and 5. Cooling to below 25 degrees C prolonged the latency but did not decrease the SNAP amplitude. Among the patients with peripheral neuropathy, dorsal sural SNAP was absent in 68 (97%), whereas only 54 (77%) showed abnormalities of sural sensory conduction. The diagnostic sensitivity of sensory nerve conduction studies in peripheral neuropathies may be significantly improved by the use of this technique for evaluating the action potential of the dorsal sural nerve.Muscle & Nerve 06/2001; 24(6):817-20. DOI:10.1002/mus.1074 · 2.31 Impact Factor