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A Journal on Physiopathology and Surgery of the Foot

Indexed/Abstracted in: EMBASE, Scopus



Chirurgia del Piede 2009 August;33(2):75-83

language: Italian

Focal nerve lesions of the distal segment of the tibial nerve: a novel neurophysiological approach

Troni W. 1,2, Berra E. 3, Parino E. 2, Pisani P. C. 2, Pisani G. 2

1 Servizio di Neurologia e Neurofisiologia Clinica Clinica San Luca, Torino, Italia
2 Unità di Chirurgia del Piede, Clinica Fornaca, Torino, Italia
3 Clinica Neurologia II, Dipartimento di Neuroscienze Università di Torino, Torino, Italia


Aim. Conventional neurophysiological examination for suspected focal nerve lesions of the distal segment of the tibial nerve is often imprecise in discriminating between entrapment inside the tarsal tunnel (TT) and a location distal to the tunnel. Segmental analysis of motor nerve conduction velocity (MNCV) distal to the upper margin of the TT can be performed when compound muscle action potentials (CMAPs) are recorded using a coaxial electrode, which prevents simultaneous recording of activity by nearby muscle groups.
Methods. CMAPs of the flexor hallucis brevis to assess the medial plantar nerve (MPN), of the flexor brevis of the fifth toe and of the first dorsal interosseous (FDI) to assess the superficial and the deep lateral plantar nerve (SLPN and DLPN, respectively) were evoked by stimulating them at three points above (S1) and below (S2) the lacinate ligament and at the sole of the foot (S3 for the MPN and S4 for the LPN).
Results and conclusion. In 25 lower extremities examined in 20 healthy subjects, the mean MNCV of the proximal (S1 to S2) and the intermediate (S2 to S3/S4) segments was 44.5±4.7 and 40.7±5.6 m/s, respectively, for the MPN; 43.5±5.9 and 39.4±5.6 m/s, respectively, for the SLPN; 42.6±4.2 and 40.9±5.8 m/s, respectively, for the DLPN. The mean values of the motor terminal latency index (TLI), a parameter for assessing nerve conduction distal to S3/S4, were 0.29±0.05 for the MPN and 0.33±0.04 for the LPN.

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