Topographic Anatomy Of Tibial Nerve And Its Terminal Branches In Relation With The Posterior Tarsal Tunnel With Clinical Correlations

Background: Variations in the level of terminal branching of tibial nerve into medial and lateral plantar nerve inthe posterior tarsal tunnel and its relations with posterior tibial artery has tremendous clinical importance.Tibial nerve and its terminal branches are at risk of entrapment in the posterior tarsal tunnel which is called astarsal tunnel syndrome. The results of surgeries for tarsal tunnel syndrome are variable or suboptimal. Thereason could be poor understanding of detailed anatomy of the tarsal tunnel and potential sites of nervecompression. Information regarding the same can help in endoscopic decompression surgeries for tarsal tunnelsyndrome with minimal exposure of the region to be operated. Knowledge regarding these variations can alsohelp the anesthetists to give ultrasonography guided ankle block without puncturing the blood vessels.Materials and Methods: The authors have studied topographic anatomy of tibial nerve and its terminal branchesin relation with posterior tarsal tunnel in 50 formalinized cadaveric feet. Authors divided the location of divisionof tibial nerve in posterior tarsal tunnel (PTT) into seven levels and also categorized the distance between thepoint of terminal division of tibial nerve (TN) and point of terminal division of posterior tibial artery (PTA) in fourcategories.Results and conclusion: Tibial nerve divides relatively higher than the posterior tibial artery in the PTT. Both lie inthe same compartment in the tarsal tunnel. The tibial nerve is situated deep to posterior tibial blood vessels .Theneurovascular bundle is covered by an unyielding fibrous tissue which could be the reason for the entrapment.Commonest division level of tibial nerve in PTT is level 4 which means the division lies in the range of 6mm to10mm above the distal border of flexor retinaculum. In 52% of feet the distance between point of division of TNand point of division of PTA is in a range between 0-5mm above the distal border of flexor retinaculum fallingunder category 1.

Características morfológicas y morfométricas del músculo aductor del hállux y sus ramos motores / Morphological and morphometric characteristics of the hallux adductor muscle and its motor branches

El hállux se encuentra en aducción en relación al eje del pie y para mantener esta posición requiere de una adecuada alineación ósea, la que está determinada principalmente por la actividad muscular. Una de las estructuras involucradas en esta función es el músculo aductor del hállux, el cual puede producir hállux valgus o hállux rígido cuando ocurre un desbalance en su actividad normal. A pesar de la importancia de este músculo, existen pocos estudios de su complejo neuromuscular. El objetivo de esta investigación fue describir las características morfológicas y morfométricas del músculo aductor del hállux y sus ramos motores en 30 miembros inferiores. Se disecó la planta del pie hasta alcanzar el plano del músculo aductor del hállux y sus ramos motores. La longitud media de la cabeza oblicua del músculo aductor del hállux fue de 78,16 mm (±13,35) con un ancho máximo promedio de 20,55 mm (±2,59) y un tendón de 25,87 mm (±7,97) de longitud. Respecto a las mismas medidas en la cabeza transversa, estas fueron 39,55 (±8,26), 15,04 (±3,52) y 18,51 (±10,04), respectivamente. La inervación de ambas cabezas del músculo aductor del hállux provenía del ramo profundo del nervio plantar lateral. En la mayoría de las muestras dicho nervio emitió un ramo para la cabeza oblicua y uno para la cabeza transversa. La cabeza oblicua presentaba uno o dos puntos motores, localizados generalmente en su tercio medio. La cabeza transversa presentaba sólo un punto motor localizado frecuentemente en su tercio lateral. El conocimiento de las características morfológicas y morfométricas del músculo aductor del hállux y de sus ramos motores son clínicamente significativos, puesto que permiten realizar una aproximación de la localización del punto motor en los procedimientos electromiográficos.

The hallux is adducted in relation to the axis of the foot and to maintain this position requires adequate bone alignment, which is determined mainly by muscle activity. One of the structures that is involved in this function is the adductor muscle of the hallux, which can produce hallux valgus or rigid hallux when an imbalance occurs in its normal activity. Despite the importance of this muscle, there are few studies of its neuromuscular complex. The objective of this study was to describe the morphological and morphometric characteristics of the adductor muscle of the hallux and its motor branches in 30 lower limbs. The sole of the foot was dissected until it reached the plane of the muscle and its motor branches. The average length of the oblique head of the adductor muscle of the hallux was 78.16 mm (± 13.35), with an average maximum width of 20.55 mm (± 2.59) and a tendon of 25.87 mm (± 7, 97) in length. Regarding the same measurements of the transverse head were 39.55 (± 8.26), 15.04 (± 3.52) and 18.51 (± 10.04), respectively. The innervation of both heads came from the deep branch of the lateral plantar nerve. In most of the samples, said nerve emitted a bouquet for the oblique head and one for the transverse head. The oblique head had one or two motor points, generally located in its middle third. The transverse head had only one motor point that was usually in its lateral third. The knowledge of the morphological and morphometric characteristics of the adductor muscle of the hallux and its motor branches are clinically significant, since they allow an approximation of the location of the motor point in electromyographic procedures.

Superficial course of the medial plantar nerve: case report / 대한해부학회지

The medial and lateral plantar nerves are branched from the tibial nerve and move to the tip of the toes. A variation of medial plantar nerve was found on the left side of a 78-year-old Korean male cadaver. The tibial nerve was divided into the lateral and medial plantar nerves beneath the plantar flexor. The medial plantar nerve passed deep to plantar aponeurosis and superficial to the flexor digitorum brevis. It gave off a common plantar digital nerve and then divided into three proper plantar digital nerves near the metatarsal bases. In this article, we report a superficial course of the medial plantar nerve and describe its unique morphology and discuss the clinical significance of this variation.

CT morphological characteristics of plantar nerves and their significances in diabetic foot / 中国医学影像技术

Objective To analyze CT morphologicl characteristics of tibial nerve,lateral and medial plantar nerves and their clinical significances in the diabetic foot (DF) patients.Methods Bilateral feet (DF group) of 33 patients diagnosed as type 2 diabetes mellitus with DF were examined with CT.Meanwhile,36 uninjured feet (NDF group) of patients with single-side foot wound were taken as the controls.CT findings of distal part of tibial nerve,medial plantar nerve and lateral plantar nerve on the same plane were observed with CT post-processing technique.The morphological measurements were done at the points of A1 (tibial nerve measuring position),A2 (proximal part of medial plantar nerve measuring position),A3 (distal part of medial plantar nerve measuring position) and A4 (lateral plantar nerve measuring position).Both of the anteroposterior and transverse diameters were measured and compared between DF and NDF groups.Results Plantar nerves (tibial nerve,medial plantar nerve and lateral plantar nerve) of DF patients were thick (52/66,78.79 ％),and the edges of nerve were indistinct (51/66,78.78％).The anteroposterior and transverse diameters of measurement points A1,A2 and A4 in DF group were larger than those in NDF group (all P＜0.01).There was no statistical difference of the anteroposterior and transverse diameters of point A3 between the two groups (both P＞0.05).Conclusion The plantar nerves of DF patient were thick with indistinct edges.The observation of continuous morphological characteristics and the diameter measurements of the plantar nerve can be performed with CT post-processing technique,which can provide more information for clinical diagnosis of DF.

Primeros ramos del nervio plantar lateral: revisión anátomo - clínica / First branches of the lateral plantar nerve: anatomo- clinical review

El nervio plantar lateral es un ramo terminal del nervio tibial, inerva la mayor parte de la musculatura del pie, y otorga inervación sensitiva a parte de la planta del pie. En esta revisión abordamos diversos aspectos del nervio plantar lateral desde su origen hasta su división, dando énfasis a aquellos ramos que por su disposición anatómica han sido señalados como causantes de síndrome de compresión, y a variaciones anatómicas importantes que deben ser conocidas cuando se aborda la región plantar. Numerosos estudios se han realizado para describir el trayecto y relaciones de los primeros ramos del nervio plantar lateral. Los ramos emitidos directamente por el nervio plantar lateral están destinados a los músculos abductor del dedo mínimo y cuadrado plantar, además de un ramo cutáneo lateral y ramos vasculares para los vasos plantares laterales y para el ligamento plantar largo. Como variación anatómica es posible encontrar ramos calcáneos mediales, tronco común de ramos calcáneo medial y para el músculo abductor del dedo mínimo, 2 ó 3 ramos para el músculo cuadrado plantar, tronco común para los músculos abductor del dedo mínimo y cuadrado plantar, ramo para el músculo flexor corto del dedo mínimo y ramo "anastomótico" para el nervio plantar medial. Cada vez más, es más necesario tener conocimientos acabados de la anatomía del pie, particularmente en aquellos procedimientos quirúrgicos que requieren precisión, con abordajes menos radicales y buenos resultados.

The lateral plantar nerve is a terminal branch of the tibial nerve, which innervates most of the foot's musculature, and also provides sensory innervation to the sole of the foot. In this present review we address various aspects of the lateral plantar nerve from its origin to its division, emphasizing those branches that, as a result of their anatomical disposition have been identified as causing compression syndrome. Furthermore, thorough knowledge and experience of anatomical variations are essential in procedures of the plantar region. Numerous studies have been carried out to accurately describe the path and relationship of the first branches of the lateral plantar nerve. Branches originating directly from the lateral plantar nerve are for the abductor digiti minimi and quadratus plantae muscles, in addition to a lateral cutaneous branch.Among these anatomical variations it is possible to find medial calcaneal branches, common trunk for medial calcaneal branches and abductor digiti minimi muscle, vascular branches for the plantar vessels, 2 or 3 branches for the quadrate plantae muscle, common trunk for the abductor digiti minimi muscle an quadratus plantae muscle,branch for the flexor digiti minimi brevis muscle, "anastomotic" branch for the medial plantar nerve and branch for long plantar ligament. Updated and absolute knowledge of the anatomy of the foot are necessary, particularly during those surgical procedures that require precision, with fewer invasive approaches and positive results.

Compressive neuropathy of the first branch of the lateral plantar nerve: a study by magnetic resonance imaging / Neuropatia compressiva do primeiro ramo do nervo plantar lateral: estudo por ressonância magnética

Abstract Objective: To assess the prevalence of isolated findings of abnormalities leading to entrapment of the lateral plantar nerve and respective branches in patients complaining of chronic heel pain, whose magnetic resonance imaging exams have showed complete selective fatty atrophy of the abductor digiti quinti muscle. Materials and Methods: Retrospective, analytical, and cross-sectional study. The authors selected magnetic resonance imaging of hindfoot of 90 patients with grade IV abductor digiti quinti muscle atrophy according to Goutallier and Bernageau classification. Patients presenting with minor degrees of fatty muscle degeneration (below grade IV) and those who had been operated on for nerve decompression were excluded. Results: A female prevalence (78.8%) was observed, and a strong correlation was found between fatty muscle atrophy and plantar fasciitis in 21.2%, and ankle varices, in 16.8% of the patients. Conclusion: Fatty atrophy of the abductor digiti quinti muscle is strongly associated with neuropathic alterations of the first branch of the lateral plantar nerve. The present study showed a significant association between plantar fasciitis and ankle varices with grade IV atrophy of the abductor digiti quinti muscle.

Resumo Objetivo: Avaliar a prevalência de achados isolados que causam compressão do primeiro ramo do nervo plantar lateral em pacientes com queixa de dor crônica no calcanhar, cujos exames de ressonância magnética mostraram atrofia gordurosa seletiva completa do músculo abdutor do quinto dedo. Materiais e Métodos: Estudo retrospectivo, analítico e transversal. Selecionamos exames de ressonância magnética do retropé de 90 pacientes que apresentavam atrofia muscular grau IV do abdutor do quinto dedo utilizando a classificação de Goutallier e Bernageau. Foram excluídos do estudo pacientes com níveis menores de degeneração muscular (abaixo do grau IV). Resultados: Houve predomínio do sexo feminino de 78,8% e alto índice de concordância da atrofia gordurosa do músculo abdutor do quinto dedo com fasciite plantar e varizes no tornozelo, respectivamente, encontrados em 21,2% e 16,8% dos pacientes. Conclusão: Atrofia gordurosa do músculo abdutor do quinto dedo está fortemente associada a alterações neuropáticas do primeiro ramo do plantar lateral. Nosso estudo mostrou associação significativa entre a fasciite plantar e varizes do tornozelo com atrofia grau IV do abdutor do quinto dedo.

Nervios digitales palmares comunes del ramo superficial del nervio ulnar y nervios digitales plantares comunes del ramo superficial del nervio plantar lateral: un error anatómico en terminologia anatomica / Common palmar digital nerves from the superficial branch of the ulnar nerve and common plantar digital nerves from superficial branch of the lateral nerve: an anatomical error in terminologia anatomica

Terminologia Anatomica contempla la existencia de nervios digitales palmares comunes del ramo superficial del nervio ulnar y nervios digitales plantares comunes del ramo superficial del nervio plantar lateral. De acuerdo a la mayoría de los textos clásicos y estudios anatómicos de las regiones de la palma de la mano y de la planta del pie, solo existiría un nervio digital palmar común (IV) originado del ramo superficial del nervio ulnar y un nervio digital plantar común (IV) con origen en el ramo superficial del nervio plantar lateral. Realizamos una revisión anatómica de la inervación cutánea de la palma de la mano observando el comportamiento de los nervios mediano y ulnar y de la planta del pie a través de los nervios plantares medial y lateral, comentamos la literatura relacionada y concluimos que debe corregirse la Terminologia Anatomica, en el término A14.2.03.046(Nn. digitales palmares comunes) y en el término A14.2.07.071(Nn. digitales plantares comunes), los cuales deberían denominarse N. digital palmar común y N. digital plantar común, ambos corresponderían al IV nervio digital palmar común y IV nervio digital plantar común, respectivamente.

Terminologia Anatomica contemplates the existence of common palmar digital nerves from the superficial branch of the ulnar nerve and common plantar digital nerves from the superficial branch of the lateral plantar nerve. According to most classical texts and anatomical studies of the regions palmar and plantar, there would only be common palmar digital nerve (IV) originated from the superficial branch of the ulnar nerve and common plantar digital nerve (IV) arising from the superficial branch of lateral plantar nerve. We conducted an anatomical review of the cutaneous innervation of the palm observing the behavior of the median and ulnar nerves, and the foot through the medial and lateral plantar nerves. In this study we discuss the related literature and conclude that Terminologia Anatomica must be corrected in the A14.2.03.046 term (Nn. common palmar digital) and in A14.2.07.071 term (Nn. common plantar digital ), which should be called: common palmar digital nerve and common plantar digital nerve, corresponding to both the IV common palmar digital nerve and IV common plantar digital nerve, respectively.

Intraneural Ganglion Cyst of the Peripheral Nerve: Two Cases Report / 대한골관절종양학회지

Ganglion cysts that occurred within sheaths of peripheral nerves have been documented in literatures, but it is relatively rare condition. The peroneal nerve is the most common site of involvement. Other reported sites of involvement are the radial, ulnar, median, sciatic, tibial and posterior interosseous nerves. We report a case of the intraneual ganglion cyst within peroneal nerve and another case of the intraneural ganglion cyst within a medial plantar nerve that were successfully excised without neurologic complication.

Anatomical Landmark Analysis of Medial Plantar Proper Digital Nerve:a Cadaver Dissection Study

OBJECTIVE: To analyze the bifurcating points of medial plantar proper digital (MPPD) nerve by using anatomical landmarks on plane coordinates and thus determine the ideal stimulation site for MPPD sensory nerve conduction studies. METHOD: We dissected 10 feet from five adult cadavers and identified the bifurcation points of the MPPD nerve. Two reference lines in relation to anatomical landmarks were defined. A vertical line connecting the mid-point of heel (H) and tip of great toe (G) was defined as the HG line. A transverse line connecting the navicular tuberosity (N) and tuberosity of 5th metatarsal bone (M) was defined as the NM line. The bifurcation points of the 10 MPPD nerves were expressed in X, Y coordinates in relation to these two axis. RESULTS: The bifurcation points were located at approximately 40% (40.0+/-2.4; mean+/-SD) of the HG line from the mid-point of heel (H) and at approximately 37% (36.5+/-3.6) of the NM line from the navicular tuberosity (N). The majority of these points were found to be clustered close to the HG line. CONCLUSION: The data on the MPPD nerve bifurcation points may be useful to localize the appropriate stimulation site that could be used in MPPD nerve conduction studies.

Plantar Nerve Conduction Studies in Diabetic Sensory Polyneuropathies With Normal Routine Conduction Studies

BACKGROUND: The results of a routine nerve conduction study (NCS) are sometimes normal in diabetic patients with clinical manifestations of sensory polyneuropathy, especially in the early stage. We report on the value of a plantar NCS in diabetic sensory polyneuropathy with normal results from a routine NCS. METHODS: Mixed nerve conduction data in the medial and lateral plantar nerves of both feet were obtained orthodromically in 47 normal subjects and 30 patients with diabetic sensory polyneuropathies with normal results from a routine NCS. The latency and amplitude of compound nerve action potentials (CNAPs) of plantar nerves were normal in the normal subjects. The results of a plantar NCS in the patient group were compared with these normal values. RESULTS: Nerve conduction abnormalities were found in 14 patients (46.7%). The rates of abnormal findings were 33.3% (20 of 60 nerves) and 31.7% (19 of 60 nerves) in the medial and lateral plantar nerves, respectively. A definite polyneuropathy pattern was found in 10 patients (33.3%). The CNAP amplitude was low or absent in 12 patients (85.7%) with abnormal nerve conduction, and 8 patients (57.1%) showed a prolonged CNAP latency. CONCLUSIONS: A plantar NCS is useful for detecting nerve conduction abnormalities in diabetic sensory polyneuropathy when normal results are obtained from a routine NCS. The diagnostic sensitivity of a routine NCS can be significantly increased by adding a plantar NCS when evaluating patients with sensory polyneuropathies, especially in the early stage.

Tarsal Tunnel Syndrome Combined with Diabetic Neuropathy

OBJECTIVE: To investigate the frequency of tarsal tunnel syndrome (TTS) in the diabetic neuropathy patients. METHOD: Electrodiagnostic study was performed to diagnose diabetic neuropathy and tarsal tunnel syndrome (TTS) in 56 patients (male 25, female 31) with diabetes mellitus. The frequency of combined TTS in diabetic neuropathy patients was calculated. RESULTS: Out of 56 diabetic patients, 52 patients were diagnosed as diabetic peripheral neuropathy. The frequency of concomitant TTS was 22 cases in 52 diabetic patients with diabetic neuropathy. CONCLUSION: In diabetic neuropathy group, the frequency of TTS was higher than general population.

Medial Plantar Nerve Injury after Screw Fixation of the Calcaneus Fracture

We present a case of medial plantar nerve injury by screw tip after open reduction and internal fixation of intraarticular calcaneus fracture. We reviewed the risk and prevention technique of medial plantar nerve injury in fixing the calcaneus fracture.

Morfometría de los Nervios Tibial y Plantares / Morphometry of the Tibial and Plantar Nerves

La inervación motora de los músculos del pie y susvariaciones anatómicasson importantes para el correcto diagnóstico de las lesiones de nervios periféricos y su tratamiento posterior. Con frecuencia, el pie es afectado por accidentes y la microcirugía reparadora requiere de abundante y detallada información anatómica para efectuar con éxito sus procedimientos. La falta de información morfométrica y estereológica de los nervios destinados a la musculatura del pie, nos motivó a plantear esta investigación. Se estudiaron 5 pies de cadáveres, adultos, en los cuales se disecaron la terminación del nervio tibial y el origen de los nervios plantares, medial y lateral. A través de cortes histológicos transversales de los nervios tibial y plantares, obtuvimos información cuantitativa sobre medidas morfométricas (número de fascículos, área de los fascículos, número de fibras por fascículo, número de fibras por nervio). Los resultados obtenidos fueron tratados estadísticamente y se registraron fotográficamente las muestras más representativas. El número de fascículos en el nervio tibial varió entre 19 y 39 con un promedio de 28,6 (D.S. 7.13), en los nervios plantares laterales varió entre 8 y 18 con un promedio de 14,8 (D.S. 3.96) y en los nervios plantares mediales varió entre 9 y 19 con un promedio de 12,4 (D.S. 3,91). El área promedio de los fascículos en los nervios tibial, plantar medial y plantar lateral fue de 3,66mm², 1,8mm² y 1,48 mm², respectivamente. Con los datos obtenidos esperamos contribuir al conocimiento morfológico y morfométrico de las estructuras nerviosas del pie, sirviendo de apoyo anatómico y quirúrgico.

Motor innervations of foot muscles and anatomic variations are very important for the correct diagnose of the lesions of peripheral nerves and their afterward treatment. Frequently, the foot is affected by accidents and reparatory microsurgery, which requires abundant and detailed anatomic information to be able to carry out successfully all necessary procedures. Lack of morphometric and stereological facts of the nerves of foot muscles, motivated us to execute this research. Here, five adult corpse feet were studied, where the tibial termination nerves, the origin of the medial and lateral plantar nerves. With transversal histological cuts of plantar and tibial nerves, quantitative information was obtained on morphometric measures (fascicule numbers, fascicule areas, number of fibers per fascicule, number of fibers per nerve). The obtained results were statistically analyzed and the most representative samples, photographically registered. The number of fascicules in the tibiae nerve varied between 19 to 39, with an average of 28.6 (D.S. 7.13), in the lateral plantar nerves it varied between 8 to 18, with an average of 14,8 (D.S. 3.96) and in the medial plantar nerves, it varied between 9 to 19, with an average of 12,4 (D.S. 3,91). The average area of the fascicules, in the tibia, medial plantar and plantar lateral nerves, was 3,66mm², 1,8mm² and 1,48 mm². With the obtained data, it is expected to contribute to morphological and morphometric knowledge of foot nerve structure, which can be used for anatomicsustain, as well as chirurgic support.

Transtarsal Conduction Velocities of Medial and Lateral Plantar Nerve Recorded by Orthodromic Near-Nerve Recordings

OBJECTIVE: Tarsal tunnel syndrome (TTS) is relatively rare and can be difficult to diagnose with conventional electrodiagnostic techniques. To increase the diagnostic sensitivity, we measured transtarsal conduction velocities of medial and lateral plantar nerves recorded by orthodromic near-nerve recording. METHOD: Twenty normal subjects (aged 24~59) were studied. For below flexor retinaculum (BFR) recordings, near-nerve needle recording electrodes were positioned posteriorly to the flexor digitorum longus tendon in medial plantar nerve and anteriorly to the calcaneus in lateral plantar nerve at the level of lower border of medial malleolus. For above flexor retinaculum (AFR) recordings, near-nerve needle recording electrodes were positioned anteriorly to the Achilles tendon 4 cm proximal to the BFR recording electrodes in medial and lateral plantar nerves. Stimulating ring electrodes were placed to the digit I and V. RESULTS: Transtarsal latencies and conduction velocities for medial plantar nerve were 0.7+/-0.1 msec, 56 6 m/sec, respectively. Transtarsal latencies and conduction velocities for lateral plantar nerve were 0.8+/-0.1 msec, 54+/-6 m/sec, respectively. CONCLUSION: This approach may improve the diagnostic sensitivity in TTS.

Distal Motor Nerve Conduction Studies of Medial Plantar Nerve, Lateral Plantar Nerve and Inferior Calcaneal Nerve

OBJECTIVE: To determine the reference values for the diagnosis of isolated entrapment neuropathies of medial and lateral plantar nerve and inferior calcaneal nerve distal to the tarsal tunnel. METHOD: The subjects were neurologically healthy 30 adults (15 males, 15 females). Distal motor nerve conduction study of medial and lateral plantar nerves and inferior calcaneal nerve was performed. The recording muscles for medial and lateral plantar nerves and inferior calcaneal nerve were flexor hallucis brevis, flexor digiti minimi brevis, and abductor digiti minimi pedis, respectively. The stimulation was done at distal and proximal to the tarsal tunnel to differentiate the tarsal tunnel syndrome and the entrapment neuropathy of distal to the tarsal tunnel. The distance of recording and distal stimulation site was fixed to 10 cm for medial and lateral plantar nerves. The skin temperature was maintained 33degrees C or above. The proximal latency, distal latency, peak to peak amplitude, conduction velocity and residual latency were measured. The reference values were obtained by 95 percentile values. RESULTS: The reference values for the diagnosis of isolated entrapment neuropathies of medial plantar nerve, lateral plantar nerve and inferior calcaneal nerve distal to tarsal tunnel are as follows. 1) Medial plantar nerve: distal latency, > 4.3 msec; side to side difference, > 0.7 msec 2) Lateral plantar nerve: distal latency, > 4.1 msec; side to side difference, > 0.6 msec 3) Latency difference of medial and lateral plantar nerve: > 0.7 msec 4) Inferior calcaneal nerve: distal latency, > 4.3 msec; distal peak latency, > 7.2 msec; side to side difference of distal onset latency, > 1.5 msec; side to side difference of distal peak latency, > 0.8 msec; residual latency, > 3.0 msec CONCLUSION: The distal motor nerve conduction method used in this study and the reference values could be used to differentiate entrapment neuropathies of medial and lateral plantar nerve and inferior calcaneal nerve distal to the tarsal tunnel from tarsal tunnel syndrome.

The Value of the Medial Plantar Sensory Nerve Conduction Study in Diabetic Patient

OBJECTIVE: The purposes of this study were to obtain the reference values of latency and amplitude of the medial plantar sensory nerve action potential(SNAP) in normal controls and to evaluate the diagnostic sensitivity of medial plantar sensory nerve conduction study(NCS) in diabetic neuropathy. METHOD: Thirty healthy controls(mean age, 48.7 years; range, 38~59 years) and 33 diabetic patients(mean age, 50.8 years; range, 37~64 years) were included in this study. The inclusion criteria for diabetic patients were subjects with the normal peroneal and tibial compound muscle action potentials, obtainable sural SNAPs and intact pressure-perception to Semmes-Weinstein monofilament 5.07. RESULTS: The medial plantar sensory nerve action potentials were obtainable in all control subjects and the reference values of onset latency and peak to peak amplitude were 4.29+/-0.49 msec and 3.1+/-1.34 V, respectively. All 33 diabetic patients showed the normal latency and 3 of them showed the low amplitude in sural SNAPs. The medial plantar SNAPs were obtainable in 24 diabetic patients. Among 9 patients with unobtainable medial plantar SNAPs, 6 showed the normal sural SNAPs and 3 showed the low sural SNAPs. The sensitivities of medial plantar SNAPs to sural nerve and sural SNAPs to medial plantar sensory nerve were 100%(3/3) and 27.3%(3/11) respectively. CONCLUSION: We concluded that medial plantar sensory NCS was more valuable in the early diagnosis of diabetic neuropathy than the sural NCS and Semmes-Weinstein monofilament (North Coast Medical Inc, USA).