Anatomy of the sural nerve related to calcaneal tendon, intermalleolar line and small saphenous vein / Anatomía del nervio sural en relación con el tendón calcáneo, la línea intermaleolar y la vena safena parva

Sural nerve (SN) courses from the posterior aspect of leg to the lateral side of ankle and foot. Anatomy of the SN is of clinical importance due to its involvement in nerve biopsy, nerve graft harvesting including injuries during calcaneal tendon repair. Despite substantial knowledge in the literature, more easily located landmarks and data regarding the symmetry are still needed. Ninety-eight lower extremities from 31 males and 18 females were dissected in this study. The SN originated from the union between the medial and lateral sural cutaneous nerves in 52.0 % of the legs. The distance from the union point to the intermalleolar line (IML) was 16.3±8.4 (SD) cm. The ratio of this distance to the fibular length (apex of head to lateral malleolus or LM) was 0.47±0.23 cm. In 84.7 % of the legs, the SN initially coursed medial to and then crossed the lateral border of calcaneal tendon at the distance of 8.4±2.1 cm above the IML. The ratio to the fibular length was 0.25±0.06 cm. At the level of IML, the SN was posterior to the most prominent part of the LM in 95.9 % of the legs with the distance of 2.6±0.5 cm. At the closest point, the SN was lateral to the small saphenous vein in 74.5 % of the legs and the distance from this point to the IML was 10.6±4.7 cm. The ratio to the fibular length was 0.31±0.14 cm. Side difference or asymmetry was observed in a substantial number of specimens. These data are crucial for not only localizing the SN during biopsy and graft harvesting but also avoiding the nerve injury during relevant surgical procedures.

El nervio sural (NS) transcurre por la región posterior de la pierna, el tobillo y el pie. La anatomía del NS es de importancia clínica durante la realización de una biopsia, el desarrollo de injerto de nervio, incluyendo lesiones del nervio durante la reparación del tendón calcáneo. A pesar del conocimiento sustancial en la literatura, aún se necesitan puntos de referencia más fáciles de localizar e información sobre la simetría. Noventa y ocho miembros inferiores de 31 hombres y 18 mujeres fueron disecados. El NS se originó a partir de la unión entre los nervios cutáneo sural medial y cutáneo sural lateral en el 52,0 % de las piernas. La distancia desde el punto de unión a la línea intermaleolar (IML) fue de 16,3±8,4 (SD) cm. La relación de esta distancia a la longitud de la fíbula (vértice de la cabeza al maléolo lateral o LM) fue de 0,47±0,23 cm. En el 84,7 % de las piernas, el NS se ubicó inicialmente medial y luego cruzó el margen lateral del tendón calcáneo a una distancia de 8,4±2,1 cm proximal a la IML. La relación de longitud de la fíbula fue de 0,25±0,06 cm. A nivel de la IML, el NS se localizaba posterior a la parte más prominente de la LM en el 95,9 % de las piernas, con una distancia de 2,6±0,5 cm. En el punto más cercano, el NS se localizaba lateral a la vena safena parva en 74,5 % de las piernas y la distancia desde este punto hasta la IML fue de 10,6±4,7 cm. La relación de longitud de la fíbula fue 0,31±0,14 cm. La diferencia entre los lados o asimetría se observó en un número considerable de ejemplares. Estos datos son esenciales no sólo para localizar el NS durante la biopsia y la realización del injerto sino también para evitar la lesión del nervio durante procedimientos quirúrgicos relevantes.

Hind limb sensory innervation in rats: comparison between sural and saphenous nerve morphometry / Inervación sensorial de los miembros posteriores en ratas: comparación morfométrica entre los nervios sural y safeno

Although numerous studies investigate sensory recovery of the hind paw of the rat after nerve damage, still no comprehensive overview of its normal innervation is present in the literature. We investigated the morphometry of myelinated fibers in the sural and saphenous nerves and analyzed their size distributions in young rats. Six 30-day-old female Wistar rats were perfused with 2.5% glutaraldehyde and their right and left sural and saphenous nerves were prepared for light microscopy and morphometry. Morphometric data were compared between segments (proximal versus distal) and sides (right versus left) for the same nerves. Also, segments from right or left sides were compared between nerves (sural versus saphenous). Both, the sural and saphenous nerves, exhibited proximal to distal symmetry on both sides as well as left-right symmetry. Histograms of the diameter of the myelinated fibers were unimodal in both nerves, regardless of segments or sides with the peaks of the fibers size occurring between 2.5 and 4.0 µm. The axon distributions reflected the myelinated fiber distributions, with the sural and saphenous nerves peaking between 1.5 and 2.0 µm. The G ratio (the ratio between the axon and fiber diameters) distributions were also unimodal, with peaks at 0.6 for both nerves. This study contributes to the literature with information on the myelinated fibers morphometry from the two sensory nerves responsible for the rat hind limb innervation. This information is valuable for a better understanding of the possible contribution of collateral sprouting from the sural or saphenous nerves on the paw sensory territory recovery observed after one of these nerves is damaged.

Aunque numerosos estudios investigan la recuperación sensorial del miembro pélvico o posterior de la rata después del daño en los nervios, aún no existe en la literatura una visión global de su inervación normal. Investigamos la morfometría de fibras mielínicas de los nervios sural y safeno y analizamos sus distribuciones de tamaño en ratas jóvenes. Seis ratas Wistar de 30 días de edad fueron perfundidas con 2,5% de glutaraldehído, se prepararon los nervios sural y safeno derecho e izquierdo para microscopía de luz y morfometría. Datos morfométricos fueron comparados entre los segmentos (proximal vs distal) y laterales (derecho vs izquierdo) para los mismos nervios. Además, los segmentos de los lados derecho e izquierdo se compararon entre los nervios (sural vs safeno). Ambos nervios sural y safeno exhibieron una simetría proximal a distal en ambos lados, así como una simetría izquierda-derecha. Histogramas del diámetro de las fibras mielinizadas eran unimodales en ambos nervios, independientemente de los segmentos o de los lados, siendo los peaks del tamaño de las fibras entre 2,5 y 4,0 micras. Las distribuciones de los axones reflejan las distribuciones de fibras mielinizadas, de los nervios sural y safeno que alcanzaban entre 1,5 and 2,0 µm. La relación de G (relación entre los diámetros de los axones y de fibra) eran también unimodales, alcanzando 0,6 para ambos nervios. Este estudio contribuye a la literatura con los datos de la morfometría de fibras mielinizadas de ambos nervios sensoriales responsables de la inervación de la extremidad pélvica de la rata. Esta información es valiosa para una mejor comprensión de los nervios sural y safeno en la recuperación sensorial del miembro después de que uno de estos nervios ha sido dañado.

Study of variations in medial sural cutaneous nerve, lateral sural cutaneous nerve and peroneal communicating nerve.

The sural nerve complex includes the Medial sural cutaneous nerve (MSCN), Lateral sural cutaneous nerve (LSCN), Peroneal communicating nerve (PCN) and Sural nerve. The sural nerve is the most frequently used donor nerve for peripheral nerve grafting. LSCN can be an alternative to sural nerve in situations requiring a limited length of nerve graft material, the peroneal communicating nerve may also be harvested. Fifty lower limb specimens were dissected and data was collected. The study included 16 male and 9 female cadavers. MSCN was observed in all 50 specimens, out of which 74% specimens had normal course and 22% had a transmuscular course. LSCN was present in 82% of specimens. PCN was arising from Common Peroneal Nerve (CPN) directly in 16% and as a common trunk with LSCN in 14% of specimens. PCN was absent in 28% of cases. So knowledge of variation in these nerves will help the surgeons while considering these nerves for nerve grafting.

Can Wistar rats be used as the normotensive controls for nerve morphometry investigations in spontaneously hypertensive rats (SHR)? / Ratos Wistar podem ser utilizados como os controles normotensos dos ratos espontaneamente hipertensos (SHR) em investigações morfométricas de nervos periféricos?

PURPOSE: We compared the sural nerve morphology among Wistar (WR), Wistar-Kyoto (WKY) and Spontaneously hypertensive (SHR) rats, including the nerve fascicles and myelinated fibers morphometry. METHODS: Age matched (20 weeks) female WR (N=6), WKY (N=6) and SHR (N=7) had their right and left sural nerves removed, embedded in epoxy resin, and observed by light microscopy. Morphometric analysis was performed with the aid of computer software. RESULTS: Despite presenting the same age, WR were heavier than WKY and SHR, as were SHR compared to WKY. Systolic arterial pressure was higher in SHR compared to WR, but no differences between SHR and WKY or WR and WKY were observed. The sural nerves were morphometrically symmetric between proximal and distal segments on the same side and between sides in all strains with no differences in the myelinated fiber number. Schwann cell number and density were smaller in SHR and G ratio was larger in SHR, indicating that SHR have thinner myelinated fibers. CONCLUSION: Sural nerve morphology is similar between WKY and WR, allowing the use of WR as the SHR controls in morphological investigations involving peripheral neuropathies.

OBJETIVO: Comparar a morfologia do nervo sural em ratos Wistar (WR), Wistar Kyoto (WKY) e espontanemanete hipertensos (SHR), incluindo a morfometria dos fascículos e fibras mielínicas. MÉTODOS: Os nervos surais direito e esquerdo de WR (N=6), WKY (N=6) e SHR (N=7), com 20 semanas de idade foram removidos e preparados para inclusão em resina epóxi e microscopia de luz. A morfometria foi realizada com o auxílio de um programa de computador. RESULTADOS: Apesar de apresentarem a mesma idade, WR são mais pesados que os WKY e SHR. Ainda, SHR são mais pesados que os WKY. A pressão arterial sistólica foi significativamente maior nos SHR comparados aos WR, sem diferença entre WKY e SHR ou WR e WKY. Os nervos surais são morfometricamente simétricos entre segmentos proximal e distal e entre lados direto e esquerdo nas três diferentes linhagens, sem diferença no número de fibras mielínicas. O número e a densidade de células de Schwann foram menores e a razão G foi maior nos SHR, indicando a presença de fibras mielínicas com bainha mais fina. CONCLUSÃO: A morfologia do nervo sural é semelhante ente WR e WKY, permitindo o uso de WR como controles dos SHR nas investigações envolvendo neuropatias periféricas.

Entrapment of the sural nerve on gastrocnemius muscle: histological analysis / Compresión del nervio sural en el músculo gastrocnemio: análisis histológico

Anatomical variations in the formation of the sural nerve are common, although the topographical localization of this nerve is constant. In this report, we describe the histological analysis of anomalous course of the medial sural cutaneous nerve which descended through the gastrocnemius via a tunnel formed within the muscle and fascia. This anatomical curiosity are clinically important when evaluating sensory axonal loss in distal axonal neuropathies since sural nerve mononeuropathy is less likely to occur.

Las variaciones anatómicas en la formación del nervio sural son comunes, aunque la localización topográfica de este nervio es constante. En este reporte se describe el análisis histológico del nervio cutáneo sural medial de curso anómalo, que descendió a través de los músculos gastrognemios en un túnel formado en el músculo y la fascia. Esta curiosidad anatómica es de importancia clínica cuando se evalúa la pérdida sensitiva distal en neuropatías axonales, desde mononeuropatía del nervio sural a otras de menor frecuencia.

Formación del nervio sural en individuos chilenos / Sural nerve formation in Chilean individuals

La inervación cutánea de la región posterior de la pierna esta dada por el nervio cutáneo sural medial (NCSM), el nervio cutáneo sural lateral (NCSL), el nervio sural (NS) y el nervio safeno. Estos ramos son variables pudiendo los dos primeros, ser independientes o estar unidos y formar el nervio sural. Con el propósito de determinar la formación del nervio sural y los niveles de origen de los nervios NCSM y NCSDL, disecamos 12 piernas formolizadas, 7 izquierdas y 5 derechas, de individuos chilenos, adultos. El punto de origen y unión de los nervios NCSM y NCSL se localizó en relación a una línea transversal trazada entre los puntos más prominentes de los cóndilos femorales (LBE), así como una línea trazada entre los dos maléolos (LBM). La distancia entre ambas líneas fue en promedio 31,8 cm.; el punto de origen del NCSL se situó en promedio a 3,75 cm proximal a la LBE y el del NCSM a 2,23 cm proximal a la misma línea. En 7 muestras (58,3 por ciento) observamos unión de los dos ramos formando el NS ( en dos de ellas a través de un ramo comunicante fibular) y en las restantes se mantuvieron independientes. El punto de unión de los nervios referidos fue localizado proximal a la LBM. Los resultados obtenidos complementarán el conocimiento anatómico de la inervación sensitiva de la pierna.

The skin of the posterior region of the leg is supplied by the medial sural cutaneous (MSCN), lateral sural cutaneous (LSCN), sural (SN) and the safenous nerves. These nerves present variations where the first and second nerves can be independents or both join to form the sural nerve. The objective of this research was to determine the sural nerve formation and the origin level of the MSCN and LSCN. We dissected 12 legs fixed in formaldehyde 10 percent (7 of the left side and 5 of the right side), from of adult Chilean individuals. The origin and join points of the MSCN and LSCN nerves were localized in relation to horizontal line between the prominent points of the femoral condyles (BCL), so as a horizontal line between the two malleolus (BML), respectively. The distance between both lines was average 31.8 cm; the origin point of the LSCN was 3.75 cm proximal to BCL and the origin point of the MSCN was 2.23 cm proximal to this line. In 7 cases we observed both nerves forming the sural nerve (in two of them, by a fibular communicant branch) and in rest cases were independents. The joint point of the referred nerves was localized proximal to BML. These results are a contribution to the anatomic knowledge of the sensitive innervation of the leg.

Retalho sural para reconstrução do pé / Sural flap for reconstruction of the foot

Introdução: as perdas de substância localizadas no pé mostram-se bastante desafiadoras quanto a sua reconstrução. Os retalhos livres microcirúrgicos eram primeira escolha quando se necessitava de uma cobertura mais elaborada. Com a publicação de Masquelet e Col. (1992), abriu-se uma nova possibilidade de tratamento dessas lesões. Objetivo: mostrar que o retalho neurocutâneo sural constitui-se numa alternativa efetiva para o tratamento de lesões extensas no pé. Métodos: o retalho sural foi utilizado em 24 pacientes, no período de 1990 a 2006. Descreve-se a técnica de confecção deste retalho para cobrir lesões situadas no pé. Resultados: todos os defeitos foram corrigidos, com baixo índice de complicações. Discussão: Os retalhos microcirúrgicos, por muito tempo, foram a opção principal para o tratamento de lesões extensas localizadas no pé. Para a realização deste procedimento faz-se necessária a participação de equipe especializada e material especial. O retalho neurocutâneo sural substitui, em parte, os retalhos microcirúrgicos, com a vantagem de apresentar menor dificuldade técnica, confecção mais rápida, pequena morbidade e ser eficaz. Conclusão: o retalho neurocutâneo sural é eficiente na cobertura de lesões com perda de substância no pé e substitui, em muitos casos, o retalho microcirúrgico.

Background: the reconstructions related to loose of foot substance are challenging. The microsurgical flaps were the first choice when a more elaborated coverture was needed. With Masquelet e Col's publication (1992) a new possibility of treating those lesions was opened: the sural neurocutaneus flap. Objective: to show that the sural neurocutaneus flap is an effective alternative to treat extensive injuries on the foot. Methods: the sural neurocutaneus flap was used to cover the traumatic injuries on the foot of 24 patients, between the years of 1990 and 2006. This flap is made from the vascularization that follows the sural nerve and has become an excellent option for the treatment of lost of foot substance. Resultads: all the flaps were corrected with a low complication average.Discussion: the microsurgical flap asforalong time the main option when itcametotreating extensive injuries on the foot. The sural neurocutaneus flap replaces, partially, this flap, with the advantage of presenting a lower technical difficulty and also for being produced quicker, with small morbidity. Conclusions: the sural neurocutaneus flap is efficient in covering injuries with lost of foot substance.

Morphometric data of normal sural nerve in Thai adults.

Morphometry has an important role in the interpretation of sural nerve biopsies. It is used for early detection of structural abnormalities in peripheral neuropathies. This application requires a comparison with data of normal population. However, most data in the literature were of Western subjects with a small number of samples. In this study the authors reported the morphometric data of sural nerve harvested within 24 hours after death from 78 Thai subjects without known causes of neuropathy. The samples were transversely sectioned and analyzed for the number and area of fascicles, the total number of myelinated axons, myelinated fiber diameter; myelinated axon diameter, myelin sheath thickness, g ratio and myelinated axon density. Results were discordant in some measurement parameters compared to previous reports. These data are valuable for the early recognition of peripheral nerve diseases from biopsied sural nerve of Thai subjects.

The Relative Contributions of the Medial Sural and Peroneal Communicating Nerves to the Sural Nerve

The medial sural cutaneous nerve (MSCN) and peroneal communicating nerve (PCN) conjoin in the calf area to form the sural nerve (SN). In previous anatomic studies, there was unresolved debate as to the main contributor to the sural nerve, and the relative contributions of MSCN and PCN had not been studied. The purpose of this study is to determine their relative neurophysiologic contributions to the SN by nerve conduction study (NCS). A total of 47 healthy subjects (25 males and 22 females, mean age 29.6+/-10.4 yrs, range 20-59 yrs) participated in the study. This study employed the orthodromic nerve conduction technique: stimulation at the ankle and recording at the mid calf (SN); specifically, we preformed stimulation at the mid calf (MSCN, PCN) and recording at 14cm proximal to the middle of the popliteal fossa (MSCN) and fibular head (PCN). The onset and peak latencies (ms) were SN 2.3+/-0.2 and 3.0+/-0.2; MSCN 2.1+/-0.2 and 2.8+/-0.2; and PCN 2.1+/-0.2 and 2.8+/-0.2. The peak-to-peak amplitudes (micro) and areas (nVsec) of the SN, MSCN, and PCN were 9.7+/-3.9, 7.0+/-4.7, and 5.0+/-3.2; and 7.2+/-2.9, 5.7+/-3.4, and 4.0+/-2.4, respectively. The side-to-side difference was not statistically significant. The main contributor to the SN was found to be the MSCN. The relative contribution ratio of the MSCN to the PCN was 1.37:1 by amplitude and 1.42:1 by area. However, in 32.9% of the subjects, the contribution of the PCN was greater than that of the MSCN.

Anomalous course of the medial sural cutaneous nerve and its clinical implications

The sural nerve is formed by the union of the medial sural cutaneous nerve, which is a branch of the main trunk (the tibial nerve), and the common fibular communicating branch of the lateral sural cutaneous nerve, which is a branch of the common fibular nerve. Anatomical variations in the formation of the sural nerve are common, although the topographical localization of this nerve is constant. In this report, we describe three cases of an anomalous course of the medial sural cutaneous nerve which descended through the gastrocnemius via a tunnel formed within the muscle. Such anatomical variations of the sural nerve are clinically important when evaluating sensory axonal loss in distal axonal neuropathies since sural nerve mononeuropathy is less likely to occur.

Near nerve potential of sural nerve in leprosy

Na hanseníase, as fibras de pequeno calibre são acometidas antes que as fibras mais grossas, ocasião em que o estudo da condução torna-se anormal. Neste estudo, utilizou-se a técnica de registro com eletrodos justa-nervo com a finalidade de aumentar a precocidade e a acurácia diagnóstica, devido à sua capacidade de detectar potenciais oriundos de fibras com cerca de 3-6 mm. Contrário às nossas expectativas, o componente principal do potencial sensitivo do nervo sural foi anormal em todos os pacientes, enquanto a velocidade de condução mínima foi normal ou discretamente alterada em 3 pacientes. Além disso, os resultados são sugestivos de degeneração axonal e não mielinopatia, como seria esperado em uma doença que compromete inicialmente a bainha de mielina. Para um melhor entendimento da fisiologia e fisiopatologia, e para aumentar a precocidade diagnóstica, é fundamental estudar casos bem precoces e correlacionar os dados neurofisiológicos com a respectiva anatomia patológica.

Limits of variation of fiber distribution in the sural nerve of man

Although the sural nerve is the most extensively studied nerve in man, there is a dearth of data regarding the normal variations in the size-frequency distribution of axons in normal subjects; criteria for assessing the normality of a given individual are not available. Therefore, in everyday practice, the surgical pathologist may meet with difficulty in interpretit the biopsy of one particular individual, in whom the distribution is slightly different from the curves published. The object of this work is to detect the normal limits of variation in the distribution of diameters of muelinated and unmyelinated fibers in normal subjects and to establish the criteria that permit the calculated curves to be used in veryday clinical practice. Normal sural nerves of 19 patients were analyzed. Ages ranged between 18 months and 55 years. Morphometric analysis was performed with the Histoscan X automatic image processing analyzer, and , for statistical analysis, mixtures of lognormal distributions were fitted and tested with Pearson's statistics. Nerves of three diabetic patients were used for testing the method. They were clearly classified as abnormal. The curves, therefore, have been proven useful for everyday surgical pathology practice

Vasculite do tipo poliarterite nodosa na AIDS associada a polirradiculopatia pelo citomegalovírus / Nerve polyarteritis nodosa-like vasculitis in AIDS associated to cytomegalovirus polyradiculopathy

O presente trabalho teve por objetivo descrever um caso de polirradiculopatia por CMV associada a vasculite de nervo periférico. Foi realizada biópsia de nervo sural em uma mulher com AIDS que desenvolveu uma tetraparesia de rápido aparecimento além de disestesia, causada por polirradiculopatia por citomegalovírus (CMV). O estudo histopatológico da biópsia do nervo sural evidenciou uma vasculite mononuclear com necrose fibrinóide de parede arterial. Embora vasculite de nervo na AIDS seja rara e interpretada como resultado de distúrbios imunológicos devidos à infecçäo pelo HIV ou crioglobulinemia, e näo haja descriçäo de vasculite pelo CMV, nós sugerimos, baseados nos fatos apresentados, que no presente caso a vasculite possa ter sido devida à infecçäo pelo CMV

Anatomia cirugica do nervo sural / Surgical anatomy of the sural nerve

O nervo sural e comumente utilizado como enxerto nas reconstrucoes de nervos porque apresenta acesso facil e sequela minima, apos sua retirada. Apesar de apresentar constancia na sua localizacao topografica, as variacoes anatomicas do nervo sural sao frequentes. Assim, foram dissecadas 38 pernas em 19 cadaveres visando determinar o padrao de formacao do complexo nervo sural. Os dados obtidos foram divergentes da literatura, quando a frequencia de ocorrencia dos dois padroes classificamente conhecidos (Padrao I e II). Alem disso, tambem foi possivel identificar dois outros padroes (Padrao III e IV) de formacao do nervo sural, que ainda nao havia sido descrito previamente. O Padrao I, no qual o servo sural e proveniente da uniao do nervo cutaneo sural medial e do nervocomunicante poroneal, foi encontrado em 21 por cento dos casos. A frequencia na literatura e de 65,6 por cento a 80 por cento. O Padrao II, no qual o nervo sural origina-se a partir do nervo cutaneo sural medial com frequencia na literatura de 20 a 34,2 por cento, foi identificado em 52,6 por cento dos casos...

Estudo anatômico do nervo sural / Anatomical study of sural nerve

É apresentado um estudo anatômico do nervo sural, provavelmente a melhor fonte de nervo do corpo humano. Enfatizam-se o comprimento do nervo, o calibre, o padräo fascicular e a pequena seqüela deixada pela sua retirada. Estabeleceu-se, nos 38 membros inferiores dissecado, o padräo de formaçäo do nervo sural

Valor del bloqueo terapéutico de los nervios tibial posterior y sural en el tratamiento del espolón calcáneo / Value of therapeutical blockade of posterior tibial and sural nerves in the treatment of calcaneal spur

Se realiza una introducción explicando las características más importantes del síndrome del espolón calcáneo. Se presenta un breve resumen de la anatomía de los nervios tibial posterior y sural. Se describen las técnicas de bloqueo de los nervios tibial posterior y sural. Se muestran los resultados obtenidos en 14 pacientes remitidas a nuestro servicio por padecer de este síndrome doloroso y que fueron tratadas con bloqueos terapéuticos