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Ann Anat 191 (2009) 389—398

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RESEARCH ARTICLE

Microanatomical and immunohistochemical studyof the human radial nerve at the antecubital fossa

S. Chakravarthy Marxa,�, Pramod Kumarb, S. Dhalapathyc,Keerthana Prasadd, C. Anitha Marxe

aDepartment of Anatomy, Kasturba Medical College, Manipal, Karnataka 576104, IndiabDepartment of Plastic Surgery, Kasturba Medical College, Manipal, Karnataka 576104, IndiacDepartment of Endocrine Surgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGI), Lucknow,Uttar Pradesh, IndiadManipal Centre for Information Science, Manipal, Karnataka 576104, IndiaeDepartment of Computer Science, Manipal Institute of Technology, Manipal, Karnataka 576104, India

Received 26 February 2009; received in revised form 24 April 2009; accepted 27 April 2009

KEYWORDSRadial nerve;Fascicular pattern;Connective tissuesheaths;Morphometry;Aging;Sympathetic fiber

ee front matter & 2009aanat.2009.04.005

ing author. Tel.: +91 973ess: marxchakravarthy@

SummaryBackground: Poor prognosis of radial nerve repair in elderly patients may be due tochanges in intraneural anatomy with age. Also, chances of Complex Regional PainSyndrome-Type I (CRPS-I) following radial nerve injury are comparatively high. Thepresent study is to find the fascicular pattern of radial nerve (at antecubital fossa),microanatomic morphometric characteristics of its connective tissue componentsand changes with age and study of intraneural sympathetic fiber content.Methods: Twenty human (21–87 years) cadaveric radial nerves have been collectedfrom antecubital fossa and the study has been performed at magnifications (10� ,20� and 40� objective) after routine histological (hematoxylin & eosin stain)processing was done for morphometric analysis (total cross-sectional, fascicular andnon-fascicular area) and immunohistochemical (tyrosine hydroxylase) processing forsympathetic fibers.Results: The radial nerve is of a polyfascicular type with a grouped pattern of nervefascicular distribution. The number of fascicles range from 9 to 17, whereas thenumber of fascicles per square millimeter of a cross-sectional area is 1.95. In elderlycases, there is significant increase in total radial nerve cross-sectional area due to anincrease in its non-fascicular connective tissue area and excessive adipose tissuedeposition in interfascicular domains. The average sympathetic fiber area is0.046mm2 without definite relationship to age.Conclusion: There is an increase in total nerve cross-sectional area of the radialnerve in elderly cases. There is no relationship of sympathetic content to age. Our

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9867221.yahoo.co.in (S. Chakravarthy Marx).

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S. Chakravarthy Marx et al.390

study makes an attempt to build a normal data base for radial nerve which might behelpful during the application of diagnostic procedures.& 2009 Elsevier GmbH. All rights reserved.

Introduction

A cross-section of a nerve trunk has bothfascicular and non-fascicular components. Thenumber, size and distribution of fascicles vary overshort distances, even a few millimeters (Graifet al., 1991; Bendszuc et al., 2004; Korompiliaset al., 2006). The non-fascicular component iscomposed of connective tissue, adipose tissue,blood vessels, lymphatics with intercellular spacesand nervi nervorum (Sunderland, 1964, 1990;Weller and Cervo’s-Navarro, 1977). Thoroughknowledge of nerve fascicular and non-fascicularmorphology is necessary for the diagnostic applica-tion of ultrasound and computed tomography (CT)scan as well as for its successful surgical repair (Ikedaet al., 1996; Maravilla and Bowen, 1998; Bendszucet al., 2004).

The radial nerve (RN) is the largest peripheralnerve in the upper limb arising from the branchesof the posterior division of anterior nerve roots ofbrachial plexus. Radial nerve injuries can resultfrom complex humerus fractures, direct nervetrauma, gunshot wounds, compressive neuropa-thies, neuritis or (rarely) due to malignant tumorformation and surgical complications (Rodrıguez-Gomez, 1998; Rosenbaum, 1999; Cognet et al.,2002; Lowe et al., 2002; Thomsen and Dahlin, 2007;Lee et al., 2008; Tsai and Steinberg, 2008). Themanagement of these nerve injuries depends upona thorough understanding of peripheral nerveanatomy.

Review of literature

The biomechanical characteristics and protec-tion against stretching of peripheral nerves are theresult of their anatomic structure (connectivetissue sheath) (Barkmeier and Luschei, 2000;Phillips et al., 2004 ; Vivo et al., 2004; Topp andBoyd, 2006). Various studies have shown that theamount of connective tissue varies in differentperipheral nerves, even in different parts of thesame nerve (Barkmeier and Luschei, 2000; Tillettet al., 2004).

The studies on total peripheral nerve cross-sections of human digital nerves, great auricularnerve or the inferior alvelolar nerve did notmention changes in the non-fascicular area with

age (Svane et al., 1986; Rayatt et al., 1998;Goldberg et al., 2007). In the available literature,there are only data for this parameter on humansural nerve, rat tibial nerve, rat sciatic nerve, dogtrochlear nerve, human facial nerve and humansciatic nerve (Jacobs and Love, 1985; Ceballoset al., 1999; Azcoitia et al., 2003; Vivo et al., 2004;Captier et al., 2005; Sladjana et al., 2008). Authorsof late have found that there is a statisticallyinsignificant increase in the total nerve cross-sectional area but a higher percentage of con-nective tissue in relation to nervous tissue. It playsan important role in predicting prognosis afternerve repair (Bonnel et al., 1982; Sladjana et al.,2008). Also, after peripheral nerve injuries, com-plications such as Complex Regional Pain Syndrome-Type I are yet to be fully understood.

Poor prognosis of radial nerve repair in elderlypatients may be due to the changes in intraneuralanatomy with age. The chance of CRPS-I followingradial nerve injury is comparatively high.

In this study, we observed the cross-sectionalanatomy and microanatomy of the radial nerve atthe antecubital fossa in relation to age, and thechanges in fascicular, non-fascicular componentsand the sympathetic fiber content.

Materials and methods

Anatomical dissection

Twenty fresh human (12 male and 8 female)cadaveric radial nerves were collected for thestudy from the antecubital fossae. The cadavers’age ranged from 21 to 87 years, the mean age andstandard deviation (SD) was found to be 50.5 and21.47. These cadavers were donated to theDepartment of Anatomy, Kasturba Medical College,Manipal, India. During their lifetime, these indivi-duals had neither neurologic nor metabolic dis-orders, nor any other kind of radial nerve damage.First, the cubital fossa roof was dissected and itscontents were identified.

Tissue sampling

Two centimeters of radial nerve tissue wasobtained just above the lateral epicondyle byreflecting the brachialis and brachioradialis muscles

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Figure 1. Anterior view of the right antecubital fossashows the site of radial nerve sample collection. SRN –

superficial branch of the radial nerve and DRN – deepbranch of the radial nerve.

Figure 2. Photomicrograph of the radial nerve at theantecubital fossa stained with hematoxylin and eosin(H&E) shows fascicular and non-fascicular connectivetissue pattern during aging process. (A) Radial nerve of a87-year-old individual containing a large amount ofadipose tissue (fat) in the epifascicular and interfasci-cular connective tissue region (100� ); (B) shows theselected boxed area of Figure 1(A) in (200� ); (C) showsthe selected boxed area of Figure 1(A) in (400� ); Figures1(A)–(C) show the increased amount of adipose tissue innon-fascicular region of the radial nerve in elderlyindividual. (D) radial nerve of a 25-year-old individualcontaining a clearly lesser amount of adipose tissue (fat)in the epifascicular and interfascicular connective tissueregion (100� ); (E) shows the selected boxed area ofFigure 1(A) in (200� ); (F) – shows the selected boxedarea of Figure 1(A) in (400� ); Figures 1(D)–(F) show theclearly lesser amount of adipose tissue in non-fascicularregion of the radial nerve in the young individual. Scalebar ¼ 100 mm valid for all the images. Arrows indicate theamount of adipose tissue (fat) present in non-fasciculararea.

Microanatomy of human radial nerve 391

(Figure 1). These nerve tissues were collectedwithin 6–10 h after death.

Tissue processing

The obtained RN tissues were fixed immediatelywith 4% paraformaldehyde solution and embeddedin paraffin. For frozen section immunohistochem-ical studies, pieces of fixed nerves were treatedwith 30% sucrose solution for 24 h, and then storedat �70 1C. Nerve tissue was processed for histolo-gical (paraffin sections) and immunohistochemicalstaining (frozen sections) in the Anatomy depart-ment, Kasturba Medical College, Manipal, India.

Histological hematoxylin and eosin (H&E)staining

Six micron thick paraffin sections were placedon gelatin-coated slides. Selected sections wereprocessed for eosin and hematoxylin staining

(Figure 2). Nerve sections were hydrated in gradedalcohol and brought to distilled water. Thesesections were stained with hematoxylin stain for2min and eosin stain for 30 s. Then the sectionswere washed with distilled water, dehydrated in agraded series of alcohol, cleared with xylene andmounted with coverslips. Finally, H and E stainedsections were observed under binocular lightmicroscope and photographed with Motic liveimage programme (Version 2.0, Motic China GroupCo., Ltd.) for morphometric analysis (Figure 3).

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Figure 3. The results of the automated measurement ofthe individual fascicular area shown as white in (A) andthe non-fascicular area shown as blue in (B) of a singleradial nerve were calculated by the image analysissoftware in (40� ). In (40� ) magnification, 1mm2

fascicular or non-fascicular area ¼ approx. 450� 450pixels. Scale bar ¼ 100 mm. (For interpretation of thereferences to color in this figure legend, the reader isreferred to the web version of this article.)

Figure 4. (A) photomicrograph shows a single fascicle ofthe radial nerve at antecubital fossa that was stainedwith tyrosine hydroxylase (TH) immunohistochemistry(100� ). (B) shows the result of the automated measure-

S. Chakravarthy Marx et al.392

Immunohistochemical (IHC) staining forsympathetic fibers

Stored nerve tissues were processed for cryostatsectioning. Seven micron cryostat sections weretaken on polylysine-coated slides. Randomly se-lected sections were processed for immunohisto-chemistry (Auplish and Hall, 1998; Balogh et al.,1999, 2002).

ment of sympathetic fiber area (white) of the samefascicle that was calculated by the image analysissoftware (100� ). (C) shows the selected area of Figure7(A) under higher magnification (400� ) with arrowspointing to sympathetic fibers. In (100� ) magnification,1mm2 sympathetic fibers area ¼ approx. 712� 712 pix-els. Scale bar ¼ 100 mm valid for all the images. (Forinterpretation of the references to color in this figurelegend, the reader is referred to the web version of thisarticle.)

Fund details

The fund for the study was collected fromKasturba Medical College, Manipal, India. Theantibodies and chemicals used were purchasedfrom Sigma-Aldrich Chemicals Private Limited,Bangalore, India.

Immunohistochemical procedure

At first, the sections were washed in phosphatebuffer saline (PBS), treated with normal goat serumsolution for 30min to block the non-specific bindingof immunoglobulin. Then the sections were incu-bated overnight at 4 1C in a primary antibody(rabbit anti-tyrosine hydroxylase, 1:1000). Thenext day, the sections were incubated in peroxidaseblocking solution for 10min to block the endogen-ous peroxidase activity. Then they were treatedwith secondary antibody (goat anti-rabbit IgG) andtertiary antibody (HRP-Streptavidin) for 30min andthe colour was developed by treating the sectionswith diaminobenzidine (DAB) for 5–10min. Finally,the immuno-stained sympathetic fibers were iden-tified under the light microscope. Sections werewashed in distilled water briefly, dehydrated ingraded alcohol, cleared with xylene and mountedwith coverslips. All the stained sections were

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Microanatomy of human radial nerve 393

photographed with Motic live image programme formorphometric analysis (Figure 4).

A normal Wister rat adrenal gland, sciatic nerveand sympathetic plexus of the carotid artery wereused as control tissues. For negative controls, theprimary antibody was replaced by a non-immunerabbit serum or the secondary antibody wasomitted.

Morphometric analysis

The morphometric analysis was performed underthe light microscope with projection screen with amagnification of 100� , 200� and 400� . An in-house developed image analysis software namedTissue Quant (TQ, Version 1.0) was used for theautomated measurement of total nerve cross-sectional area, fascicular area, non-fascicular areaand sympathetic fiber area.

The first part of the study (hematoxylin and eosinstaining) included the estimation of the totalnumber of fascicles (total Nf) present in the totalRN nerve cross-sectional area, the measurement of

Table 1. Human radial nerve (RN) morphometric paramete

Age Cross-sectional area in mm2

Total Nf Total (Asc) Fascicular(Af)

Nonfasc(Ano

21 9 5.63 2.14 3.4925 10 5.78 3.11 2.6729 13 5.72 2.23 3.4929 11 6.96 3.15 3.8131 14 6.38 1.98 4.4034 15 6.35 2.15 4.2036 12 6.50 2.96 3.5439 17 7.72 2.56 4.7142 13 6.66 2.06 4.6143 11 6.26 2.46 3.8047 13 6.90 2.58 4.3248 14 8.03 2.50 5.5352 11 7.91 3.11 4.8061 12 6.53 2.32 4.2268 14 6.98 2.25 4.7474 11 6.67 3.22 3.4578 11 8.48 3.05 5.4282 12 8.68 2.84 5.8584 15 9.52 2.97 6.5587 9 9.65 2.73 6.92

Total Nf – total number of fascicles per radial nerve (RN), Asc – totafascicular connective tissue sheath area, Asym – sympathetic fibersfascicular area), Nf/mm2 – number of fascicles per mm2 (total numbThe total cross-sectional area (Asc) increases with increase in age. Thall cases. Nf/mm2 – number of fascicles per mm2 ranges from 1 to 3

total radial nerve cross-sectional area (Asc),individual and total fascicular area (Af) and non-fascicular area (Anonf). The number of radial nervefascicles (Nf) per square millimeter was obtainedby total number of fascicles in RN divided by totalcross-sectional area of the RN (Nf ¼ Total Nf/Asc).The second part of the study (tyrosine hydroxylase– immunohistochemistry) included the counting ofsympathetic fibers and the measurement of thearea occupied by the sympathetic fibers.

Statistical analysis

Data was analyzed using ‘‘Graph pad instat’’(Version 3.06, Graph pad Software Inc.) and ‘‘SPSS’’(Version 11.5, The Predictive Analytics Company)statistical packages. Mutual correlation betweenall the RN morphometric parameters (total RNcross-section, number of fascicles, total fasciculararea, non-fascicular connective tissue area, size ofthe fascicles and sympathetic fibers area) wascarried out. Each data was analyzed for range,mean and standard mean of error (SEM) .

rs absolute values.

-icularnf)

Sym. area(Asym)

Sym. index(SI)

Nf/mm2

0.042 0.020 20.029 0.009 20.054 0.024 20.064 0.020 20.073 0.037 20.056 0.026 30.026 0.009 20.032 0.012 20.035 0.017 20.035 0.014 20.039 0.015 20.058 0.023 20.072 0.023 20.027 0.012 20.047 0.021 20.051 0.016 20.043 0.014 10.035 0.012 20.056 0.019 20.046 0.017 1

l (whole) cross-sectional area, Af – fascicular area, Anonf – non-area, SI – sympathetic index (sympathetic fibers area divided byer of fascicles divided by total cross-sectional area).e non-fascicular area (Anonf) is higher than the fascicular area in. There is no significant change in sympathetic area.

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Results

The study of the RN cross-section showed thedifference in number, size, shape and distributionof the fascicles. In all cases, RN fascicular patternbelonged to the polyfascicular type with clusteredfasciculi. It also showed the difference in theamount of connective and adipose tissues in non-fascicular area.

The RN’s total cross-sectional area, fasciculararea, non-fascicular connective area and sympa-thetic fiber area (Auplish and Hall, 1998; Baloghet al., 1999, 2002) were obtained during morpho-metric analysis (Tables 1 and 2) (Figures 5–7).

The number of fascicles in RN ranged from 9 to 17(12.3570.47, mean7SEM). The total nerve cross-sectional area ranged from 5.63 to 9.65mm2

(7.1470.27). The number of fascicles per squaremillimeter of cross-sectional area ranged from1 to 3 f/mm2 (1.9570.09). The fascicular area

Table 2. Descriptive statistics of all evaluated cases RN m

Parameter Area in mm2

Total Nf Asc Af

Mean 12.35 7.14 2.62Std. error. of mean (SEM) 0.47 0.27 0.09LCL (95%) 11.37 6.59 2.43UCL (95%) 13.32 7.70 2.81Sample size (N) 20 20 20

Total Nf – total number of fascicles per radial nerve (RN), Asc – totafascicular connective tissue sheath area, Asym – sympathetic fibersfascicular area), Nf/mm2 – number of fascicles per mm2 (total numbLCL – lower limit of confidence interval, UCL – upper limit of confid

Figure 5. Total radial nerve cross-sectional area (Asc) and nlines showing a linear increase in these morphometric paramfascicular connective tissue and adipose tissue in elderly cas

ranged from 1.98 to 3.22mm2 (2.6270.09). Thenon-fascicular connective tissue area ranged from2.67 to 6.92mm2 (4.5370.24). The sympatheticfiber area ranged from 0.026 to 0.073mm2

(0.04670.003) (Tables 1 and 2).RN’s non-fascicular connective tissue area and

fascicular area were well developed in all agecases. In elderly cases, the RN non-fascicularconnective tissue area was predominantly in-creased compared to fascicular area (Figure 5)due to the increased amount of adipose tissue (fat)deposition in it (Figure 2A–C). Finally, the totalnerve cross-sectional area was found to be in-creased in the elderly cases. Whereas in theyounger cases, there was a very much loweramount of adipose tissues (fat) in the non-fasci-cular area and there was not much difference in thetotal nerve cross-sectional area (Figure 2D–F).

Also, the sizes of the individual fascicles of theRN that ranged from 0.01 to 0.92mm2 (0.2270.01)

orphometric parameters.

Anonf Fsize Nf/mm2 Asym SI

4.53 0.22 1.95 0.05 0.0180.24 0.01 0.09 0.003 0.0014.02 0.19 1.77 0.04 0.015.04 0.24 2.13 0.05 0.0220 247 20 20 20

l (whole) cross-sectional area, Af – fascicular area, Anonf – non-area, SI – sympathetic index (sympathetic fibers area divided byer of fascicles divided by total cross-sectional area).ence interval.

on-fascicular area (Anonf) bar charts together with trendeters during the aging process. The increase in the non-es leads to an increase in total cross-sectional area.

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Figure 6. Radial nerve fascicular area (Af) and non-fascicular area (Anonf) bar charts together with trend lines showingthe linear increase in non-fascicular morphometric parameters due to adipose tissue deposits and constant fascicularmorphometric parameter during the aging process.

Figure 7. The graph shows the radial nerve mean of totalcross-sectional area (1 ¼ Asc), fascicular area (2 ¼ Af),non-fascicular area (3 ¼ Anonf), fascicular size(4 ¼ Fsize) and number of fascicles per square millimeter(5 ¼ Nf/mm2) for comparison. Each bar representsmean+SEM (standard error of mean). There is increasednon-fascicular connective tissue and adipose tissuecausing an increase in the total cross-sectional area ofthe radial nerve at the antecubital fossa.

Figure 8. XY (scatter) chart shows variety of fasciclessize, which were present in all 20 radial nerves ofdifferent age groups; 95% of the fascicles sizes was below0.6mm2.

Figure 9. The graph contains the mean of fascicular size(Fsize), sympathetic fiber area (Asym) and sympatheticindex (SI) and compares the area occupied by thesympathetic fibers in a fascicle. Each bar representsmean+SEM (standard error of mean).

Microanatomy of human radial nerve 395

was measured. In the majority of instances, thefascicular size (95%) was below 0.6mm2 (Table 2)(Figure 8).

The ratio between the sympathetic fiber areaand the total fascicular area of RN ranged from0.009 to 0.026mm2 (0.01870.001). For our con-venience, the ratio was termed as sympatheticindex of the nerve (SI) (SI ¼ Asym/Af) (Tables 1and 2) (Figure 9). These values might be used forthe sympathetic nerve-related problems.

Discussion

The morphologists focused on the fascicularisa-tion of the peripheral nerves during the earlytwentieth century. Soon after, the neurosurgeonsand the orthopedists who usually perform micro-surgical interventions on peripheral nerves realizedits significance in the diagnosis and treatment of

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S. Chakravarthy Marx et al.396

the nerve lesions (Goldberg et al., 2007). Hence,they started implementing fascicularisation, as arecovery of nerve lesions mainly focusing on thenerve fibers becomes critical especially in theelderly due to alterations with increase in age.We focus on the connective tissue that undergoeschange during the aging process, which is similar tothat of the nerve fiber.

We have analyzed the cross-sectional anatomyand microanatomy of the radial nerve at theantecubital fossa with regard to changes in fasci-cular and non-fascicular components during theaging process and the area occupied by sympa-thetic fibers, respectively.

Fascicular component

RN at antecubital fossa is observed to have apolyfascicular pattern in all cases. The number offascicles ranged from 9 to 17 (mean 12.35). Thenumber of RN fascicles per square millimeterranged from 1 to 3 f/mm2 (mean 1.95). Ninety fivepercent of the RN fascicular size ranged between0.01 and 0.6mm2 (Figure 6). We could not trace thedata for the same parameter in the availableliterature for comparison.

Non-fascicular components

RN’s non-fascicular connective tissue was welldeveloped in all cases. In elderly cases, the RN non-fascicular connective tissue area was predomi-nantly increased compared to fascicular area dueto the increased amount of adipose tissue (fat)deposition in it. Finally, the total nerve cross-sectional area was found to be increased in elderlycases. In younger cases, there was less adiposetissue in the non-fascicular area and no differencein the total nerve cross-sectional area. This may bethe cause of poor outcome following nerve repair inthe elderly cases.

Total cross-sectional area

During our study, we found the RN total cross-sectional area was maximally (9.65mm2) in an 87-year-old and minimally (5.63mm2) in a 21-year-oldcases. There was an increase in the non-fascicularconnective tissue and adipose tissue in elderly casescausing increase in the total cross-sectional area.

Sympathetic fiber area

CRPS-I is a complication in radial nerve injuryinvolving sympathetic system. We identified

the sympathetic fiber area of the radial nerve(Figure 4) in antecubital fossa. To correlate andcompare sympathetic fiber-related problems fol-lowing peripheral nerve injuries at different sites,we assigned sympathetic index to radial nerve atantecubital fossa by sympathetic fiber area (Asym)divided by the total fascicular area (Af) of the RN(SI ¼ Asym/Af). There are limited studies whichquantify sympathetic fiber content in the upperlimb (Morgan et al., 1983; Auplish and Hall, 1998;Balogh et al., 1999, 2002). We did not find data onthe same parameter in the available literature forcomparison. There is no significant change in thesympathetic nerve fiber area with age.

Limitations of the study

To carry out this study, we took samples onlyfrom the donated bodies of the Anatomy depart-ment, Kasturba medical college, Manipal, Indiaduring the daytime. Also, the samples werecollected within 6–10 h of death to avoid thedegradation of tyrosine hydroxylase enzyme forimmunohistochemistry. This study has been done onthe anatomy of the radial nerve at antecubitalfossa in 20 individuals. The study represents Indianpopulation, which differs in physical build from thewest. The data in the available literature studywere carried out by ultrasonography in UnitedStates of America (USA) and United Kingdom (UK).

Clinical importance

Knowledge about nerve fascicular morphology isnecessary for the diagnostic application of ultra-sound and CT as well as for its successful surgicalrepair (Ikeda et al., 1996; Maravilla and Bowen,1998; Bendszuc et al., 2004).

It has become clear that radial nerve conditionssuch as entrapment, hereditary neuropathies,acquired neuropathies, trauma, partial or fullnerve transections and nerve tumors result in anincrease radial nerve cross-sectional fascicularand/or non-fascicular area.

Our study makes an attempt to build normal database for radial nerve at antecubital fossa. This datacan be extrapolated for clinical use. Any discre-pancy in anatomical normal value and on imageanalysis may help the clinician to diagnose parti-cular nerve problems.

Ninety five percent of the RN fascicular size atantecubital fossa was found to be below 0.6mm2.This additional information can be used by thesurgeons to carry out their nerve repair procedure.

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Microanatomy of human radial nerve 397

Larger amount of adipose tissue in interfasciculararea of elderly cases makes microsurgical repara-tion of injured radial nerve more difficult and leadsto poor outcome.

Sympathetic index might help to diagnose/pre-dict the sympathetic system-related problem CRPS-I in the area of distribution of the radial nerve.

Three reports (Phillips et al., 2004; Foxall et al.,2007; Cartwright et al., 2008) have discussed thecross-sectional area of the radial nerve at ante-cubital fossa by ultrasonography showing3.1–9.3mm2 in healthy individuals and our studyvalue 7.1mm2 is comparable to these.

Our study contributes to the knowledge of RN’snormal fascicular pattern, size, area and non-fascicular (connective) tissue area arrangementand sympathetic fiber area in relation to changewith advancement of age.

Conclusions

Better knowledge of RN’s normal fascicularpattern and connective tissue arrangement, sym-pathetic fiber area as well as their changes duringthe aging process might be helpful during theapplication of diagnostic procedures. Our studymakes an attempt to create a normal data base forradial nerve at the antecubital fossa.

Acknowledgements

The authors thank M.S. Rao, M.R. Kumar, M.Biswabina Ray , Department of Anatomy, KasturbaMedical College, Manipal, Karnataka, India for theirvaluable suggestions and guidance.

Authors’ contribution

�

Study design by S. Chakravarthy Marx, P.Kumar � Data collection by S. Chakravarthy Marx � Statistical analysis by S. Chakravarthy Marx � Data interpretation by S. Chakravarthy Marx, P.

Kumar, S. Dhalapathy, P. Keerthana, C. Anitha Marx

� Manuscript preparation by S. Chakravarthy Marx,

S. Dhalapathy

� Literature search by S. Chakravarthy Marx, C.

Anitha Marx

� Funds collection by S. Chakravarthy Marx, P. Kumar.

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