internal topography

8
rk. )2, the ~in the -.l[S. 27, Copyrighl 1986 by The Journal of Bone and Joint Surgery, Incorporated Anatomical Basis for Repair of Ulnar and Median Nerves in the Distal Part of the Forearm by Group Fascicular Suture and Nerve-Grafting *t* BY JIMMY A. CHOW§, LIEUTENANT COLONEL, MEDICAL CORPS, UNITED STATES ARMY, ALLEN L. VAN BEEK, M.D.§, Z. JOHN BILOS, M.D.§, WASHINGTON, DAVID L. MEYER§, LIEUTENANT COLONEL, MEDICAL CORPS, UNITED STATES ARMY, AND MARTHA C. JOHNSON, PH.D.§, WASHINGTON, D.C. From Walter ReedArmy Medical Center, Washington, D.C., Uni~brmed Services University School of Medicine,Bethesda, Maryland, and Cook County Hospitaland Hektoen Institute of Medical Research, Chicago, Illinois ABSTRACT: The topography of the intraneural fas- cicular groups must be understood if the treatment of acute lacerations of the major nerves in the forearm is to be successful. Most lacerations in the upper extremity occur at the wrist and in the distal half of the forearm. With microsurgical longitudinal dissections and serial sections, we studied the intraneural topography of the fascicular groups of the median and ulnar nerves utiliz- ing forty-five fresh frozen or refrigerated specimens. We devised a new technique of light photography to dem- onstrate the distinct boundaries of the fascicular groups. The intraneural fascicular groups provide the anatom- ical basis for the recommended surgical techniques of group fascicular repair and nerve-grafting. In 1945, Sunderland reported his classic study, "The Intraneural Topography of the Radial, Median and Ulnar Nerves"5, and in 1968 his book Nerves and Nerve Injuries 6 was published. Since then, his description of the intraneural fascicular pattern has been widely quoted and has been confirmed by the studies of Jabaley et al. and Williams. For our purposes, two points may be drawn from Sun- derland’s reports. I. The funicular pattern in both the ulnar and median nerves is continually modified along the length of each nerve by repeated divisions, anastomoses, and changes in the rel- ative positions of the funiculi. The changes in position of individual funiculi may take place within a short expanse of the nerve, often in a segment of 2.5 millimeters or less. 2. The funiculi (also called fascicles or bundles) ar- range themselves in definite groups that are usually iden- tifiable along the course of the nerve for distances of several centimeters, especially in the distal portions of the two * Thisarticle was accepted for publication prior to July I, 1985. No conflict-of-interest statement was requested from the authors. + The opinions or asse,--r,i;.’,~s coa~ained herein are the private views nerves. Sunderland reported that the bundles in the branches of each nerve course as separate and distinct groups within the nerve, and despite the changing patterns of the individual funiculi in cross section, the bundle groups, during their course in the nerve, are individually identifiable for variable, and often considerable, distances above the site of branch- ing. Many cIinicians have cited our first point to support claims that a precise anatomical realignment of fascicles in the~ repair of lacerated peripheral nerves is impossible. Our second point generally has been overlooked, as it relates to surgical treatment. The present study was prompted by clinical observa- tions by the principal one of us (J. A. C.) made at the Cook County Hospital between July I978 and June 1979. Of fifty- six cases of laceration of the major peripheral nerves of the .upper extremity, forty-one were lacerations of the median or ulnar nerve, or both, at the wrist or in the distal half of the forearm. These observations emphasized the significance of in- traneural fascicular group topography in the tte-atment of acute lacerations of the major nerves at the wrist and distal half of the forearm. Also, the fascicular group arrangement is more constant distally in the major nerves of the upper and lower extremities. We decided to attempt to reconfirm Sunderland’s ob- servations on the intraneural topography of the median and ulnar nerves, with special attention to the fascicular groups, and to amplify his studies. Our purpose was to investigate the anatomical feasibility of suturing the groups of fascicles individually. Materials and Methods We used forty-five fresh refrigerated or fresh frozen specimens of the upper extremity, and in seventeen speci- mens we did a microsurgical longitudinal dissection of the (’::,.:i:’:.,.!ar groups o;: ’&~ media~ and ~ir<u" ,~rve~: We traced

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Page 1: Internal Topography

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Copyrighl 1986 by The Journal of Bone and Joint Surgery, Incorporated

Anatomical Basis for Repair of Ulnar and Median Nervesin the Distal Part of the Forearm

by Group Fascicular Suture and Nerve-Grafting*t*

BY JIMMY A. CHOW§, LIEUTENANT COLONEL, MEDICAL CORPS, UNITED STATES ARMY, ALLEN L. VAN BEEK, M.D.§,

Z. JOHN BILOS, M.D.§, WASHINGTON, DAVID L. MEYER§, LIEUTENANT COLONEL, MEDICAL CORPS, UNITED STATES ARMY,

AND MARTHA C. JOHNSON, PH.D.§, WASHINGTON, D.C.

From Walter Reed Army Medical Center, Washington, D.C., Uni~brmed Services University School of Medicine, Bethesda, Maryland, andCook County Hospital and Hektoen Institute of Medical Research, Chicago, Illinois

ABSTRACT: The topography of the intraneural fas-cicular groups must be understood if the treatment ofacute lacerations of the major nerves in the forearm isto be successful. Most lacerations in the upper extremity

occur at the wrist and in the distal half of the forearm.With microsurgical longitudinal dissections and serialsections, we studied the intraneural topography of thefascicular groups of the median and ulnar nerves utiliz-ing forty-five fresh frozen or refrigerated specimens. Wedevised a new technique of light photography to dem-onstrate the distinct boundaries of the fascicular groups.The intraneural fascicular groups provide the anatom-ical basis for the recommended surgical techniques ofgroup fascicular repair and nerve-grafting.

In 1945, Sunderland reported his classic study, "TheIntraneural Topography of the Radial, Median and UlnarNerves"5, and in 1968 his book Nerves and Nerve Injuries6

was published. Since then, his description of the intraneuralfascicular pattern has been widely quoted and has beenconfirmed by the studies of Jabaley et al. and Williams.

For our purposes, two points may be drawn from Sun-derland’s reports.

I. The funicular pattern in both the ulnar and mediannerves is continually modified along the length of each nerveby repeated divisions, anastomoses, and changes in the rel-

ative positions of the funiculi. The changes in position ofindividual funiculi may take place within a short expanseof the nerve, often in a segment of 2.5 millimeters or less.

2. The funiculi (also called fascicles or bundles) ar-range themselves in definite groups that are usually iden-tifiable along the course of the nerve for distances of several

centimeters, especially in the distal portions of the two

* This article was accepted for publication prior to July I, 1985. Noconflict-of-interest statement was requested from the authors.

+ The opinions or asse,--r,i;.’,~s coa~ained herein are the private views

nerves. Sunderland reported that the bundles in the branchesof each nerve course as separate and distinct groups withinthe nerve, and despite the changing patterns of the individualfuniculi in cross section, the bundle groups, during theircourse in the nerve, are individually identifiable for variable,and often considerable, distances above the site of branch-ing.

Many cIinicians have cited our first point to supportclaims that a precise anatomical realignment of fascicles inthe~ repair of lacerated peripheral nerves is impossible. Oursecond point generally has been overlooked, as it relates tosurgical treatment.

The present study was prompted by clinical observa-tions by the principal one of us (J. A. C.) made at the CookCounty Hospital between July I978 and June 1979. Of fifty-six cases of laceration of the major peripheral nerves of the.upper extremity, forty-one were lacerations of the medianor ulnar nerve, or both, at the wrist or in the distal half ofthe forearm.

These observations emphasized the significance of in-traneural fascicular group topography in the tte-atment ofacute lacerations of the major nerves at the wrist and distalhalf of the forearm. Also, the fascicular group arrangementis more constant distally in the major nerves of the upperand lower extremities.

We decided to attempt to reconfirm Sunderland’s ob-servations on the intraneural topography of the median andulnar nerves, with special attention to the fascicular groups,and to amplify his studies. Our purpose was to investigatethe anatomical feasibility of suturing the groups of fasciclesindividually.

Materials and Methods

We used forty-five fresh refrigerated or fresh frozenspecimens of the upper extremity, and in seventeen speci-mens we did a microsurgical longitudinal dissection of the(’::,.:i:’:.,.!ar groups o;: ’&~ media~ and ~ir<u" ,~rve~: We traced

Page 2: Internal Topography

274J. A, CHOW ET AL.

ULNAR

15MM

DORSAL

F~, 1-AFigs. I-A through l-D: Histological sections of the left ulnar nerve, one centimeter apart (hematoxyii~ and eosin, × 10),Fig. l-A: At a level fifteen millimeters proximal to the radial styloid process.

of the median and ulnar nerves in the proximaI part of theforearm were followed in the proximal direction, utilizinga similar microsurgical dissection technique, tn ten speci-mens we made a series of sections at five-millimeter inter-

vals and studied them by a method similar to that describedby Sunderland~. We used hematoxylin and eosin and Mas-son trichrome stains. Special attention was directed to thegroup fascicular patterns of the median and ulnar nerves

Page 3: Internal Topography

AIqAT~3~6~C-AL BASIS FOR REPAIR OF ULNAR AND MEDIAN NERVEg 275

FI~,

Th(rty-fi,~e millimeters proximal to the raOi~l s~yloid process.

(Figs. t-A through I-D and 5), This empt~asis was different~:rom those of previously published anatomical stugies,which focused their attention on the individual fascicles of~!~e nerves.

We also devised a new pt~otographic technique to studya series of consecutive segments of the median and ulnarnerves in sixteen specimens (Pigs. 2-A and 2-B). The los-titular group topography of tl-te median and alaar nerveswas studied in two specimens utilizing a series of sections,from the edge of the palm to tt~e proximal part of the arm,by scanning electron microscopy. The technique was de-

scribed by Van Beck etal, -~ in. 1979 (Fig. 3).In, addition to the data obtainefi from t~e,~e fort~-fw~

fresh specimens, additional information was obtained fromdissection of sixty-si~ f~rmalin-fixed specimens f~m ca-davera to determine the locations and c~urses of the motorfascic~lar groups of the ulnar nerve at the wrist and in thedistal part of the forearm.

Results

Ulnar Nerve

The ulnar nerve gives rise to three terminal branc/Tes

Page 4: Internal Topography

276 J. A. CHOW ET AL.

FIG. 2-AFigs. 2-A and 2-B: Conventional photographs of cross-sectional surfaces of segments of the left ulnar nerve made with a camera that had a bellows

attachment (x 5).Fig. 2-A: Fifty millimeters proximal to the radial styloid process.

at the level of the proximal edge of the palm-- one muscularand two cutaneous (Fig. 4). The first is a branch that suppliesthe hypothenar muscles and interosseus muscles. One cu-taneous branch proceeds to the fourth web space as thecommon digital nerve, while the other supplies the hypoth-

enar skin and the ulnar side of the little finger. These threebranches can be followed proximally as three distinct fas-cicular groups for fifty millimeters from the radial styloidprocess (Figs. 1-A through l-D). The two sensory groupsmerge at that level. From the fifty-millimeter to the ninety-

frown ~he sensor3’ fascicular groui~ ~S !.

Page 5: Internal Topography

ANATOMICAL BASIS FOR REPAIR OF ULNAR AND MEDIAN NERVES 277

hreefas -,loid~upstety-

150MM

ULNAR

FIG. 3Scanning electron micrograph of the left ulnar nerve, 150 millimeters proximal to the radial styloid process. Note the intraneural epineurium (arrows)

and the fascicular group from the dorsal cutaneous branch located at the ulnar portion of the nerve.

millimeter level, the merged sensory and the motor fasciclescan be identified as two distinct fascicular groups separatedby a firm condensation of connective tissues (the intraneuralepineurium) (Figs. 2-A and 2-B). At the ninety-millimeterlevel, these two groups merge. The motor fascicular groupmay therefore be identified as a distinct entity from the tip

of the radial styloid process to a point ninety millimetersproximal to the palm. In all but two of the 111 specimensthat Were studied, the motor fascicular group of the ulnarnerve at the distal part of the forearm was located at theulnar-dorsal position or central dorsal position. In the ex-ceptional two specimens, it was located at the radial-dorsal

nerve (left forearm).

’.GERY VOL. 68-A, NO. 2. FEBRUARY 1986

Page 6: Internal Topography

278 J.A. CHOW ET AL.

RADIAL

20MM DORSAL

F~G. 5

Histological section of the right median nerve at a level twenty millimeters proximal to the radial styloid process. A indicates the radially locatedcombined motor and sensory group. The motor fascicles to the thenar muscles are on the volar aspect of this group. B and C are the sensory fasciculargroups from the common digital nerves of the second and third web spaces, respectively (hematoxylin and eosin, x 10).

position. At the level of the distal third of the forearm, themotor fascicular group constituted 30 to 35 per cent of thetotal fascicular cross-sectional area of the ulnar nerve.

The dorsal cutaneous branch is separate from the maintrunk of the ulnar nerve at, and distal to, the junction of themiddle and distal thirds of the forearm (eighty to ninetymillimeters from the palm). It was followed proximally asa separate fascicular group, running side by side with thecombined fascicular group from the three terminal branches,from the ninety-millimeter level to the 250-millimeter levelproximal to the palm (Fig. 3).

In the proximal half of the forearm, the fasciculargroups that ~correspond to the three terminal branches at theproximal edge of the palm become distinct. However, atthe elbow, the specific fascicular groups that form the motorbranches to the flexor carpi ulnaris and the ulnar half of theflexor digitorum profundus can be readily identified. Theyremain as distinct entities for approximately ten centimetersproximal to the elbow.

Median Nerve

At the level of the wrist and in the distal quarter of theforearm, three fascicular groups may be identified in themedian nerve, and they can be traced as separate entitiesfor five to seven centimeters proximal to the proximal edgeof the palm. At the ulnar side, there are two sensory fas-cicular groups (Fig.-5), which form the two common digitalnerves to the third and second web spaces. On the radialside, there is one large fascicular group consisting of sensoryand mo~#r --’:~:,:cicies ....... t~e :;e~sorv fascicles continue d{:;taI!yas ’&c cadi’~.! ~igital nerve :)f ~he index ~:ic.:2=.:~:

cles are in the volar-radial position.The motor fascicles to the two radial lumbrical muscles

are also located in the mixed sensory-motor fasciculargroup, situated ulnar to the motor fascicular group to thethenar muscles. More distally, in the palm, the motor branchto the index lumbrical muscle accompanies the radial digitalnerve of the index finger. The motor branch to the lumbricalmuscle of the long finger accompanies the common digitalnerve to the second web space. The motor fascicles of themedian ner*e at the distal end of the forearm constitute only10 per cent of the total fascicular cross-sectional area of thenerve.

The palmar cutaneous branch is separate from the mainpart of the median nerve at approximately seventy milli-meters proximal to the radial styloid process, and its sensoryfascicular group can be traced proximally as an entity to the150-millimeter level; that is, to the middle third of the fore-arnq.

In the proximal half of the forearm, the fasciculargroups that correspond to the terminal branches becomeindistinct, but the motor fascicular groups that terminate asbranches to the muscles of the forearm may be traced forabout ten centimeters proximally from the site of branching.

Discussion

Because the major nerves at the distal part of the fore-arm are lacerated so frdquently, a study of the topographyof the intraneural fascicular groups at these levels has specialclinical significance.

Our findings are based on st. ~.die~ c;f f~’>.~’~’e fresh

Page 7: Internal Topography

ANATOMICAL BASIS FOR REPAIR OF ULNAR AND MEDIAN NERVES

the distinct entities of the fascicular groups at serial levels(Figs. 2-A and 2-B).

The surgical relevance of our findings should be em-phasized because they provide an anatomical basis for groupfascicular repair. In 1917, Langley and Hashimoto, of Cam-bridge University, suggested the idea of separate suture offascicular groups, and advised cutting open the inner, denseepineurial sheath (intraneural epineurium). The techniqueof group fascicular repair has been described by Van Beckand Kleinert8 as well as by Sunderland7 (Fig. 6). Utilizingthe operating microscope, one may readily identify, match,align, and repair the fascicular groups.

Group fascicular repair may be conceptualized as inner

279

segment of nerve is lost, the fascicles at the two nerve endswill not correspond, so that fascicle-to-fascicle repair byperineurially placed sutures is precluded. Under such con-ditions, one should be able to identify corresponding fas-cicular groups rather than individual fascicles at the nerveends, and then microsurgical group fascicular repair will bepossible because the fascicular groups remain as identifiableentities for several centimeters proximal to the wrist.

In the surgical treatment of acute lacerations of themajor peripheral nerves, we advocate microsurgical groupfascicular repair or microsurgical epineurial repair with cor-rect alignment of the fascicular groups. We do not advocatefascicular (perineurial) repair.

F~. 6

Group fascicular repair.

"/

F~. 7

Group fascicular nerve-grafting,

epineurial repair. The epineurium may be divided into ex-ternal epineurium and intraneural epineurium. The externalepineurium surrounds the entire nerve, while the intraneuralepineurium separates and surrounds individual fasciculargroups or individual fascicles (Figs. 1-B and 2-B). Theepineurium, either external or intraneural, lends itself toseparate suturing without injury to the encased fasciculargroups. Utitizir~ the operating microscope, sutures may becar.:g:~i!)’ ap?ii::< c~< size c.~.:.:::the t’ascicuIar gr~>:ps. ’.,; i~.>.’.~,t

~ess surgical trauma and resuita~ .<a,.’ri;~g. If a signii:~ ::~nt

The fascicular group arrangement of major peripheralnerves is also important for the technique of interfascicularnerve-grafting as described by Millesi and Millesi et al.3’4.

They pointed out that, using the operating microscope, nervegrafts can be utilized to bridge the gap between the corre-sponding fascicular groups (Fig. 7).

We believe that the relatively constant location of themotor fascicular group of the ulnar nerve at the distal partof ..~ f~;,:." ~-m i:.~ >av:i,::’.’~ " i~~,~.:.~:...t. In all but two oft~te i11 ~:;<>c:cic~~ens t!,:x~ ,.~..~: .tudied, that fascicular group~, :: :~ : .::.’ "2t ~},: :i:: ¯ .’,.," cer,.tral dorsal positi.op., in

in~r~ .ic rrmsck:s ;;;. ~i:e ha~=,d, one should make a special

Page 8: Internal Topography

280 J. A. CHOW ET AL.

effort during nerve suture to correctly identify and align thismotor fascicular group.

We recognize the value of the early work ofSunderland5 and the later contributions of Jabaley et al. andWilliams, and most of the points that they made have beenconfirmed in our study. Our dissections constitute a largernumber of specimens than do the previously published re-ports, and we further highlight the privileged anatomical

fact of the more constant fascicular group arrangement inthe intraneural topography of the ulnar and median nervesat the distal part of the forearm, where the majority of acutelacerations occur clinically.

NOTE: Lieutenant Colonel Chow is indebted to Sir Sydney Sunderland for proofreading themanuscript and to Dr. Michael Jabaley, Dr. Brace Williams, and Dr. Hanuo Millesi for adviceand encouragement during the preparation of this work. The authors thank Mr. George Holborow.Mr. Gregory Holmes, Mr. Paul Niner, and Ms. lngrid Lynch for technical assistance. They alsothank Gary G. Wind, M.D., for preparation of the line drawings.

Referencest. JABALEY, M. E.; WALLACE, W. H.; and HECKLER, F. R.: Internal Topography of Major Nerves of the Forearm and Hand: A Current View. I.

Hand Surg., 5: 1-18, 1980.2. LANGLEY, J. N., and HASHIMOTO, M.: On the Suture of Separate Nerve Bundles in a Nerve Trunk and on Internal Nerve Plexuses. J. Physiol.,

51: 318-346, 1917. :3. MILLESI, H.: Nerve Grafts -- Indications, Techniques and Prognosis. In Management of Peripheral Nerve Problems, p. 417. Edited by G. E.

Omer, Jr., and Morton Spinner. Philadelphia, W. B. Saunders, 1980.4. MILLESI, H.; MEISSL, G.; and BERGER, A.: The Interfascicular Nerve-Grafting of the Median and Ulnar Nerves. J. Bone and Joint Surg., 54..A:

727-750, June 1972.5. SUNDERLAND, SYDNEY: The Intraneural Topography of the Radial. Median and Ulnar Nerves. Brain, 68: 243-298, 1945.6. SUNDERLAND, SYDNEY: Nerves and Nerve Injuries. Edinburgh, Churchill Livingstone, 1968.7. SUNDERLAND, SYDNEY: Nerves and Nerve Injuries. Ed. 2. Edinburgh, Churchill Livingstone. 1978.8. VAN BEEK, ALLEN, and KLEINERT, H. E.: Practical Microneurorrhaphy. Orthop. Clin. North America, 8: 377-386, 1977.9. VAN BEEK, A. L.; JACOBS, S. C.; and ZOOK, E. G.: Examination of Peripheral Nerves with the Scanning Electron Microscope. Plast. and Reconstr.

Surg., 63: 509-519, 1979.10. WILLIAMS, H. B.: Peripheral Nerve Injuries in Children. In Symposium on Pediatric Plastic Surgery, pp. 266-282. Edited by D. A. Kernahan, H.

G. Thompson, and B. S. Bauer. St. Louis, C. V. Mosby, 1982.