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810 | VOLUME 61 | NUMBER 4 | OCTOBER 2007 www.neurosurgery-online.com CLINICAL STUDIES “FAT P ADAND “LITTLE FINGER PULPSIGNS ARE GOOD INDICATORS OF PROPER RELEASE OF CARPAL TUNNEL OBJECTIVE: The release of the transverse carpal ligament (TCL) for relief of carpal tun- nel syndrome has been a standard operative procedure since the early 1950s. Although complications are not common after the open surgical technique, a small but significant group of patients will have similar symptoms after surgery or will experience new symp- toms in the postoperative period. Incomplete section of the TCL is the major cause of these complications. The authors have described two signs that confirm a complete release of the TCL, called the “fat pad” and “little finger pulp” signs. METHODS: Between 2000 and 2003, we treated 643 hands in 611 patients (45 men and 566 women; age range, 32–76 yr; mean age, 58.2 yr). All patients were examined 6 months after the procedure, with special attention given to the persistence or recur- rence of symptoms. The presence of palmar scar pain, residual numbness, patient sat- isfaction, and time to return to work were also evaluated. A longitudinal incision (2 cm) at the base of the palm was used to release the TCL. A good indicator that the distal TCL has been released is the visualization of a fatty tissue (“fat pad” sign). This fatty tis- sue is always present underneath the most distal fibers of the TCL, covering the sensory digital branches of the median nerve. To confirm the complete release of the proximal fibers of the TCL, we should be able to introduce the little finger pulp in a proximal direction underneath the distal flexion crease of the wrist (“little finger pulp” sign). When both signs are confirmed, we can be certain that the TCL is completely released. RESULTS: Night pain disappeared immediately after surgery in all patients except three. There were seven complications (1%) not related to the palmar scar and 10 complica- tions (1.5%) related to it. However, all of these complications disappeared an average of 3 months postoperatively. Patient satisfaction was 100%, and the mean time to return to work and full activity was 22 days (range, 14–36 d). CONCLUSION: Two surgical observations that are reliable to confirm a complete release of the TCL were described. The first, called the “fat pad” sign, is useful to determine whether or not the distal end of the TCL has been adequately released, whereas the “little finger pulp” sign indicates whether or not the proximal end of the TCL has been fully divided. KEY WORDS: Carpal tunnel, Complications, Median nerve Neurosurgery 61:810–814, 2007 DOI: 10.1227/01.NEU.0000280075.82080.A8 www.neurosurgery-online.com Ignacio R. Proubasta, M.D. Hand Surgery Unit, Orthopaedic Department, Hospital Sant Pau, Barcelona, Spain Alberto Lluch, M.D., Ph.D. Institut Kaplan, Barcelona, Spain Claudia G. Lamas, M.D. Hand Surgery Unit, Orthopaedic Department, Hospital Sant Pau, Barcelona, Spain Barbara T. Oller, M.D. Hand Surgery Unit, Orthopaedic Department, Hospital Sant Pau, Barcelona, Spain Joan P. Itarte, M.D. Hand Surgery Unit, Orthopaedic Department, Hospital Sant Pau, Barcelona, Spain Reprint requests: Ignacio R. Proubasta, M.D., Servicio de Cirugía Ortopédica y Traumatología, Hospital Sant Pau, Barcelona, Spain Email: [email protected] Received, September 26, 2006. Accepted, May 23, 2007. S ince it was first described by Sir James Paget (26) in 1854, carpal tunnel syndrome (CTS) has been the best under- stood and most common of peripheral compression neu- ropathies. In 1913, Pierre Marie and Charles Foix (24) recom- mended decompression of the median nerve by sectioning the transverse carpal ligament (TCL), but it was not until 1929 that the first surgical decompression was performed by Sir James Learmonth on a patient with posttraumatic nerve compression (17). However, a review of the Mayo Clinic indicates that the first release of the TCL for median nerve compression was per- formed by Herbert Galloway and Andrew McKinnon in Winnipeg, Canada, in 1924, on a patient with a posttraumatic neuropathy (1). The wide recognition of spontaneous CTS has only been as recent as the early 1950s, largely through the writ- ings of George Phalen (5). In 1951, Phalen described his tech- nique using a transverse incision at the distal wrist crease, with proximal and distal extension as needed. However, it was not until the 1970s, with the work of Taleisnik (36) and Lluch (20),
Transcript
Page 1: "Fat pad" and "Little finger pulp"

810 | VOLUME 61 | NUMBER 4 | OCTOBER 2007 www.neurosurgery-online.com

CLINICAL STUDIES

“FAT PAD” AND “LITTLE FINGER PULP” SIGNS ARE GOOD INDICATORS OF PROPERRELEASE OF CARPAL TUNNEL

OBJECTIVE: The release of the transverse carpal ligament (TCL) for relief of carpal tun-nel syndrome has been a standard operative procedure since the early 1950s. Althoughcomplications are not common after the open surgical technique, a small but significantgroup of patients will have similar symptoms after surgery or will experience new symp-toms in the postoperative period. Incomplete section of the TCL is the major cause ofthese complications. The authors have described two signs that confirm a completerelease of the TCL, called the “fat pad” and “little finger pulp” signs.METHODS: Between 2000 and 2003, we treated 643 hands in 611 patients (45 menand 566 women; age range, 32–76 yr; mean age, 58.2 yr). All patients were examined6 months after the procedure, with special attention given to the persistence or recur-rence of symptoms. The presence of palmar scar pain, residual numbness, patient sat-isfaction, and time to return to work were also evaluated. A longitudinal incision (2 cm)at the base of the palm was used to release the TCL. A good indicator that the distalTCL has been released is the visualization of a fatty tissue (“fat pad” sign). This fatty tis-sue is always present underneath the most distal fibers of the TCL, covering the sensorydigital branches of the median nerve. To confirm the complete release of the proximalfibers of the TCL, we should be able to introduce the little finger pulp in a proximaldirection underneath the distal flexion crease of the wrist (“little finger pulp” sign).When both signs are confirmed, we can be certain that the TCL is completely released.RESULTS: Night pain disappeared immediately after surgery in all patients except three.There were seven complications (1%) not related to the palmar scar and 10 complica-tions (1.5%) related to it. However, all of these complications disappeared an averageof 3 months postoperatively. Patient satisfaction was 100%, and the mean time to returnto work and full activity was 22 days (range, 14–36 d).CONCLUSION: Two surgical observations that are reliable to confirm a complete releaseof the TCL were described. The first, called the “fat pad” sign, is useful to determinewhether or not the distal end of the TCL has been adequately released, whereas the“little finger pulp” sign indicates whether or not the proximal end of the TCL has beenfully divided.

KEY WORDS: Carpal tunnel, Complications, Median nerve

Neurosurgery 61:810–814, 2007 DOI: 10.1227/01.NEU.0000280075.82080.A8 www.neurosurgery-online.com

Ignacio R. Proubasta, M.D.Hand Surgery Unit,Orthopaedic Department,Hospital Sant Pau,Barcelona, Spain

Alberto Lluch, M.D., Ph.D.Institut Kaplan,Barcelona, Spain

Claudia G. Lamas, M.D.Hand Surgery Unit,Orthopaedic Department,Hospital Sant Pau,Barcelona, Spain

Barbara T. Oller, M.D.Hand Surgery Unit,Orthopaedic Department,Hospital Sant Pau,Barcelona, Spain

Joan P. Itarte, M.D.Hand Surgery Unit,Orthopaedic Department,Hospital Sant Pau,Barcelona, Spain

Reprint requests:Ignacio R. Proubasta, M.D.,Servicio de Cirugía Ortopédica yTraumatología,Hospital Sant Pau,Barcelona, SpainEmail: [email protected]

Received, September 26, 2006.

Accepted, May 23, 2007.

Since it was first described by Sir James Paget (26) in 1854,carpal tunnel syndrome (CTS) has been the best under-stood and most common of peripheral compression neu-

ropathies. In 1913, Pierre Marie and Charles Foix (24) recom-mended decompression of the median nerve by sectioning thetransverse carpal ligament (TCL), but it was not until 1929 thatthe first surgical decompression was performed by Sir JamesLearmonth on a patient with posttraumatic nerve compression(17). However, a review of the Mayo Clinic indicates that the

first release of the TCL for median nerve compression was per-formed by Herbert Galloway and Andrew McKinnon inWinnipeg, Canada, in 1924, on a patient with a posttraumaticneuropathy (1). The wide recognition of spontaneous CTS hasonly been as recent as the early 1950s, largely through the writ-ings of George Phalen (5). In 1951, Phalen described his tech-nique using a transverse incision at the distal wrist crease, withproximal and distal extension as needed. However, it was notuntil the 1970s, with the work of Taleisnik (36) and Lluch (20),

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that the longitudinal incision along the line of the ring fingerbecame the recommended approach.

The most common complication after endoscopic or opencarpal tunnel release is the incomplete release of the TCL (2, 3,5, 6, 9–11, 13, 14, 16, 19, 22, 30, 35, 37, 38). When this occurs, thepreoperative symptoms usually persist or recur shortly afterthe initial decompression. Incomplete division of the TCL isavoidable by using a large longitudinal incision crossing thewrist flexion creases, which allows adequate visualization ofthe proximal and distal boundaries of the TCL. However, whena short palmar incision is used (4, 7, 18, 33), it is difficult tovisualize the entire TCL and, as a consequence, incompleterelease of the TCL may occur.

This article discusses two surgical observations that are reli-able to confirm a complete release of the TCL. The first, calledthe “fat pad” sign, is useful to determine whether or not thedistal end of the TCL has been adequately released, whereasthe “little finger pulp” sign indicates whether or not the prox-imal end of the TCL has been fully divided.

MATERIALS AND METHODS

A retrospective review was conducted on all patients treated forCTS with a short palmar incision. Between 2000 and 2003, we treated643 hands in 611 patients (45 men, 566 women; age range, 32–76 yr;mean age, 58.2 yr). The surgical procedure was identical in all cases. Allpatients were examined 6 months after the procedure, with specialattention given to persistence or recurrence of symptoms. The presenceof palmar scar pain, residual numbness, patient satisfaction, and timeto return to work were also evaluated.

TechniqueAll procedures were performed under regional block anesthesia with

a tourniquet placed on the proximal arm. A longitudinal incision at thebase of the palm was used. The incision was made in line with the lon-gitudinal axis of the flexed ring finger. The intersection of this longitu-dinal line with the Kaplan line (i.e., a line parallel to the ulnar aspect ofthe extended thumb) marked thedistal extent of the incision.Proximally, the incision endedjust distal to the distal wrist flex-ion crease (Fig. 1). The subcuta-neous tissue was divided untilthe TCL could be visualized. Theflexor retinaculum was dividedon its ulnar border next to thehook of the hamate bone. Whenusing this short skin incision, it isimportant to have the surgicalassistant retracting on the skinedges both proximally and dis-tally to optimize the exposure.With experience, good retraction,and good lighting, the length ofthe skin incision may be short-ened, thus reducing postopera-tive pain and recovery time.Using a MacDonald dissectorplaced underneath the distal

NEUROSURGERY VOLUME 61 | NUMBER 4 | OCTOBER 2007 | 811

GOOD INDICATORS OF PROPER RELEASE OF THE CARPAL TUNNEL

edge of the TCL, the median nerve was protected during ligamentdivision. A good indicator that the distal TCL has been released is thevisualization of a fatty tissue after the Mac Donald dissector wasremoved. This fatty tissue is always present underneath the most dis-tal fibers of the TCL, covering the sensory digital branches of themedian nerve (Fig. 2). The proximal edge of the TCL is then divided.The proximal fibers of the TCL blend imperceptibly with the distalforearm fascia, which can bedivided up to 1 cm proximal tothe skin incision. To confirm thecomplete release of the proximalfibers of the TCL, we should beable to introduce the little fingerpulp in a proximal directionunderneath the distal flexioncrease of the wrist (Fig. 3). Wecall this maneuver the “little fin-ger pulp” sign (21). When bothsigns are confirmed, we can becertain that the TCL is com-pletely released. The skin is approximated with interrupted 5–0monofilament sutures, and an antebrachial plaster cast is applied withthe wrist in slight extension. Finger exercises are encouraged after sur-gery. The plaster and sutures are removed 2 weeks after surgery.

RESULTS

Night pain disappeared immediately after surgery in allpatients but three. There were no major complications relatedto neural, vascular, or tendon damage. There were seven com-plications not related to the palmar scar (Group 1) and 10 com-plications related to it (Group 2). In Group 1, three patients(0.5%) with transient postoperative hand numbness in themedian nerve distribution, three patients (0.5%) with residualhand pain similar in nature but milder in intensity to the pre-operative pain, and one patient (0.1%) with finger hypersensi-tivity were observed. These seven complications account for 1%of all cases. In Group 2, four patients (0.6%) complained ofoccasional scar tenderness and six (0.9%) complained of palmarscar pain, mainly to the touch. These 10 complaints correspondto an overall complication rate of 1.5%. All of these complica-tions disappeared an average of 3 months postoperatively.

FIGURE 1. Photograph showingthat the incision begins at theintersection of Kaplan’s line and aline drawn along the longitudinalaxis of the flexed ring finger until1 cm above of the distal flexorcrease of the wrist.

FIGURE 3. Photograph illustrat-ing the “Little finger pulp” sign.

FIGURE 2. Photograph illustrating the “fat pad” sign(arrows).

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812 | VOLUME 61 | NUMBER 4 | OCTOBER 2007 www.neurosurgery-online.com

PROUBASTA ET AL.

Patient satisfaction was 100%, and the mean time period toreturn to work and full activity was 22 days (14–36 d).

DISCUSSION

CTS is the best understood and most common of the periph-eral compression neuropathies and, therefore, the most fre-quent hand operation. The common surgical treatment for CTSin patients who have failed to improve with conservative meas-ures is open carpal tunnel release. Although the longitudinaldivision of the TCL consistently relieves symptoms in mostpatients, some may complain of persistence of symptoms aftersurgery due to an incomplete release of the TCL (2, 3, 5, 9, 11,13, 16, 30, 35, 37) (Table 1). Some authors (8, 23) have stated thatcommon indications for reoperation include previous incom-plete surgery and postoperative fibrosis causing recurrence ofsymptoms. Although the standard longer incision that crossesthe wrist crease allows complete visualization of the TCL fromthe forearm fascia proximal to the superficial palmar arch dis-tally, many experienced hand surgeons successfully use shorterlongitudinal incisions that do not cross the wrist crease to min-imize scar tenderness, scar retraction, and injury to the thenarsensory branch of the median nerve.

The “fat pad” and “little finger pulp” signs described in thisarticle have been helpful in confirming complete division of theTCL; neither sign is new. In reference to the “little finger pulp”sign, Phalen indicates that “after section of the TCL thereshould be sufficient room in the carpal tunnel to permit acurved Kelly hemostat to slide easily into the palm or to allowthe moistened little finger of the surgeon to pass readily alongthe median nerve into the palm” (29, p 223). Although Phalenverifies the complete section of the proximal edge of the reti-naculum in a proximal-distal direction and we made it in adistal-proximal direction, the principle of the “little pulp sign”is the same. With regard to the “fat pad sign,” in 1997, Ragbiret al. (31) described the “yellow fat sign,” which is a constant

pad of palmar fat found at the distal end of the TCL and con-stitutes a reliable indicator of the complete release of the distaledge of TCL. This appreciation is the same one that we havebeen using for many years (21). In a comprehensive review ofthe anatomy of the carpal tunnel by Skandalakis et al. (34), areference has been made to the specialized palmar fat related tothe superficial arterial palmar arch in an area noted as the “dis-tal zone,” which was later verified in radiological (25), endo-scopic (12), and surgical (32) studies. For this reason, when thedistal edge of the retinaculum has been completely released,the fat pad described appears. Our results support the resultsof most of these studies, as no permanent complications andvery few transient complications were observed (15).

CONCLUSION

This study has several limitations because there is no controlgroup. However, we have been using this technique withoutany modifications since 1984, after it was proposed by the sen-ior author (AL), assuring a complete release of the TCL andproviding immediate and permanent relief of median nervecompression at the carpal tunnel.

REFERENCES

1. Amadio PC: The first carpal tunnel release? J Hand Surg [Br] 20:40–41, 1995.2. Assmus H: Correction and reintervention in carpal tunnel syndrome. Report

of 185 reoperations [in German]. Nervenarzt 67:998–1002, 1996.3. Assmus H, Dombert T, Staub F: Reoperations for CTS because of recurrence

or for correction [in German]. Handchir Mikrochir Plast Chir 38:306–311,2006.

4. Avci S, Sayli U: Carpal tunnel release using a short palmar incision and a newknife. J Hand Surg [Br] 25:357–360, 2000.

5. Bagatur AE: Analysis of the causes of failure in carpal tunnel syndrome sur-gery and the results of reoperation [in Turkish]. Acta Orthop Traumatol Turc36:346–353, 2002.

6. Botte MJ, von Schroeder HP, Abrams RA, Gellman H: Recurrent carpal tun-nel syndrome. Hand Clin 12:731–743, 1996.

a TCL, transverse carpal ligament.

TABLE 1. Results of revision carpal tunnel release after previous open carpal tunnel release surgerya

No. of Intact parts Scar Medical Other No abnor-Series (ref. no.)

interventions of the TCL tetheringFibrosis

injury causes malities

Langloh and Linscheid, 1972 (16) 34 21 (62%) — — — — —

Conolly, 1978 (9) 35 9 (31%) 4 — 7 10 5

Kern et al., 1993 (13) 16 10 (62%) 4 — 1 1 —

Assmus, 1996 (2) 185 91 (49%) 58 — — — 36

Bagatur, 2002 (5) 26 23 (88%) — 1 — 2 —

Unglaub et al., 2005 (37) 38 26 (68%) 8 3 — — 1

Stütz et al., 2006 (35) 200 108 (54%) 46 17 12 4 13

Pülzl et al., 2006 (30) 48 16 (33%) 24 — 8 — —

Assmus et al., 2006 (3) 57 34 (60%) 15 — 3 — 5

Frick and Baumeister, 2006 (11) 63 38 (60%) 21 2 1 1 —

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7. Bromley GS: Minimal-incision open carpal tunnel decompression. J HandSurg [Am] 19:119–120, 1994.

8. Cobb TK, Amadio PC: Reoperation for carpal tunnel syndrome. Hand Clin12:313–323, 1996.

9. Conolly WB: Pitfalls in carpal tunnel decompression. Aust N Z J Surg48:421–425, 1978.

10. Forman DL, Watson HK, Caulfield KA, Shenko J, Caputo AE, Ashmead D:Persistent or recurrent carpal tunnel syndrome following prior endoscopiccarpal tunnel release. J Hand Surg [Am] 23:1010–1014, 1998.

11. Frick A, Baumeister RG: Re-intervention after carpal tunnel release [inGerman]. Handchir Mikrochir Plast Chir 38:312–316, 2006.

12. Jimenez DF, Gibbs SR, Clapper AT: Endoscopic treatment of carpal tunnelsyndrome: A critical review. J Neurosurg 88:817–826, 1998.

13. Kern BC, Brock M, Rudolph KH, Logemann H: The recurrent carpal tunnelsyndrome. Zentralbl Neurochir 54:80–83, 1993.

14. Kessler FB: Complications of the management of carpal tunnel syndrome.Hand Clin 2:401–406, 1986.

15. Klein RD, Kotsis SV, Chung KC: Open carpal tunnel release using a 1-centimeter incision: Technique and outcomes for 104 patients. PlastReconstr Surg 111:1616–1622, 2003.

16. Langloh ND, Linscheid RL: Recurrent and unrelieved carpal-tunnel syn-drome. Clin Orthop Relat Res 83:41–47, 1972.

17. Learmonth GR: The principle of decompression in the treatment of certaindiseases of peripheral nerves. Surg Clin N Am 13:905–913, 1933.

18. Lee WP, Strickland JW: Safe carpal tunnel release via a limited palmar inci-sion. Plast Reconstr Surg 101:418–426, 1998.

19. Louis DS, Greene TL, Noellert RC: Complications of carpal tunnel surgery.J Neurosurg 62:352–356, 1985.

20. Lluch A: Palmar approach in carpal tunnel syndrome. Personal revision in147 hands [in Spanish]. Rev Esp Cir Mano 12:8–32, 1984.

21. Lluch A: Carpal Tunnel Syndrome [in Spanish]. Barcelona, Editorial Mitre, 1987,p 116.

22. MacDonald RI, Lichtman DM, Hanlon JJ, Wilson JN: Complications of surgi-cal release for carpal tunnel syndrome. J Hand Surg [Am] 3:70–76, 1978.

23. MacKinnon SE, Dellon AL: Painful sequelae of peripheral nerve injury, inMackinnon SE, Dellon AL (eds): Surgery of the Peripheral Nerve. New York,Meriscola, 1989, pp 455–519.

24. Marie F, Foix C: Atrophie isolée de l’eminence thénar d’origin neuritique.Role du ligament annulaire antérieur du carpe dans la pathogénie de la lesion[in French]. Rev Neurol 26:647–649, 1913.

25. Mesgarzadeh M, Schneck CD, Bonakdarpour A: Carpal tunnel: MR imaging.Part I. Normal anatomy. Radiology 171:743–748, 1989.

26. Paget J: Lectures on Surgical Pathology. Philadelphia, Lindsay and Blakiston,1854, ed 2, p 42.

27. Palmer AK, Toivonen DA: Complications of endoscopic and open carpal tun-nel release. J Hand Surg [Am] 24:561–565, 1999.

28. Phalen GS: Spontaneous compression of the median nerve at the wrist. J AmMed Assoc 145:1128–1133, 1951.

29. Phalen GS: The carpal-tunnel syndrome. Seventeen years’ experience in diag-nosis and treatment of six hundred fifty-four hands. J Bone Joint Surg Am48:211–228, 1966.

30. Pülzl P, Estermann D, Piza-Katzer H: Surgical treatment of persisting andrecurrent carpal tunnel syndrome from 1999 to 2003 [in German]. HandchirMikrochir Plast Chir 38:300–305, 2006.

31. Ragbir M, Devaraj VS, Evans D: The ‘yellow fat sign’—A reliable indicator ofthe completeness of carpal tunnel release. Eur J Plast Surg 20:212–213, 1997.

32. Rodner CM, Katarincic J: Open carpal tunnel release. Tech Orthop 21:3–11,2006.

33. Serra JM, Benito JR, Monner J: Carpal release with short incision. PlastReconstr Surg 99:129–135, 1997.

34. Skandalakis JE, Colborn GL, Skandalakis PN, McCollam SM, SkandalakisLJ: The carpal tunnel syndrome: Part II. Am Surg 58:77–81, 1992.

35. Stütz N, Gohritz A, van Schoonhoven J, Lanz U: Revision surgery after carpaltunnel release—Analysis of the pathology in 200 cases during a 2 year period.J Hand Surg [Br] 31:68–71, 2006.

36. Taleisnik J: The palmar cutaneous branch of the median nerve and theapproach to the carpal tunnel. An anatomical study. J Bone Joint Surg Am55:1212–1217, 1973.

37. Unglaub F, Goldbach C, Hahn P: Reoperation in carpal tunnel syndrome.Retrospective analysis [in German]. Nervenarzt 76:1506, 1508–1510,1512–1514, 2005.

38. Urbaniak JR, Desai SS: Complications of nonoperative and operative treat-ment of carpal tunnel syndrome. Hand Clin 12:325–335, 1996.

COMMENTS

In this study, the authors describe two useful observations as part oftheir surgical technique for carpal tunnel release surgery. Most

peripheral nerve surgeons are very familiar with the "fat pad" sign androutinely use it as an indicator for the presence of vascular arcades and,thus, the proper release of distal transverse carpal ligament. In ourexperience, the more common cause of surgical failure is incompletedivision of the proximal aspect of the ligament. This proximal edge ofthe transverse carpal ligament blends imperceptibly into the distal fore-arm aponeurosis, and this may be sectioned under direct visualizationfor up to 1 cm proximal to the skin incision by the assistant elevatingthe skin edge. We routinely palpate both proximately and distallywithin the incision to make sure that no remaining areas of compres-sion are identified. Proubasta et al. use the term "little finger pulp" todescribe this technique, which is equivalent to our finger palpationtechnique of the proximal aspect of the carpal tunnel. It is commend-able that they report excellent results in 643 carpal tunnel release pro-cedures with few complications. This is a reasonably large clinicalseries in the context of this common entrapment neuropathy. It pro-vides important reminders to surgeons who perform carpal tunnelrelease on how to avoid the common mistake of incomplete division ofthe transverse carpal ligament.

Jason H. HuangEric L. Zager Philadelphia, Pennsylvania

This is a brief but worthwhile study describing two useful signs thatdemonstrate the complete division of the transverse carpal liga-

ment both distally and proximally. Because incomplete division of theligament is such a common cause of surgical failure, application ofthese two intraoperative “tests” may help prevent that outcome. I havebeen using these two tests for many years since I was taught them byDr. Edgar Kahn, one of the early advocates of local anesthesia and thelongitudinal incision (1). However, I think that these two points havebeen largely handed down as part of our “oral tradition.” It is good andquite useful to see them in print.

I would add one other helpful technique. When sectioning the liga-ment in a proximal direction, the proximal portion of the ligament canbe seen under direct vision if the wrist is strongly dorsiflexed and theproximal end of the skin incision is retracted and elevated with a veinretractor. A Metzenbaum scissor can then be used to divide the liga-ment all the way to and through its junction with the forearm fascia.The little finger pulp can then easily be felt beneath the skin of the fore-arm, proximal to the distal wrist crease.

John E. McGillicuddy Ann Arbor, Michigan

1. Kahn EA: The surgery of peripheral nerve injuries, in Kahn EA, Crosby EA,Schneider RC, Taren JA (eds): Correlative Neurosurgery. Springfield, Charles C.Thomas, 1969, ed 2, pp 516–518.

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GOOD INDICATORS OF PROPER RELEASE OF THE CARPAL TUNNEL

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PROUBASTA ET AL.

This article by Proubasta et al. introduces neurosurgeons to widelyknown signs that are commonly used by hand surgeons when

they perform carpal tunnel release surgery. For more than a decade,I have applied them routinely in my own practice and have foundthem useful in ensuring adequate proximal and distal median nerve

decompression. A blunt ball tip dissector could also be used insteadof a little finger.

Robert J. SpinnerRochester, Minnesota

Parkinson’s disease and deep-brain stimulation of the subthalamic nucleus (STN). Anatomic structures involved inthe symptoms of Parkinson’s disease (top). Illustrations (boxed) showing simplified schematic of basal ganglia “wiring.”Inhibitory (red lines) and excitatory (green lines) connections are drawn in varying thicknesses to illustrate level of activ-ity. Stimulation of the STN: lower left figure illustrates the effect of inhibition of an overactive STN by normalizing theinhibitory outflow from the internal segment of the globus pallidus to the thalamus. From Lang AE: Subthalamic stim-ulation for parkinson’s disease—living better electrically? N Engl J Med 349:1888–1891, 1998.


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