Ulnar neuropathy at the wrist associated withaberrant flexor carpi ulnaris insertion

A 36-year-old man who sustained an industrial hyperextension injury of the wrist complainedof dysesthesia and pain in the ulnar nerve distribution, aggravated for months by wrist movementuntil exploration. The operation revealed an anomalous insertion of the flexor carpi ulnaristendon disrupting a major portion of the ulnar nerve proximal to the pisiform. The symptomswere relieved completely after neurolysis and modification of the insertion of the tendon.(J II'\:"D SURG 1988;13'\:382-4.)

John J. O'Hara, MD, and Janet H. Stone, OTR, CST, Torrance and Lomita, Calif.

Compression neuropathy of the ulnarnerve at the wrist is a well described syndrome distalto the pisiform.':' The great majority of these lesionsoccurs in Guyon's canal, resulting from occupationaltrauma, ulnar thrombosis, and ganglia."? Anomalies ofthe flexor digiti minirni, abductor digiti minimi, flexorcarpi ulnaris, and palmaris brevis have been implicatedin ulnar neuropathy at the wrist.8,14 Instances of ulnarnerve entrapment proximal to the pisiform have beenrarely reported in the literature.":"

Our patient demonstrated a previously undescribedanomaly of the insertion of the flexor carpi ulnaris,disrupting the fascicular pattern of the ulnar nerve andresulting in a compression neuropathy syndrome sub­sequent to a closed occupational trauma of the wrist.The diagnosis was aided by electromyography andnerve conduction studies. Surgical exploration and de­compression resulted in complete relief of pain anddysesthesia and reversal of the electrical block.

Case reportA 36-year-old man who was dominant on the right side

incurred an occupational injury; his dominant hand was pulledinto a buffing machine, and he violently pulled it out. Hedeveloped numbness and tingling on the dorsal-radial aspectof the right wrist with accompanying stiffness of the wrist

From the Hand Surgery Service, Harbor General/UCLA, Torrance,Calif., and private practice in hand therapy, Lomita, Calif.

Received for publication Sept. 23. 1986; accepted in revised formOct. 23, 1987.

No benefits in any form have been received or will be received froma commercial party related directly or indirectly to the subject ofthis article,

Reprint requests: John J. O'Hara, MD, 4201 Torrance Blvd. Suite640, Torrance, CA 90503.

370 TilE JOURNAL OF llANO SURGERY

and digits. Initial examination was made by another physi­cian. X-ray filrns were normal, and the patient's wrist wasplaced in a splint by this physician. The radial wrist symptomsgradually diminished; however, he experienced increasingnumbness and tingling in the small and ring fingers, accom­panied by pain with even slight wrist movement or extensionof the ulnar digits. As a result of the pain, he was unable toperform his usual industrial duties as a machinist.

On initial physical examination in our office 4 weeks afterthe date of injury, we noted that the patient held his handrigidly in his lap and demonstrated no evidence of motordeficit of either the median or ulnar nerves. A Tinel signcould not be elicited.

His symptoms suggested a possible neuropraxic stretchinjury to the ulnar nerve. Results from further x-ray filmswere normal, including a profile view of the pisiform. Weelected to continue conservative management with a morecompletely immobilizing brace.

The thumb and radial wrist problems gradually resolved;however, the patient began to complain bitterly of stingingpain radiating into the small and ring fingers and of persistingnumbness and tingling in the ulnar distribution of the hand.The patient was reluctant to even close the hand. There was,however, no evidence of clinical weakness of the musclessupplied by the ulnar nerve. A Tinel sign became apparentover the ulnar nerve at and proximal to the pisiform, At thispoint approximately 4 months after injury, electromyographyand nerve conduction studies were done, which indicated alower motor neuron lesion involving the ulnar nerve distally.

Surgical exploration was undertaken. A palmar incision(Fig. 1) extending through Guyon's canal allowed completeexposure of the ulnar nerve. No abnormality was found. Dis­section was therefore done proximally in a zigzag fashion.Thickening and deviation of the ulnar fascicles of the ulnarnerve became apparent at and just proximal to the pisiform.Exposure of the distal 6 ern of the flexor carpi ulnaris tendonrevealed a split insertion, with approximately one fifth of the

Vol. 13A. No.3May 1988

Fig. I. The ulnar fascicles of the ulnar nerve arc shownpenetrating the flexor carpi ulnaris; the ulnar nerve is deviatedtoward the flexor carpi ulnaris and around the pisiform.

tendon inserted 5 mm radially 10 the major insertion. Thesplit in the tendon fascicles extended 4 Col proximally,

Dissection of the ulnar nerve revealed that the two medialfascicle groups of the nerve split from the major trunk andpenetrated the split in the tendon from the dorsum, proximally.exiting palmarly and distally (Fig. I) . The displaced groupsthen rejoined the major trunk of the nerve adjacent 10 thepisiform. The displaced fascicles, which represented approx­imately one third of the substance of the nerve, were induratedand thickened.

The radial insertion of the tendon was detached allowingthe nerve 10 approximate the major trunk. Epine~rolys i s o~fthe displaced fascicle groups was carried out. The anomaloustendon insertion was then reinserted adjacent to the majorinsertion of the flexorcarpi ulnaris. The ulnar nerve lay freelyin the wound. After operation the patient had gradual. com­plete relief of pain and was able to usc his hand normally.He regained full range of motion in the Iincers and wrist andfull strength in the~hand . Results of subsequent clcctrodi­agnostic nerve studies reverted to normal.

Discussion

With regard to the ulnar nerve at the wrist , puzzlingclin ical syndromes may indicate anomalous or aberrantmuscles as sources of compression neuropathy. Previ­ously reported anomalous muscles usually have been avariant of the accessory flexor digiti minimi arising

UII/ar neuropathy til wrist 371

from the flexor compartment , traversing Guyon'sspace , and inserting into the abductor digiti quinti ."Fibrovascular bands that ari se from the ulnar artery andcommunicate with the belly of the flexor carpi ulnaris,causing compression of the ulnar nerve, and a lesionof the ulnar nerve cau sed by a mass of hyper­troph ied fibers of the flexor carpi ulnaris have beende scribed . IS. 16 In this instance we encountered an anom­

alous tendon insertion compromising a major portionof the ulnar nerve proximal to the pisiform,

This anomaly described for the first time in this ar­ticle, although obviously rare, should be kept in mindduring any surgery in the area of the flexor carpi ulnarisinsertion. i.e . opponcnsplasty, co Green's procedure, ex­cision of the pisiform, etc.

REFERENCES

I. Dupont C, Clouthier GE. Prcvast J. et al. Ulnar tunnelsyndrome at the wrist. J BoneJoint Surg 1967;47IA):757.

2. Vanderpool OW, Chalmers J, Lamb DW, ct al. Peripheralcompression lesions of the ulnar nerve . J Bone Joint Surg1968;50[U):792.

3. Eversmann WW Jr. Compression and entrapment neu­ropathies of the upper extremity. J HArm SURG 1983;8:759-66.

4. Shea JD. McClain EJ. Ulnar nerve compression syn­dromes at and below the wrist. J Bone Joint Surg1969;5IIA) :I095-1103.

5. Uriburu UF. Morchio FJ, Marin JC. Compression syn­drome of the deep motor branch of the ulnar nerve (piso­hamate hiatus syndrome). J Bone Joint Sura 1976'58[A):145-7. ~ .

6. Hayes JR, Mulholland RC, O'Connor BT. Compressionof the deep palmar branch ofthc ulnar nerve. Case report.J Bone Joint Surg 1969;51[(3):469-72.

7. Grundbcrg AB. Ulnar tunnel syndrome. J HAI'D SURG1984;913:72-4.

8. Gloobe H, Pccket P. An anomalous muscle in the canalof Guyon. Anat Anz 1973;133:477-9.

9. Simodynes EE. Cochran RM. Anomalous muscles in thehand and wrist. Report of three cases. J HAI'D SURG1981 ;6:553-4.

10. Schjelderup H. Aberrant muscle in the hand causing ulnarnerve compression, in Proccedinus of the Second HandClub. J Bone Joint Surg 19M;46B:361.

II . Still M Jr. Kleinert HE. Anomalous muscles and nerveentrapment in the wrist and hand. Plast Rcconstr Surg1973;52:39-l-400.

12. Kleinert HE. Hayes JE. The ulnar tunnel syndrome. PlastRcconstr Surg 1971 ;47:21.

13. Tonkin MA. Lister GO. The palmaris brevis profundus.An anomalous muscle associated with ulnar nervecompression at the wrist. J HMm SURG 1985;lOA:862-4.

14. Lahey MD, Aulicino PL. Anomalous muscles associ-

O'Hara and SIOIII'

atcd with compression neuropathies. Orthop Rev 1986;15:199-208.

15. Holtzman RNN, Mark MH, Mukund RP, Wiener LI\I.Ulnar nerve entrapment neuropathy in the forearm.J HAt'D SURG 1984;9A:576-8.

16. Dubs J. Ganglion der Nervcnschcidc des nervus ulnaris.Dtsch Mcd Wochenschr 1922;48:68.

17. Harrelson JM, Newman 1\1. Hypertrophy of the flexorcarpi ulnaris as a cause of ulnar nerve compression inthe distal part of the forearm. Case report. J Done JointSurg 1975;57A:554.

The Journal ofHAND SURGERY

18. Turner MS, Caird D~1. Anomalous muscles and ulnarnerve compression at the wrist. Hand 1977;9;140-2.

19. Jeffery AK. Compression of the deep palmar branch ofthe ulnar nerve by an anomalous muscle. Case reportand review. J Done Joint Surg 1971 ;53[1;718-23.

20. Wood YE. Nerve compression following opponcnsplastyas a result of wrist anomalies. Report of a case. J HANDSURG 1980;5:279-81.

Limited open reduction of the lunate facet incomminuted intra-articular fractures of thedistal radius

Intra-articular incongruity of the distal radius at the radiocarpal joint is a bad prognostic feature;reduction by closed or open operative techniques is important. However, both techniques havelimitations. We describe a new technique of reduction of the lunate facet under radiographiccontrol, with very limited operative exposure and tissue trauma. In two cases anatomic restorationof the radiocarpal joint was obtained by this technique and maintained with external and limitedinternal fixation. Follow-up results are very encouraging. Currently we suggest use of this simpletechnique when faced with an incongruous radiocarpal joint after unsatisfactory attempts atclosed reduction. (J Hxxn SURG 1988;I3A:384·9.)

T. Axelrod, MD, MSc, D. Paley, MD, fRCS(C), J. Green, BSc, andR.Y. McMurtry, MD, FRCS(C), fACS, Toronto, o,«.. Canada

Intra-articular incongruity of the distal ra­dius at the radiocarpal joint is a bad prognostic featureand is associated with a high incidence of early andrapid joint degeneration and osteoarthritis.' Open rc-

From the Orthopedic/Trauma Division and the Head Trauma/Emer­gency Services, Sunnybrook Medical Centre, and the OrthopedicDivision, Hospital for Sick Children, Toronto, Onl., Canada.

Received for publication June 30. 1986; accepted in revised fonnSept. is. 1987.

No benefits in any form have been received or will be received froma commercial party related directly or indirectly to the subject ofthis article.

Reprint requests: R. Y. McMurtry, MD, Sunnybrook Medical Centre,AI Room 1034.2075 Bayview Ave., Toronto, Ont., M4N 3M5.Canada.

372 THE JOURNAL Of IIAt'D SURGERY

duction and internal fixation of these fractures involvesextensive exposure, devascularization of small bonyfragments, and detachment of ligamentous and capsularattachments. Open reduction and internal fixation(ORIF) is not always feasible because of the extent ofcomminution and the degree of porosity of the bone.

To restore the congruity of the radiocarpal joint, yetpreserve all the soft tissue attachments to the fractureddistal radius, a method of restoration under fluoroscopiccontrol was developed. This technique is combined withexternal fixation and percutaneous pinning to stabilizethe distal radial fracture.

The prerequisite for this procedure is a distal radialfracture with intra-articular extension and greater than2 mm of radiocarpal incongruity that remains irreduc­ihle after adequate attempts at closed reduction.