Posterior interosseous nerve entrapment syndrome and spontaneous rupture of the extensor pollicis longus tendon are rare conditions. The authors describe the bizarre combination of a spontaneous rupture of the extensor pollicis longus tendon in a 82-year-old lady with a posterior interosseous nerve syndrome. As far as the authors know, this is the first description of such an association in the literature. Surgical exploration revealed compression of the posterior interosseous nerve at the proximal portion of the supinator muscle and at Henry's leash. The nerve was freed, and the tendon of the extensor index proprius was transferred to the extensor pollicis longus. Six months after the procedure, the patient had resumed her daily activities, showing a good functional result

Almeida, MA

Casal, D

Moniz, P

Videira e Castro, J

Repositório do Centro Hospitalar de Lisboa Central, EPE

ÓRGÃO OF IC IAL DA SOC IEDADE PORTUGUESA DE REUMATOLOGIA - ACTA REUMATOL PORT. 2010;35:85-985C A S O C L Í N I C OA P O S T E R I O R I N T E R O S S E O U S N E R V E S Y N D R O M EA S S O C I AT E D W I T H S P O N T A N E O U S R U P T U R EO F T H E E X T E N S O R P O L L I C I S L O N G U S T E N D O NDiogo Casal*, Paula Moniz*,Videira e Castro**, Maria Angélica-Almeida****Resident at Department of Plastic and Reconstructive Surgery,São José Hospital**Chief Consultant at Department of Plastic and ReconstructiveSurgery, São José Hospital ***Head of the Department of Plastic and Reconstructive Surgery, São José Hospital, Lisbon, Portugal don in an elderly lady with PIN syndrome. As far asthe authors could determine this is the first descrip-tion of such an association in the literature.  Case ReportA 82-year-old right-handed lady was referred to theHand Clinic for increasing ill-defined pain and so-reness in the dorsum of her left forearm and wristfor the previous three months. She also complainedof progressive weakness in the extension of her fin-gers, during that period. In particular, she mentio-ned that, around one month previously, when shewas holding her grand-child, she felt an intensepain in the dorsum of the radial aspect of the dor-sum of her wrist, after which she was unable to ac-tively extend the interphalangeal joint of her leftthumb, nor keep it extended after passively puttingit in that position. She denied ever having numb-ness. She didn't have any significant co-morbiditiesand was only taking non-steroidal anti-inflamma-tory drugs for the pain.Physical examination revealed moderate painduring palpation of the proximal forearm at the le-vel of the supinator muscle. Pain was also elicitedin that position when the patient was asked to su-pinate her left forearm against resistance. Therewas no Tinel sign. Manual muscle testing scoreswere: abductor pollicis longus: 3; extensor pollicisbrevis: 3; EPL: 0; extensor digitorum communis: 3;extensor indicis proprius (EIP): 3; extensor digitiminimi: 4; and extensor carpi  ulnaris: 4. Strengthof the extensors carpi radialis longus and breviswere 5, as was the strength in the remainder of theforearm and arm muscles. However, she was una-ble to extend her left thumb at the interpahalangealjoint, and showed a reduced power at the metacar-palphalangeal joint (Fig. 1). There seemed to be alack of continuity of the EPL tendon at the medialborder of the snuff box area. There was no sensorydisturbance. Abstract Posterior interosseous nerve entrapment syndro-me and spontaneous rupture of the extensor polli-cis longus tendon are rare conditions. The authorsdescribe the bizarre combination of a spontaneousrupture of the extensor pollicis longus tendon in a82-year-old lady with a posterior interosseous ner-ve syndrome.  As far as the authors know, this is thefirst description of such an association in the lite-rature.  Surgical exploration revealed compressionof the posterior interosseous nerve at the proximalportion of the supinator muscle and at Henry's le-ash. The nerve was freed, and the tendon of the ex-tensor index proprius was transferred to the exten-sor pollicis longus. Six months after the procedure,the patient had resumed her daily activities, sho-wing a good functional result. Keywords: Entrapment Neuropathies; Radial Ner-ve Lesion; Tendon Injuries; Tendon Transfer. IntroductionPosterior interosseous nerve (PIN) entrapmentsyndrome is rare, corresponding to less than 0,7%of all upper limb peripheral nerve compressionsyndromes1.  Annual incidence of this syndrome isestimated to be only around 0,003%2. Spontaneousrupture of the extensor pollicis longus (EPL) tendonis even rarer, with only a few cases reported in theliterature3. The authors describe the unlikely com-bination of a spontaneous rupture of the EPL ten-ÓRGÃO OF IC IAL DA SOC IEDADE PORTUGUESA DE REUMATOLOGIA - ACTA REUMATOL PORT. 2010;35:85-986AN UNUSUAL POSTERIOR INTEROSSEOUS NERVE SYNDROMERadiographic analysis of the cervical spine,shoulder, arm, forearm, and wrist showed no signi-ficant abnormalities. Ultrasonography revealed nomasses or other changes affecting the radial or pos-terior interosseous nerves. However, rupture of theEPL tendon was confirmed ultrasonographically.Electromyographic testing confirmed the presen-ce of PIN palsy of moderate severity.Upon surgical exploration, the PIN was found tobe compressed at the entrance of the supinatormuscle, and also by a pair of recurrent veins thatformed the classical leash of Henry (Fig. 2). A trueFrohse's arcade wasn't present. A myotomy of thesuperficial head of the supinator muscle was per-formed, and the PIN was freed from all compres-sions. The EPL tendon's distal stump was grosslyragged and adhered to the surrounding tissue (Fig. 3). The proximal stump of the EPL tendon hadretracted into the forearm. As the patient had ada-mantly expressed her intention of not having unaf-fected tendons used to try to rehabilitate the com-promised ones, the EIP tendon was transferred tothe distal stump of the EPL, and these two tendonswere sutured together using the Pulvertaft techni-que (Fig. 4). The patient was immobilized in ashort-arm cast with the wrist in abduction and ex-tension for 5 weeks. Afterwards, she underwent anintensive physiotherapy program. Six months af-ter the operation, she had no pain, and had regai-ned full thumb motion (Fig. 5). Extension of the re-maining fingers returned to normal, with the ex-ception of the EIP, which had been used to restorethe EPL function (Fig. 6). She resumed her daily activities with no limitation. Figure 1. Patient’s left hand at presentation, when askedto maximally extend her fingers and to abduct her thumb.There was severe limitation in the extension of the interphalangeal and metacarpal-phalangeal joints of thethumb, as well as in thumb’s abduction. Extension is possible in the last four digits, but extension strength isseverly diminished.The patient is only able to fully extendthe third finger by pushing it with the fourth finger, as it is seen in the picture. Figure 3. Intraoperative view of the dorsum of the patient's left hand and wrist.The extensor pollicis longustendon was found to be disrupted at Lister’s tubercle, andthe distal end of the ruptured tendon was grossly frayedand adhered to the surrounding tissue.The proximalstump of this tendon wasn’t found. 1. Distal stump of theextensor pollicis longus tendon; 2. Extensor indicis proprius tendon.Figure 2. Intraoperative view of the dorsum of the patient's left forearm, after  myotomy of the superficialhead of the supinator muscle. Henry’s leash is seen compressing the posterior interosseous nerve.1. Posterior Interosseous Nerve; 2. Superficial radial nerve; 3. Superficial head of the supinator muscle;4. Deep head of the supinator muscle; 5. Brachioradialismuscle; 6. Henry’s leash. ÓRGÃO OF IC IAL DA SOC IEDADE PORTUGUESA DE REUMATOLOGIA - ACTA REUMATOL PORT. 2010;35:85-987DIOGO CASAL E COL.DiscussionThe differential diagnosis of a patient with pain inthe dorsum of the forearm and wrist with weaknessin the extensor muscles of the fingers includes pos-terior interosseous syndrome, extensor tendonrupture or subluxation, neuralgic amyotrophy, cer-vical radiculopathy,  brachial plexopathy, and fo-cal myopathy2, 4-7. However, in our patient, therewere no changes in superficial sensibility, and mo-tor impairment was almost confined to extensordigitorum communis, abductor pollicis longus, ex-tensor pollicis brevis, EIP, and more pronouncedlyto EPL. Regarding mechanical limitations to fingerand thumb extension, the hallmark of extensortendon subluxation is the ability to maintain butnot actively obtain metacarpal-phalangeal exten-sion, whereas tendon rupture is characterized bythe inability of both obtaining and maintaining ex-tension, as it was observed in this patient2. Takingall these data into consideration, the two most like-ly diagnoses would be a PIN syndrome and a spon-taneous rupture of the EPL tendon. The reportmade by the patient of a sudden pain in the dor-sum of the wrist after which she couldn't activelyextend her thumb is, in fact, highly suggestive of atendon rupture. This hypothesis is further suppor-ted by the patient's physical examination in whichthere seemed to be an interruption of the EPL ten-don at the medial border of the snuff box area. However, on clinical grounds alone, a partialPIN syndrome in which the EPL muscle was moreseverely affected couldn't be entirely discarded8. Infact, it is well established that the PIN is usuallycompressed at the level of the supinator muscle,producing the classical presentation of droppedfingers and thumb, with a variable degree of painin the dorsal and lateral forearm and wrist2,9,10.Figure 4. Intraoperative view of the dorsum of the patient's left wrist.The extensor indicis tendon was sectioned at the metacarpal-phalangeal joint and the proximal portion was transferred to the distal stump ofthe extensor pollicis longus tendon. 1. Extensor pollicislongus tendon; 2. Extensor index proprius tendon;3. Suture of the extensor pollicis longus and the extensorindicis proprius tendon using the Pulvertaft technique.Figure 5. Six months postoperatively, the patient showednormal extension across the interphalangeal and metacarpal-phalangeal joints of her left thumb.Figure 6. Six months postoperatively, the patient showednormal extension of all fingers, including the index finger.She also presented normal thumb abduction. ÓRGÃO OF IC IAL DA SOC IEDADE PORTUGUESA DE REUMATOLOGIA - ACTA REUMATOL PORT. 2010;35:85-988AN UNUSUAL POSTERIOR INTEROSSEOUS NERVE SYNDROMEHowever, compression can also occur more dis-tally, producing uneven distribution of weaknessin the territory of the PIN, and causing partial PINsyndromes2. Typically, when the medial branch ofthe PIN is involved, weakness of the extensor car-pi ulnaris, extensor digiti minimi, and extensor di-gitorum communis ensues, while when there isentrapment of its lateral branch weakness of theabductor pollicis longus, extensor pollicis brevis,EPL, and EIP is present11. Moreover, even cases ofisolated EPL paralysis have been described as verylocalized forms of PIN palsy8. In our patient, electromyography confirmedthe clinical diagnosis of PIN syndrome, and ultra-sonography corroborated the rupture of the EPLtendon. These two ancillary tests are often reques-ted in this context: electromyography for establis-hing the topography and severity of the lesion10;and ultrasonography as a cheap, non-invasive me-thod for identifying extrinsic causes of nerve en-trapment, as ganglions or lipomas12. Although MRIprovides clearer visual discrimination than sono-graphy, it is seldom used2 13. Spontaneous rupture of the EPL has rarely beenreported in the literature3. Various mechanismshave been proposed to account for spontaneoustendon ruptures. Among these are necrosis causedby pressure, crush injury, nutrition impairment,attrition of the tendon on a sharp fragment of boneor callus, attrition on a roughened area of the ra-dius or from nonunion of Lister’s tubercle, te-nosynovitis from repetitive activities or sports, ora combination of impaired nutrition and attritionof the tendon3, 14. In this patient this last mecha-nism probably played a major role. Interestingly, asfar as the authors know, this is the first time a caseof spontaneous rupture of the EPL associated withPIN syndrome is reported in the literature.Usually, in a classical PIN syndrome, a course ofconservative therapy, including rest, activity mo-dification, splinting, stretching, nonsteroidal me-dications, and sometimes steroid injections, wouldbe standard therapy until about three months after the development of complaints1, 2. After thatperiod, if functional recovery is absent or symp-toms are worsening, most authors would recom-mend surgery, as motor endplates must be reinner-vated within 1 year, if motor function is to be res-tored15. However, in this case the indication for sur-gery was clear, since the patient was already havingsymptoms for 3 months, and because she had EPLrupture. For the surgical treatment of EPL rupture therewere three options: primary repair, tendon graf-ting, and tendon transfer3. Primary repair is onlypossible in early cases3, 14. In our patient, as thiswas not the case, and as the proximal stump of theEPL tendon had retracted proximally, the only pos-sibilities would be tendon grafting or tendon trans-fer3, 14. Given that the patient refused the use ofunaffected tendons, a EIP  tendon was transferredto the EPL tendon to rehabilitate the function of thelast.Notwithstanding the atypical presentation ofthis patient and her advanced age, six months after surgery, the therapeutic outcome was satis-factory, and the patient was able to return to herdaily activities, with no significant functional im-pairment. In fact, operative release of the PIN andsurgical treatment of EPL rupture are generally suc-cessful, being unsuccessful cases usually relatedto long-lasting clinical syndromes with severe mo-tor deficit10, 16. Hence, it is important that every doc-tor is familiarized with these conditions, so thatthese diagnoses can be made early and therapystarted accordingly. Correspondence toDiogo CasalRua Luís Pastor de Macedo, N 32, 5 D1750-159Lisbon, PortugalE-mail: diogo_bogalhao@yahoo.co.ukReferences1. Arle JE, Zager EL. Surgical treatment of common en-trapment neuropathies in the upper limbs. MuscleNerve 2000;23:1160-1174.2. Dang AC, Rodner CM. Unusual compression neuro-pathies of the forearm, part I: radial nerve. J HandSurg Am 2009;34:1906-1914.3. Kurklu M, Bilgic S, Yurttas Y, Safaz I, Komurcu M.Spontaneous rupture of the extensor pollicis longustendon due to a small osteophyte. Acta ReumatolPort 2009;34:555-556.4. Rosenbaum R. Disputed radial tunnel syndrome.Muscle Nerve 1999;22:960-967.5. Erdem S, Demirci M, Tan E. Focal myopathy mi-micking posterior interosseous nerve syndrome.Muscle Nerve 2001;24:969-972.6. Kaneko K, Taguchi T, Toyoda K, et al. Unilateral dropfinger due to cervical spondylosis at the C6/7 inter-vertebral level. J Orthop Sci 2003;8:616-620.7. Andreisek G, Crook DW, Burg D, Marincek B, Weis-haupt D. Peripheral neuropathies of the median, ra-dial, and ulnar nerves: MR imaging features. Radio-graphics 2006;26:1267-1287.8. Horton TC. Isolated paralysis of the extensor pollicis ÓRGÃO OF IC IAL DA SOC IEDADE PORTUGUESA DE REUMATOLOGIA - ACTA REUMATOL PORT. 2010;35:85-989DIOGO CASAL E COL.longus muscle: a further variation of posterior inte-rosseous nerve palsy. J Hand Surg Br 2000;25:225--226.9. Suematsu N, Hirayama T. Posterior interosseous ner-ve palsy. J Hand Surg Br 1998;23:104-106.10. Fernandez E, Pallini R, Lauretti L, Scogna A, Di Rien-zo A. Neurosurgery of the peripheral nervous system:the posterior interosseous nerve syndrome. SurgNeurol 1998;49:637-639.11. Lubahn JD, Cermak MB. Uncommon nerve com-pression syndromes of the upper extremity. J AmAcad Orthop Surg 1998;6:378-386.12. Martinoli C, Bianchi S, Pugliese F, et al. Sonographyof entrapment neuropathies in the upper limb (wristexcluded). J Clin Ultrasound 2004;32:438-450.13. Hashizume H, Nishida K, Nanba Y, Shigeyama Y, In-oue H, Morito Y. Non-traumatic paralysis of the pos-terior interosseous nerve. J Bone Joint Surg Br1996;78:771-776.14. Fujita N, Doita M, Yoshikawa M, Fujioka H, Sha N,Yoshiya S. Spontaneous rupture of the extensor polli-cis longus tendon in a professional skier. Knee SurgSports Traumatol Arthrosc 2005;13:489-491.15. Lowe JB, 3rd, Sen SK, Mackinnon SE. Current ap-proach to radial nerve paralysis. Plast Reconstr Surg2002;110:1099-1113.16. Lloyd TW, Tyler MP, Roberts AH. Spontaneous ruptu-re of extensor pollicis longus tendon in a kick boxer.Br J Sports Med 1998;32:178-179.3e Initiative 2010Cascais, Portugal8 a 9 de Outubro 2010VI Jornadas de Reumatologia e Medicina Familiar do AlgarveVilamoura, Portugal22 a 23 de Outubro 2010 

A Posterior Interosseous Nerve Syndrome Associated With Spontaneous Rupture of the Extensor Pollicis Longus Tendon

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A Posterior Interosseous Nerve Syndrome Associated With Spontaneous Rupture of the Extensor Pollicis Longus Tendon

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