Painful nerve compression beyond the carpal tunnel: recognizing the lacertus syndrome

Abstract

The most common nerve compression in the upper extremity is that of carpal tunnel syndrome. Although generally recognized and treated, as much as a 20% failure rate is reported. Recent publications are indicating that one of the sources of persistent median nerve symptoms may be missed proximal median nerve entrapments, of which the lacertus fibrosus represents a principal cause of compression, and rarely other sites such as the flexor superficialis arch or pronator teres. Compression by the lacertus fibrosus is called lacertus syndrome, and as this is a clinically diagnosed entity, only rarely confirmed using electrodiagnostic or imaging studies, it is frequently overlooked. Clinicians regularly treating patients with carpal tunnel syndrome or patients with signs of median nerve neuropathy should be aware of the lacertus fibrosus as a possible compression site. In this review, we will define lacertus syndrome, describe its clinical manifestations and diagnosis, and demonstrate surgical techniques used to treat it.

Keywords

Carpal tunnel syndrome / dynamic nerve compression / lacertus syndrome / median nerve / nerve decompression / nerve surgery

References

[1] Hagert E.CORR Insights(®): Carpal tunnel syndrome impairs thumb opposition and circumduction motion.Clin Orthop Relat Res2014;472:2534-5 PMCID:PMC4079890

[2] Upton AR.The double crush in nerve entrapment syndromes.Lancet1973;2:359-62

[3] Hagert E. Nerve entrapment syndromes. In: Chang J, Neligan PC, eds. Neligan’s Plastic Surgery. Vol 6. 5 ed. Philadelphia, PA; USA: Elsevier; 2024:499-525.

[4] Hagert E.Clinical diagnosis and wide-awake surgical treatment of proximal median nerve entrapment at the elbow: a prospective study.Hand2013;8:41-6 PMCID:PMC3574476

[5] Ahmad AA,Thavamany AS,Ganapathy SS.Lacertus syndrome: an outcome analysis after lacertus release.J Hand Surg Glob Online2023;5:498-502.

[6] Snoeck O,Sprio E.The lacertus fibrosus of the biceps brachii muscle: an anatomical study.Surg Radiol Anat2014;36:713-9

[7] Archambault G,Hagert E,Sobczak S.Effect of lacertus fibrosus release on perineural pressure of the median nerve at the elbow: a cadaveric study.Int Orthop2023;47:1277-84.

[8] Peters BR,Chi D.Complete foot drop with normal electrodiagnostic studies: sunderland "zero" ischemic conduction block of the common peroneal nerve.Ann Plast Surg2022;88:425-8

[9] Hagert E,Hagert CG.Lacertus syndrome: a ten year analysis of two hundred and seventy five minimally invasive surgical decompressions of median nerve entrapment at the elbow.Int Orthop2023;47:1005-11 PMCID:PMC10014674

[10] Johnson RK,Shrewsbury MM.Median nerve entrapment syndrome in the proximal forearm.J Hand Surg Am1979;4:48-51

[11] Tang JB.Median nerve compression: lacertus syndrome versus superficialis-pronator syndrome.J Hand Surg Eur Vol2021;46:1017-22

[12] Ayhan E,Cevik K.Pinch strength analyses in lacertus syndrome.Hand Surg Rehabil2023;42:305-9

[13] Cheng CJ,Beck JL.Scratch collapse test for evaluation of carpal and cubital tunnel syndrome.J Hand Surg Am2008;33:1518-24

[14] Lalonde D.Lacertus syndrome: a commonly missed and misdiagnosed median nerve entrapment syndrome.BMC Proc2015;9:A74 PMCID:PMC4445778

[15] Cline JA,Adams JM.Experience with proximal median nerve entrapment by the lacertus fibrosus.Hand2023; Online ahead of print:

[16] Pisquiy JJ,Gonzalez GA.Validity of using the scratch collapse test in the lower extremities.Plast Reconstr Surg2022;150:194e-200e.

[17] El-Haj M,Sharma K,Mackinnon SE.Median nerve compression in the forearm: a clinical diagnosis.Hand2021;16:586-91. PMCID:PMC8461194

[18] Telleman JA,Goedee HS,Visser LH.Ultrasound scanning in the diagnosis of peripheral neuropathies.Pract Neurol2021;21:186-95

[19] Fowler JR,Tosti R,Imbriglia JE.Comparison of ultrasound and electrodiagnostic testing for diagnosis of carpal tunnel syndrome: study using a validated clinical tool as the reference standard.J Bone Joint Surg Am2014;96:e148

[20] Lin TY,Wu WT.Ultrasonography for the diagnosis of carpal tunnel syndrome: an umbrella review.J Neurol2022;269:4663-75.

[21] Wu CH,Özçakar L.Sonographic tracking of the upper limb peripheral nerves: a pictorial essay and video demonstration.Am J Phys Med Rehabil2015;94:740-7.

[22] Özdemir A,Güleç A,Cebeci H.Clinical, radiological, and electrodiagnostic diagnosis of pronator syndrome concurrent with carpal tunnel syndrome.J Hand Surg Am2020;45:1141-7

[23] Andreisek G,Burg D,Weishaupt D.Peripheral neuropathies of the median, radial, and ulnar nerves: MR imaging features.Radiographics2006;26:1267-87.

[24] Kollmer J.Imaging of the hand: What should be considered regarding the nerves?.Radiologe2021;61:375-81

[25] Graesser EA,Brogan DM.Future considerations in the diagnosis and treatment of compressive neuropathies of the upper extremity.J Hand Surg Glob Online2023;5:536-46 PMCID:PMC10382897

[26] Lundborg G.The pathophysiology of nerve compression.Hand Clinics1992;8:215-27.

[27] Rydevik B.Permeability of intraneural microvessels and perineurium following acute, graded experimental nerve compression.Scand J Plast Reconstr Surg1977;11:179-87

[28] Malik T,Abd-Elsayed A.Pathophysiology of work-related neuropathies.Biomedicines2023;11:1745 PMCID:PMC10296724

[29] Dahlin LB.The neurone and its response to peripheral nerve compression.J Hand Surg Br1990;15:5-10.

[30] Bridgeman C,Kothari MJ.Clinical and electrophysiological presentation of pronator syndrome.Electromyogr Clin Neurophysiol2007;47:89-92

[31] Chan L,Comstock BA.The relationship between electrodiagnostic findings and patient symptoms and function in carpal tunnel syndrome.Arch Phys Med Rehabil2007;88:19-24

[32] Concannon MJ,Petroski GF.The predictive value of electrodiagnostic studies in carpal tunnel syndrome.Plast Reconstr Surg1997;100:1452-8

[33] Freedman M,Pothast J,Simon J.Electrodiagnostic evaluation of compressive nerve injuries of the upper extremities.Orthop Clin North Am2012;43:409-16

[34] Greenwald D,Adams D,Moffit M.Effective surgical treatment of cubital tunnel syndrome based on provocative clinical testing without electrodiagnostics.Plast Reconstr Surg2006;117:87e-91e

[35] Tang DT,Davidge KM,Mackinnon SE.Nerve entrapment: update.Plast Reconstr Surg2015;135:199e-215e

[36] Azócar C,Orellana P,Liendo R.Intraoperative immediate strength recovery following lacertus fibrosus release in patients with proximal median nerve compression at the elbow.Int Orthop2023;47:2781-6

[37] Apard T,Duparc F.Percutaneous ultrasound-guided release of the lacertus fibrosus for median nerve entrapment at the elbow.Cardiovasc Intervent Radiol2022;45:1198-202