Martin-Grüber anastomosis: a literature review
Pedro Vinícius Rojek Halla, Maria Clara Cardoso Seba, Marcus Levy Gonçalves Mello Santos, Aimée Augusta Guilhermina Savelkoul, Paulo Henrique Pires de Aguiar
Abstract
Introduction: Martin-Grüber anastomosis (MGA) is an anomalous communicating branch between the median and ulnar nerves in the proximal forearm. Its incidence varies when different diagnostic methods are compared, being one of the most common nerve variations in the forearm. Method: A systematic literature review was conducted on PubMed using the terms “Median-ulnar anastomosis” or “Martin-Grüber Anastomosis”, resulting in 100 articles found. After limiting the search to a 10-year period (2014-2024), 34 results remained. Of these, 23 were selected by the authors, but only 21 articles were available. After full reading, 20 articles were included. Result: It was observed that this anastomosis, more often unilateral, is more prevalent on the right side, and may be associated with trisomy 21 and result from autosomal dominant inheritance. Its diagnosis is based on changes in compound motor action potential recorded in the intrinsic muscles of the hand during electrical stimulation of the ulnar and median nerves at the wrist and elbow. Discussion: MGA, a neural communication between the median and ulnar nerves in the forearm, triggers the transfer of nerve fascicles from the median to the ulnar nerve, resulting in a modification of the normal anatomical pattern of motor and sensory innervation of the hand. Clinically, it may contribute to misdiagnoses of conditions affecting the innervation of upper limb muscles, such as carpal tunnel syndrome, cubital tunnel syndrome, and Hansen’s neuropathy. This anatomical variant, often asymptomatic, is incidentally discovered during electromyography. Treatment is generally not indicated, except in the presence of significant neurological symptoms, where it may vary depending on the severity and nature of the symptoms presented by the patient. Conclusion: MGA is a common anatomical variation in the forearm, with variable prevalence and autosomal dominant inheritance. Its diagnosis is based on specific electrophysiological tests, while its presence may erroneously influence the diagnosis of various neurological conditions of the upper limb. Generally asymptomatic, therapeutic intervention is limited to situations where significant neurological symptoms arise, and the treatment method may vary according to the severity of the symptoms.
Keywords
References
1. Burakgazi AZ, Russo M, Bayat E, Richardson PK. Ulnar neuropathy with prominent proximal Martin-Gruber anastomosis. Int J Neurosci. 2014;124(7):542-6. http://doi.org/10.3109/00207454.2013.858336. PMid:24147570.
2. Burakgazi AZ, Russo M, Bayat E, Richardson PK. Underrecognized anomaly: proximal Martin-Gruber anastomosis at the elbow. J Clin Neurophysiol. 2014;31(1):31-4. http://doi.org/10.1097/WNP.0000000000000018. PMid:24492443.
3. Diz-Díaz J, Gómez-Muñoz E, Sañudo J, Maranillo E, Pascual-Font A, Vazquez T. Which is the function of a Martin-Gruber connection? Clin Anat. 2019;32(4):501-8. http://doi.org/10.1002/ca.23339. PMid:30664256.
4. Erra C, Coraci D, De Franco P, Granata G, Padua L. Peripheral nerve tumors associated with Martin-Gruber anastomosis. Clin Neurophysiol. 2015;126(2):428-30. http://doi.org/10.1016/j.clinph.2014.05.019. PMid:24969374.
5. Hefny M, Sallam A, Abdellatif M, Okasha S, Orabi M. Electrophysiological evaluation and clinical implication of Martin-Gruber anastomosis in healthy subjects. J Hand Surg Asian Pac Vol. 2020;25(1):87-94. http://doi.org/10.1142/S2424835520500125. PMid:32000594.
6. Kaur N, Singla RK, Kullar JS. Martin-Gruber anastomosis: a cadaveric study in North Indian population. J Clin Diagn Res. 2016;10(2):AC09-11. http://doi.org/10.7860/JCDR/2016/16447.7247. PMid:27042438.
7. Pasutharnchat N, Amornvit J, Taychargumpoo C, Santananukarn M. Mid palm recording technique, a new electrodiagnostic approach in Martin-Gruber anastomosis. Clin Neurophysiol Pract. 2020;5:79-82. http://doi.org/10.1016/j.cnp.2020.03.001. PMid:32280838.
8. Sharma MS. Commentary on prevalence of Martin-Gruber anastomosis in healthy subjects: an electrophysiological study from Raigarh, Chhattisgarh. Neurol India. 2021;69(4):956. http://doi.org/10.4103/0028-3886.325375. PMid:34507419.
9. Caetano EB, Vieira LÂ, Caetano MF, Cavalheiro CS, Razuk M Fo, Sabongi JJ No. Intramuscular Martin-Gruber anastomosis. Acta Ortop Bras. 2016;24(2):94-7. http://doi.org/10.1590/1413-785220162402149097. PMid:26981044.
10. Ertekin A. An assessment of Martin-Gruber anastomosis discrepancies between healthy individuals and patients with carpal tunnel syndrome in motor nerve conduction studies. Current Journal of Neurology. 2023;22(3):179-87. http://doi.org/10.18502/cjn.v22i3.13798. PMid:38011374.
11. Martin SP, Schauer KT, Czyrny JJ, Ablove RH. Electrophysiological findings in common median-ulnar nerve interconnections and their clinical implications. J Hand Surg Am. 2019;44(10):884-94. http://doi.org/10.1016/j.jhsa.2019.04.010. PMid:31272699.
12. Roy J, Henry BM, PĘkala PA, Vikse J, Saganiak K, Jerzy A, et al. Median and ulnar nerve anastomoses in the upper limb: a meta-analysis. Muscle Nerve. 2016;54(1):36-47. http://doi.org/10.1002/mus.24993. PMid:26599506.
13. Smith JL, Siddiqui SA, Ebraheim NA. Comprehensive summary of anastomoses between the median and ulnar nerves in the forearm and hand. J Hand Microsurg. 2019;11(1):1-5. http://doi.org/10.1055/s-0038-1672335. PMid:30911205.
14. Sinha MM, Sur A, Ughade JM. Prevalence of Martin-Gruber anastomosis in healthy subjects: an electrophysiological study from Raigarh, Chhattisgarh. Neurol India. 2021;69(4):950-5. http://doi.org/10.4103/0028-3886.325369. PMid:34507418.
15. Cavalheiro CS, Filho MR, Pedro G, Caetano MF, Vieira LA, Caetano EB. Clinical repercussions of Martin-Gruber anastomosis: anatomical study. Rev Bras Ortop. 2016;51(2):214-23. http://doi.org/10.1016/j.rboe.2016.02.003. PMid:27069892.
16. Sinanović O, Zukić S, Lepuzanović M, Tinjić N, Muftić M. Sensory fibers in Martin-Gruber anastomosis: an electrophysiological study. Psychiatr Danub. 2022;34(Suppl 10):173-6. PMid:36752258.
17. Erra C, Coraci D, De Franco P, Granata G, Padua L. Corrigendum to “Peripheral nerve tumors associated with Martin-Gruber anastomosis”. Clin Neurophysiol. 2016;127(10):3385. http://doi.org/10.1016/j.clinph.2016.06.002. PMid:27554246.
18. Nimma A, Bhat S. Bilateral Martin-Gruber and Marinacci anastomoses in the same patient: a case report. Neurodiagn J. 2020;60(3):185-94. http://doi.org/10.1080/21646821.2020.1804286. PMid:33006514.
19. Arányi Z, Böhm J. Unusual ultrasonographic findings after nerve trauma explained by Martin-Gruber anastomosis. Clin Neurophysiol. 2015;126(2):427-8. http://doi.org/10.1016/j.clinph.2014.05.017. PMid:24954300.
20. Gans P, van Alfen N. Nerve ultrasound showing Martin-Gruber anastomosis. Muscle Nerve. 2017;56(5):E46-7. http://doi.org/10.1002/mus.25746. PMid:28718962.
Submitted date:
05/16/2025
Reviewed date:
05/22/2025
Accepted date:
05/30/2025
Publication date:
08/27/2025
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