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Purpose: This report describes a bilateral persistent median artery (PMA) originating from the ulnar artery and terminating at different levels of the upper limb. The PMA coexisted with a bilateral bifid median nerve (MN) and two bilateral interconnections (ICs characterized with the symbol -) of the MN with the ulnar nerve (UN) (MN-UN) and a unilateral reverse IC (UN-MN). Emphasis was given to the artery's developmental background. Methods: The PMA was identified in an 80-year-old formalin-embalmed donated male cadaver. Results: The right-sided PMA terminated at the wrist, posterior to the palmar aponeurosis. Two neural ICs were identified: the UN joined the MN deep branch (UN-MN), at the forearm's upper third, and the MN deep stem joined the UN palmar branch (MN-UN), at the lower third (9.7 cm distally to the 1st IC). The left-sided PMA ended in the palm giving off the 3rd and 4th proper palmar digital arteries. An incomplete superficial palmar arch was identified by the contribution of the PMA, radial, and ulnar arteries. After the MN bifurcation into superficial and deep branches, the deep branches formed a loop, that was penetrated by the PMA. The MN deep branch communicated with the UN palmar branch (MN-UN). Conclusions: The PMA should be evaluated as a causative factor of carpal tunnel syndrome. The modified Allen's test and the Doppler ultrasound may detect the arterial flow and the angiography may depict the vessel thrombosis in complex cases. PMA could also be a "salvage" vessel for the hand supply, in radial and ulnar artery trauma. [ABSTRACT FROM AUTHOR]

Abstract Background Martin–Gruber anastomosis (MGA) is one of the most common anomalous innervations of the upper limb. It may alter the usual clinical picture and electrophysiological characteristics of median nerve (MN) injury or ulnar nerve (UN) injury. Aim To determine the mutual relation between MGA and carpal tunnel syndrome (CTS) regarding their association and to explore whether certain patterns of MGA are more prevalent in patients with CTS. Methods This study included 100 forearms of 64 subjects. They were 37 subjects complaining of unilateral or bilateral clinical symptoms of idiopathic CTS according to the criteria of the American Academy of Neurology and 27 subjects healthy or having traumatic lesions in either the upper or lower limbs with no neurological disorders. Electrophysiological studies of the MN and UN for the confirmation of CTS as well as the validation of MGA were done. Results By electrophysiological examination, MGA was encountered in 22% forearms of all the studied groups, mostly females. MGA type II and type III were the commoner types, each occurring in 40.9%, while type I and type IV each occurred in 9.1%. MGA type II was prevalent in the control group, while type III associated subjects with only clinical CT symptoms. Conclusion MGA is not prevalent in patients with CTS. Different types of MGA are present in CTS, but MGA was not implicated in the occurrence, severity, or electrodiagnostic features of CTS.

The median-to-ulnar communicating branch (MUC) is an asymptomatic variant of the upper limb innervation that can lead to interpretation errors in routine nerve conduction studies. The diagnosis of carpal tunnel syndrome (CTS) or ulnar nerve lesions can be complicated by the presence of MUC. In this study, we describe electrophysiological features of MUC in CTS patients presenting to our clinic. We enrolled MUB cases from consecutive CTS patients referred to our laboratory between the years 2014 and 2019. MUC was present in 53 limbs (36 patients) from the studied population. MUC was bilateral in 53% of patients. MUC type II was the most common subtype (74%), followed by types III and I; more coexisting MUC types were found in the majority of tested limbs. A positive correlation was demonstrated between the severity of CTS and the presence of positive onset, faster CV, or a double component of the compound muscle action potentials. We emphasize the importance of suspecting the presence of MUC in CTS in the presence of a positive onset or a double component in routine motor conduction studies.

Introduction: Median and ulnar motor nerve conduction study recording from median-innervated 2nd lumbrical and ulnar-innervated 1st palmar and 2nd dorsal interossei is designated in electrodiagnostic evaluation of carpal tunnel syndrome. In this technique, both responses are recorded by the same surface recording electrode placing over their shared motor point in mid-palm. To the best of our knowledge, this technique has never been utilized in demonstration of Martin-Gruber anastomosis. Case reports: By applying this technique to the conventional CMAP comparison method, the authors accordingly demonstrated Martin-Gruber anastomosis in four cases. Three presented with focal mononeuropathies of the upper limbs, including a severe carpal tunnel syndrome, a mild to moderate carpal tunnel syndrome, and an ulnar neuropathy. One was a normal individual. Significance: This report described a new electrophysiological pattern of MGA. Adding the mid-palm recording to conventional CMAP comparison method provides a broader view in terms of innervation of MGA. This technique is not complicated and can be added to the electrophysiological investigation for complete studying of the innervated muscles in MGA.

Carpal tunnel syndrome is a clinical syndrome of numbness, tingling, burning, and/or pain on hands associated with localized compression of the median nerve at the wrist. The common connection between the median and ulnar nerves, called Martin-Gruber anastomosis (MGA), may cause changes in electroneurography findings in the forearms. MGA is asymptomatic and usually diagnosed incidentally during the neurophysiological assessment of the median and ulnar nerves. The presence of MGA is not a rare condition and thus we have to keep this fact in mind in routine clinical and neurophysiological examinations to avoid some diagnostic and therapeutic mistakes. [ABSTRACT FROM AUTHOR]

The median-to-ulnar communicating branch (MUC) is an asymptomatic variant of the upper limb innervation that can lead to interpretation errors in routine nerve conduction studies. The diagnosis of carpal tunnel syndrome (CTS) or ulnar nerve lesions can be complicated by the presence of MUC. In this study, we describe electrophysiological features of MUC in CTS patients presenting to our clinic. We enrolled MUB cases from consecutive CTS patients referred to our laboratory between the years 2014 and 2019. MUC was present in 53 limbs (36 patients) from the studied population. MUC was bilateral in 53% of patients. MUC type II was the most common subtype (74%), followed by types III and I; more coexisting MUC types were found in the majority of tested limbs. A positive correlation was demonstrated between the severity of CTS and the presence of positive onset, faster CV, or a double component of the compound muscle action potentials. We emphasize the importance of suspecting the presence of MUC in CTS in the presence of a positive onset or a double component in routine motor conduction studies. [ABSTRACT FROM AUTHOR]

Background: Martin Gruber anastomosis is a common anomaly in forearm between median and ulnar nerve. It may lead to technical pitfall or misinterpretation of nerve conduction studies of these nerves.Objective: The aim of this studywasto determine the prevalence of Martin-Gruber Anastomosis (MGA) in healthy Raigarh subjects by electrophysiological evaluation.Subjects and Methods: A cross-sectional study was conducted in both forearms of 140 healthy subjects. Electrophysiological studies were performed to measure compound muscle action potentials of abductor pollicis brevis, abductor digiti minimi and first dorsal interosseous muscles when stimulated from distal (wrist) and proximal (elbow) site. Descriptive and analytic statistics were performed using SPSS software.Results: MGA was found in 44 (15.71%) out of the 280 forearms in 30 (21.4%) out of 140 subjects. It was present in 14 males and 16 females. Most frequent type of MGA was of Type II in both genders. The MGA was found bilaterally in 14 subjects. In unilateral cases 8 subjects had MGA in right forearm and 8 subjects had MGA in left forearm.Conclusions: The high prevalence of MGA in the Raigarh population suggest that the orthopedics and neurosurgeons should also take in account this anatomic anomaly while analyzing median and ulnar nerve conduction studies or needle electromyography. [ABSTRACT FROM AUTHOR]

Anomalous innervations are commonly encountered on electrodiagnostic testing and may be mistaken for a pathological process, especially if seen in multiple nerves. While crossover of median-to-ulnar fibers in the forearm (Martin-Gruber anastomosis) has been frequently described, the corresponding ulnar-to-median crossover (Marinacci anastomosis) is much less commonly seen. There have been no reported cases of both of these anomalous innervations occurring together. We describe a novel case of bilateral Martin-Gruber and Marinacci anastomoses in the same patient. The importance of the case lies in the fact that the multiple pseudo-conduction blocks that result from these crossovers could potentially be misinterpreted as being pathological in nature, illustrating the need for electromyographers to be familiar with common anomalous innervations in the upper extremity and with techniques to identify them. [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to determine the prevalence of Martin-Gruber Anastomosis (MGA) in healthy Egyptian subjects, and to discuss the available literature regarding MGA subtypes and their clinical implications. Methods: An electrophysiological study was conducted in both forearms of 140 healthy subjects. This included the ulnar and median nerves. Compound muscle action potentials were recorded from abductor pollicis brevis, abductor digiti minimi, and first dorsal interosseous muscles. Other measurements included the compound motor action potential amplitude and its innervation ratio. Results: MGA was found in 56 of the 280 forearms. This included 20 men and 36 women. Type II MGA subtype was the most frequent in both genders. The MGA was bilateral in 6 subjects and more frequent on the right side. The highest mean amplitude and innervation ratio were recorded at first dorsal interosseus muscle. Conclusions: The prevalence of MGA in the studied sample of the Egyptian population is 20%. It is important for Hand, Orthopaedic and Neurosurgeons to be aware of this anatomic variation in order to explain paradoxical motor and sensory loss in patients. [ABSTRACT FROM AUTHOR]

Introduction Martin–Gruber anastomosis (MGA) is one of the most common anomalous innervations present in the body. Missing these anomalous innervations may easily be mistaken for technical pitfalls or even for actual pathology. Aim The aim of the current study was to determine the presence and the frequency of MGA by electrophysiological examination in a sample of Egyptian subjects. Subjects and methods It is a cross-sectional study of consecutive apparently healthy volunteers. The study included 200 forearms from 100 apparently healthy Egyptian volunteers in a single-center public-hospital-based electromyography laboratory. Electrophysiological studies in the form of motor conduction study for the median and ulnar nerves were performed by recording the hypothenar, first dorsal inerosseous, and thenar muscles. Qualitative data were analyzed using Pearson’s Chi-square test and Fisher’s exact test. Results The present study included 69 (69%) women. MGA was found in 39 (19.5%) forearms of 26 (26%) subjects electrophysiologically. There was no statistical significant difference between the occurrence of MGA in men versus women (P=0.127). The most common form was MGA to the first dorsal interosseous muscle. It was present in 30 (15%) forearms of 24 (24%) subjects. MGA to thenar muscles was present in 13 (6.5%) forearms of 12 (12%) subjects. MGA to the abductor digiti minimi muscle was present in five (2.5%) forearms of five (5%) subjects. Conclusion Martin–Gruber anastomosis is present in Egyptians. The frequency of occurrence of MGA in a sample of Egyptian subjects was found to be 26% in electrophysiological examination.

The Martin-Gruber anastomosis (MGA) is the anastomosis in which the anastomotic branch originates proximally from the median nerve (MN) and unites distally with the ulnar nerve (UN). This is the most common form of "anomalous" innervation that have been reported in the upper part of the forearm. This study has a purpose to report the incidence, type, topography of MGA found and access the lenght and diameter of these anastomosis. For this study, 60 anterior forearms (30 right and 30 left) from adult adavers were dissected. The presence of MGA was verified in 18,33% forearms. Single MGA anastomosis was found in 90,9%, corresponding to type A in 10%, type B in 10% and type C in 80%, while double MGA was found in 9,1%, both been duplification of type C. Anastomoses were found mainly on the right side in anatomical examination (seven against four). No statistically significant difference was found between men and women regarding the frequency of the MGA. In pattern I, the course of of MGA was transveral in 90% of cases, and arched in 10%, while in pattern II, the superior connection was tranversal and the inferior was oblique. The MGA passed in front of the ulnar artery in 3 cases and behind in 9 cases. The average length of the anastomosis was 6.2 cm, while the average diameter was 1.14 mm. The anastomoses between MN and UN are clinically relevant so therefore the knowledge of the existance of the MGA in the forearm, types of presentation and topography is extremely important for the correct diagnosis of neuropathies as well as essential to diferrentiate a complete damage from a partial injuries of peripheral nerves. [ABSTRACT FROM AUTHOR]

Introduction: The most frequently described anomalous neural connections between the median and ulnar nerves in the upper limb are: Martin-Gruber anastomosis (MGA), Marinacci anastomosis (MA), Riche-Cannieu anastomosis (RCA), and Berrettini anastomosis (BA). The reported prevalence rates and characteristics of these anastomoses vary significantly between studies.Methods: A search of electronic databases was performed to identify all eligible articles. Anatomical data regarding the anastomoses were pooled into a meta-analysis using MetaXL 2.0.Results: A total of 58 (n = 10,562 upper limbs) articles were included in the meta-analysis. The pooled prevalences were: MGA, 19.5% (95% confidence interval [CI], 16.2%-23.1%); MA, 0.7% (95% CI, 0.1%-1.7%); RCA, 55.5% (95% CI, 30.6%-79.1%); and BA, 60.9% (95% CI, 36.9%-82.6%). The results also showed that MGA was more commonly found unilaterally (66.8%), on the right side (15.7%), following an oblique course (84.8%), and originating from the anterior interosseous nerve with a prevalence of 57.6%.Conclusions: As anastomoses between the median and ulnar nerves occur commonly, detailed anatomical knowledge is essential for accurate interpretation of electrophysiological findings and reducing the risk of iatrogenic injuries during surgical procedures. Muscle Nerve 54: 36-47, 2016. [ABSTRACT FROM AUTHOR]

Background: In nerve conduction laboratory, various types of cases are encountered. These are generally referred for electrophysiological investigation of the most common syndromes such as carpel tunnel syndrome where there is partial or total sparing of the thenar muscles from the effect of compression of their nerve supply. So for the assessment of traumatic and entrapment lesions of median and ulnar nerves, the knowledge of these anastomosis is important. Aims and Objectives: The purpose of this study was to assess the prevalence of this anastomosis in healthy individuals, to draw attention of clinicians or surgeons from neurophysiology field to this anastomosis, and to avoid misinterpretations of different studies of needle electromyography and other nerve conduction studies. Materials and Methods: A total of 150 healthy volunteers were selected from the medical students aged 17-30 years. Surface recording electrodes were placed on the hand abductor pollicis brevis, abductor digiti minimi, and the first dorsal interossei (FDI) of each subject. Using surface electrodes, we percutaneously stimulated the median and ulnar nerves at the wrist and the elbow. Rectangular pulses of 0.2 ms duration were used and the stimulus strength was supramaximal. Compound muscle action potential (CMAP) was recorded. CMAP from the FDI, hypothenar, and thenar muscles larger (at least 1.0 mV) on median nerve stimulation at the elbow than at the wrist and that from one or more of these sites larger (at least 1.0 mV) on stimulation of ulnar nerve at the wrist than at the elbow were accepted as indicators of the presence of the MGA. Analysis was carried out using Statistical Package for Social Sciences, version 10.0. P-value o0.05 was considered as statistically significant. Results: The type of anastomosis frequently observed was type II, which was observed in 12 subjects; type I was observed in 3; type I + II was observed in 2; and type III was observed in 1 subject. Conclusion: Because of its high incidence and different electrodiagnostic considerations, MGA should be considered to be of great clinical significance for correct diagnosis and for planning appropriate therapy in peripheral lesions of median and ulnar nerves. [ABSTRACT FROM AUTHOR]

Introduction It is important to understand the presence of Martin-Gruber anastomosis in patients with complete ulnar neuropathy at the elbow. Case Report: We describe a patient with complete ulnar neuropathy at the elbow and Martin-Gruber anastomosis in the forearm, mimicking incomplete ulnar neuropathy with complete conduction block in the forearm segment. Ultrasonography of the ulnar nerve around the elbow demonstrated severe swelling of the ulnar nerve, which was compatible with severe ulnar neuropathy at the elbow. Conclusions: This case report demonstrates that combination of ultrasonography with electrophysiological studies can provide more detailed information about the changes of nerve structures and lesion sites. Muscle Nerve, 2013 [ABSTRACT FROM AUTHOR]

The branching pattern of the ulnar nerve in the forearm is of great importance in anterior transposition of the ulnar nerve for decompression after neuropathy of cubital tunnel syndrom and malformations resulting from distal end fractures of the humerus. In this study, 37 formalin-fixed forearms were used to demonstrate the muscular branching patterns from the main ulnar nerve to the flexor carpi ulnaris muscle (FCU) and ulnar part of the flexor digitorum profundus muscle (FDP). Eight branching patterns were found and classified into four groups according to the number of the muscular branches leaving the main ulnar nerve. Two (Group I) and three (Group II) branches left the main ulnar nerve in 18 and 17 forearms respectively. The remaining two specimens had four (Group III) and five (Group IV) branches each. Usually one or two branches were associated with the innervation of the FCU. However, in 2 cases, three and in one, four branches to FCU were observed. The FDP received a single branch in all cases, except in four, all of which had two branches. In six forearms, a common trunk was observed arising from the ulnar nerve to supply the FCU and FDP. The distribution of the muscular branches to the revealed muscles was outlined in figures and the distance of the origin of these branches from the interepicondylar line was measured in millimeters. The first muscular branch leaving the main ulnar nerve was the FCU-branch in all specimens. The terminal muscular branch of the ulnar nerve to the forearm muscles arose at the proximal 1/3 of the forearm in all specimens. In 7 forearms, Martin-Gruber anastomosis in form of median to ulnar was observed. [ABSTRACT FROM AUTHOR]

Objective: To estimate the real occurrence of the motor median-to-ulnar nerve anastomosis in the proximal forearm (Martin–Gruber anastomosis, MGA), as its frequency varies between 6 and 44% in the literature and to investigate the incidence of the ulnar-to-median nerve anastomosis in the distal forearm.Methods: Compound muscle action potentials (CMAP) recorded over thenar, hypothenar, and first dorsal interosseus muscle on median or ulnar nerve stimulation at wrist and elbow and collision blocks of the median and ulnar nerve were compared in a group of 50 healthy volunteers. Particular precautions were undertaken in order to avoid false positive results due to stimulus spread to the neighboring nerve. Cases of uncertain MGA were classified as either MGA or non-MGA on the basis of posterior probabilities estimated by discriminant analysis.Results: The estimated frequency of MGA was 54% using the potential comparison method and 46% using the collision technique. An ulnar-to-median nerve anastomosis was not found in any subject.Conclusions: While the MGA is very common, the ulnar-to-median nerve anastomosis is a rarity. Standard nerve conduction studies of the median nerve with CMAP recordings solely over thenar will detect less than 14% of MGA cases. [Copyright &y& Elsevier]

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