Ulnar nerve compression at the elbow: Is there still strong evidence in the literature to perform transposition, or should we only decompress the nerve?
Javier Robla Costales1, Mariano Socolovsky2, Javier Fernández Fernández1, Javier Ibáñez Plágaro1, José García Cosamalón1, Gilda Di Masi2, José María Otero2
1Complejo Asistencial de León, España
2Instituto de Neurociencias, Facultad de Medicina, Universidad de Buenos Aires, Argentina
ABSTRACT
After carpal tunnel syndrome, ulnar nerve compression at the elbow is the most frequent compression neuropathy of the upper limb. When conservative treatment fails, patients are considered for surgery. Several surgical procedures have been developed over the years, including simple neurolysis, submuscular transposition, subcutaneous transposition and epicondilectomy, but the discussion regarding which treatment option is best remains opened despite the enormous volume of literature existing in the field. At present, guidelines based on prospective randomized studies for choosing a determined operative technique are not available. In this review, seven recent published papers regarding the management of idiopathic, symptomatic ulnar nerve compression at the elbow are presented and analyzed. The first one reviews the history of surgery to relieve symptoms of ulnar nerve compression at the elbow. The second one is an analysis of the literature comparing different surgical techniques. The third one reviews and analyzes the technique of simple decompression of the ulnar nerve at the level of the elbow. The next two papers are prospective randomized controlled studies comparing simple decompression versus anterior subcutaneous transposition and submuscular transposition of the ulnar nerve. The last two articles analyze respectively the efficacy of surgical intervention in patients with symptoms of compression and normal electrodiagnostic studies, and the causes of the failed ulnar nerve surgery.
(1) History of the Surgical Treatment of Ulnar Nerve Compression at the Elbow (Neurosurgery, Vol. 49, No. 2, August 2001)
INFORMATION
Since ulnar compression as a clinical entity was described, many surgical options have been proposed to treat it. In 1816, Henry Earle described the first surgical technique to treat ulnar nerve compression at the elbow, consisting in sectioning the nerve proximal to the cubital tunnel. Pain was successfully controlled after this procedure, but secondarily the patient experienced sensory anesthesia in the territory of the ulnar nerve and paralysis of the little finger. This was the only surgical option known at that time. Conservative treatment for ulnar nerve palsy, such as hydrotherapy, massage, and application of electrical current, had many supporters in those years. In 1898, Benjamin Farquhar Curtis reported for the first time a new technique, the anterior subcutaneous transposition. According to some authors, anterior transposition was the treatment method of choice at the beginning of the 20th century. This treatment modality gained popularity based on the well comprehensible factors involved in the development of an ulnar neuritis: the repetitive friction and traction during elbow movements. Therefore, removing the nerve from its natural course into a more relaxed one is a logical treatment. Anterior transposition initially was performed subcutaneously. One of the most frequent criticisms of this procedure was the superficial position of the nerve, where it is more prone to trauma. In 1917, Rudolf Klaussner described a technique of transposing the nerve into a muscular bed, the anterior intramuscular transposition. During the first half of the twentieth century both techniques were carried out by many authors. In 1942, another technique for anterior transposition was described by Learmonth, namely the anterior submuscular transposition. Before the 1950s, decompression of the nerve was still an alternative surgical option, but it did not have many supporters. Geoffrey Vaughan Osborne, in 1957, proposed that ulnar nerve palsy was caused by compression and not by friction or traction as was generally believed. He reported the existence of a band of fibrous tissue bridging the head of the flexor carpi ulnaris, which lies directly over the ulnar nerve. He noticed that it was slack during elbow extension and tightened with elbow flexion, and the division of this band that nowadays bears his name was enough to relieve the symptoms. So, decompression was sufficient to relieve the symptoms. Feindel and Stratford, in 1958 reported a similar observation, the compression of the ulnar nerve in the cubital tunnel, and they proposed the same theory. Thus, Osborne, Feindel, and Stratford described nearly contemporarily the same clinical entity and therapy. At the same time, King and Morgan described another technique: the medial epicondylectomy. Since then and until today, the authors refer that no new concepts on surgical treatment of ulnar nerve palsy have been developed. In the last few years, an endoscopic approach was described, but this is nothing more than a simple decompression, focused only in dividing the arcuate ligament.
ANALYSIS
This interesting article describes some of the principal contributions to the management of the ulnar nerve compression at the elbow over the lasts two centuries, including a number of procedures designed to transpose or decompress the nerve. In 1898, Curtis described a nerve transposition, and since then influenced the following six decades of ulnar surgery. During this period, variations of the transposition technique were described. It was not till 1960, that simple decompression of the nerve started to be viewed as an alternative to transposition in order to solve the problem of the ulnar nerve at the elbow. The following four decades increased the interest, and also the discussion, regarding this topic. At the time this analyzed article was published (year 2001), it was clear that none of the different procedures was elected as the best for ulnar nerve compression at the elbow.(2) Surgical management of ulnar nerve compression at the elbow: an analysis of the literature (J Neurosurg 89:722–727, 1998)
INFORMATION
Despite the enormous volume of literature concerning surgical treatment of ulnar nerve compression at the elbow, which option is the most effective is still open to question. There is a dearth of prospective randomized studies on which to base guidelines for choosing one operative treatment over another. In this article the authors review the literature from January 1970 to July 1997 about the surgical treatment for cubital ulnar nerve compression. They describe that three are the main surgical techniques used during this year’s: medial epicondylectomy, simple decompression, and anterior transposition (subcutaneous, intramuscular, or submuscular). They analyze the results of each study and compare results of different surgical techniques.The authors searched the literature, using inclusion and exclusion criteria for reports, to avoid articles with few patients and posttraumatic cases. For grading the patients’ preoperative status, they used the classification of McGowan and the outcome was graded using the scale proposed by Alnot and Frajman. Outcome was also graded more simply as improved, unchanged, or worse. They performed statistical analyses to compare pre- and postoperative status among different treatment groups by using the chi-square and Kruskal–Wallis tests.From a total of 192 retrieved papers, 60 reports were included. Only three of them were prospective studies. Some studies offered a comparison of two or more surgical options; however, none of these was a randomized study. Most of the reports selected were studies discussing one of the main surgical techniques, not comparing it to another one. In total, 3024 patients of these reports were included. They found that McGowan grades were not equally divided, with a statistical significance in the statistical analysis. Patients with lower grades were seen more frequently in the group treated by simple decompression, followed by those who underwent anterior subcutaneous transposition and medial epicondylectomy, and less frequently in the groups treated by either anterior intramuscular or anterior submuscular transposition. In the statistical analysis of the surgical options, patients who underwent simple decompression had the most favorable outcome, followed in order by those who had anterior intramuscular transposition, medial epicondylectomy, and anterior submuscular transposition. Those patients who underwent anterior subcutaneous transposition had the worst outcome (p , 0.0001; Kruskal–Wallis test). When outcome was graded more simply, a significant difference was also found (p , 0.001; chi-square test). Patients who underwent simple decompression and anterior intramuscular transposition had the best outcome, followed by those who had medial epicondylectomy, anterior subcutaneous transposition, and, finally, anterior submuscular transposition. It is remarkable the fact that 2% of patients experienced deterioration even after surgical treatment. In the stratified analysis of the treatment modalities related to the patients’ preoperative status, for McGowan Grade 1, it was not possible to draw any conclusions, because of the few patients treated by anterior subcutaneous, intramuscular, and submuscular transposition. Statistically significant differences were not demonstrable for the patients with McGowan Grade 2. For patients with a preoperative McGowan Grade 3, those treated by anterior intramuscular transposition had the best outcome, whereas patients who underwent simple decompression or anterior submuscular transposition fared better than those treated by medial epicondylectomy or anterior subcutaneous transposition (p , 0.0001; Kruskal–Wallis test). The authors concluded that simple decompression is an adequate surgical procedure in cases of ulnar nerve compression at the elbow. However, they report that the anterior intramuscular transposition provides the best outcome for patients with the highest McGowan grade, followed by simple decompression and anterior submuscular transposition. The authors emphasize that this results must be interpreted carefully, and they suggest the need for prospective randomized studies.ANALYSIS
In our opinion, this paper should be interpreted carefully because few conclusions can be taken from it. Only two of the studies examined in this paper were prospective, and some of the remaining papers provided incomplete information. Furthermore, the McGowan and outcome grades were retrospectively assigned for each study in which they were not plainly reported. The preoperative condition of the patients was not equally divided among the different treatment groups, so, the cohorts were not homogeneous. Patients treated by simple decompression more frequently had a lower McGowan grade, whereas those treated by anterior submuscular transposition more often had a higher McGowan grade. This is important when determining the outcome, because patients with fewer symptoms are likely to have a better outcome, although in some reports the authors found that outcome was not related to preoperative status. Nevertheless such limitations, the authors conclude that simple decompression is the procedure of choice because of its technical simplicity, vascular preservation, and early rehabilitation. If the nerve is found subluxated, they will transpose it. We appreciate the efforts of the authors in carrying out the analysis of such information, and the fact that they recognize the limitations of their study.(3) 3. Ulnar nerve entrapment neuropathy at the elbow: simple decompression (Neurosurgery. 2004 Nov;55[5]:1150-3. Review.
INFORMATION
Ulnar nerve entrapment neuropathy at the elbow, or the cubital tunnel syndrome, is frequently encountered in neurosurgical practice as the second most common peripheral nerve entrapment after carpal tunnel syndrome. Patients typically present with weakness or atrophy of the hand as well as paresthesias in the ulnar nerve distribution. The diagnosis can be confirmed with a careful clinical examination and electrophysiological studies. Patients who have failed conservative therapy are considered for surgery. In the author’s opinion, although a number of surgical options are available, simple decompression of the ulnar nerve can achieve satisfactory results with appropriate patient selection. Patients with intraoperative nerve subluxation, advanced age, prolonged duration of symptoms, and weakness of intrinsic hand musculature are associated with poorer outcomes, and therefore may be amenable to a more complex procedure, as nerve transposition. The authors describe the relevant anatomy and surgical techniques for simple in situ decompression of the ulnar nerve at the elbow. The advantages of this procedure are its relative simplicity; preservation of vascular supply to the nerve, which remains in its anatomic location; and short postoperative recovery time, enabling early physical therapy and rehabilitation.ANALYSIS
This article describes the procedure of simple decompression of the ulnar nerve at the level of the elbow for patients with ulnar entrapment syndrome. No outcomes or results are provided, but the technique is well documented and the drawings are of value. The authors have comprehensively delineated the evaluation and conservative treatment and the decision making to advance toward surgical intervention. The basis for the simple decompression of the ulnar nerve is highlighted and remains the most common procedure for this level of entrapment. It is important to analyze each patient individually, defining if there is any intrinsic abnormality -as subluxation or prior elbow fracture-, and decide the best surgical technique on the basis of the preoperative evaluation and the intraoperative findings. A remarkable idea is that the majority of patients will benefit from the simple decompression.
(4) Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve, at the elbow (Neurosurgery 2005 Mar;56(3):522-30; discussion 522-30)
INFORMATION
The authors of this paper have designed and performed a prospective randomized controlled study to compare the clinical outcome of participants treated by simple decompression of the ulnar nerve versus anterior subcutaneous transposition. One hundred fifty-two patients, between 1999 and 2002, met the inclusion criteria and were randomized into two surgical groups: 75 were assigned to simple decompression, and 77 were assigned to subcutaneous transposition. Participants were followed for 1 year after surgery, evaluating the outcome with the McGill Pain Questionnaire and the SF-36 health status questionnaire. The main outcome measure was clinical outcome 1 year after surgery. The percentage of participants requiring reoperation within 1 year of the initial procedure was another outcome measure evaluated. Statistical analysis was performed by an independent and blinded investigator. Comparisons between groups were performed with the Student’s t test. After surgery, a gradual statistically significant and clinically important improvement in outcome was observed. Six weeks after surgery, only 12 of 75 participants in the SD group and 17 of 77 participants in the AST group were completely free of signs and symptoms. At 1 year of follow-up, 36 of 75 participants in the simple decompression group and 46 of 77 participants in the anterior subcutaneous transposition group were completely free of signs and symptoms. The difference in outcome between simple decompression and anterior subcutaneous transposition did not reach statistical significance. Nevertheless, the outcome scales used improved with time in both groups. The preoperative grade did not have any effect on the outcome, irrespective of the surgical procedure performed. Comparing both groups, outcome was not related to the presence of subluxation or luxation of the ulnar nerve. The main difference between both techniques according to the authors’ findings was in their complications rate: 9,6% in simple decompression, and 31,1% in anterior submuscular transposition. Those complications were mostly not serious, and included sensory loss over the scar, superficial infection, seroma, etc. Eighteen failures of the surgery were reported. Five participants refused further surgery and thirteen participants (6 in the simple decompression group) underwent reoperation within the study period, of whom 5 (2 in the simple decompression group) worsened after the first operation. Except for 4 participants, fibrosis around the ulnar nerve was found in all cases. The authors conclude that it is difficult to draw meaningful conclusions from this study, because the outcomes of these two surgical techniques are equivalent, but they remark that this is the first prospective, randomized, controlled study comparing single decompression and anterior subcutaneous transposition, with large homogeneity cohorts. So, they emphasize that both surgical options are equally effective for the treatment of idiopathic ulnar neuropathy at the elbow, but they favor simple decompression because of its surgical simplicity and fewer complications.
(5) 5. Randomized, prospective study comparing ulnar neurolysis in situ with submuscular transposition. (Neurosurgery 2006 Feb;58(2):296-304; discussion 296-304).
INFORMATION
In this article the authors design a randomized prospective study onto clarify the optimal surgical strategy for idiopathic, symptomatic ulnar nerve compression at the elbow in terms of overall outcome and morbidity. Previously to this paper, two prospective randomized studies were published both of which compared simple decompression with anterior subcutaneous transposition. So, they present another randomized study comparing simple decompression with another form of transposition, submuscular transposition.Forty-four surgical candidates were recruited prospectively and were randomized into the neurolysis (23 patients) or transposition (21 patients) arm of the study. Preoperative and postoperative outcomes were assessed symptomatically and by performance on McGowen and Louisiana State University Medical Center grading systems at 1 month, 6 months, and 1 year. In overall terms, both procedures were equally effective in producing objective neurological improvement (61% in the neurolysis group, 67% in the transposition group), there was no statistical significance in the difference in outcomes. In the different subgroups created for the stratified analysis (low-grade, high-grade lesions, and medium and high grade cases together), there was objective improvement in all of the groups, but also no statistical difference in outcome with the chi-square and Yates continuity correction. No person was made worse by the surgery neurologically, and only one patient failed to improve symptomatically. Wound complications, however, were more significant in the transposition group. Three of 21 in the transposition group that required hospitalization and intravenous antibiotics, compared with 0 of 23 in the neurolysis group experienced a deep wound infection. Among these patients, there were no unequivocal risks factors for infection. The difference in infection rates approached but did not reach statistical significance. They believe that some factors like local ischemia, the increased dead space and the increased time taken for transposition may contribute to the increased risk of infection in the transposition group. The authors conclude that idiopathic symptomatic ulnar nerve compression at the elbow is adequately treated by both neurolysis in situ and submuscular transposition. Submuscular transposition was associated with a higher incidence of complications; therefore, they suggest the simpler procedure of neurolysis in situ as the treatment of choice. Finally, the authors remark that their study is in complete agreement with the two other previously published randomized prospective studies.ANALYSIS
We will analyze these two papers together. We did it so because the two papers are designed in a similar fashion and their results are comparable. Both of them are well designed prospective randomized controlled studies. These studies use appropriate inclusion and exclusion criteria, clinical and electrodiagnostic confirmation of ulnar nerve entrapment at the elbow, an effective randomization protocol, and good follow-up with objective evaluation tools. These facts make their results trustable and applicable to daily practice. The first one, comparing simple decompression versus anterior subcutaneous transposition has a large cohort of patients, with 152 patients in total. The second one compares simple decompression versus submuscular transposition; the background idea of this study is to complete the comparison between simple decompression versus all the existing techniques for transposition, beginning by the previous prospective randomized trials. Several minor shortcomings can be found in these two papers, but it is important to highlight that these kinds of trials are the way to obtain true conclusions, and they are in the right direction. These reports are an important contribution to the existing literature on surgical treatment of ulnar neuropathy. Of them, one can conclude that simple decompression and the techniques for transposition analyzed produce similar clinical improvement in a majority of patients with ulnar nerve entrapment at the elbow, and there seems to be no significant difference between them regarding the final results. The only shortcoming that we want to remark is the small cohort of the second trial; we question if significant differences between the two groups would be appreciated with a larger cohort of patients. Even thought the authors failed to demonstrate the superiority of one technique over the other in terms of results, it is important to point out that if there are two techniques that have a similar outcome, the simpler and technically easier one should be usually applied as the first choice. The asymmetry in the rate of complications favors this choice. Therefore, simple decompression should turn into the preferred method to treat ulnar nerve compression at the elbow.(6) Simple decompression versus anterior submuscular transposition of the ulnar nerve in severe cubital tunnel syndrome: a prospective randomized study. (Neurosurgery 56:108-117, 2005)
INFORMATION
In this paper, the authors report the results of a prospective randomized study that compares simple decompression of the ulnar nerve versus submuscular transposition with flexor-pronator mass Z lengthening in patients with severe cubital tunnel syndrome. During five years, from 1998 to 2003, they recluted 70 patients with severe cubital tunnel syndrome for the study: 35 patients were submitted to simple decompression, and 35 patients were treated by anterior submuscular transposition. The preoperative status was determined by use of Dellon’s classification. The selected patients had Dellon’s Grade 3 (severe syndrome). The mean follow-up period after surgery was 47 and 46.94 months for each group.Postoperative clinical and electrophysiological outcomes were assessed 6 months after surgery in all 70 patients. According to the Bishop scoring system, which assesses subjective and objective parameters, 19 patients (54.3%) of simple decompression group were clinically graded as excellent, 9 (25.7%) were graded as good, and 7 (20%) were graded as fair; in submuscular transposition group, 18 patients (51.43%) were graded as excellent, 11 (31.43%) as good, and 6 (17.14%) as fair. In the follow-up of every patient no modifications were presented in the final Bishop score with regard to the score at the 6-month follow-up.
Neither severe complications nor recurrences were observed in those two groups. They did not found statistically significant difference between the two groups with regard to the clinical or the electrophysiological outcome. The surgical treatment gains in simple decompression group and submuscular transposition group were 80% and 82.86%, respectively (good to excellent results). The authors conclude that simple decompression is also an effective treatment for severe cubital tunnel syndrome, with some technical advantages .This advantages are the simplicity of the procedure, the short rehabilitation time, the little handling of the nerve, and the integrity of the muscular complex. This study demonstrate that the two surgical approaches, simple decompression and anterior submuscular transposition with Z lengthening, are equally effective in the treatment of severe cubital tunnel syndrome.
ANALYSIS
The present study is the first prospective randomized study on the surgical treatment of severe cubital tunnel syndrome. The authors selected a well-matched set of cohorts for this trial of surgery for cubital tunnel syndrome. Seventy patients with Dellon Grade 3 ulnar neuropathy had either simple decompression or neurolysis and submuscular placement of the nerve. Those patients were similar in age, sex, affected side and co morbidity, so, the cohorts were comparable. The patients were well randomized by using their reservation numbers in the hospital. The clinical and electroneuromyographic diagnosis of severe cubital tunnel syndrome was made in all the patients by the same blinded evaluator, a neurologist, which is one of the strengths of this study. The patients were successively evaluated by another blinded evaluator, a neurosurgeon, to confirm the indication at surgery and to evaluate the eventual criteria of exclusion by the randomization. Both of them are coauthors.The 35 patients having simple decompression were operated on by another author, whereas the operations on 35 patients having anterior submuscular placement were performed by a different neurosurgeon, coauthor too.
Clinical and electrophysiological outcomes were recorded by the neurologist who performed the original evaluation outcomes at 6 months. Outcomes were both good and quite comparable in both groups of patients.
Of interest, the authors used the submuscular placement of the nerve in all the patients who had a Dellon Grade 3 level of severity and were excluded of the study because of its criteria.
In our opinion, this study has been carefully performed and analyzed. Globally, it is an excellent trial because of the well selected cohorts, its thorough design and the well selected statistical analysis.
SYNTHESIS
After the description of the ulnar nerve transposition at the ending of the 19th century, and the revitalization of the simple decompression of the nerve in the 1960´s, the treatment of the ulnar nerve compression at the elbow did not evolved substantially. The fact that many different techniques are employed by different surgeons might mean that all, or may be none of these techniques, are good enough compared to the others to be elected unanimously as the standard one. During the years 2005 and 2006, new and important information was published regarding this field: the appearance of three well-done, prospective studies comparing transposition versus decompression of the nerve, changed the scenario. Having both techniques good results, one may conclude that simple decompression, due to its technical simplicity, less handling of the nerve, and minimal but demonstrable minor complication rate, should be the election in the vast majority of cases. Nerve transposition, both subcutaneously or submuscularly, remain reserved for special cases, e. g. when a nerve subluxation is diagnosed intraoperatively. The fact that both techniques are similar in terms of long-term results, could explain why it took more than a century to abandon the concept that ulnar nerve must be transposed routinely at the elbow when treating this compressive syndrome.