Cubital Tunnel Syndrome Info In-depth Evidence

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview

• Cubital tunnel syndrome management involves a review of related anatomy, clinical presentation, and current management options with an emphasis on contemporary outcomes research [1].
• A subset of patients with cubital tunnel syndrome may benefit from earlier referral for hand surgery evaluation and earlier surgery [2].
• Surgical failures are more frequent in cases of cubital tunnel syndrome than in cases of carpal tunnel syndrome [4].
• Management of failed cubital tunnel syndrome is made exceedingly difficult by the previous surgical procedure and resultant scarring of the nerve [4].
• Patients with failed cubital tunnel syndrome may present with persistence of the same preoperative symptoms with no change in clinical status [4].
• Patients with failed cubital tunnel syndrome may present with relief of symptoms for several months to years followed by recurrent problems [4].
• Patients with failed cubital tunnel syndrome may exhibit new symptoms of neurologic loss or pain after cubital tunnel surgery [4].
• Amyotrophic lateral sclerosis or Pancoast tumors can be accompanied by ulnar nerve symptoms that mimic cubital tunnel syndrome [4].
• If sensory loss far exceeds motor complaints, a sensory neuropathy should be considered in the differential diagnosis of cubital tunnel syndrome [4].
• If motor complaints exceed sensory complaints, compression in the Guyon canal should be considered, especially if proximal extrinsic hand muscles are normal and there is no thenar atrophy [4].
• If there is additional thenar atrophy, radiculopathy or rarely compression in the thoracic outlet with the very rare Gilliatt “true” neurogenic thoracic outlet syndrome should be considered [4].
• If extrinsic motors are equally involved, brachial plexus neuritis can be considered, or upper motor neuron disease if deep tendon reflexes are increased [4].
• Electrodiagnostic studies by an experienced examiner are critical in the differential diagnosis and localization of the level of compression for cubital tunnel syndrome [4].
• Failure to relieve symptoms may imply an incomplete decompression of the primary surgical procedure or an incorrect diagnosis [4].
• Recurrence of symptoms after a period of 6 months or more after initial relief usually implies a new site of ulnar nerve compression in the previous surgical field [4].
• Severe causalgia-type pain at the elbow radiating into the medial aspect of the forearm suggests a neuroma of the MABC [4].
• Severe causalgia-type pain in the ulnar nerve distribution suggests an injury to the ulnar nerve itself [4].
• A proximal percussion test above the area of the previous surgical site along the course of the basilic vein will result in pain and/or paresthesia in the distribution of the MABC if there is a neuroma of this nerve [4].
• Percussion along the course of the ulnar nerve above the area of the previous surgery will result in paresthesia and pain in the ulnar nerve distribution if there is a problem with the ulnar nerve itself [4].
• Palpation along the course of the ulnar nerve in the distal forearm progressing to the region of the surgical site will result in deep pain distal to the previous surgical site if a new compression point has developed at the site of the distal surgical exposure [4].
• The finding of deep pain distal to the previous surgical site is common if great care has not been taken to ensure smooth transposition of the ulnar nerve from its distal position in the forearm underneath the flexor carpi ulnaris to the transposition site at the elbow [4].
• The patient-reported outcome of surgical treatment of cubital tunnel syndrome is good but is affected by preoperative symptom severity [6].
• Surgery was effective in treating cubital tunnel syndrome with more than 90% of patients cured or showing improvement in a multicenter study with a mean follow-up of 92 months [7].
• More rigorous scientific studies are needed to determine the most effective surgical approaches for cubital tunnel syndrome [8].
• Endoscopic cubital tunnel decompression has gained popularity with early short-term results being encouraging, showing satisfactory outcomes and minimal complications [9].
• The purpose of recent reviews is to summarize the most up-to-date literature regarding cubital tunnel syndrome and propose a treatment algorithm to provide clarity about the challenges of treating this complex patient population [10].
• There is currently no consensus on the best surgical treatment of cubital tunnel syndrome [11].
• Carpal tunnel and cubital tunnel syndrome requiring surgery is more common in deprived patients and occurs at an earlier age [17].
• The 2008 meta-analysis represents the best cumulative evidence to date examining the surgical management of cubital tunnel syndrome [21].
• The EVOCU study aims to provide an evidence-based recommendation on which method has the best efficacy, patient treatment experience, and safety profile for cubital tunnel syndrome by comparing open and endoscopic release [30].
• Most surgeons use more than one operative procedure in their treatment of patients with cubital tunnel syndrome [37].
• The selection of the operative procedure for cubital tunnel syndrome is influenced by patient factors and surgeon preference [37].

Anatomy & Pathophysiology

Epidemiology & Prevalence

• Cubital tunnel syndrome is the second most common entrapment neuropathy of the upper extremity behind carpal tunnel syndrome [3].
• Cubital tunnel syndrome is the second most common peripheral nerve entrapment disorder of the upper extremity after carpal tunnel syndrome [23].
• The incidence of cubital tunnel syndrome is reported to be nearly 21 cases per 100,000 people per year [3].
• The prevalence of cubital tunnel syndrome in the United States population is between 1.8% and 5.9% according to the most recent population study [44].

Anatomical Susceptibility & Biomechanics

• The ulnar nerve’s posterior location and superficial course make it particularly susceptible to irritation, compression, and traction particularly with elbow motion [23].
• A cadaver study using three-dimensional modeling found that elbow flexion diminished the volume of the cubital tunnel and elongated the nerve [23].
• Elbow flexion can contribute to cubital tunnel syndrome through both compression and nerve tension [23].
• The humeral trochlea protrudes into the cubital tunnel during elbow flexion, causing dynamic morphologic changes in the ulnar nerve [69].
• With elbow flexion, the ulnar nerve did not move appreciably in the distal–proximal direction directly at the cubital tunnel, but maximal excursion was in the fatty region proximal to the elbow [67].
• Tearing of the ulnar collateral ligament significantly increased elbow valgus laxity, which in turn elongated the ulnar nerve during simulated throwing motion [70].
• Increased elbow flexion in patients with cubital tunnel syndrome influences the intraneural blood flow of the ulnar nerve [84].
• Shoulder position changes the ulnar nerve strain around the elbow in living patients with cubital tunnel syndrome [82].
• Ulnar nerve gliding was most severe during passive wrist movement in elbow flexion and forearm supination [89].
• A cadaveric study could not detect a definitive effect of elbow deformity on ulnar nerve strain or demonstrate the extent of acceptable clinical elbow deformity [92].

Sites of Compression & Etiology

• The most common site of ulnar nerve entrapment is about the elbow [23].
• Ulnar nerve compression may stem from space occupying lesions [23].
• Ulnar nerve compression may occur proximally at the ligament of Struthers (medial intermuscular septum) [23].
• Ulnar nerve compression may occur distally from fascial bands between the ulnar and humeral heads of the flexor carpi ulnaris [23].
• Ulnar nerve compression may occur about the roof of the cubital tunnel in patients with an anconeus epitrochlearis [23].
• The dorsal ulnar cutaneous nerve arises from the ulnar nerve approximately 6 cm proximal to the wrist [3].
• The dorsal ulnar cutaneous nerve innervates the ulnar aspect of the dorsum of the hand [3].
• Diminished sensation in the distribution of the dorsal ulnar cutaneous nerve localizes the lesion proximal to this branch and likely within the cubital tunnel [3].
• Preserved dorsal sensation in the distribution of the dorsal ulnar cutaneous nerve may localize the lesion to Guyon canal in the wrist [3].
• Definitions for the degree of ulnar nerve instability at the elbow are not uniformly agreed upon [35].

Clinical Presentation & Pathophysiology

• Pain is not a common symptom of cubital tunnel syndrome, but an aching pain localized to the elbow or proximal forearm may be reported [3].
• Patients typically present with worsening sensory numbness of the hand and digits in an ulnar distribution [3].
• Symptoms may progress to involve motor weakness of the hypothenar musculature and clawing of the hand due to loss of intrinsic musculature [3].
• Clinical manifestations include dysesthesias in the small finger and ulnar side of the ring finger exacerbated by prolonged elbow flexion [23].
• Later in the disease process, patients may complain of grip weakness and hand atrophy [23].
• More advanced findings include intrinsic muscle weakness of the hand, hypothenar wasting, and resulting functional impairment [23].
• The severity of cubital tunnel syndrome is divided into three categories: mild dysfunction (intermittent paresthesias and subjective weakness), moderate dysfunction (intermittent paresthesias and measurable weakness), and severe dysfunction (persistent paresthesias and measurable weakness) [44].
• The increased pressure in the cubital tunnel could be important, as exposure to a lesser extraneural pressure by repetitive non-maximum elbow flexion might be more deleterious [81].

Classification

Epidemiology and Presentation

• Cubital tunnel syndrome is the most common form of entrapment of the ulnar nerve and the second most common nerve compression syndrome of the upper extremity [25].
• Pain is not a common symptom of cubital tunnel syndrome, though an aching pain localized to the elbow or proximal forearm may be reported [3].
• Symptoms progress to involve motor weakness of the hypothenar musculature and clawing of the hand due to loss of intrinsic musculature [3].
• Patients with cubital tunnel syndrome present later in the course of their disease than patients with carpal tunnel syndrome [5].

Diagnostic Localization and Imaging

• Diagnosis is made by clinical history and physical examination, with adjunct electrophysiology and imaging as needed [3].
• A detailed ulnar nerve examination should assess sensation in the distribution of the dorsal ulnar cutaneous nerve, which innervates the ulnar aspect of the dorsum of the hand [3].
• Diminished sensation in the dorsal ulnar cutaneous nerve territory localizes the lesion proximal to this branch and likely within the cubital tunnel [3].
• Preserved dorsal sensation localizes the lesion to Guyon canal in the wrist [3].
• Electrophysiology is helpful to ensure proper diagnosis and targeted treatment [3].
• Subluxation or dislocation of the ulnar nerve during elbow flexion can be palpated and may be associated with increased symptoms [3].
• Ulnar nerve mobility may be associated with dislocation of the medial head of the triceps [3].
• Ultrasonography demonstrates hypoechoic, enlarged nerve fascicles with a sensitivity of 46% to 100% and specificity of 43% to 97% [3].
• MRI demonstrates enlarged, T2-hyperintense nerve lesions proximal to a point of compression with distal muscle atrophy, with sensitivity as high as 95% and specificity of 80% [3].
• High-resolution ultrasound is an effective diagnostic tool for cubital tunnel syndrome and its etiologies, showing good correspondence to clinical and ENMG classifications [46].
• High-definition ultrasound can be used for diagnosis of cubital tunnel syndrome with an accuracy on par with electrophysiological methods [79].

Severity Grading Systems

• McGowan introduced a three-grade classification system for ulnar nerve function in 1950 [78].
• McGowan Grade I lesions are classified as minimal, with symptoms of paresthesias and numbness but no weakness [78].
• McGowan Grade II lesions are intermediate, characterized by wasting of the interosseous muscles [78].
• McGowan Grade III lesions are severe, characterized by complete intrinsic muscle paralysis [78].
• The difference between McGowan Grade II and Grade III is based solely on the degree of muscle weakness [78].
• McGowan’s system is essentially a preoperative rating of intrinsic muscle function [78].
• There is currently no consensus on any scoring system for cubital tunnel syndrome [78].
• Available scoring systems either rate subjective symptoms, which are difficult to quantify, or fail to compare preoperative and postoperative conditions [78].
• Further development of a classification system may be warranted to standardize treatment for ulnar nerve instability [35].

Differential Diagnosis and Mimics

• Amyotrophic lateral sclerosis or Pancoast tumors can be accompanied by ulnar nerve symptoms [4].
• If sensory loss far exceeds motor complaints, a sensory neuropathy should be considered [4].
• If extrinsic motors are equally involved, brachial plexus neuritis can be considered or upper motor neuron disease if the deep tendon reflexes are increased [4].
• Electrodiagnostic studies by an experienced examiner are critical in the differential diagnosis and localization of the level of compression [4].

Post-Surgical Classification

• The classification of failed cubital tunnel syndrome is similar to that for carpal tunnel syndrome [4].
• Patients may have persistence of the same preoperative symptoms with no change at all in their clinical status [4].
• Patients may have relief of symptoms for several months to years and then have recurrent problems [4].
• Patients may exhibit new symptoms of neurologic loss or pain (or both) after the cubital tunnel surgery [4].
• Severe causalgia-type pain at the elbow radiating into the medial aspect of the forearm suggests a neuroma of the medial antebrachial cutaneous nerve [4].
• A proximal percussion test above the area of the previous surgical site along the course of the basilic vein will result in pain and/or paresthesia in the distribution of the medial antebrachial cutaneous nerve if there is a neuroma of this nerve [4].

Clinical Presentation

Epidemiology and Demographics

• Cubital tunnel syndrome occurs more frequently in men than in women [48].
• Men with cubital tunnel syndrome are more likely to present with muscle atrophy than women [15].
• Cubital tunnel syndrome in pediatric or adolescent patients is rare [26].

Symptoms and Signs

• Pain is not a common symptom of cubital tunnel syndrome, but an aching pain localized to the elbow or proximal forearm may be reported by patients [3].
• Unlike carpal tunnel syndrome, pain is not a typical symptom in most cases of early cubital tunnel syndrome [48].
• The onset of symptoms is often gradual, presenting as a combination of weakness, numbness, and paresthesias in the distribution of the ulnar nerve [48].
• Patients may report pain and numbness along the ulnar forearm and elbow [23].
• Loss of vibratory and light touch sensation gradually progresses to loss of two-point discrimination [48].
• Motor deficits and muscle wasting occur later in the disease process than sensory changes [48].
• Progression of the disease involves motor weakness of the hypothenar musculature and clawing of the hand due to loss of intrinsic musculature [3].
• In severe cases, intrinsic atrophy and clawing occur, with progression to positive Froment and Wartenberg signs [48].
• Patients may complain of grip weakness and hand atrophy later in the disease process [23].

Physical Examination and Diagnostic Localization

• The diagnosis is made by clinical history and physical examination, with adjunct electrophysiology and imaging as needed [3].
• A detailed ulnar nerve examination should assess sensation in the distribution of the dorsal ulnar cutaneous nerve to localize the lesion [3].
• The dorsal ulnar cutaneous nerve innervates the ulnar aspect of the dorsum of the hand and arises from the ulnar nerve approximately 6 cm proximal to the wrist [3].
• Diminished sensation in the dorsal ulnar cutaneous nerve territory localizes the lesion proximal to this branch, likely within the cubital tunnel [3].
• Preserved dorsal sensation suggests the lesion may be localized to Guyon canal in the wrist [3].
• Identification of dislocating structures is important as it may affect surgical decision making [3].
• Clinical evaluation is paramount in the diagnosis of cubital tunnel syndrome because electrodiagnostic testing often is not sufficiently sensitive to detect changes associated with the syndrome [24].
• There is no consensus reference standard for the diagnosis of Cubital Tunnel Syndrome, and provocative tests have inadequate or inconsistent sensitivity and specificity [16].
• Diagnosis should be discussed in terms of probabilities rather than certainties [16].
• Reported sensitivities for Tinel’s test and elbow flexion/compression test for cubital tunnel syndrome are 70% and 91%, respectively [45].
• False-positive rates of 20% to 30% have been reported for Tinel’s test and elbow flexion/compression test in asymptomatic individuals [45].
• Many conditions can mimic cubital tunnel syndrome, including amyotrophic lateral sclerosis, Pancoast tumors, sensory neuropathy, Guyon canal compression, radiculopathy, thoracic outlet syndrome, brachial plexus neuritis, and upper motor neuron disease [4].
• If motor complaints exceed sensory complaints and proximal extrinsic hand muscles are normal with no thenar atrophy, compression in the Guyon canal should be considered [4].
• Nearly forty percent of patients with a provisional diagnosis of CubTS had either another nerve pathology or a normal test [28].

Imaging and Electrophysiology

• Ultrasonography can demonstrate hypoechoic, enlarged nerve fascicles with a sensitivity of 46% to 100% and specificity of 43% to 97% [3].
• MRI can demonstrate enlarged, T2-hyperintense nerve lesions proximal to a point of compression with distal muscle atrophy, with sensitivity as high as 95% and specificity of 80% [3].
• EMG/NCS may be ordered to confirm the extent of compression as well as sites, including identifying additional sites of compression such as above the elbow in the cervical spine [23].
• Elbow flexion testing exacerbates dysesthesias in the small finger and ulnar side of the ring finger [23].

Presentation Timing and Severity

• Patients with carpal tunnel syndrome present earlier in the course of their disease than patients with cubital tunnel syndrome [5].
• Patients often present later during the course of cubital tunnel syndrome because pain is not a typical early symptom [48].

Investigations

Clinical Presentation and History

• Cubital tunnel decompression is associated with prior trauma to the anatomic site [77].

Physical Examination

• Preserved dorsal sensation may localize the lesion to Guyon canal in the wrist [3].
• There is no consensus reference standard for the diagnosis of Cubital Tunnel Syndrome [16].
• Provocative tests have inadequate or inconsistent sensitivity and specificity for Cubital Tunnel Syndrome [16].
• Diagnosis of Cubital Tunnel Syndrome should be discussed in terms of probabilities rather than certainties [16].

Electrodiagnostic Testing

• Nearly forty percent of patients with a provisional diagnosis of Cubital Tunnel Syndrome had either another nerve pathology or a normal nerve conduction test [28].
• Most patients concomitantly treated for ulnar nerve compression at the elbow and carpal tunnel syndrome have objective findings of both conditions [73].

Imaging

• MRI and ultrasonography imaging techniques are being utilized to aid in the diagnosis of ulnar neuropathy at the elbow [3].
• These imaging techniques can be helpful adjuncts in the preoperative setting and when evaluating recurrent or persistent symptoms [3].
• The ulnar nerve cross-sectional area measured by ultrasound imaging is useful for the diagnosis of cubital tunnel syndrome [64].
• Ulnar nerve cross-sectional area is most significantly different between patients and controls at the medial epicondyle [64].
• Power Doppler ultrasound demonstrated high predictive value for severe cubital tunnel syndrome defined by axonal loss [80].
• MRI is an effective diagnostic modality for cubital tunnel syndrome [53].
• Clinicians should be aware of primary synovial chondromatosis as a causative factor of cubital tunnel syndrome [53].
• Only a small number of individuals with MRI evidence of an anconeus epitrochlearis muscle had clinical evidence of ulnar neuropathy [66].

Treatment

Non-Operative Management

• Conservative management for cubital tunnel syndrome includes activity modification, anti-inflammatory medications, and therapy [3].
• First-line treatment includes NSAIDs, night splints to avoid elbow flexion, elbow pads, and behavioral modification [23].
• The majority of patients with mild or moderate symptoms benefit from conservative treatment [27].
• Conservative treatment is usually attempted for 3 months before surgical treatment is considered [44].
• Svernlöv reported improvement in 89.5% of patients with mild-to-moderate cubital tunnel syndrome treated conservatively with elbow extension splinting, patient education, and activity modification [44].
• Non-operative treatment of cubital tunnel syndrome in pediatric and adolescent patients is unlikely to resolve symptoms [29].

Operative Management: General Principles and Outcomes

• Surgery was effective in treating cubital tunnel syndrome with more than 90% of patients cured or showing improvement [7].
• None of the surgical techniques has demonstrated universal superiority above all others, but all appear to be effective in the treatment of cubital tunnel syndrome [55].
• Most surgeons use more than one operative procedure in their treatment of patients with cubital tunnel syndrome, and selection is influenced by patient factors and surgeon preference [37].
• In a study of 235 patients who underwent cubital tunnel decompression between 2010 and 2014, 88.5% had satisfactory outcomes [23].
• Patients with longer and more severe preoperative symptoms were more likely to report unsatisfactory outcomes after cubital tunnel decompression [23].
• In a follow-up study of 119 operated cases at least 2 years after anterior transmuscular transposition, 75% of patients who underwent unilateral procedures reported improvement [13].
• In a follow-up study of 119 operated cases at least 2 years after anterior transmuscular transposition, 68% of patients with bilateral surgery reported improvement [13].
• Nonsmokers had significantly better outcomes than smokers following anterior transmuscular transposition of the ulnar nerve [13].
• There were no significant differences in outcomes for patients with workers’ compensation/litigation, obesity, concomitant carpal tunnel syndrome, or abnormal preoperative nerve conduction studies following anterior transmuscular transposition [13].
• Patients with severe and chronic compression, atrophy, and dense sensory loss should be cautioned that surgery will arrest progression and improve symptoms but will not return normal strength or sensation [13].
• In mild to moderate cases, surgery results in return of “painless” functional sensation to the digits innervated by the ulnar nerve and reinnervation of muscles innervated by the ulnar nerve distal to the cubital tunnel [13].

Operative Management: In Situ Decompression

• In situ decompression has a reported success rate of 65.3% to 94.1% [3].
• In situ decompression of the ulnar nerve is a reliable treatment for cubital tunnel syndrome with a low failure rate [36].
• Simple decompression through a small skin incision can be recommended for the treatment of cubital tunnel syndrome if the indication is appropriate [40].
• In a study of 18 elbows in 17 patients treated by simple decompression using only a 1.5–2.5 cm skin incision, clinical results were evaluated as excellent for four elbows, good for ten, and fair for four [40].
• Improvement of symptoms occurred in all patients treated with simple decompression through a small skin incision [40].
• Dislocation of the ulnar nerve was not observed in patients treated with simple decompression through a small skin incision [40].
• In situ decompression has a complication rate of 3% [3].
• The rate of secondary surgery for in situ release is 2.5% [3].
• In a prospective randomized study, in situ decompression had an 11% occurrence of postoperative hematoma, none of which required operative intervention [44].
• In a retrospective study comparing in situ release with transposition, the complication rate for in situ release was 2.5% [44].
• The overall rate of secondary surgery for both in situ release and transposition of the ulnar nerve together was 6% [44].
• In a study of 56 patients, only 7% had recurrent symptoms postoperatively following in situ decompression [44].
• In patients with ulnar neuropathy and no evidence of active subluxation, in situ decompression is feasible and cost-effective [3].
• A recent trend has been for more surgeons to perform in situ decompression rather than ulnar nerve transposition due to similar outcomes but higher complication and revision surgery rates for transposition [3].
• In a meta-analysis, both in situ decompression and decompression with transposition showed clinical improvement with no significant differences in electrodiagnostic or clinical outcomes [23].
• In situ decompression shows increased strain value in flexion [23].
• Revision surgery after simple decompression is more common in patients with a previous elbow fracture or dislocation, younger patients (<50 years old), tobacco users, and patients having surgery for mild symptoms [44].

Operative Management: Anterior Transposition

• Anterior transposition of the ulnar nerve can be performed subcutaneously, intramuscularly, or in a submuscular fashion [3].
• Subcutaneous transposition has a reported success rate of 77.7% to 94% [3].
• Anterior transposition involves more mobilization of the nerve and more extensive degrees of dissection of the soft tissues around the elbow compared to in situ decompression [3].
• Complication rates for anterior transposition are reported to be up to 14%, likely due to a more extensive dissection required [3].
• Rates of secondary surgery were higher in patients undergoing anterior transposition (11.1%) compared to in situ release (2.5%) [3].
• Anterior transposition should be considered in patients where ulnar nerve subluxation/dislocation is apparent and reproducible during elbow flexion on physical examination [3].
• Anterior transposition demonstrates increased regional strain when the arm is in extension [23].
• In a prospective randomized study, patients with transposed nerves had greater narcotic consumption, scar sensitivity, and poorer patient-rated elbow evaluation prior to 8 weeks after surgery compared to in situ decompression [44].
• Differences in morbidity between in situ decompression and anterior transposition were not significant after 8 weeks [44].
• The transposition group had a 15% frequency of hematoma, only one of which required operative debridement [44].
• In a retrospective study comparing in situ release with transposition, the complication rate for transposition was 11% [44].
• The subluxated or “perched” ulnar nerve with elbow flexion after in situ release should be transposed to prevent symptomatic instability [44].
• Transposition is required in 21% to 34% of in situ releases, most often in younger males [44].
• In a retrospective review of 67 in situ releases, 45% were unstable and required transposition [44].
• At 5 years after surgery, patients with instability that required transposition were less likely to have persistent symptoms and more likely to have a lower Disabilities of the Arm, Shoulder, and Hand (DASH) score than the stable cohort who had simple in situ release [44].
• No significant differences in results have been reported after release of the cubital tunnel, subcutaneous anterior transposition, or submuscular anterior transposition [44].
• Good results have been reported in ulnar neuropathies treated by anterior nerve transposition and construction of a fasciodermal sling from the antebrachial fascia overlying the flexor pronator muscles [44].
• Treatment of refractory tardy ulnar nerve palsy may require removal of the nerve from its groove, neurolysis if necessary, and anterior transposition of the nerve to the flexor surface of the elbow [44].

Operative Management: Endoscopic Techniques

• Endoscopic techniques are being increasingly utilized for cubital tunnel syndrome [3].
• Outcomes for endoscopic techniques have been similar to in situ decompression for symptom relief and return to work, with higher scar satisfaction among patients [3].
• The current study demonstrates similar effectiveness between the endoscopic (ECTuR) and open (OCTuR) techniques for treatment of idiopathic cubital tunnel syndrome with similar outcomes, complication profiles, and reoperation rates [54].
• Equivalent clinical outcomes, patient satisfaction and recurrence rates were observed between open and endoscopic techniques [59].
• The endoscopic technique was associated with a significantly lower complication rate compared to open decompression [59].
• Preliminary data demonstrate that dual endoscopic carpal and cubital tunnel release is a safe and effective treatment option for patients who present with concurrent cubital and carpal tunnel syndromes recalcitrant to nonsurgical management [50].

Operative Management: Medial Epicondylectomy

• Medial epicondylectomy for cubital tunnel syndrome provides relief or improvement of symptoms in most patients, with minimal morbidity [51].
• The procedure is recommended for patients with cubital tunnel syndrome associated with abnormal nerve-conduction velocity [41].
• Good results of 45% to 93% have been reported after medial epicondylectomy [44].
• Persistent medial elbow pain has been reported in up to 45% of patients 6 months after medial epicondylectomy [44].
• In comparing minimal medial epicondylectomy with partial medial epicondylectomy, no difference in improvement was found, and the minimal epicondylectomy technique was recommended [44].
• Both minimal medial epicondylectomy and anterior subcutaneous transposition can be used for the treatment of cubital tunnel syndrome with a high rate of satisfaction [52].
• Younger age, associated workers’ compensation claims, lesser disease severity, and preoperative opioid use were all associated with the need for revision surgery after medial epicondylectomy [23].
• Care must be taken when performing medial epicondylectomy not to compromise the integrity of the ulnar collateral ligament [23].

Operative Management: Revision and Recurrent Symptoms

• Recurrent or persistent symptoms after surgery can be difficult to treat [3].
• In patients with recurrent symptoms, a significant proportion (77%) can experience either motor and/or sensory improvement after revision cubital tunnel decompression [3].
• 23% of patients with recurrent symptoms achieve complete recovery from symptoms at final follow-up after revision cubital tunnel decompression [3].
• Reoperation after primary surgery of cubital tunnel syndrome gave satisfactory results for patients who fail conservative treatment [19].
• Management of surgical failures is made exceedingly difficult by the previous surgical procedure and resultant scarring of the nerve [4].
• Severe causalgia-type pain at the elbow radiating into the medial aspect of the forearm suggests a neuroma of the medial antebrachial cutaneous nerve (MABC) [4].
• For the surgical treatment of recurrent cubital tunnel, some authors advocate for revision neurolysis with amniotic membrane wrapping [23].
• Of 18 patients who underwent revision neurolysis with amniotic membrane allograft wrapping following at least two previous failed decompressions, significant improvements were noted in VAS and DASH outcome measures as well as pinch strength and elbow motion [23].
• Ulnar neurolysis with amniotic membrane allograft wrapping is a safe and effective treatment for patients with debilitating recurrent cubital tunnel syndrome [23].
• In patients with recurrent symptoms, improvement after revision surgery may be due to pain relief even when neurologic findings do not improve [3].

Complications

Operative Complications

• Complications from in situ decompression and anterior transposition include ulnar instability, infection, and medial antebrachial cutaneous nerve injury [3].
• The reported complication rate for in situ decompression is 3% [3].
• The reported complication rate for anterior transposition is up to 14% [3].
• Higher complication rates for anterior transposition are likely due to the more extensive dissection required to complete the nerve transposition [3].
• Rates of secondary surgery were higher in patients undergoing anterior transposition compared to in situ release (11.1% vs 2.5%) [3].
• The short-term complication rates of cubital tunnel surgery are low at 3.2% [31].
• Short-term complication rates for cubital tunnel surgery are higher for patients with chronic kidney disease [31].
• Surgical failures in cubital tunnel syndrome are more frequent than in carpal tunnel syndrome [4].
• Management of surgical failures in cubital tunnel syndrome is made exceedingly difficult by the previous surgical procedure and resultant scarring of the nerve [4].
• New compression points can develop at the site of distal surgical exposure if great care is not taken to ensure smooth transposition of the ulnar nerve from its distal position in the forearm underneath the flexor carpi ulnaris to the transposition site at the elbow [4].
• Poor outcomes and unnecessary revision surgeries for cubital tunnel syndrome can be avoided with intraoperative attention to 7 structures distal to the medial epicondyle [60].

Recurrent or Persistent Symptoms

• Improvement in recurrent symptoms after revision surgery may be due to pain relief even when neurologic findings do not improve [3].
• Results of revision surgery for recurrent or persistent cubital tunnel syndrome are less predictable and satisfying than primary surgery [39].
• Improvements in pain and paresthesias are noted in approximately 75% of patients after revision procedures for cubital tunnel syndrome [68].

Recovery

• The patient-reported outcome of surgical treatment for cubital tunnel syndrome is good but is affected by preoperative symptom severity [6].
• This study documents resolution of symptoms in an extra-ulnar distribution after cubital tunnel release [12].
• Reliable, reproducible, and valid outcomes measures are lacking from the surgical literature for cubital tunnel syndrome [18].
• The short-term complication rates of cubital tunnel surgery are low (3.2%), but higher for patients with chronic kidney disease [31].
• This treatment approach leads to superior range of motion, improved or resolved ulnar neuropathy, and good to excellent long-term functional outcomes [32].
• There are no significant differences in long-term outcomes after open and retractor-endoscopic in situ decompression of the ulnar nerve in cubital tunnel syndrome [38].
• Patients with an AE experience quicker symptom improvement after cubital tunnel release than those without the anomalous muscle [42].

Key Evidence

• [L5] This article reviews related anatomy, clinical presentation, and current management options for cubital tunnel syndrome with an emphasis on contemporary outcomes research. [1] (10.1016/j.jhsa.2015.03.011)
• [L3] A subset of patients with cubital tunnel syndrome may benefit from earlier referral for hand surgery evaluation and earlier surgery. [2] (10.1177/15589447211058821)
• [L4] Patients with carpal tunnel syndrome present earlier in the course of their disease than patients with cubital tunnel syndrome. [5] (10.1016/j.jhsa.2007.03.009)
• [L3] The patient-reported outcome of surgical treatment of cubital tunnel syndrome is good but is affected by preoperative symptom severity. [6] (10.1016/j.jhsa.2009.05.014)
• [L4] Surgery was effective in treating cubital tunnel syndrome with more than 90% of patients cured or showing improvement. [7] (10.1016/j.otsr.2014.03.009)
• [L4] More rigorous scientific studies are needed to determine the most effective surgical approaches for cubital tunnel syndrome. [8] (10.1007/s12178-020-09650-y)
• [L5] Endoscopic cubital tunnel decompression has gained popularity with early short-term results being encouraging, showing satisfactory outcomes and minimal complications. [9] (10.1136/jisakos-2020-000506)
• [L4] The purpose of this review is to summarize the most up-to-date literature regarding cubital tunnel syndrome and propose a treatment algorithm to provide clarity about the challenges of treating this complex patient population. [10] (10.1016/j.jhsg.2022.07.008)
• [L5] There is currently no consensus on the best surgical treatment of cubital tunnel syndrome. [11] (10.1016/j.ocl.2012.07.017)
• [L3] This study documents resolution of symptoms in an extra-ulnar distribution after cubital tunnel release. [12] (10.1007/s11552-014-9688-9)
• [L4] Men with cubital tunnel syndrome are more likely to present with muscle atrophy than women. [15] (10.1177/1558944716643096)
• [L4] There is no consensus reference standard for the diagnosis of Cubital Tunnel Syndrome, and provocative tests have inadequate or inconsistent sensitivity and specificity; diagnosis should be discussed in terms of probabilities rather than certainties. [16] (10.1016/j.jhsa.2011.03.021)
• [L4] Carpal tunnel and cubital tunnel syndrome requiring surgery is more common in deprived patients and occurs at an earlier age. [17] (10.1177/1753193420939384)
• [L3] Reliable, reproducible, and valid outcomes measures are lacking from the surgical literature for cubital tunnel syndrome. [18] (10.1016/j.jhsa.2009.05.010)
• [L4] Reoperation after primary surgery of cubital tunnel syndrome gave satisfactory results for patients who fail conservative treatment. [19] (10.1055/s-2001-19937)
• [L1] This report represents the best cumulative evidence to date examining the surgical management of cubital tunnel syndrome. [21] (10.1016/j.jhsa.2008.03.006)
• [L4] Clinical evaluation is paramount in the diagnosis of cubital tunnel syndrome because electrodiagnostic testing often is not sufficiently sensitive to detect changes associated with the syndrome. [24] (10.1016/j.hcl.2013.08.019)
• [L5] Cubital tunnel syndrome is the most common form of entrapment of the ulnar nerve and the second most common nerve compression syndrome of the upper extremity. [25] (10.1016/s0749-0712(21)00356-5)
• [L3] Cubital tunnel syndrome in pediatric or adolescent patients is rare and can be treated successfully with surgical intervention. [26] (10.1016/j.jhsa.2012.01.016)
• [L2] The majority of patients suffering from cubital tunnel syndrome with mild or moderate symptoms benefit from conservative treatment. [27] (10.1177/1753193408098480)
• [L4] Nearly forty percent of patients with a provisional diagnosis of CubTS had either another nerve pathology or a normal test. [28] (10.1016/j.jse.2020.01.064)
• [L4] Non-operative treatment of cubital tunnel syndrome in pediatric and adolescent patients is unlikely to resolve symptoms. [29] (10.1016/s0363-5023(11)60063-4)
• [L2] This study aims to provide an evidence-based recommendation on which method has the best efficacy, patient treatment experience, and safety profile for cubital tunnel syndrome by comparing open and endoscopic release. [30] (10.1186/s12891-023-06234-y)
• [L4] The short-term complication rates of cubital tunnel surgery are low (3.2%), but higher for patients with chronic kidney disease. [31] (10.1016/j.jhsa.2017.01.020)
• [L4] This treatment approach leads to superior range of motion, improved or resolved ulnar neuropathy, and good to excellent long-term functional outcomes. [32] (10.1016/j.jse.2023.12.003)
• [L4] Definitions for the degree of ulnar nerve instability at the elbow are not uniformly agreed upon, and further development of a classification system may be warranted to standardize treatment. [35] (10.1055/s-0038-1665548)
• [L4] In situ decompression of the ulnar nerve is a reliable treatment for cubital tunnel syndrome with a low failure rate. [36] (10.1177/1753193408101467)
• [L4] Most surgeons use more than one operative procedure in their treatment of patients with cubital tunnel syndrome and the selection of the operative procedure is influenced by patient factors and surgeon preference. [37] (10.1007/s11552-008-9133-z)
• [L3] There are no significant differences in long-term outcomes after open and retractor-endoscopic in situ decompression of the ulnar nerve in cubital tunnel syndrome. [38] (10.1227/neu.0b013e3182846dbd)
• [L4] Results of revision surgery for recurrent or persistent cubital tunnel syndrome are less predictable and satisfying than primary surgery. [39] (10.1016/j.jhsa.2011.11.024)
• [L4] [40] (10.1054/jhsb.2002.0821)
• [L4] The procedure is recommended for patients with cubital tunnel syndrome associated with abnormal nerve-conduction velocity. [41] (10.2106/00004623-198062060-00016)
• [L3] Patients with an AE experience quicker symptom improvement after cubital tunnel release than those without the anomalous muscle. [42] (10.1016/j.jhsa.2017.06.033)
• [L2] [45] (10.1016/j.jhsa.2008.05.022)
• [L4] HRU proved to be an effective diagnostic tool for cubital tunnel syndrome and its etiologies, showing good correspondence to clinical and ENMG classifications. [46] (10.1016/j.otsr.2014.03.008)
• [Paper] [48] (10.1016/j.hcl.2007.06.001)
• [L4] Preliminary data demonstrate that dual endoscopic carpal and cubital tunnel release is a safe and effective treatment option for patients who present with concurrent cubital and carpal tunnel syndromes recalcitrant to nonsurgical management. [50] (10.1007/s11552-013-9552-3)
• [L5] Medial epicondylectomy for cubital tunnel syndrome provides relief or improvement of symptoms in most patients, with minimal morbidity. [51] (10.1016/s0749-0712(21)00325-5)
• [L3] Both methods can be used for the treatment of cubital tunnel syndrome with a high rate of satisfaction. [52] (10.1016/j.jse.2005.10.007)
• [Case_report] MRI is an effective diagnostic modality, and clinicians should be aware of primary synovial chondromatosis as a causative factor of cubital tunnel syndrome. [53] (10.1177/1758573216683396)
• [L1] The current study demonstrates similar effectiveness between the endoscopic (ECTuR) and open (OCTuR) techniques for treatment of idiopathic cubital tunnel syndrome with similar outcomes, complication profiles, and reoperation rates. [54] (10.1177/1558944715616097)
• [L4] None of the techniques in this review has demonstrated universal superiority above all others, but all appear to be effective in the treatment of cubital tunnel syndrome. [55] (10.3389/fsurg.2018.00048)
• [L1] [59] (10.1136/jisakos-2016-000112)
• [L5] Poor outcomes and unnecessary revision surgeries for cubital tunnel syndrome can be avoided with intraoperative attention to 7 structures distal to the medial epicondyle. [60] (10.1177/1558944718771390)
• [L1] The ulnar nerve CSA measured by US imaging is useful for the diagnosis of cubital tunnel syndrome (CuTS), and is most significantly different between patients and controls at the medial epicondyle. [64] (10.1016/j.apmr.2017.08.467)
• [L4] Only a small number of individuals with MRI evidence of an AEM had clinical evidence of ulnar neuropathy. [66] (10.1016/j.jse.2018.03.021)
• [L5] With elbow flexion, the ulnar nerve did not move appreciably in the distal–proximal direction directly at the cubital tunnel, but maximal excursion was in the fatty region proximal to the elbow. [67] (10.1016/j.jhsa.2012.03.016)
• [L4] [68] (10.1016/j.jhsa.2018.03.057)
• [L5] The humeral trochlea protrudes into the cubital tunnel during elbow flexion, causing dynamic morphologic changes in the ulnar nerve. [69] (10.1016/j.jse.2022.05.026)
• [L5] Tearing of the UCL significantly increased elbow valgus laxity, which in turn elongated the ulnar nerve during simulated throwing motion. [70] (10.1016/j.jse.2019.02.009)
• [L3] Most patients concomitantly treated for ulnar nerve compression at the elbow and carpal tunnel syndrome have objective findings of both conditions. [73] (10.1177/1558944718813669)
• [L4] Cubital tunnel decompression is associated with prior trauma to the anatomic site. [77] (10.1016/j.jhsa.2017.07.009)
• [L5] [78] (10.5435/00124635-199809000-00003)
• [L4] [79] (10.1177/1753193416635803)
• [L3] Power Doppler ultrasound demonstrated high predictive value for severe cubital tunnel syndrome defined by axonal loss. [80] (10.1177/15589447221127334)
• [L4] The increased pressure in the cubital tunnel could still be important, as exposure to a lesser extraneural pressure by repetitive non-maximum elbow flexion might be more deleterious. [81] (10.3109/2000656x.2012.747962)
• [L4] To the best of our knowledge, this is the first study showing that shoulder position changes the ulnar nerve strain around the elbow in living patients with CubTS. [82] (10.1016/j.jse.2015.01.014)
• [L3] Increased elbow flexion in patients with CuTS influences the intraneural blood flow of the ulnar nerve. [84] (10.1016/j.jhsa.2021.06.024)
• [L4] Ulnar nerve gliding was most severe during passive wrist movement in elbow flexion and forearm supination. [89] (10.5397/cise.2024.00934)
• [L5] The study could not detect a definitive effect of elbow deformity on ulnar nerve strain or demonstrate the extent of acceptable clinical elbow deformity. [92] (10.1186/s12891-022-05786-9)

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