Evaluation of the Scratch Collapse Test for Carpal and Cubital Tunnel Syndrome-A Prospective, Blinded Study

Sensitivity, Specificity, and Reliability of the CTS-6 for Carpal Tunnel Syndrome Administered by Medical Assistants

PURPOSE

The CTS-6 can be used clinically to diagnose carpal tunnel syndrome (CTS) and has demonstrated high levels of interrater reliability when administered by nonexpert clinicians. Our purpose was to assess sensitivity (Sn), specificity (Sp), and interrater reliability of the CTS-6 when administered by medical assistants (MAs).

METHODS

A series of patients presenting to an academic, upper-extremity surgery clinic were screened using CTS-6 between May and June of 2023. The CTS-6 was first administered by one of seven MAs and then by one of four fellowship-trained upper-extremity surgeons. In addition to recording baseline demographics, the results of each of the six history and examination components of the CTS-6 were recorded, as was the cumulative CTS-6 score (0-26). Surgeons were blinded to the scores obtained by the MAs. Interrater reliability (Cohen's kappa) was determined between the groups with respect to the diagnosis of CTS and the individual CTS-6 items. Sensitivity/specificity was calculated for the MA-administered CTS-6, using the score obtained by the surgeon as the reference standard. A CTS-6 score >12 was considered diagnostic of CTS.

RESULTS

Two hundred eighteen patients were included, and 26% had a diagnosis of CTS. The MA group demonstrated a Sn/Sp of 84%/91% for the diagnosis of CTS. Interrater reliability was substantial (Cohen's kappa: 0.72, 95% confidence interval: 0.62-0.83) for MAs compared with hand surgeons for the diagnosis of CTS. For individual CTS-6 components, agreement was lowest for the assessment of two-point discrimination (fair) and highest for the assessment of subjective numbness (near perfect).

CONCLUSIONS

The CTS-6 demonstrates substantial reliability and high Sn/Sp when administrated by MAs in an upper-extremity clinic. These data may be used to inform the development of CTS screening programs and future investigations in the primary care setting.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

The Scratch-Collapse Test: Are Electrodiagnostic Changes Measurable?

INTRODUCTION

Carpal tunnel syndrome is commonly managed by hand and upper extremity surgeons. Though electrodiagnostics are considered the gold standard diagnosis, the scratch collapse test (SCT) was introduced to address uncertainty, despite remains controversial. To address this, we sought to identify if the SCT can correlate with EDS studies if the SCT can identify actual changes in measures of nerves.

METHODS

We reviewed patients who underwent electrodiagnostic studies (EDX) and SCT for carpal tunnel syndrome (CTS). Demographic data as well as sensorimotor amplitudes, latencies, and velocities on nerve conduction and electromyography were collected. Analogous values based on SCT findings were analyzed for statistical significance.

RESULTS

Three hundred fifty patients with CTS were included. Sensory and motor velocities and amplitudes were significantly lower in patients with a positive SCT. Motor values were independent of age, though younger patients had larger measured changes. Obese patients did not show any motor EDX changes with the scratch collapse test, though thinner patients did. All changes were seen in nerve conduction only.

CONCLUSIONS

Carpal tunnel can be a difficult problem to diagnose as one study does not singularly determine the condition. The SCT was introduced to facilitate easier diagnosis. We demonstrate that the SCT correlates with changes on nerve conduction studies, especially in relation to decreased amplitudes and velocities, suggesting that it does identify changes in nerve with compression, specifically axonal, and myelin damage. These findings support the use of the SCT maneuver to evaluate and diagnose in appropriate patients.

On the Physiology of the Sensory-Collapse Test

The sensory-collapse test (formerly the scratch-collapse test) is a physical examination finding describing a momentary inhibition of external shoulder rotation following light stimulation of an injured nerve in the ipsilateral limb. Similar to other physical examination tests designed to interrogate nerve compression, such as the Phalen or Tinel tests, its test characteristics demonstrate variation. There remains speculation about the test's existence and anatomic basis. The literature of mammalian reflex physiology was reviewed with an emphasis on the sensory pathways from the upper extremity, the extrapyramidal system, and newly discovered pathways and concepts of nociception. A clear reflex pathway is described connecting the stimulus within an injured nerve through the afferent pathways in the fasciculus cuneatus in the spinal cord directly to the lateral reticulospinal tract, resulting in the inhibition of extensor muscles in the proximal limb (eg, shoulder) and activation of the limb flexors by acting upon alpha and gamma motor neurons. The sensory-collapse test represents a reflex pathway that teleologically provides a mechanism to protect an injured nerve by withdrawal toward the trunk and away from the noxious environment.

Cubital Tunnel Syndrome: Does a Consensus Exist for Diagnosis?

PURPOSE

Cubital tunnel syndrome (CuTS) is the second most common compressive neuropathy of the upper extremity. We aimed to determine a consensus among experts using the Delphi method for clinical criteria that could be validated further for the diagnosis of CuTS.

METHODS

The Delphi method was used for establishing a consensus among a group of expert panelists, comprising 12 hand and upper-extremity surgeons, who ranked the diagnostic clinical importance of 55 items related to CuTS on a scale from 1 (least important) to 10 (most important). The average and SDs of each item were calculated, and Cronbach α was used to assess homogeneity among the panelist-ranked items.

RESULTS

All panelists answered the 55-item questionnaire. A Cronbach α value of 0.963 was obtained on the first iteration. The top criteria that were considered most clinically relevant to the diagnosis of CuTS among the group were determined based on the most highly ranked and correlated items among the expert panelist group. The criteria based on which there was agreement were as follows: (1) paresthesias in ulnar nerve distribution, (2) symptoms precipitated by increased elbow flexion/positive elbow flexion tests, (3) positive Tinel sign at the medial elbow, (4) atrophy/weakness/ late findings (eg, claw hand of the ring/small finger and Wartenberg or Froment sign) of ulnar nerve-innervated muscles of the hand, (5) loss of two-point discrimination in ulnar nerve distribution, and (6) similar symptoms on the involved side after successful treatment on the contralateral side.

CONCLUSIONS

Our study demonstrated a consensus among an expert panelist group of hand and upper-extremity surgeons on potential diagnostic criteria for CuTS. This consensus on diagnostic criteria may help clinicians readily diagnose CuTS in a standardized form; however, further weighting and validation are necessary prior to the development of a formal diagnostic scale.

CLINICAL RELEVANCE

This study is the first step in producing a consensus on how to diagnose CuTS.

Sensitivity and Specificity of Examination Maneuvers for Carpal Tunnel Syndrome: A Meta-Analysis

Our purpose was to assess the diagnostic validity (sensitivity (Sn) and specificity (Sp)) of physical examination maneuvers for carpal tunnel syndrome (CTS). This meta-analysis utilized the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Studies assessing exam maneuvers (including components of the CTS-6) for CTS were identified in MEDLINE (Medical Literature Analysis and Retrieval System Online) and Embase (Excerpta Medica Database) databases. Assessed maneuvers assessed included: Phalen's test, Tinel's sign, Durkan test, scratch-collapse test, Semmes-Weinstein monofilament (SWM), and static 2-point discrimination (2PD) test. Data extracted included: article name, total number of subjects/hands, type of exam, and exam Sn/Sp. Forest plots were presented to display the estimated Sn/Sp and boxplots were used to demonstrate the locality, spread, and skewness of the Sn/Sp through the quartiles. After screening 570 articles, 67 articles involving 8924 hands were included. Forty-eight articles assessed Phalen's test, 45 assessed Tinel's sign, 21 assessed the Durkan test, seven assessed the scratch-collapse test, 11 assessed SWM, and six assessed the static 2PD test. Phalen's test demonstrated the greatest median Sn (0.70, (Q1, Q3): (0.51, 0.85)), followed by the Durkan test (0.67, (Q1, Q3): (0.46, 0.82)). 2PD demonstrated the highest median Sp (0.90, (Q1, Q3): (0.88, 0.90)), followed by SWM (0.85, (Q1, Q3): (0.51, 0.89)). There is considerable variability with respect to the validity of physical exam tests used in the diagnosis of CTS. Upper-extremity surgeons should be aware of inherent limitations for individual exam maneuvers. In the absence of a uniformly accepted diagnostic gold standard, a combination of exams, along with pertinent patient history, should guide the diagnosis of CTS.

Modern Treatment of Cubital Tunnel Syndrome: Evidence and Controversy

Cubital tunnel syndrome is the second most common peripheral mononeuropathy in the upper extremity. However, the diagnosis and treatment of cubital tunnel syndrome remains controversial without a standard algorithm. Although diagnosis can often be made from the patient's history and physical examination alone, electrodiagnostic studies, ultrasound, computed tomography (CT), and magnetic resonance image (MRI) can also be useful in diagnosing the disease and selecting the most appropriate treatment option. Treatment options include conservative nonoperative techniques as well as various surgical options, including in situ decompression with or without transposition, medial epicondylectomy, and nerve transfer in advanced disease. 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.

Patient-Reported Outcomes and Provocative Testing in Peripheral Nerve Injury and Recovery

Background  Peripheral nerve function is often difficult to assess given the highly variable presentation and subjective patient experience of nerve injury. If nerve assessment is incomplete or inaccurate, inappropriate diagnosis and subsequent treatment may result in permanent dysfunction. Objective  As our understanding of nerve repair and generation evolves, so have tools for evaluating peripheral nerve function, recovery, and nerve-related impact on the quality of life. Provocative testing is often used in the clinic to identify peripheral nerve dysfunction. Patient-reported outcome forms provide insights regarding the effect of nerve dysfunction on daily activities and quality of life. Methods  We performed a review of the literature using a comprehensive combination of keywords and search algorithms to determine the clinical utility of different provocative tests and patient-reported outcomes measures in a variety of contexts, both pre- and postoperatively. Results  This review may serve as a valuable resource for surgeons determining the appropriate provocative testing tools and patient-reported outcomes forms to monitor nerve function both pre- and postoperatively. Conclusion  As treatments for peripheral nerve injury and dysfunction continue to improve, identifying the most appropriate measures of success may ultimately lead to improved patient outcomes.

A Comprehensive Review of Cubital Tunnel Syndrome

Cubital Tunnel Syndrome (CuTS) is the compression of the ulnar nerve as it courses through the cubital tunnel near the elbow at the location colloquially referred to as the "funny bone". CuTS is the most commonly diagnosed mononeuropathy after carpal tunnel syndrome. Cubital tunnel syndrome can manifest as numbness, tingling, or pain in the ring/small fingers and dorsoulnar hand. Repetitive pressure, stretching, flexion, or trauma of the elbow joint are known causes of CuTS. Chronic ulnar nerve compression and CuTS, when left untreated, can lead to atrophy of the first dorsal interosseus muscle and affect one's quality of life to the point that they are no longer able to participate in daily activities involving fine motor function. It is estimated that up to 5.9% of the general population have had symptoms of CuTS. CuTS is underdiagnosed due to lack of seeking of treatment for symptoms. Compression or damage to the ulnar nerve is the main cause of symptoms experienced by an individual with CuTS. Repetitive elbow pressure or a history or elbow joint trauma or injury are additional known causes that can lead to CuTS. Common presentations of CuTS include paresthesia, clumsiness of the hand, hand atrophy and weakness. The earliest sign of CuTS is most commonly numbness and tingling of the ring and 5th finger. Older patients tend to present with motor symptoms of chronic onset; younger patients tend to have more acute symptoms. Pain and point tenderness at the medial elbow may also be seen. CuTS lacks universally agreed upon diagnostic and treatment algorithms. CuTS can be diagnosed by physical exam using Tinel's sign, flexion-compression tests, palpating the ulnar nerve for thickening presence of local tenderness along the nerve. Ultrasound and nerve conduction studies may be used in combination with physical exam for diagnosis. Conservative treatment for CuTS is almost always pursued before surgical treatment and includes elbow splints, braces, and night-gliding exercises. Surgical treatment may be pursued in severe CuTS refractory to conservative treatment. Surgical options include open and endoscopic in-situ decompression, medial epicondylectomy, and anterior transposition of the ulnar nerve. CuTS is a prevalent disease that, if left untreated, can significantly alter an individual's quality of life. Therefore, an accurate diagnosis and appropriate treatment is paramount in reducing further damage and preventing worsening or future symptoms.

Validity of Using the Scratch Collapse Test in the Lower Extremities

BACKGROUND

The scratch collapse test is a provocative test that has been successfully used for peripheral neuropathies. The elbow is the main testing site, but there may be times when use of the upper extremities is contraindicated. This study sought to determine the sensitivity of using the scratch collapse test on the lower extremity for upper extremity neuropathies.

METHODS

One hundred patients with an electromyographically confirmed diagnosis of carpal tunnel or cubital tunnel syndrome were prospectively enrolled. As a control, the scratch collapse test was conducted normally using the elbow as a testing site. After a baseline was established, the test was repeated using eversion of the foot and ankle against an inversion force.

RESULTS

Of the 100 study patients, 89 had a positive scratch collapse test on the upper extremity and 84 had a positive test on the lower extremity. In the 51 patients with carpal tunnel syndrome, 45 had a positive test on the upper extremity (sensitivity, 88.2 percent; 95 percent CI, 76.13 to 95.56 percent), and 42 had a positive test of the lower extremity (sensitivity, 82.35 percent; 95 percent CI, 69.13 to 91.60 percent). In the 49 patients with cubital tunnel syndrome, 44 had a positive test on the upper extremity (sensitivity, 89.8 percent; 95 percent CI, 77.77 to 96.6 percent), and 42 had a positive test on the lower extremity (sensitivity, 85.7 percent; 95 percent CI, 72.76 to 94.06 percent).

CONCLUSION

There were no statistically significant differences in the sensitivities of the scratch collapse test on the upper or lower extremities, suggesting that the lower extremity could serve as an alternative site for the scratch collapse test.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

The Reliability of the CTS-6 for Examiners With Varying Levels of Clinical Experience

PURPOSE

To assess the interrater reliability of the CTS-6 for examiners with varying levels of clinical expertise. We also aimed to analyze this instrument's sensitivity (Sn) and specificity (Sp), using the CTS-6 score obtained by a hand surgeon as a reference standard.

METHODS

Three examining groups consisting of medical students, occupational hand therapists, and hand surgeons examined a consecutive series of patients in an academic upper-extremity clinic. A total of 3 examiners (1 from each group) recorded a CTS-6 score for each patient. The examiners were blinded to the scores from the other groups. The interrater reliability was determined between the groups with respect to the diagnosis of CTS and the individual CTS-6 components. Sn and Sp were calculated for each of the groups using the CTS-6 obtained by the hand surgeons as the reference standard.

RESULTS

Two hundred seven patients were included. For the diagnosis of CTS (CTS-6 score of 12 or greater as determined by a hand surgeon), there was substantial agreement between the 3 groups (Fleiss kappa 0.73; 95% CI [0.65 -0.82]; P < .05). For individual CTS-6 components, the agreement between the groups was highest for assessing subjective numbness and lowest for assessing a Tinel sign (Fleiss kappa of 0.77 and 0.49, respectively). The Sn/Sp for diagnosing CTS was 87%/91% for the medical student group and 81%/95% for the occupational hand therapist group.

CONCLUSIONS

The CTS-6 can be reliably used as a screening and diagnostic tool for CTS by clinicians with a variety of experience levels and without specific fellowship training in upper-extremity surgery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic I.