Utility of magnetic resonance imaging in diagnosing ulnar neuropathy at the elbow.

OBJECTIVE: Magnetic resonance imaging (MRI) of the ulnar nerve is being increasingly employed in the diagnosis of ulnar neuropathy at the elbow (UNE). Our aims were to: (i) assess the sensitivity of MRI in diagnosing UNE, especially in cases where neurophysiologic studies were non-localizing, (ii) determine the spectrum of MRI abnormalities in patients presenting with symptoms and signs of ulnar neuropathy, (iii) assess whether MRI findings differ between grades of UNE severity, and (iv) to see if MRI findings give an input into the pathological mechanisms of UNE. METHODS: Clinical, neurophysiologic, and radiologic (MRI) records were reviewed in 52 patients with symptoms and signs of ulnar neuropathy. Ulnar nerve MRI studies were assessed by an unblinded observer. RESULTS: The sensitivity of MRI at diagnosing UNE was higher than conventional nerve conduction studies, 90 versus 65%, respectively. In patients with non-localizing neurophysiologic studies (n=19), MRI disclosed changes consistent with UNE in 16 (84%) cases. The most frequent MRI findings included a combination of high signal intensity and nerve enlargement (63%), followed by nerve compression (27%) and isolated high signal intensity (23%), and isolated nerve enlargement (2%). There was no significant difference between patients with localizing and non-localizing neurophysiologic testing. Lastly, there were no differences between different grades of UNE, suggesting that UNE may be a neurophysiologically heterogeneous disorder. CONCLUSIONS: MRI studies proved to be more sensitive than conventional nerve conduction studies at diagnosing UNE. In addition, the MRI studies were highly sensitive in patients with non-localizing UNE. SIGNIFICANCE: Our study shows that MRI of the ulnar nerve should be used in patients with clinical features of UNE especially in those with non-localizing neurophysiologic testing.     

Increased nerve vascularization detected by color doppler sonography in patients with ulnar neuropathy at the elbow indicates axonal damage

Introduction: The aim of this study was to establish the prevalence of increased intraneural vascularization detected by ultrasonography (IVUS) in patients with ulnar neuropathy at the elbow (UNE) and to determine its relationship to clinical, ultrasonographic, and electrodiagnostic findings. Methods: High‐resolution ultrasonography and color Doppler imaging were performed in 137 patients with confirmed UNE, 24 patient controls, and 70 healthy controls (HCs). Results: IVUS was found in 21 (15%) of 137 patients with UNE, in 1 (4%) of 24 patient controls, and in 0 of 70 HCs (P = 0.001). Patients with IVUS were more likely to have severe weakness (P = 0.01), severe atrophy of ulnar‐innervated muscles (P = 0.008), axonal damage (P = 0.001), and more pronounced nerve enlargement (P = 0.03) than those without IVUS. Conclusions: IVUS in the ulnar nerve can be detected in patients with UNE and is associated with nerve enlargement and clinical and electrodiagnostic severity. In addition, IVUS is associated with axonal damage. Muscle Nerve, 2013     

Short segment sensory nerve stimulation in suspected ulnar neuropathy at the elbow: A pilot study

Introduction: Routine ulnar nerve conduction studies may be normal in very mild ulnar neuropathies at the elbow (UNE). Short segment ulnar sensory stimulation across the elbow may detect mild abnormalities in these cases. Methods: Short segment ulnar sensory nerve stimulation was performed in 20 controls and 15 patients with clinically suspected mild UNE. Greatest peak latency shift and amplitude drop between 2 adjacent stimulation sites were calculated. Results: The upper limit of normal for peak latency shift and amplitude reduction between sites was 0.7 ms and 15%, respectively. Abnormal latency shift was detected in 12 of 15 patients and focal sensory conduction block in 6 of 15 patients. In 5 of 7 patients in whom all other studies were normal, sensory inching was abnormal. Discussion: Ulnar sensory short segment stimulation may provide diagnostic confirmation and localization of the site of nerve compression in mild UNE, and may improve UNE detection when all other studies are normal. Muscle Nerve 59 :125–129, 2019     

Patterns and parameters describing nerve thickening in compression and entrapment ulnar neuropathies at the elbow

ObjectiveTo compare pattern and parameters describing nerve thickening in ulnar neuropathy at the elbow (UNE) due to external compression in the retrocondylar groove (RTC), and entrapment under the humeroulnar aponeurosis (HUA).MethodsIn a group of our previously reported UNE patients we ultrasonographically (US) measured ulnar nerve cross-sectional areas (CSA) on 6–8 standard locations in the elbow segment. We compared CSA patterns in both groups, and determined diagnostic utility of selected CSA based parameters.ResultsWe studied 79 patients (81 arms) with UNE due to external compression, and 53 patients (55 arms) due to entrapment. Maximal ulnar nerve CSA (>16 mm²), maximal CSA change (>7 mm²/1–2 cm) and maximal/minimal CSA ratio (>2.6) were significantly larger in UNE due to entrapment. They also differentiated these arms from arms with compression with sensitivities of 78%, 87% and 80%, and specificities of 90%, 94%, and 85%, respectively.ConclusionMaximal difference in CSA between points separated by 1–2 cm (>7 mm²/1–2 cm) very efficiently differentiated between UNE due to external compression and entrapment.SignificanceThe proposed parameter will hopefully complement precise localization in determining underlying mechanism of UNE. This may help physicians to determine the most appropriate treatment for UNE and possibly other focal neuropathies of unknown cause; i.e., conservative treatment for external compression and surgery for entrapment.     

Neurologic examination and instrument‐based measurements in the evaluation of ulnar neuropathy at the elbow

Introduction: The aim of the study was to compare the utility of instrument‐based assessment of peripheral nerve function with the neurologic examination in ulnar neuropathy at the elbow (UNE). Methods: We prospectively recruited consecutive patients with suspected UNE, performed a neurologic examination, and performed instrument‐based measurements (muscle cross‐sectional area by ultrasonography, muscle strength by dynamometry, and sensation using monofilaments). Results: We found good correlations between clinical estimates and corresponding instrument‐based measurements, with similar ability to diagnose UNE and predict UNE pathophysiology. Discussion: Although instrument‐based methods provide quantitative evaluation of peripheral nerve function, we did not find them to be more sensitive or specific in the diagnosis of UNE than the standard neurologic examination. Likewise, instrument‐based methods were not better able to differentiate between groups of UNE patients with different pathophysiologies. Muscle Nerve 57 : 951–957, 2018     

Cold elbow syndrome: spurious slowing of ulnar nerve conduction velocity

Low temperature decreases nerve conduction velocity (NCV). The across-elbow segment of the ulnar nerve is superficial and may be particularly susceptible to decreased temperature. We evaluated patients without clinical ulnar neuropathy at the elbow (UNE) but with isolated slowing of the across-elbow ulnar NCV (normal group), and patients with clinical and electrodiagnostic findings of UNE (UNE group). All subjects had ulnar motor nerve studies completed before and after warming. The mean across-elbow NCV was 43.4 m/s and 48.6 m/s (P < 0.0001) in the normal group, and 37.4 m/s and 37.7 m/s (P = 0.90) in the UNE group, before and after warming, respectively. There was no change in the forearm segment NCV in either group. Seventeen of 32 subjects in the normal group had completely normal studies after warming. No patients with UNE developed normal across-elbow NCV with warming. Low temperature slows across-elbow ulnar NCV in normal subjects without impact on the forearm segment. Warming of the elbow improves across-elbow ulnar NCV in normals, but does not reverse the abnormalities in patients with UNE. Elbow warming should become a routine part of ulnar nerve conduction studies, especially when there is isolated conduction slowing in the across-elbow segment.     

Prognostic indicators from electrodiagnostic studies for ulnar neuropathy at the elbow

Introduction: We examined the prognostic value of electrodiagnostic (EDX) studies for ulnar neuropathy at the elbow (UNE). Methods: In this retrospective study, EDX results were compared with subjective recovery (resolution of symptoms) and surgery in patients diagnosed with UNE. Results: Of the 193 patients, 59 with “definite” UNE were included in the analysis. The combination of conduction block across the elbow to the first dorsal interosseous (FDI) and normal distal compound muscle action potential (CMAP) amplitude from the abductor digiti minimi (ADM) was strongly associated with recovery: 86% of these subjects achieved full subjective recovery compared to only 7% without conduction block and with an abnormal CMAP. There were no EDX predictors of surgery. Conclusion: EDX results contain useful prognostic information in UNE. Muscle Nerve, 2011     

Electrodiagnosis of ulnar neuropathy at the elbow (Une): A bayesian approach

Introduction: In ulnar neuropathy at the elbow (UNE), we determined how electrodiagnostic cutoffs [across‐elbow ulnar motor conduction velocity slowing (AECV‐slowing), drop in across‐elbow vs. forearm CV (AECV‐drop)] depend on pretest probability (PreTP). Methods: Fifty clinically defined UNE patients and 50 controls underwent ulnar conduction testing recording abductor digiti minimi (ADM) and first dorsal interosseous (FDI), stimulating wrist, below‐elbow, and 6‐, 8‐, and 10‐cm more proximally. For various PreTPs of UNE, the cutoffs required to confirm UNE (defined as posttest probability = 95%) were determined with receiver operator characteristic (ROC) curves and Bayes Theorem. Results: On ROC and Bayesian analyses, the ADM 10‐cm montage was optimal. For PreTP = 0.25, the confirmatory cutoffs were >23 m/s (AECV‐drop), and <38 m/s (AECV‐slowing); for PreTP = 0.75, they were much less conservative: >14 m/s, and <47 m/s, respectively. Conclusions: (1) In UNE, electrodiagnostic cutoffs are critically dependent on PreTP; rigid cutoffs are problematic. (2) AE distances should be standardized and at least 10 cm. Muscle Nerve 49 :337–344, 2014     

Apparent conduction block in patients with ulnar neuropathy at the elbow and proximal Martin-Gruber anastomosis

A Martin-Gruber anastomosis (MGA) commonly results in an abnormal decline in amplitude across the forearm segment when ulnar motor nerve conduction studies are performed. A recent report described a proximal MGA resembling partial conduction block in a patient with ulnar neuropathy at the elbow (UNE). As a result, we screened patients with similar findings. We detected a proximal MGA in three patients over a period of 2 years, which suggests that this may be an under-recognized anomaly. We conclude that a proximal MGA must be excluded in all cases of UNE showing apparent partial conduction block across the elbow segment.     

Localization of ulnar neuropathy with conduction block across the elbow

We performed short segment incremental stimulation on 13 consecutive patients with ulnar neuropathy across the elbow (UNE) and conduction block. Conduction block occurred proximal to the medial epicondyle in 62%, at the epicondyle in 23%, and below the elbow in 15%. The ulnar nerve may be more prone to external compression above the elbow than previously recognized. Short segment incremental studies are useful to identify conduction block above the elbow in such patients.     

A novel points system to predict the prognosis of ulnar neuropathy at the elbow

Introduction: In this study we aimed to identify prognostic factors of ulnar neuropathy at the elbow (UNE) and developed a scoring system to establish the prognosis. Methods: We collected baseline clinical, electrophysiologic, and ultrasonographic data from 2 cohorts. The outcomes for all patients were determined on follow‐up. Prognostic factors were determined using single and multiple variable analyses. A points system was developed to determine the risk for an unfavorable outcome. Results: Of the 220 patients with UNE 178 (81%) could be re‐evaluated. Four variables were retained in the prediction model for a points system. An unfavorable outcome was associated with right‐sided UNE, more severe weakness of the abductor digiti minimi (ADM), and more pronounced ulnar nerve thickening. A compound muscle action potential amplitude reduction across the elbow of ≥16% (particularly if ≥ 50%) was associated with a more favorable outcome. Conclusion: Outcome in UNE may be predicted by scoring 4 parameters. Muscle Nerve 55: 698–705, 2017     

Sonographic incidence of ulnar nerve (sub)luxation and its associated clinical and electrodiagnostic characteristics

Introduction: The aim of this study was to assess the presence of (sub)luxation of the ulnar nerve in patients with ulnar neuropathy at the elbow (UNE) compared with healthy controls (HC). We assessed its clinical patterns, electrodiagnostic, and sonographic characteristics. Methods: Using high-resolution sonography, we studied the incidence of (sub)luxation in a cohort of 342 patients and 70 HC. Results: Subluxation occurred in 14% and luxation in 6.7% of the UNE patients versus 5.7% and 5.7%, respectively, in HC (no significant differences). Pain at the elbow occurred more often in patients with (sub)luxation (P = 0.007). Electrodiagnostic and sonographic findings did not differ between patients with or without (sub)luxation. Conclusions: The incidence of ulnar nerve (sub)luxation between patients with UNE and HC does not differ. UNE patients with (sub)luxation do not have specific clinical or electrodiagnostic findings, apart from experiencing pain at the elbow more often. Muscle Nerve 47: 849–855, 2013     

Relations between sensory symptoms,touch sensation,and sensory neurography in the assessment of the ulnar neuropathy at the elbow

ObjectivesTo evaluate sensitivity, specificity and predictive values of sensory findings in ulnar neuropathy at the elbow (UNE), differences according to UNE localization and pathophysiology, and relation between the sites of sensory symptoms, abnormal evaluation of sensation and neurographic findings of ulnar sensory nerve.MethodsHand diagram and Semmes-Weinstein monofilaments were used for clinical evaluation in four ulnar hand territories. Sensory neurography was measured in the fourth and fifth digits-wrist segments (U5) and in the dorsal ulnar cutaneous nerve.ResultsWe enrolled 75 idiopathic UNE cases and 180 controls. Symptoms in the fifth digit, reduction of touch sensation and U5 sensory nerve action potential amplitude (SNAPa) had the highest sensitivity, specificity and predictivity in UNE diagnosis. The normal/abnormal sensory clinical findings of the fifth digit matched with normal/abnormal U5 SNAP more than the matching of sensory parameters in the other ulnar hand sites. Sensory anomalies were more frequent in predominantly axonal than demyelinating UNE. There were no differences according to UNE location.ConclusionSensory anomalies of the fifth digit are constant findings in UNE more than anomalies of the other ulnar nerve hand regions.SignificanceProbably the fascicles from fifth digit are the most liable to damage at elbow.     

Is medial elbow pain correlated with cubital tunnel syndrome? An electrodiagnostic study

Introduction: Medial elbow pain is often considered to be a symptom associated with ulnar neuropathy at the elbow (UNE). We examined the relationship between medial elbow pain and a positive electrodiagnostic (EDx) test result for UNE. Methods: We performed a retrospective review of 884 patients referred for EDx evaluation of UNE. Regression models were used to determine the odds ratios between clinical findings and a positive EDx result for UNE. Results: Patients reported medial elbow pain in 44.3% of cases. Clinical factors that correlated with a positive EDx study result for UNE included male gender, small and ring finger numbness, ulnar intrinsic weakness, and age. Medial elbow pain was negatively correlated with a positive EDx result. Conclusions: This study demonstrates a negative correlation between medial elbow pain and a positive EDx result for UNE. Medial elbow pain should not be considered a clear diagnostic symptom of UNE. Muscle Nerve 53: 252–254, 2016     

Which ultrasonographic measure has the upper hand in ulnar neuropathy at the elbow?

ObjectiveTo compare the diagnostic accuracy of ultrasonographic ulnar nerve diameter, cross-sectional area (CSA) and swelling ratio measurement in ulnar neuropathy at the elbow (UNE).MethodsUltrasonographic diameter, CSA, and swelling ratio measurements were compared with a reference standard including clinical examination, electrophysiological studies, and follow-up in a prospective cohort of patients. All patients in whom a diagnosis of UNE was considered were eligible for the study. Reference values for ultrasonography were obtained in 73 healthy volunteers.ResultsOf 191 patients, 137 had UNE or probable UNE, while 54 had another condition and these were analysed as patient controls. Patients with UNE had a larger ulnar nerve diameter, CSA and swelling ratio than healthy controls and patient controls (p < 0.01). The diagnostic accuracies of these different measurements were comparable with a specificity of 78–87%, a positive predictive value of 87–90%, a sensitivity of 42–61% and negative predictive value of 37–44%. ROC-analysis for these measurements showed an area under the curve of 0.75–0.77.ConclusionUltrasonographic measurements of ulnar nerve diameter, CSA and swelling ratio have comparable diagnostic value, which was lower than reported previously.SignificanceUltrasonographic ulnar nerve diameter, CSA and swelling ratio measurements are equally useful in diagnosing UNE.     

Localization of ulnar neuropathy at the elbow using new stimulator for the inching test.

OBJECTIVE: To evaluate the usefulness of the TenElectrodes, a new stimulator for inching test, in the diagnosis and localization of ulnar neuropathy at the elbow (UNE). METHODS: Sixty-two ulnar nerves in 40 control subjects and 24 ulnar nerves in 23 patients with typical symptoms and signs of UNE were studied. The inching test of ulnar motor nerve using TenElectrodes was done along 8 cm across the elbow in the extended position. RESULTS: In the inching test of the control group, the mean segmental latency difference was 0.19+/-0.08 ms. Maximal latency difference over a 1 cm segment did not exceed 0.40 ms in any of the controls but exceeded 0.5 ms or more in all clinical UNE patients. In all UNE patients, the lesion sites were identified by the inching test using TenElectrodes: the retroepicondylar groove (54.2%), the humeroulnar arcade (29.2%), and dual compression (16.6%). CONCLUSIONS: TenElectrodes is a useful stimulator for the inching test in the diagnosis of UNE. The precise localization of compression was possible in all patients with UNE and the most common site was the retroepicondylar groove.     

Utility of nerve conduction studies and ultrasonography in ulnar neuropathies at the elbow of different severity

ObjectiveTo report the sensitivity and the ability to precisely localize ulnar neuropathies at the elbow (UNE) of different severity by ultrasonography (US) and compare it to standard 10-cm nerve conduction studies (NCSs), and 2-cm short-segment NCSs (SSNCSs) across the elbow.MethodsIn a group of consecutive UNE patients, a prospective and blinded study was performed. The evaluation included clinical examination, electrodiagnostic (EDx) and US studies. We compared US and NCSs for sensitivity and the ability to precisely localize the UNE of different clinical severity.ResultsWe studied 202 affected arms of 197 UNE patients. Clinically very mild UNE was diagnosed in seven, mild in 43, moderate in 99 and severe in 53 arms. The sensitivities of SSNCSs were 14%, 67%, 93% and 100%, of 10-cm NCSs, 29%, 44%, 80% and 96%, and of US 14%, 47%, 59% and 89%, respectively. Precise UNE localization was possible using SSNCSs in 29%, 56%, 78% and 85%, and using US in 29%, 44%, 70% and 98%, respectively.ConclusionThe present study demonstrated that NCSs are more sensitive than US for the diagnosis of UNE of all clinical grades of severity. US was more efficient in localizing clinically severe, and SSNCSs in localizing mild or moderate UNE.SignificanceWe recommend SSNCSs as the first confirmatory test in UNE across all grades of severity.     

Ultrasonography of ulnar neuropathy at the elbow: Axonal involvement leads to greater nerve swelling than demyelinating nerve lesion

ObjectiveTo evaluate nerve size parameters measured by ultrasound in patients with ulnar neuropathy at the elbow (UNE) and to correlate them with the type of nerve lesion.MethodsThe largest cross sectional area (CSA_max) of the ulnar nerve around the elbow and the cubital-to-humeral nerve area ratio (CHR) were measured in 50 elbows with UNE and in 87 elbows of 50 healthy subjects. CSA_max and CHR were compared between controls and patients with predominantly demyelinative and axonal nerve involvement. Subgroups of patients with pure sensory and mixed sensorimotor axonal lesion were also compared.ResultsIn patients with axonal nerve involvement, a significantly larger CSA_max and CHR were found when compared to those with predominantly demyelinating nerve lesion; both groups differed significantly from healthy controls. CSA_max values in patients with sensorimotor axonal lesion were significantly higher than in those with pure sensory axonal involvement.ConclusionCSA_max and CHR highly correlate with the type of nerve pathology in UNE, with a significantly larger nerve swelling seen in axonal lesions, as compared to demyelinating lesions.SignificanceIn addition to helping in the localization of nerve lesion, ultrasonography may also reflect the type and degree of nerve lesion as assessed by electrophysiological means.     

Effect of body mass index on ulnar nerve conduction velocity, ulnar neuropathy at the elbow, and carpal tunnel syndrome

Both high and low body mass index (BMI) have been reported as risk factors for ulnar neuropathy at the elbow (UNE), and a high BMI as a risk factor for carpal tunnel syndrome (CTS). To determine whether the extremes of BMI are risk factors for UNE or CTS, and whether BMI affects calculation of median and ulnar motor nerve conduction velocity (NCV), we retrospectively analyzed the electrodiagnostic records of control patients, UNE patients, and CTS patients. The BMI was calculated for 50 patients with a sole diagnosis of UNE and compared to the BMI of 50 patients with CTS and 50 control subjects. The mean BMIs were 25.9 +/- 4.4, 30.1 +/- 5.5, and 28.3 +/- 5.6 for the UNE, CTS, and controls, respectively. By one-way analysis of variance, the difference in BMI between the UNE patients and the normal patients was significant (P < 0.01). In the control groups, increasing BMI directly correlated with increasing ulnar motor NCV across the elbow but not with forearm NCV. Across-elbow (AE) ulnar motor NCV may be falsely increased in patients with a high BMI, probably due to distance measurement factors. Not only do relatively slender individuals have comparatively slower AE ulnar NCVs, they are also at increased risk for developing UNE. Patients with a high BMI are at increased risk for CTS.     

Ultrasonography in ulnar neuropathy at the elbow: Relationships to clinical and electrophysiological findings

INTRODUCTION: Though ultrasonography (US) is commonly used in the diagnosis of carpal tunnel syndrome (CTS), there are only few studies on the utility of US in ulnar neuropathy at the elbow (UNE). The aims of this study were to measure the cross-sectional area (CSA) of the ulnar nerve at the elbow and to correlate CSA values with clinical and electrophysiological findings. PATIENTS AND METHODS: Thirty-three UNE patients (mean age 50.1 years) were consecutively enrolled. Diagnosis was based on clinical findings and slowing of the motor conduction velocity (MCV) of the ulnar nerve across the elbow. CSAs of the ulnar nerve were measured within the cubital tunnel at the level of the medial epicondyle (CSA-M) and approximately 2cm proximal to this point (CSA-I). Correlations between CSA and demographic, clinical (ordinal severity scale and self-administered symptom questionnaire), and electrophysiological findings (neurographic results and ordinal electrophysiological severity scale) were calculated using Spearman's correlation coefficient. RESULTS: The mean CSA-M and CSA-I were 9.6+/-8.5 and 9.3+/-5.6mm2, respectively. Fifteen (45.5%) and eight (24.5%) cases showed abnormal CSA-M and CSA-I values, respectively (mean+2S.D. compared to a control group of the same age). All cases with abnormal CSA-I had abnormal CSA-M except one. Significant relationships were only found between CSA-M and CSA-I with across elbow MCV, sensory action potential amplitude, and the electrophysiological severity scale score. DISCUSSION: Our study showed anomalous CSA values in less than 50% of the UNE cases. This is less than the reported percentages in the few literature reports. This difference may be due to our enrolment criteria or to the electrophysiological and US techniques. It is likely that the CSAs measured by axial scan at a fixed level of the cubital tunnel may have lower diagnostic sensitivity than the same technique used in CTS.