Clinical and neurophysiological recovery of ulnar nerve conduction block at the elbow.

INTRODUCTION/AIMS: An important mechanism of peripheral nerve motor and sensory dysfunction is conduction block (CB). However, recovery from mechanically induced CB has been rarely studied in humans. The aim of this study was to describe clinical, electrodiagnostic (EDx), and ultrasonographic (US) characteristics of CB recovery in ulnar neuropathy at the elbow (UNE). METHODS: We recruited a group of consecutive patients presenting to our EDx laboratory with UNE and >50% motor CB. Patients' histories were obtained and neurologic, EDx, and US examinations were repeated every 1-3 mo for at least 12 mo. RESULTS: We studied 10 patients (5 men), with a mean age of 63 y (range, 51-81 y). In all affected arms CB was localized to the retrocondylar groove. Following conservative management, myometrically measured index finger abduction improved from a median of 49% to 100% relative to the contralateral index finger, and ulnar nerve CB decreased from a median of 74% to 6%. Most of the improvement took place within 8 mo of symptom onset, and 6 mo after receiving treatment instructions. Mean motor nerve conduction velocity improved from 15 to 27 m/s in the most affected 2-cm ulnar nerve segment. DISCUSSION: The resolution of CB after typical chronic compression may take longer than after acute compression. This should be considered by clinicians when estimating prognosis for discussions with patients.

Validation of clinical criteria for referral to head imaging in the neurologic emergency setting.

BACKGROUND: In recent decades, diagnostic imaging became an important generator of large increases in medical spending. Inappropriate head CT referrals also increase population irradiation and unnecessarily burden and frighten patients. OBJECTIVE: To validate previously proposed clinical criteria for referral to head imaging (age > 55 years, focal neurological deficit, changed mental state, nausea or vomiting, coagulation disorder, cancer) in a setting of emergency neurological service. METHODS: We retrospectively analyzed electronic records of 500 consecutive referrals to neurological emergency and 500 referrals to emergency head imaging. In patients with several referrals, only results of the first evaluation were further analyzed. We calculated relations between clinical predictors, referrals, and findings of head imaging. RESULTS: Of 486 first referrals of consecutive patients, 216 (44%) were referred to the emergency, and 100 (21%) to non-emergency head imaging. Remaining 170 (35%) were not referred to head imaging. Clinical predictors of pathologic head imaging fulfilled 77%, 41%, and 43% of patients, respectively. Pathologic head imaging had 153 of 490 (31%) referred patients. Referral criteria fulfilled 146 (sensitivity 95%) of them. Intracranial pathology was found in 7 of 125 patients not fulfilling referral criteria (negative predictive value 94%): 3 reported transient neurological symptoms, 2 sudden headache, and 2 headache with nausea and vomiting. CONCLUSION: We confirmed utility of previously proposed clinical criteria for referral to head CT in emergency neurological setting. In addition, we found transient neurological symptoms, sudden severe headache, and headache with nausea or vomiting as additional independent indications for emergency head imaging.

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.

Nerve conduction velocity and cross-sectional area in ulnar neuropathy at the elbow.

INTRODUCTION: In the precise localization of ulnar neuropathy at the elbow (UNE) we have noted discrepancies between electrodiagnostic (EDx) and ultrasonographic (US) findings. We aimed to explore the relationship between the 2 techniques. METHODS: Four study-blind examiners took a history and performed neurologic, EDx, and US examinations of a group of prospectively recruited patients with UNE. They assessed the relationship between ulnar nerve cross-sectional area (CSA) and motor nerve conduction velocity (MNCV). RESULTS: In 106 patients with UNE at the retrocondylar (RTC) groove, the highest CSA and lowest MNCV were noted in the same short segment. In 54 patients with UNE at the humeroulnar aponeurosis (HUA), the highest CSA and lowest MNCV were noted proximal to the HUA. DISCUSSION: MNCV and CSA were highly correlated in UNE. Ulnar nerve slowing proximal to the entrapment at the HUA was surprising, but consistent with previous studies done on carpal tunnel syndrome. Muscle Nerve 56: E65-E72, 2017.

Complete dislocation of the ulnar nerve at the elbow: a protective effect against neuropathy?

INTRODUCTION: Recurrent complete ulnar nerve dislocation has been perceived as a risk factor for development of ulnar neuropathy at the elbow (UNE). However, the role of dislocation in the pathogenesis of UNE remains uncertain. METHODS: We studied 133 patients with complete ulnar nerve dislocation to determine whether this condition is a risk factor for UNE. In all, the nerve was palpated as it rolled over the medial epicondyle during elbow flexion. RESULTS: Of 56 elbows with unilateral dislocation, UNE localized contralaterally in 17 elbows (30.4%) and ipsilaterally in 10 elbows (17.9%). Of 154 elbows with bilateral dislocation, 26 had UNE (16.9%). Complete dislocation decreased the odds of having UNE by 44% (odds ratio = 0.475; P = 0.028), and was associated with less severe UNE (P = 0.045). CONCLUSIONS: UNE occurs less frequently and is less severe on the side of complete dislocation. Complete dislocation may have a protective effect on the ulnar nerve. Muscle Nerve 56: 242-246, 2017.

Safety of needle electromyography of the diaphragm: Anterior lung margins in quietly breathing healthy subjects.

INTRODUCTION: Controversy persists as to whether the lung interposes on the needle electrode insertion path during diaphragm electromyography (EMG). METHODS: Using high-resolution ultrasonography, we measured the distances between the medial recess of the intercostal spaces (ICSs) around the mid-clavicular line (MCL) and the lung margin. We performed measurements bilaterally during quiet breathing in the seated and supine positions. RESULTS: We studied 10 young healthy men and found that, in the first ICS with the medial recess clearly (i.e., several cm) lateral to MCL (usually the eighth ICS), the distance between the recommended insertion site and the lung margin varied from 7.5 to 17 cm. The distance was slightly larger on the right side and in the supine position. CONCLUSIONS: This study confirms that properly conducted "trans-intercostal" needle EMG of the diaphragm is generally safe in healthy subjects. Muscle Nerve 54: 54-57, 2016.

Does ulnar nerve dislocation at the elbow cause neuropathy?

INTRODUCTION: The role of ulnar nerve dislocation in the pathogenesis of ulnar neuropathy at the elbow (UNE) is not clear. Data exist for and against a causal relationship. METHODS: We studied UNE patients and controls divided into 4 groups consisting of 203 UNE patient arms (185 with abnormal and 18 with normal diagnostic studies) and 49 controls (10 with abnormal and 39 with normal studies). In all arms we performed neurologic examination, short-segment nerve conduction studies (SSNCS), and ultrasonography (US). The frequency of partial and complete nerve dislocation was calculated in each group. RESULTS: Dislocation tended to be more common in controls compared with UNE patients (P = 0.056). It was particularly common in controls with subclinical UNE and patients with UNE symptoms but normal diagnostic studies. CONCLUSION: Our data speak against a causal relationship between ulnar nerve dislocation and UNE. However, the findings also suggest that dislocation may cause mild ulnar nerve damage.

Single fiber EMG as a prognostic tool in myasthenia gravis.

INTRODUCTION: Single fiber electromyography (SFEMG) is the most sensitive diagnostic tool for diagnosis of myasthenia gravis (MG). Its prognostic value is not known. METHODS: We retrospectively analyzed the clinical course of 232 MG patients who presented with only mild symptoms and had SFEMG of the orbicularis oculi muscle. We correlated their SFEMG results with the severity of their later clinical course. RESULTS: During the observation period 39 patients (17%) developed severe disease exacerbations, and 193 (83%) remained stable. Patients with severe disease exacerbation had a significantly higher mean jitter value (P < 0.0001), a greater percentage of fibers with increased jitter (P < 0.0001), and/or impulse blocking (P < 0.0001) on SFEMG. CONCLUSIONS: The extent of the SFEMG abnormalities in this study correlated with the later clinical course of MG. Muscle Nerve 54: 1034-1040, 2016.

Idiopathic phrenic neuropathies: A case series and review of the literature.

INTRODUCTION: Phrenic neuropathies (PNs) are a major cause of dyspnea, orthopnea, and hypercapnic respiratory failure. The aim of the study was to obtain diagnostic findings, assess therapeutic options, and review outcomes in PN patients. METHODS: From 2004 to 2013, patients with PN referred to the author's institution were studied using clinical, pulmonary function, and electrodiagnostic tests. A PubMed search of published PN reports was also done. Unilateral PN (UPN) and bilateral PN (BPN) patients were compared. RESULTS: The analysis consisted of 10 UPN and 9 BPN patients seen by the author, plus previous reports of 18 UPN and 40 BPN patients. BPN patients were older (in the author's series) and were more often hypertensive. They reported pain less often, dyspnea and orthopnea more often, and had worse results on pulmonary function tests than UPN patients. CONCLUSIONS: UPN and BPN are probably 2 variants of the same, immune-mediated focal neuropathy. Electrodiagnosis is a valuable confirmatory test for PN.

Normative values for short-segment nerve conduction studies and ultrasonography of the ulnar nerve at the elbow.

INTRODUCTION: In patients with ulnar neuropathy at the elbow (UNE), short-segment nerve conduction studies (NCS) are rarely performed due to unclear reference values. We excluded controls with subclinical UNE, calculated normative values, and tested them in UNE patients. METHODS: Clinical examination, ultrasonography (US), and 2-cm short-segment ulnar motor NCS across the elbow were performed in 49 controls and 67 UNE patients. In controls, subclinical UNE was diagnosed if at least 2 studies were outside the reference limits in the same 2-cm segment. RESULTS: Exclusion of controls with subclinical UNE produced less stringent normative values (2-cm conduction velocity: 25 to 31 m/s; US cross-sectional area: 11.6 to 9.6 mm2), which raised diagnostic sensitivity (short-segment NCS: 76% to 90%; 10-cm NCS: 72% to 85%, US: 43% to 79%). CONCLUSIONS: We propose the use of our normative values in patients with clinically definite and probable UNE after exclusion of alternative diagnoses.

Utility of sphincter electromyography and sacral reflex studies in women with cauda equina lesions.

AIMS: Sacral neurophysiologic studies have demonstrated their utility in men with suspected neurogenic sacral dysfunction. However, no similar studies have been performed in women. The present study aimed to test the utility of sacral neurophysiologic assessment in women with chronic cauda equina lesions. METHODS: Twenty-four women with clinical and radiological signs supportive of chronic cauda equina lesions, and a group of 60 control women without clinical symptoms or signs of sacral neuropathic lesion were included. Clinical examination, including testing of saddle sensation, and neurophysiologic testing, including quantitative anal sphincter EMG and clitoro-cavernosus reflex testing (on single and double electrical, and mechanical stimulation), were performed on each side separately. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. RESULTS: Respective sensitivities, specificities, positive predictive values, and negative predictive values were 63%, 92%, 83%, and 86% for quantitative anal sphincter EMG, 92-96%, 67-80%, 52-59%, and 95-96% for neurophysiologic testing of the clitoro-cavernosus reflex (using different stimulation techniques), and 96-100%, 62-75%, 50-55%, and 97-98% for their combinations. CONCLUSIONS: This study complements previous reports in men supporting the clinical utility of an neurophysiologic protocol that includes both quantitative anal sphincter EMG and sacral reflex studies for assessment of patients with suspected peripheral sacral lesions. Very high sensitivity and negative predictive value confirm high utility of sacral neurophysiologic studies in confirmation and exclusion of sacral neuropathic lesion.

No electrophysiological evidence for Onuf's nucleus degeneration causing bladder and bowel symptoms in Huntington's disease patients.

AIMS: In several degenerative neurologic diseases degeneration of Onuf's nucleus has been demonstrated using histologic and electromyographic (EMG) methods. Although Huntington's disease (HD) patients also frequently complain of bladder and bowel symptoms, degeneration of Onuf's nucleus has not been systematically studied in this group. METHODS: From our inventory of patients with genetically confirmed HD, all patients willing and capable of participating in the study, which utilized several standard questionnaires, were included. The patients reporting bladder/bowel symptoms were also asked to participate in anal sphincter EMG and sacral reflex studies. RESULTS: Of 52 patients (23 men) with genetically confirmed HD, 34 reported bladder/bowel symptoms, and 16 (8 men) of them consented to anal sphincter EMG and sacral reflex studies. Complete pattern of urinary and fecal urgency with incontinence reported 6 (38%), and incomplete 3 (19%) patients, accompanied with episodic diarrhea in another 3 (19%) patients. No patient exhibited quantitative anal sphincter EMG or sacral reflex abnormalities. However, in 81% of patients, decreased tonic anal sphincter activity and/or decreased voluntary activation were found on qualitative EMG. Lower sacral sensory thresholds and shorter reflex latencies were also found in HD patients compared to controls. CONCLUSIONS: We found no EMG signs of Onuf's nucleus degeneration in HD patients. The observed decreased anal sphincter tonic activity and voluntary activation, lower sacral sensory thresholds and shorter reflex latencies as well as the reported bladder/bowel symptoms, are probably caused by degeneration of other central nervous system structures. Neurourol. Urodynam. 33:524-530, 2014. © 2013 Wiley Periodicals, Inc.

Differentiating viral and bacterial infections: A machine learning model based on routine blood test values.

The growing threat of antibiotic resistance necessitates accurate differentiation between bacterial and viral infections for proper antibiotic administration. In this study, a Virus vs. Bacteria machine learning model was developed to distinguish between these infection types using 16 routine blood test results, C-reactive protein concentration (CRP), biological sex, and age. With a dataset of 44,120 cases from a single medical center, the model achieved an accuracy of 82.2 %, a sensitivity of 79.7 %, a specificity of 84.5 %, a Brier score of 0.129, and an area under the ROC curve (AUC) of 0.905, outperforming a CRP-based decision rule. Notably, the machine learning model enhanced accuracy within the CRP range of 10-40 mg/L, a range where CRP alone is less informative. These results highlight the advantage of integrating multiple blood parameters in diagnostics. The "Virus vs. Bacteria" model paves the way for advanced diagnostic tools, leveraging machine learning to optimize infection management.

Phrenic nerve conduction studies in patients with chronic obstructive pulmonary disease.

INTRODUCTION: The most common etiology of hypercapnic respiratory failure is chronic obstructive pulmonary disease (COPD). However, the differential diagnosis also includes neuromuscular disorders. We studied the specificity of reduced amplitude phrenic nerve compound motor action potential (CMAP) to diagnose neuromuscular disorders. METHODS: A group of patients with advanced COPD were recruited prospectively and compared with controls. Phrenic nerve CMAPs were measured bilaterally using supraclavicular surface stimulation and bipolar recording (G1: 5 cm above the xiphoid; G2: 16 cm from G1). RESULTS: A group of 20 patients (15 men) and a group of 29 controls (15 men) were included. Phrenic nerve CMAPs of patients with COPD had significantly longer latency and higher amplitude. CONCLUSION: Our study demonstrates that patients with hypercapnic respiratory failure and reduced phrenic nerve CMAP amplitude most probably have a neuromuscular disorder affecting the diaphragm and not COPD or another lung disorder.

Ultrasound diagnosis of bony nerve entrapment: case series and literature review.

INTRODUCTION: Nerve entrapment due to osseous callus formation is a rare complication after bone fracture. Electrodiagnostic studies and routine radiographic imaging often fail to demonstrate the pathology. The diagnosis is difficult and is often made incidentally upon surgical exploration. Nerve ultrasonography has not been used routinely to assess such lesions. METHODS: We report 5 cases of nerve entrapment in osseous callus after fractures that occurred in 2011 and 2012. The diagnosis was made by ultrasound (US). We then performed a review of the relevant literature. CONCLUSIONS: US is becoming an invaluable tool for diagnosing peripheral nerve entrapments. The current cases suggest that nerve US should be strongly considered as an adjunctive diagnostic tool for nerve palsies developing after trauma.

Computer protocol for the electrodiagnostic evaluation of patients with suspected median neuropathy at the wrist.

Patients with median entrapment neuropathy at the wrist (MEW) present a large burden to electrodiagnostic (EDx) services. We report here our experience with a computer protocol for EDx standardized evaluation of these patients. The computer program guiding the examiners through the history, focused clinical examination and nerve conduction studies (NCSs), and automatically generating the report was employed in patients with suspected MEW referred to our unit in year 2010. Included were 1,935 patients (3,870 hands) with suspected MEW. Median motor study had to be performed in 100 %, a ring finger sensory comparison study in 99 %, a thumb study in 23 %, wrist study in 3 % and a middle finger study in 19 % of hands with cumulative sensitivities of 45, 68, 73, 74, and 82 %, respectively. In conclusion, our computer program helped to relieve some burden, standardized NCSs and provided data needed to further develop evidence-based protocol for the NCSs in patients with suspected MEW.

No Major Nerve Regeneration Seems to Occur during Recovery of Ulnar Neuropathy at the Elbow.

Introduction: There are three main potential mechanisms of recovery after nerve lesion: (1) resolution of conduction block, (2) collateral reinnervation, and (3) nerve regeneration. Their relative contributions in recovery after focal neuropathies are not well established. Methods: In a group of previously reported prospective cohort of patients with ulnar neuropathy at the elbow (UNE), I performed a post-hoc analysis of their clinical and electrodiagnostic findings. I compared amplitudes of the compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) on ulnar nerve stimulation, as well as qualitative concentric needle electromyography (EMG) findings in the abductor digiti minimi muscle on the initial and follow-up examinations several years later. Results: Altogether, 111 UNE patients (114 arms) were studied. During median follow-up period of 880 days (range: 385-1545 days), CMAP amplitude increased (p = 0.02), and conduction block in the elbow segment recovered (from median 17% to 7%; p < 0.001). By contrast, SNAP amplitude did not change (p = 0.89). On needle EMG, spontaneous denervation activity diminished (p < 0.001), motor unit potential (MUP) amplitude increased (p < 0.001), and MUP recruitment remained unchanged (p = 0.43). Conclusions: Findings of the present study indicate that nerve function in chronic focal compression/entrapment neuropathies seems to improve mainly due to the resolution of the conduction block and collateral reinnervation. Contribution of nerve regeneration seems to be minor; the majority of axons lost in chronic focal neuropathies probably never recover. Further studies using quantitative methods are needed to validate present findings.

Ultrasonography of peripheral nerve tumours: a case series.

BACKGROUND: Peripheral nerve tumours (PNTs) are rare, but important cause of peripheral nerve dysfunction. The aim of the study was to present a series of consecutive patients with PNTs evaluated in authors' ultrasonography (US) practice. PATIENTS AND METHODS: The electronic medical records of patients with PNTs examined at our US laboratory from February 2013 to May 2020 were retrospectively reviewed. Data on gender, age, clinical features, PNT location, electrodiagnostic (EDx) features and US findings were collected. RESULTS: In the analyzed period 2845 patients were examined in our US laboratory. From these 15 patients (0.5%) with PNTs were identified. Four of them (3 with confirmed neurofibromatosis) had multiple PNTs. Half of patients (53%) presented with features of peripheral nerve damage, and others with palpable mass or pain. The most often involved nerve was ulnar (36%). PNT cross sectional areas varied from 24 mm2 to 1250 mm2 (median, 61 mm2). Based in 5 patients on histological and in remaining patients on US features, schwannoma was diagnosed in 40%, neurofibroma in 27%, and perineurioma in 27% of patients. CONCLUSIONS: As in previous reports, PNTs in our series presented with neurological symptoms, palpable mass or pain. In contrast to other focal neuropathies, particularly nerves with schwannomas, in spite of their large thickening, often demonstrated well preserved function. Adding US to our clinical practice, enabled us to diagnose these rare peripheral nerve lesions that we missed before.