The sensitivity and specificity of the neurological examination in polyneuropathy patients with clinical and electrophysiological correlations

The role of tuning fork in the evaluation of musculoskeletal disorders and pallesthesia: A scoping review

BACKGROUND

Musculoskeletal and neurological conditions disorders are important conditions that need to be assessed in clinical practice. The tuning fork (TF) has been proposed as a practical tool to investigate suspected fractures and for the evaluation of pallesthesia in subjects with peripheral neuropathy.

OBJECTIVE

the aim of this study is to define whether the tuning fork can be useful in the clinical evaluation of patients with musculoskeletal disorders and deep somatosensory dysfunctions.

METHODS

This scoping review was performed in accordance with Joanna Briggs Institute. MEDLINE, Cochrane Library, PEDro, CINAHL, Web of Science, UpToDate, Scopus Database were consulted.

RESULTS

14 studies were included in the final analysis. Nine studies regard the use of tuning fork to detect fractures. If the tuning fork was used with a stethoscope, the test reached a high sensitivity ranging between 83% and 94%. Five studies investigated the tool to evaluate pallesthesia dysfunctions among which possible differences between biceps femoris strain and simple clinical rules for detecting peripheral neuropathy.

CONCLUSION

The 128 Hz tuning fork could be potentially useful to detect some type of traumatic fractures. The Rydel-Seiffer tuning fork appears to be a useful tool for assessing potential nerve conduction deficits in the evaluation of pallesthesia.

Initial validation of the Mass. General Neuropathy Exam Tool (MAGNET) for evaluation of distal small-fiber neuropathy

INTRODUCTION/AIMS

Diagnosis of small-fiber neuropathy (SFN) is hampered by its subjective symptoms and signs. Confirmatory testing is insufficiently available and expensive, so predictive examinations have value. However, few support the 2020 SFN consensus-case-definition requirements or were validated for non-diabetes neuropathies. Thus we developed the Massachusetts General Hospital Neuropathy Exam Tool (MAGNET) and measured diagnostic performance in 160 symptomatic patients evaluated for length-dependent SFN from any cause and 37 healthy volunteers.

METHODS

We compared prevalences of abnormalities (vital signs, pupil responses, lower-limb appearance, pin, light touch, vibration and position sensitivity, great-toe strength, muscle stretch reflexes), and validated diagnostic performance against objective SFN tests: lower-leg skin-biopsy epidermal neurite densities and autonomic function testing (AFT). Sensitivity/specificity, feasibility, test-retest and inter-rater reliability, and convergence with the Utah Early Neuropathy Scale were calculated.

RESULTS

Patients' ages averaged 48.5 ± 14.7 years and 70.6% were female. Causes of neuropathy varied, remaining unknown in 59.5%. Among the 46 with abnormal skin biopsies, the most prevalent abnormality was reduced pin sharpness at the toes (71.7%). Inter-rater reliability, test-retest reliability, and convergent validity excelled (range = 91.3-95.6%). Receiver operating characteristics comparing all symptomatic patients versus healthy controls indicated that a MAGNET threshold score of 14 maximized predictive accuracy for skin biopsies (0.74) and a 30 cut-off maximized accuracy for predicting AFT (0.60). Analyzing patients with any abnormal neuropathy-test results identified areas-under-the-curves of 0.87-0.89 for predicting a diagnostic result, accuracy = 0.80-0.89, and Youden's index = 0.62. Overall, MAGNET was 80%-85% accurate for stratifying patients with abnormal versus normal neuropathy test results.

DISCUSSION

MAGNET quickly generates research-quality metrics during clinical examinations.

Inactive Matrix Gla Protein in Relation to Renal and Cardiac Functions and Cardiac Valvular Calcification Among Type 2 Diabetes Patients

Background

Matrix Gla protein (MGP) is a robust innate suppressor of the detrimental process of vascular calcification in the human body.

Objectives

The interrelationship between circulating MGP levels and renal and cardiac dysfunction, besides echocardiographic calcification score (ECS) was investigated in a sample of type 2 diabetes (T2D) patients.

Methods

The study included 130 subjects. They were 95 patients with T2D and 35 age- and sex-matched healthy controls. Patients were further subdivided into 52 T2D patients without DKD (eGFR ⩾ 60 ml/minute/1.73 m²) and 43 T2D persons with DKD (eGFR > 60 ml/minute/1.73 m²). Serum MGP levels, determined by ELISA, renal function tests, lipid profile, and echocardiography were studied in all participants.

Results

Significantly elevated circulating inactive MGP level was noted in individuals having T2D compared to controls. It correlated negatively with eGFR and left ventricular (LV) diastolic and systolic functions and positively with indices of LV hypertrophy. ECS was significantly increased in both T2D groups compared to controls and in DKD group compared to the diabetic group without DKD. A significant positive correlation was observed between inactive MGP and ECS.

Conclusion

Serum inactive MGP may contribute to the development of DKD and to the associated process of cardiac valvular calcification. It may be a beneficial diagnostic marker for early prediction of cardiac calcification and preclinical LV systolic and diastolic dysfunction in T2D patients, especially in those complicated with DKD.

Quantitative sonographic assessment of muscle thickness and fasciculations distribution is a sensitive tool for neuromuscular disorders

INTRODUCTION

Loss of muscle thickness can be demonstrated in a wide spectrum of neuromuscular disorders, while fasciculations are more frequent in amyotrophic lateral sclerosis (ALS). In the current study, we aimed to determine the sensitivity and specificity of quantitative sonographic assessment of muscle thickness and the presence of fasciculations for diagnosing various neuromuscular disorders.

METHODS

The thickness and the presence of fasciculations in eight muscles were determined by sonography in patients with myopathy (22), polyneuropathy (36), ALS (91), and spinal muscular atrophy (SMA) (31) and compared to normative values determined in 65 heathy control subjects.

RESULTS

Reduced muscle thickness in at least one relaxed muscle showed 92-100% sensitivity for diagnosing a neuromuscular disease, with a specificity of 85% for differentiating patients from heathy controls (AUC = 0.90). Subtracting distal from proximal muscle thickness may differentiate between myopathy and polyneuropathy. Fasciculations in ≥1 proximal muscle showed good diagnostic accuracy (AUC = 0.87) for diagnosing ALS.

DISCUSSION

Sonographic assessment of muscle thickness is a sensitive tool for diagnosing a wide spectrum of neuromuscular diseases, and may facilitate diagnosis even in patients with normal strength on neurological examination, while the presence of fasciculations in proximal muscles may facilitate ALS diagnosis.

The role of potassium in muscle membrane dysfunction in end-stage renal disease

OBJECTIVE

Uremic myopathy is a condition seen in end-stage renal disease (ESRD), characterized by muscle weakness and muscle fatigue, in which the pathophysiology is uncertain. The aim of this study was to assess the role of abnormal serum constituents in ESRD patients by relating them to the excitability properties of the tibialis anterior muscle, at rest and during electrically induced muscle activation, by recording muscle velocity recovery cycles (MVRC) and frequency ramp responses.

METHODS

Eighteen ESRD patients undergoing hemodialysis were evaluated by blood sample, MVRC, and frequency ramp (before and near the end of dialysis treatment), quantitative electromyography, and nerve conduction studies. Patients were compared to 24 control subjects.

RESULTS

In patients, muscle relative refractory period, early supernormality, late supernormality after 5 conditioning stimuli, and latency of the last of 15 and 30 frequency ramp pulses were strongly associated with potassium levels (p < 0.01), showing depolarization before and normalization in the end of hemodialysis.

CONCLUSIONS

In ESRD patients, the muscle membrane is depolarized, mainly due to hyperkalemia.

SIGNIFICANCE

Since normal muscle fatigue has been attributed to potassium-induced depolarization, it seems likely that this mechanism is also a major cause of the exaggerated muscle fatigue and weakness in ESRD patients.

Prediction of Diabetic Sensorimotor Polyneuropathy Using Machine Learning Techniques

Diabetic sensorimotor polyneuropathy (DSPN) is a major complication in patients with diabetes mellitus (DM), and early detection or prediction of DSPN is important for preventing or managing neuropathic pain and foot ulcer. Our aim is to delineate whether machine learning techniques are more useful than traditional statistical methods for predicting DSPN in DM patients. Four hundred seventy DM patients were classified into four groups (normal, possible, probable, and confirmed) based on clinical and electrophysiological findings of suspected DSPN. Three ML methods, XGBoost (XGB), support vector machine (SVM), and random forest (RF), and their combinations were used for analysis. RF showed the best area under the receiver operator characteristic curve (AUC, 0.8250) for differentiating between two categories—criteria by clinical findings (normal, possible, and probable groups) and those by electrophysiological findings (confirmed group)—and the result was superior to that of linear regression analysis (AUC = 0.6620). Average values of serum glucose, International Federation of Clinical Chemistry (IFCC), HbA1c, and albumin levels were identified as the four most important predictors of DSPN. In conclusion, machine learning techniques, especially RF, can predict DSPN in DM patients effectively, and electrophysiological analysis is important for identifying DSPN.

Test-retest and time dependent variation and diagnostic values of vibratory sensation determined by biothesiometer and the Rydel-Seiffer tuning fork

BACKGROUND AND AIMS

Polyneuropathy is a common neurological disorder with many potential causes. An essential part in screening, diagnosis, and follow-up evaluation of polyneuropathy is testing of the sensory function including vibratory sensation. The graduated Rydel-Seiffer tuning fork and the biothesiometer have been developed to quantify vibratory sensation through detection thresholds. The aim of this study is to compare the vibration detection thresholds determined by the two instruments regarding intraindividual temporal changes, interindividual variation in healthy subjects and comparison of the diagnostic value in patients with a clinical suspicion of polyneuropathy.

METHODS

Ninety-four healthy subjects, 98 patients with and 97 patients without a diagnosis of polyneuropathy were included. Quantitative sensory testing including biothesiometry, structured clinical examination, and nerve conduction studies were performed three times during 52 weeks in healthy subjects and once in patients.

RESULTS

There were no significant changes over time for neither the Rydel-Seiffer tuning fork nor the biothesiometer, and both had larger between-subject variation than within-subject variation. Relative intertrial variability was largest for the biothesiometer. Diagnostic value (sensitivity, specificity, positive predictive value, and negative predictive value) was moderate for both methods (Rydel-Seiffer tuning fork: 58%, 74%, 70%, 64%; biothesiometer: 47%, 77%, 68%, 59%).

INTERPRETATION

The Rydel-Seiffer tuning fork and the biothesiometer have a low test-retest and time dependent variation. They perform almost equally as diagnostic tools in patients with suspected polyneuropathy with a tendency toward better performance of the tuning fork.

Continuous erector spinae plane block at lumbar level for relief of severe pain due to hip fracture: case series

Introduction: Hip fracture pain is frequently acute and disabling and increases perioperative complications in the patient; hence it requires a multimodal analgesia approach. This case series describes the continuous erector spinae plane block at the lumbar level for hip fracture analgesia. Methods: A search was conducted of patients with hip fracture referred to the pain service of Hospital Universitario San Vicente Fundación (HUSVF) from August 2019 to March 2020, who had undergone continuous erector spinae plane block as part of their analgesic regimen. Results: A total of 6 patients, 4 females and 2 males with an average age of 75 years were identified. A reduction in pain intensity from acute to mild or absent was observed in every case, up to 24 hours after the initial injection. 66 % experienced a relapse of severe pain after 24 hours and 2 patients the catheter functionality failed after 24 hours. One patient underwent dermatome pinprick assessment. Conclusions: The continuous erector spinae plane block with a single injection provided analgesic efficacy similar to other single injection peripheral blocks, although continuous analgesia for more than 24 hours was not achieved. Some variations in the block technique described may improve the analgesic effectiveness in patients with hip fracture pain.

Early Detection of Diabetic Peripheral Neuropathy: A Focus on Small Nerve Fibres

Diabetic peripheral neuropathy (DPN) is the most common complication of both type 1 and 2 diabetes. As a result, neuropathic pain, diabetic foot ulcers and lower-limb amputations impact drastically on quality of life, contributing to the individual, societal, financial and healthcare burden of diabetes. DPN is diagnosed at a late, often pre-ulcerative stage due to a lack of early systematic screening and the endorsement of monofilament testing which identifies advanced neuropathy only. Compared to the success of the diabetic eye and kidney screening programmes there is clearly an unmet need for an objective reliable biomarker for the detection of early DPN. This article critically appraises research and clinical methods for the diagnosis or screening of early DPN. In brief, functional measures are subjective and are difficult to implement due to technical complexity. Moreover, skin biopsy is invasive, expensive and lacks diagnostic laboratory capacity. Indeed, point-of-care nerve conduction tests are convenient and easy to implement however questions are raised regarding their suitability for use in screening due to the lack of small nerve fibre evaluation. Corneal confocal microscopy (CCM) is a rapid, non-invasive, and reproducible technique to quantify small nerve fibre damage and repair which can be conducted alongside retinopathy screening. CCM identifies early sub-clinical DPN, predicts the development and allows staging of DPN severity. Automated quantification of CCM with AI has enabled enhanced unbiased quantification of small nerve fibres and potentially early diagnosis of DPN. Improved screening tools will prevent and reduce the burden of foot ulceration and amputations with the primary aim of reducing the prevalence of this common microvascular complication.

The complex association between pain and neuropathy

BACKGROUND

Several studies of patients with polyneuropathy failed to show differences between patients with and without pain. In the current study, we aimed to explore the association between neuropathic symptoms, mainly pain, and polyneuropathy characteristics.

METHODS

A prospective cross-sectional study recruiting 151 patients with non-diabetic polyneuropathy was performed between November 2016 and May 2017. A total of 38 patients with chronic inflammatory demyelinating neuropathy were excluded. Patients underwent clinical, electrophysiological and functional assessments of their polyneuropathy. Polyneuropathy characteristics were compared depending on the presence and severity of neuropathic symptoms.

RESULTS

The presence and the severity of weakness were associated with a more severe neuropathy as measured by clinical, electrophysiological and functional assessments, while the presence of pain was associated with higher sural amplitudes, and the severity of pain showed a curvilinear association with neuropathy severity.

CONCLUSIONS

Our study shows a novel finding of a curvilinear association between pain and polyneuropathy severity.

Diagnostic value of clinical examination for identifying patients with large- and small-fibre neuropathy

BACKGROUND

The diagnosis of polyneuropathy usually requires neurophysiological investigation, necessitating specialised testing and interpretation thereby increasing the time to final diagnosis.

AIMS

To investigate the predictive value of the clinical examination in patients with potential neuropathies.

METHODS

Patients were recruited based on their referral requesting neurophysiological testing. Two examiners tested ankle jerk reflexes and gradient to temperature sensation prior to the patient undergoing neurophysiology investigations, blinded to subsequent testing results. The neurophysiology investigations were either standard nerve conduction study (NCS) or thermal threshold testing (TTT) or both. These data were then analysed to determine the Kappa between examiners as well as sensitivity, specificity, and positive and negative likelihood ratios.

RESULTS

There was a modest level of agreement between examiners for ankle jerk testing (Kappa = 0.6) but poor agreement for gradient temperature testing (Kappa = 0.3). Bilateral absence of ankle jerk reflexes was moderately associated with abnormal NCS, with the following characteristics: sensitivity 72%, specificity 91%, positive likelihood ratio 7.6 and negative likelihood ratio 0.3. The presence of a temperature gradient was poorly diagnostic for abnormal TTT: sensitivity 87%, specificity 14%, with positive and negative likelihood ratios close to 1.

CONCLUSION

The absence of ankle jerks performed moderately well in identifying patients likely to have large-fibre neuropathy and could potentially be used to help decide who should be sent for NCS. Gradient temperature testing was much more subjective and did not change the likelihood of abnormal TTT.

The utility of a single simple question in the evaluation of patients with nondiabetic polyneuropathy

INTRODUCTION

A single and simple question, namely "What percentage of normal (PoNL) do you feel regarding your disease?" is feasible and valid in myasthenia gravis. In this study, we aimed to determine the validity of this question in patients with nondiabetic polyneuropathy.

METHODS

Clinical, electrophysiological, and functional and disability assessments were performed in 151 patients with nondiabetic polyneuropathy. One hundred forty patient answers were recorded for the PoNL question, and these were included in the current study.

RESULTS

The PoNL correlated moderately with functional and disability scales.

DISCUSSION

"What PoNL do you feel?" is a simple, quick, and valid question, which correlates moderately with functional and disability scales in nondiabetic polyneuropathy, and it may be incorporated in polyneuropathy assessment.

The Veterans Affairs Neuropathy Scale: A Reliable, Remote Polyneuropathy Exam

Introduction: Polyneuropathy (PN) complaints are common, prompting many referrals for neurologic evaluation. To improve access of PN care in distant community clinics, we developed a telemedicine service (patient-clinician interactions using real-time videoconference technology) for PN. The primary goal of this study was to construct a remote exam for PN that is feasible, reliable, and concordant with in-person assessments for use in our tele-PN clinics.

Methods: To construct the VA Neuropathy Scale (VANS), we searched the literature for existing, validated PN assessments. From these assessments, we selected a parsimonious set of exam elements based on literature-reported sensitivity and specificity of PN detection, with modifications as necessary for our teleneurology setting (i.e., a technician examination under the direction of a neurologist). We recruited 28 participants with varying degrees of PN to undergo VANS testing under 5 scenarios. The 5 scenarios differed by mode of VANS grading (in-person vs. telemedicine) and by the in-person examiner type (neurologist vs. technician) in telemedicine scenarios. We analyzed concordance between the VANS and a person's medical chart-derived PN status by modeling the receiver operating characteristic (ROC) curve. We analyzed reliability of the VANS by mixed effects regression and computing the intraclass correlation coefficient (ICC) of scores across the 5 scenarios.

Results: The VA Neuropathy Scale (VANS) tests balance, gait, reflexes, foot inspection, vibration, and pinprick. Possible scores range from 0 to 50 (worst). From the ROC curve, a cutoff of >2 points on the VANS sets the sensitivity and specificity of detecting PN at 98 and 91%, respectively. There is a small (1.3 points) but statistically significant difference in VANS scoring between in-person and telemedicine grading scenarios. For telemedicine grading scenarios, there is no difference in VANS scores between neurologist and technician examinations. The ICC is 0.89 across all scenarios.

Discussion: The VANS, informed by existing PN instruments, is a promising clinical assessment tool for diagnosing and monitoring the severity of PN in telemedicine settings. This pilot study indicates acceptable concordance and reliability of the VANS with in-person examinations.

Polyneuropathies

BACKGROUND

Polyneuropathies (peripheral neuropathies) are the most common type of disorder of the peripheral nervous system in adults, and specifically in the elderly, with an estimated prevalence of 5-8%, depending on age. The options for treatment depend on the cause, which should therefore be identified as precisely as possible by an appropriate diagnostic evaluation.

METHODS

This review is based on the current guidelines and on large-scale cohort studies and randomized, controlled trials published from 2000 to 2017, with an emphasis on non-hereditary types of polyneuropathy, that were retrieved by a selective search in PubMed.

RESULTS

Diabetes is the most common cause of polyneuropathy in Europe and North America. Alcohol-associated polyneuropathy has a prevalence of 22-66% among persons with chronic alcoholism. Because of the increasing prevalence of malignant disease and the use of new chemotherapeutic drugs, chemotherapy-induced neuropathies (CIN) have gained in clinical importance; their prevalence is often stated to be 30-40%, with high variation depending on the drug(s) and treatment regimen used. Polyneuropathy can also arise from genetic causes or as a consequence of vitamin deficiency or overdose, exposure to toxic substances and drugs, and a variety of immunological processes. About half of all cases of polyneu - ropathy are associated with pain. Neuropathic pain can be treated symptomatically with medication. Exercise, physiotherapy, and ergotherapy can also be beneficial, depending on the patient's symptoms and functional deficits.

CONCLUSION

A timely diagnosis of the cause of polyneuropathy is a prerequisite for the initiation of appropriate specific treatment. Patients with severe neuropathy of unidentified cause should be referred to a specialized center for a thorough diagnostic evaluation.

Timed Vibration Sense and Joint Position Sense Testing in the Diagnosis of Distal Sensory Polyneuropathy

Introduction:

Distal sensory polyneuropathy (DSP) is one of the most common neurological disorders. Although several studies have studied the role of the neurological examination in DSP, there are only limited studies on the utility of timed vibration sense (VBS) and joint position sense (JPS) testing in the diagnosis of DSP.

Objectives:

The objective is to study the utility of timed VBS testing and JPS testing at the great toe in clinical detection of DSP.

Methods:

This study was prospectively conducted in the neurology department of a tertiary care hospital in India. Patients with DSP referred to the electrophysiology laboratory from August 2017 to December 2017 were screened. Patients with symptomatic DSP which was confirmed by electrophysiological studies were taken as cases and normal participants with no symptoms or electrophysiological findings suggestive of DSP served as controls.

Results:

We studied 127 patients and 194 controls. The mean age of the patients was 48.7 (14.5) years in the patient group and 39.7 (14.5) years in the control group. The male: female ratio was 77/50 in the patient group and 112/82 in the control group. Abnormal clinical examination was found in 95% of the patients with DSP. The most common abnormal examination components were impaired ankle reflexes (70%), vibration (85%), and JPS (39.6%) sensation. Using the receiver operating characteristic curve for the diagnosis of DSP, a vibratory response lasting <8 s at the great toe had a sensitivity of 85% and specificity of 42.8%. For JPS testing at the great toe, obtaining two or more incorrect responses had a sensitivity of 33% and specificity of 87.6%.

Conclusion:

VBS testing was more sensitive and JPS testing was more specific in making a clinical diagnosis of DSP. For timed VBS, duration of >8 s at the great toe was a useful test to rule out DSP, and for JPS testing at the great toe, obtaining two or more incorrect responses was a useful test in ruling in the diagnosis of DSP.

Toronto Clinical Neuropathy Score is valid for a wide spectrum of polyneuropathies

BACKGROUND AND PURPOSE

The Toronto Clinical Neuropathy Score (TCNS) is a valid and reliable scale for the diagnosis and staging of diabetic sensorimotor polyneuropathy. In this study, we aimed to explore the performance of the TCNS in non-diabetic polyneuropathies.

METHODS

We performed a prospective study from November 2016 to May 2017 of patients with non-diabetic polyneuropathy. Patients had clinical, electrophysiological and functional assessments of their polyneuropathy, and the findings were correlated with the TCNS.

RESULTS

The TCNS correlated with all clinical, electrophysiological and disability measures of polyneuropathy, mostly at a moderate level (e.g. r = -0.58 for sural nerve action potential amplitude). Higher TCNS severity grades were associated with worse polyneuropathy on all measures in the lower limbs, and with worse electrophysiological parameters and vibration perception thresholds in the upper limbs. The scale also showed excellent reliability and accuracy (kappa, 0.92-0.93 for inter- and intra-observer reliability; area under the receiver operating characteristics curve, 0.93).

CONCLUSION

The TCNS is a valid and reliable scale for a wide spectrum of polyneuropathies, and might be useful in clinical practise and research for the diagnosis and staging of polyneuropathy.