Body mass index changes: an assessment of the effects of age and gender using the e-norms method.

BACKGROUND: To validate e-norms methodology in establishing a reference range for body mass index measures. A new method, the extrapolated norms (e-norms) method of determining normal ranges for biological variables is easy to use and recently was validated for several biological measurements. We aimed to determine whether this new method provides BMI results in agreement with established traditionally collected BMI values. METHODS: We applied the e-norms method to BMI data from 34,384 individuals and compared the ranges derived from this method with those from a large actuarially based study and explored differences in the normal range by gender, and age. RESULTS: The e-norms derived range of healthy BMI in adults is from 22.7 to 30.6, and showed that BMI is consistently higher in men than in women and increases with age, except in subjects aged 80-98 years in whom healthy BMI appears to be lower. CONCLUSIONS: Our e-norms derived healthy BMI ranges agree with traditionally obtained actuarially based methods, supporting the validity and ease of use of our method.

Effects of Tourniquets in the Development of Pain States: a Novel Clinical Pilot Study and Review of Utilization of Tissue Oximetry to Measure Neural Ischemia.

PURPOSE OF REVIEW: Approximately 20% of patients undergoing surgery develop persistent lower extremity pain following total knee arthroplasty. Animal studies have confirmed that prolonged tourniquet time increases the risk of endoneural ischemia and can mediate or modulate the development of chronic pain. The use of Near InfraRed Spectroscopy (NIRS) adjacent to nerve tissue, previously described as ONG has been shown to detect early neural compromise and has demonstrated clinical utility in carpal tunnel diagnosis. RECENT FINDINGS: In this pilot study, we recruited 10 healthy adult volunteers to undergo oxyneurography (ONG) and sensory nerve conduction testing (sNCT). We performed testing on the upper and lower extremities in each individual. The tourniquet was applied followed by measurements of sNCT and ONG as described. We observed a significant drop in the mean ONG index at 3 and 5 min following tourniquet inflation in upper and lower extremities. Similar to raw ONG values, there was significant variability in sNCT measurements, which in general increased from baseline with tourniquet inflation. In the upper extremity, there was a significant increase in sNCT with tourniquet inflation, while in the lower extremity, there was a trend towards significance. The use of ONG can be supported as a diagnostic tool to detect nerve ischemia and to potentially reduce the incidence of tourniquet-mediated or -modulated neural ischemia and reduce the development of chronic post-tourniquet pain.

Amyotrophic lateral sclerosis-A case report and mechanistic review of the association with toluene and other volatile organic compounds.

Unmasking of latent neurodegenerative disease has been reported following exposure to chemicals that share one or more mechanisms of action in common with those implicated in the specific disease. For example, unmasking of latent Parkinson's disease (PD) has been associated with exposure to anti-dopaminergic agents, while the progression of pre-existing mild cognitive impairment and unmasking of latent Alzheimer's disease has been associated with exposure to general anesthetic agents which promote Aß protein aggregation. This literature review and clinical case report about a 45-year-old man with no family history of motor neuron disease who developed overt symptoms of a neuromuscular disorder in close temporal association with his unwitting occupational exposure to volatile organic compounds (VOCs) puts forth the hypothesis that exposure to VOCs such as toluene, which disrupt motor function and increase oxidative stress, can unmask latent ALS type neuromuscular disorder in susceptible individuals.

Determining jitter values in the very young by use of the e-norms methodology.

INTRODUCTION: The diagnosis of myasthenia gravis in very young infants is a challenging one. In young infants, stimulated single-fiber electromyography (StimSFEMG) is the most appropriate technique, but it has serious limitations due to the absence of reference values in this subpopulation. Here we present our efforts to derive a reference range of jitter in a patient cohort of infants <3 years of age using the extrapolated norms, or e-norms, technique. METHODS: The e-norms method was used to calculate jitter mean consecutive difference (MCD) descriptive statistics for children <3 years of age. RESULTS: The e-norms derived jitter upper MCD limit was 45 µs in children <1 year, 33 µs in those <2 years, and 26 in those <3 years of age. CONCLUSION: In the absence of jitter reference values for the very young, the e-norms method can be used as an alternative to derive these values from laboratory cohorts. Muscle Nerve 55: 51-54, 2017.

Motor unit potential change with contraction level: a concentric macro electromyography study.

INTRODUCTION: Motor unit action potential (MUAP) reference values are usually given per muscle and age group. Our aim was to evaluate the change in MUAP size at different contraction levels using the concentric macro (ConMac) EMG technique. METHODS: ConMac needles were used to record the electrode cannula MUAP and measure its amplitude and area during weak, moderate, and strong muscle contractions. RESULTS: MUAP area and amplitude gradually increased from weak to strong contraction levels in all muscles studied. MUAP amplitudes were larger in distal than in proximal muscles, likely because of a higher fiber density distally. CONCLUSIONS: MUAP normal values in the literature per muscle do not take into account the contraction level at which they were recorded and can misrepresent the interpretation of normal. Concentric macro EMG is a simple and useful complement to routine EMG studies and yields additional information on MUAP neurophysiology.

Oxyneurography: a new technique for the measurement of nerve oxygenation.

INTRODUCTION: Near-infrared spectroscopy (NIRS) is a non-invasive technique used to measure tissue oxygenation. In this study we describe oxyneurography (ONG), a novel application of the NIRS technique in non-invasive surface measurement of oxygenation in ulnar nerve. METHODS: NIRS sensors were applied directly over the ulnar epicondylar groove to measure the ulnar nerve ONG index, a ratio of oxygenated over total hemoglobin content. Ulnar motor conduction studies were obtained in all subjects. RESULTS: The ONG index and ulnar motor conduction had a positive linear association. Ulnar motor conduction could be linearly predicted by the ONG index. The ONG index showed a sensitivity of 1.0 and a specificity of 0.852 for the presence of an ulnar neuropathy symptom. During limb ischemia, the ONG index gradually decreased. CONCLUSIONS: Oxyneurography can lead to the early detection of a compromise in a nerve's oxygenation status leading to neuropathy.

Deriving pediatric nerve conduction normal values in the very young (<3 years).

OBJECTIVE: This work describes our efforts to obtain nerve conduction studies normal values in a pediatric cohort between birth and 3 years of age using the extrapolated norms or e-norms method. Interpretation of these studies poses major challenges when no reliable normal values can be found in the literature. METHODS: The e-norms method was used to derive a reference range of upper and lower extremity sensory and motor nerve conductions normal values from a pediatric cohort referred to an EMG Laboratory for nerve conduction studies. RESULTS: E-norms were calculated for Median, Ulnar, Superficial Peroneal, Sural, and Medial Plantar sensory studies, and for Median, Ulnar, Peroneal, and Tibial motor studies. CONCLUSIONS: Pediatric electrodiagnostic testing is a very challenging undertaking. The ability to obtain and use normal values from the neurophysiologist's own referral pool adds great value to their diagnostic work-up. SIGNIFICANCE: EMG and nerve conduction studies can yield invaluable information in the diagnostic work-up of young infants. Using the e-norms method improves on the analysis and interpretation of electrophysiological studies in this age group.

Validating e-norms methodology in ophthalmic biometry.

OBJECTIVE: To validate the extrapolated norms or e-norms methodology in establishing a reference range for the biometric data used for intraocular lens power calculation. METHODS AND ANALYSIS: All measurements were performed with an optical low-coherence reflectometer. A novel technique, the e-norms methodology, was used to determine the normative values of measurements. RESULTS: Eyes (n=500) were measured to evaluate the axial length (AL), K readings (Ks), anterior chamber depth (ACD) and lens thickness (LT). Using the e-norms methodology, the normal AL ranged from 22.50 to 24.50 mm (mean=23.50 mm), with medium-long eyes between 24.51 and 24.99 mm and the long eyes measuring 25.00 mm and longer; the medium-short eyes ranged from 22.01 and 22.49 mm, with the short eyes measuring 22.00 mm and shorter. Normal values ranged from 2.50 to 3.50 mm for ACD (mean=3.00 mm), from 4.40 to 5.44 mm for LT (mean=4.92 mm), and from 42.50 to 44.82 dioptres for Ks (mean=43.66 dioptres). CONCLUSION: Measurements of the biometric mean values compared favourably with published data. The e-norms methodology assisted in establishing a biometric reference range. Furthermore, it allowed us to cluster patients into groups based on AL differences.

Reliability and reproducibility of visual e-norms plateau identification.

OBJECTIVE: To derive normal values from a lab's own diagnostic studies, the e-norms method relies on the proper identification of the e-norms plateau to derive descriptive statistics of the variable under study. This work was undertaken to compare the inter and intra-rater reliability of visual identification of the plateau by different raters analyzing laboratory nerve conductions study data. METHODS: Twenty raters were asked to visually identify the inflection points delineating an e-norms plateau to derive the Mean value of nerve conduction study laboratory data while blinded to the parameter they were analyzing. After a delay of 1-3 months, the same raters were asked to repeat some of the e-norms plateaus identification to assess delayed intra-rater reproducibility. RESULTS: Mean values derived from the identified plateau data were compared between raters (inter-rater) using a two factor ANOVA without replication. For the immediate inter-rater no statistically significant difference was found between the Means obtained by the different raters. For the delayed intra-rater, differences were found between raters. CONCLUSIONS: This study suggests that visual identification of the e-norms plateau inflection point is reliable between raters but more research is needed to assess reproducibility for the same raters. SIGNIFICANCE: E-norms is a promising method for deriving reference values using data that is available in most electrophysiology laboratories.

Long thoracic neuropathy caused by an apical pulmonary tumor.

Long thoracic nerve palsy has been reported to have traumatic, iatrogenic, and idiopathic causes. The authors describe the case of a 62-year-old man who presented with progressively worsening right shoulder pain, winging of the scapula, and Horner syndrome. A chest CT scan revealed an apical pulmonary mass. To the authors' knowledge, this is the first report of a long thoracic nerve palsy caused by an apical pulmonary tumor.

Facing the challenges of electrodiagnostic studies in the very elderly (>80 years) population.

OBJECTIVE: Studies on electrodiagnostic (EDX) methods usually exclude the very elderly. This also holds true for studies of normal EDX values. We analyzed the outcome and diagnostic value of EDX and collected reference data in a large cohort of patients ≥80 years of age. METHODS: Referral information, ICD-10 diagnoses and EDX data were retrieved from all patients ≥80 years of age referred for EDX studies at our department in 1995-2015. Normative data, including reference ranges, were obtained using the extrapolated norms (e-norms) method. RESULTS: 1966 unique patients (2335 examinations) were included. Only 11% were considered to have normal findings. 66% had pathological EDX findings in accordance with the indication for referral. Carpal tunnel syndrome was by far the most common diagnosis. Normative data retrieved using e-norms were similar to those of reference values from healthy subjects regarding EMG multiMUP data, but typically provided a wider normality window when applied to nerve conduction parameters. CONCLUSIONS: EDX studies are valuable in the diagnostic work-up of very elderly patients. Using the e-norms method may be a useful alternative when obtaining reference values in this age group. SIGNIFICANCE: Our findings provide additional insights to the challenges of evaluating very elderly patients with neuromuscular disease and underline the importance of including this growing part of the patient population in EDX research.

Criterion validity of the NC-stat automated nerve conduction measurement instrument.

The purpose of this study is to assess the criterion validity of peroneal and posterior tibial nerve conduction measurements obtained with the NC-stat system. Sixty patients referred to the Boston VA EMG laboratory were enrolled. Each subject had a full study of the lower extremity performed using traditional EMG equipment prior to obtaining the NC-stat measurements. These included peroneal and posterior tibial distal motor latency (DML), amplitude (AMP) and F-wave latency (FLAT) measurements. Excellent criterion validity was demonstrated for the peroneal and posterior tibial FLATs and the peroneal AMP. Acceptable criterion validity was identified in the peroneal DML and the posterior tibial AMP. The validity of the posterior tibial DML could not be demonstrated. With the exception of the peroneal DML, criterion validity was maintained in a sub-group analysis of the 50% most abnormal parameter values. The comparability of NCS performed with the NC-stat and in traditional settings has been demonstrated for motor studies of the median and ulnar nerves in previous studies. This study shows that the technology used by the NC-stat for studying the peroneal and posterior tibial nerves compares favorably as well with that obtained with traditional EMG equipment used under neurologist supervision.

Developing Normal Turns-Amplitude Clouds for Upper and Lower Limbs.

PURPOSE: Turns and amplitude analysis (T&A) is a frequently used method for automatic EMG interference pattern analysis. The T&A normal values have only been developed for a limited number of muscles. Our objective was to obtain normal T&A clouds for upper and lower extremity muscles for which no normal values exist in the literature. METHODS: The T&A normative data using concentric needle electrodes were obtained from 68 men and 56 women aged 20 to 60 years. RESULTS: Normal upper and lower extremity T&A clouds were obtained and presented in this article. CONCLUSION: The T&A normal values collected in this study maybe used to detect neurogenic and myopathic abnormalities in men and women at low-to-moderate muscle contractions. The effect of turns-amplitude data obtained at high force level of muscle contraction and its potential to falsely show neurogenic abnormalities are discussed.

E-norms: a method to extrapolate reference values from a laboratory population.

PURPOSE: Collecting reference values in subpopulations such as infants and children can pose a daunting challenge to gather through epidemiologic studies. The authors propose to evaluate a method the authors refer to as extrapolated norms (e-norms) to derive Stimulated Single Fiber EMG jitter reference values from the laboratory data of pediatric and adult cohorts. Single Fiber EMG studies are considered the gold standard test for evaluation of neuromuscular transmission disorders. METHODS: Data that lie in the plateau part of an inverted S curve derived from sorted jitter data were used to calculate descriptive statistics for pediatric and adult e-norms jitter. RESULTS: The e-norms derived jitter was 22 ± 2.83 µs for our pediatric and 21 ± 2.79 µs for our adult cohort. Our adult e-norms values compared favorably with the 22 ± 1.99 µs published jitter range derived from a healthy adult cohort. CONCLUSIONS: The e-norms method the authors describe seems to be useful in recovering reference ranges when such values are difficult to obtain, such as in a pediatric subpopulation.

Primary stroke prevention and hypertension treatment: which is the first-line strategy?

Hypertension (HT) is considered the main classic vascular risk factor for stroke and the importance of lowering blood pressure (BP) is well established. However, not all the benefit of antihypertensive treatment is due to BP reduction per se, as the effect of reducing the risk of stroke differs among classes of antihypertensive agents. Extensive evidences support that angiotensin-converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (ARB), dihydropyridine calcium channel blockers (CCB) and thiazide diuretics each reduced risk of stroke compared with placebo or no treatment. Therefore, when combination therapy is required, a combination of these antihypertensive classes represents a logical approach. Despite the efficacy of antihypertensive therapy a large proportion of the population, still has undiagnosed or inadequately treated HT, and remain at high risk of stroke. In primary stroke prevention current guidelines recommend a systolic/diastolic BP goal of <140/<90 mmHg in the general population and <130/80 mmHg in diabetics and in subjects with high cardiovascular risk and renal disease. The recent release in the market of the fixed-dose combination (FDC) of ACEI or ARB and CCB should provide a better control of BP. However to confirm the efficacy of the FDC in primary stroke prevention, clinical intervention trials are needed.