Diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy in clinical practice: A survey among Dutch neurologists.

The diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is often a challenge. The clinical presentation is diverse, accurate biomarkers are lacking, and the best strategy to initiate and maintain treatment is unclear. The aim of this study was to determine how neurologists diagnose and treat CIDP. We conducted a cross-sectional survey on diagnostic and treatment practices among Dutch neurologists involved in the clinical care of CIDP patients. Forty-four neurologists completed the survey (44/71; 62%). The respondents indicated to use the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) 2010 CIDP guideline for the diagnosis in 77% and for treatment in 50%. Only 57% of respondents indicated that the presence of demyelinating electrophysiological findings was mandatory to confirm the diagnosis of CIDP. Most neurologists used intravenous immunoglobulins (IVIg) as first choice treatment, but the indications to start, optimize, or withdraw IVIg, and the use of other immune-modulatory therapies varied. University-affiliated respondents used the EFNS/PNS 2010 diagnostic criteria, nerve imaging tools, and immunosuppressive drugs more often. Despite the existence of an international guideline, there is considerable variation among neurologists in the strategies employed to diagnose and treat CIDP. More specific recommendations regarding: (a) the minimal set of electrophysiological requirements to diagnose CIDP, (b) the possible added value of nerve imaging, especially in patients not meeting the electrodiagnostic criteria, (c) the most relevant serological examinations, and (d) the clear treatment advice, in the new EFNS/PNS guideline, would likely support its implementation in clinical practice.

Ultrasonography Findings in Severe Carpal Tunnel Syndrome.

Background: Increasing severity of carpal tunnel syndrome (CTS), as graded by nerve conduction studies (NCS), has been demonstrated to predict the speed and completeness of recovery after carpal tunnel release (CTR). The purpose of this study is to compare the cross-sectional area (CSA) of the median nerve in patients with severe and nonsevere CTS as defined by NCS. Methods: Ultrasound CSA measurements were taken at the carpal tunnel inlet at the level of the pisiform bone by a hand fellowship-trained orthopedic surgeon. Severe CTS on NCS was defined as no response for the distal motor latency (DML) and/or distal sensory latency (DSL). Results: A total of 274 wrists were enrolled in the study. The median age was 51 years (range: 18-90 years), and 72.6% of wrists were from female patients. CSA of median nerve and age were comparatively the best predictors of severity using a linear regression model and receiver operator curves. Using cutoff of 12 mm2 for severe CTS, the sensitivity and specificity are 37.5% and 81.9%, respectively. Conclusions: Ultrasound can be used to grade severity in younger patients (<65 years) with a CTS-6 score of >12.

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.

Electrodiagnostic data-driven clustering identifies a prognostically different subgroup of patients with chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE: This study aimed to explore the correlations between electrodiagnostic (EDX) features in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and to investigate whether EDX data-driven clustering can identify a distinct subgroup regarding clinical phenotype and treatment response. METHODS: We reviewed clinical and EDX data of 56 patients with definite CIDP fulfilling the 2010 European Federation of Neurological Societies and Peripheral Nerve Society criteria at two teaching hospitals. A hierarchical agglomerative clustering algorithm with complete linkage was used to partition the patients into subgroups with similar EDX features. A stepwise logistic regression analysis was performed to evaluate predictors of the long-term outcome. RESULTS: EDX data-driven clustering partitioned the patients into two clusters, identifying a distinct subgroup characterised by coexistence of prominent conduction slowing and markedly reduced distally evoked compound muscle action potential (CMAP) amplitudes. This cluster of patients was significantly over-represented by an atypical subtype (distal acquired demyelinating symmetric polyneuropathy) compared with the other cluster (70% vs 26.1%, p=0.042). Furthermore, patients in this cluster invariably showed favourable long-term treatment outcome (100% vs 63%, p=0.023). In logistic regression analyses, the initial disability (OR 6.1, 95% CI 2.4 to 25.4), F-wave latency (OR 0.93, 95% CI 0.86 to 0.98) and distal CMAP duration (OR 0.96, 95% CI 0.91 to 0.99) were significant predictors of the poor long-term outcome. CONCLUSION: Our results show that EDX data-driven clustering could differentiate a pattern of EDX features with prognostic implication in patients with CIDP. Reduced distally evoked CMAPs may not necessarily predict poor responses to treatment, and active treatment is warranted when prominent slowing of conduction is accompanied in the distal segments.

Utilization of Electrodiagnostic Testing for Carpal Tunnel Syndrome by General Practitioners Prior to Hand Surgery Consultation.

BACKGROUND: Carpal tunnel syndrome (CTS) is the most common peripheral mononeuropathy and thus is frequently encountered by general practitioners (GPs). The aim of this study is to investigate the referral pattern of GPs with regard to electrodiagnostic (EDX) testing for suspected CTS prior to hand surgery consultation, as well as to investigate the results of EDX testing for suspected CTS when requested by GPs prior to evaluation by a hand surgeon. METHODS: We retrospectively reviewed patients referred to our hand surgery clinic over a consecutive 2-year period for suspected CTS. RESULTS: A total of 403 patients were referred to our hand surgery clinic from January 1, 2016, to December 31, 2017. Of the 403, 295 (73.2%) were referred by GPs. GPs obtained prereferral EDX testing in 198 (67.1%) of these patients. EDX testing confirmed their diagnosis in 177 patients (89.4%). There were 21 patients (10.6%) identified with normal EDX testing and a more likely diagnosis reached based on clinical examination. CONCLUSIONS: GPs make up the majority of our referrals for CTS, and they obtain EDX testing prior to consultation in two-thirds of referrals. GPs appear to accurately utilize EDX testing to confirm their diagnosis prior to referral and have a low rate of normal testing where symptoms are more readily explained by an alternative diagnosis.

Variation in Nonsurgical Services for Carpal Tunnel Syndrome Across a Large Integrated Health Care System.

PURPOSE: To evaluate facility-level variation in the use of services for patients with carpal tunnel syndrome (CTS) receiving care in the Veterans Health Administration (VHA). METHODS: A national cohort of VHA patients diagnosed with CTS during fiscal year 2013 was divided into nonsurgical and operative treatment groups for comparison. We assessed the use of 5 types of CTS-related services (electrodiagnostic studies [EDS], imaging, steroid injection, oral steroids, and therapeutic modalities) in the prediagnosis and postdiagnosis periods before any operative intervention at the patient and facility levels. RESULTS: Among 72,599 patients newly diagnosed with CTS, 5,666 (7.8%) received carpal tunnel release within 12 months. The remaining 66,933 (92.2%) were in the nonsurgical group. Therapeutic modalities and EDS were the most commonly employed services after the index diagnosis and had large facility-level variation in use. At the facility level, the use of therapeutic modalities ranged from 0% to 93% in the operative group (mean, 32%) compared with 1% to 67% (mean, 30%) in the nonsurgical group. The use of EDS in the postdiagnosis period ranged from 0% to 100% (mean, 59%) in the operative treatment group and 0% to 55% (mean, 26%) in the nonsurgical group at the facility level. CONCLUSIONS: There is wide facility variation in the use of services for CTS among patients receiving operative and nonsurgical treatment. Care delivered by facilities with the highest and lowest rates of service use may suggest overuse and underuse, respectively, of nonsurgical CTS services and a lack of consideration of individual patient factors in making health care decisions regarding use. CLINICAL RELEVANCE: Surgeons must understand the degree of treatment variability for CTS, comprehend the ramifications of large variation in reimbursement and waste in the health care system, and become involved in devising strategies to optimize hand care across all phases of care.

Comparison of Interpolation Methods in the Diagnosis of Carpal Tunnel Syndrome

Background: Diagnosis of carpal tunnel syndrome is based on clinical symptoms, examination findings, and electrodiagnostic studies. For carpal tunnel syndrome, the most useful of these are nerve conduction studies. However, nerve conduction studie can result in ambiguous or false-negative results, particularly for mild carpal tunnel syndrome. Increasing the number of nerve conduction studie tests improves accuracy but also increases time, cost, and discomfort. To improve accuracy without additional testing, the terminal latency index and residual latency are additional calculations that can be performed using the minimum number of tests. Recently, the median sensory-ulnar motor latency difference was devised as another way to improve diagnostic accuracy for mild carpal tunnel syndrome. Aims: The median sensory-ulnar motor latency difference, terminal latency index, and residual latency were compared for diagnostic accuracy according to severity of carpal tunnel syndrome. Study Design: Diagnostic accuracy study. Methods: A total of 657 subjects were retrospectively enrolled. The carpal tunnel syndrome group consisted of 546 subjects with carpal tunnel syndrome according to nerve conduction studie (all severities). The control group consisted of 121 subjects with no hand symptoms and normal nerve conduction studie. All statistical analyses were performed using SAS v9.4. Means were compared using one-way ANOVA with the Bonferroni adjustment. Sensitivity, specificity, positive predictive value, and negative predictive value were compared, including receiver operating characteristic curve analysis. Results: For mild carpal tunnel syndrome, the median sensory-ulnar motor latency difference showed higher specificity and positive predictive value rates (0.967 and 0.957, respectively) than terminal latency index (0.603 and 0.769, respectively) and residual latency (0.818 and 0.858, respectively). The area under the receiver operating characteristic was highest for the median sensory-ulnar motor latency difference (0.889), followed by the residual latency (0.829), and lastly the terminal latency index (0.762). Differences were statistically significant (median sensory-ulnar motor latency difference being the most accurate). For moderate carpal tunnel syndrome, sensitivity and specificity rates of residual latency (0.989 and 1.000) and terminal latency index (0.983 and 0.975) were higher than those for median sensory-ulnar motor latency difference (0.866 and 0.958). Differences in area under the receiver operating characteristic curve were not significantly significant, but median sensory-ulnar motor latency difference sensitivity was lower. For severe carpal tunnel syndrome, residual latency yielded 1.000 sensitivity, specificity, positive predictive value, negative predictive value and area beneath the receiver operating characteristic curve. Differences in area under the receiver operating characteristic curve were not significantly different. Conclusion: The median sensory-ulnar motor latency difference is the best calculated parameter for diagnosing mild carpal tunnel syndrome. It requires only a simple calculation and no additional testing. Residual latency and the terminal latency index are also useful in diagnosing mild to moderate carpal tunnel syndrome.

Awareness of dysgeusia and gustatory tests in patients undergoing chemotherapy for breast cancer.

PURPOSE: We analyzed the prevalence of gustatory test abnormalities in breast cancer (BC) patients undergoing chemotherapy. METHODS: We enrolled 43 BC patients undergoing chemotherapy and 38 BC patients who had never undergone chemotherapy (control group). Two gustatory tests were conducted: an instillation method examining the threshold for four basic taste stimuli and an electrogustometry method measuring the threshold for perception with electric stimulation at the front two-thirds of the tongue (cranial nerve VII) and at the back third of the tongue (cranial nerve IX). The results of the two gustatory tests and clinicopathological factors were compared between the chemotherapy and control groups and between patients with and without awareness of dysgeusia in the chemotherapy group. RESULTS: In the chemotherapy group, 19 (44%) patients were aware of dysgeusia and 8 (19%) had hypogeusia using the instillation method. Although more patients had parageusia in the chemotherapy than control group, no significant differences in the results of the two gustatory tests were observed. Patients with dysgeusia awareness had a higher threshold at cranial nerve IX using the electrogustometry method than those without dysgeusia awareness; no significant differences in hypogeusia were observed using the instillation method. In fact, 74% (14/19) of patients with dysgeusia awareness could identify the four tastes accurately using the instillation method. Similar results were observed for the instillation and electrogustometry methods at cranial nerve VII. CONCLUSIONS: While approximately half of the chemotherapy patients were aware of dysgeusia, 81% (35/43) of them could accurately identify the four basic tastes using the instillation method.

The extrapolated reference values procedure: Theory, algorithm, and results in patients and control subjects.

INTRODUCTION: Reference values (RVs) are required to separate normal from abnormal values obtained in electrodiagnostic (EDx) testing. However, it is frequently impractical to perform studies on control subjects to obtain RVs. The Extrapolated Reference Values (E-Ref) procedure extracts RVs from data obtained during clinically indicated EDx testing. We compared the E-Ref results with established RVs in several sets of EDx data. METHODS: The mathematical basis for E-Ref was explored to develop an algorithm for the E-Ref procedure. To test the validity of this algorithm, it was applied to simulated and real jitter measurements from control subjects and patients with myasthenia gravis, and to nerve conduction studies from patients with various conditions referred for EDx studies. RESULTS: There was good concordance between E-Ref and RVs for all evaluated data sets. DISCUSSION: E-Ref is a promising method to develop RVs. Muscle Nerve 57: 90-95, 2018.

Current practice in regional anaesthesia in South America: An online survey. / Práctica actual de la anestesia regional en América del Sur: encuesta en línea.

OBJECTIVE: A survey was conducted in order to obtain a profile of the practice of regional anesthesia in South America, and determine the limitations of its use. METHODS: After institutional ethics committee approval, a link to an online questionnaire was sent by e-mail to anaesthesiologists in Argentina, Bolivia, Chile, Colombia, Panamá, Paraguay, Perú, and Uruguay. The questionnaire was processed anonymously. RESULTS: A total of 1,260 completed questionnaires were received. The results showed that 97.6% of the anaesthesiologists that responded used regional anaesthesia in clinical practice, 66.9% performed peripheral nerve block (PNB) regularly, 21.6% used continuous PNB techniques, and 4.6% used stimulating catheters. The primary source of training was residency programs. As regards PNB, the most common performed were interscalene (52.3%), axillary (45.1%), femoral (43.2%), and ankle block (43%). As regards the localisation technique employed, 16% used paraesthesia, 44.2% used a peripheral nerve stimulator, and 18.1% ultrasound guidance. CONCLUSIONS: Regional anaesthesia and PNB are commonly used among South American anaesthesiologists. Considering that each country has its own profile for use, this profile should guide training in clinical practice, especially in residency programs.

The Influence of Insurance Type on Management of Carpal Tunnel Syndrome: An Analysis of Nationwide Practice Trends.

BACKGROUND: The purpose of this study was to evaluate the impact of insurance type on use of diagnostic testing, treatments, and the efficiency of care for patients with carpal tunnel syndrome. METHODS: The 2009 to 2013 Truven MarketScan Databases were used to identify adult patients with carpal tunnel syndrome. Insurance type was categorized as fee-for-service versus capitated managed care. Multivariable regression models were created to evaluate the relationship between insurance type and costs, number of visits, treatment, and electrodiagnostic study use, and controlling for demographic characteristics and comorbidities. RESULTS: The cohort included 233,572 patients, of which 86 percent carried fee-for-service insurance. Predicted probabilities were clinically similar between the capitated and fee-for-service insurance types for therapy (0.23 versus 0.24), steroid injection (0.07 versus 0.09), and electrodiagnostic study use (0.44 versus 0.47). The difference in predicted probabilities between the insurance groups was greatest for surgery use (0.22 versus 0.28 for managed care and fee-for-service, respectively). The mean number of visits was similar between the two groups (2.1 versus 2.0 visits). In the controlled analysis, managed care was associated with a 10 percent decrease in cost compared to patients with fee-for-service (p < 0.001). CONCLUSIONS: Managed care was associated with a lower probability of surgery than fee-for-service, but similar use of less costly services. These data may be used to predict future practice trends with increased implementation of bundled payment reimbursement. Routine collection of validated patient outcomes measures is critical to assess patient outcomes associated with anticipated reduction of surgical services. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

Utilization of Preoperative Electrodiagnostic Studies for Carpal Tunnel Syndrome: An Analysis of National Practice Patterns.

PURPOSE: Given the lack of a reference standard diagnostic tool for carpal tunnel syndrome (CTS), we conducted a population-level analysis of patients undergoing carpal tunnel release to characterize the utilization of preoperative electrodiagnostic studies (EDS). Secondarily, we sought to determine the impact of EDS utilization on timeliness of surgery, number of preoperative physician visits, and costs. METHODS: The 2009-2013 Truven MarketScan databases were used to identify a national cohort of adult patients undergoing carpal tunnel release. Three multivariable regression models were designed to evaluate the relationship between preoperative EDS use and timing of surgical release, the number of preoperative physician visits, and total costs for CTS-related visits, while controlling for sociodemographic variables, insurance type, comorbid conditions, and treatment characteristics. RESULTS: The final study cohort included 62,894 patients who underwent carpal tunnel release, of whom 58% had preoperative EDS. Patients undergoing EDS waited 36% longer for surgical release than patients without EDS. The mean time between diagnosis and surgery was predicted to be 183 days for patients who underwent preoperative EDS and 135 days for patients who did not. Patients having EDS experienced 1 additional visit, $996 greater total costs, and $112 additional out-of-pocket costs on average. Occupational therapy consultation and steroid injection were also associated with increased time to surgery, but with one-fourth and one-third the added cost of EDS, respectively. CONCLUSIONS: On the basis of national practice trends, providers do not consistently agree with the practice of performing EDS before carpal tunnel release. Given the uncertain utility of routine EDS before carpal tunnel release and its association with delays to surgery and increased costs, further evaluation of EDS in relation to patient preferences and value of care is warranted. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Electrodiagnostic Testing and Treatment for Carpal Tunnel Syndrome in Canada.

OBJECTIVES: 1) Assess which electrodiagnostic studies Canadian clinicians use to aid in the diagnosis of carpal tunnel syndrome (CTS). 2) Assess whether Canadian clinicians follow the American Association of Neuromuscular & Electrodiagnostic Medicine/American Academy of Neurology/American Academy of Physical Medicine and Rehabilitation Practice Parameter for Electrodiagnostic Studies in CTS. 3) Assess how Canadian clinicians manage CTS once a diagnosis has been established. METHODS: In this prospective observational study, an electronic survey was sent to all members of the Canadian Neuromuscular Group (CNMG) and the Canadian Association of Physical Medicine and Rehabilitation (CAPM&R) Neuromuscular Special Interest Group. Questions addressed which electrodiagnostic tests were being routinely used for the diagnosis of carpal tunnel syndrome. Management recommendations for CTS was also explored. RESULTS: Of the 70 individuals who completed the survey, fourteen different nerve conduction study techniques were reported. Overall, 36/70 (51%) of participants followed the AANEM/AAN/AAPM&R Practice Parameter. The standard followed by the fewest of our respondents with 64% compliance (45/70) was the use of a standard distance of 13 to 14 cm with respect to the median sensory nerve conduction study. Regarding management, 99% would recommend splinting in the case of mild CTS. In moderate CTS, splinting was recommended by 91% of clinicians and 68% would also consider referral for surgery. In severe CTS, most recommended surgery (93%). CONCLUSIONS: There is considerable variability in terms of which electrodiagnostic tests Canadian clinicians perform for CTS. Canadian clinicians are encouraged to adhere to the AANEM/AAN/AAPM&R Practice Parameter for Electrodiagnostic Studies in CTS.

Trends in carpal tunnel surgery: an online survey of members of the American Society for Surgery of the Hand.

PURPOSE: To investigate the current treatment patterns of carpal tunnel surgery by members of the American Society of Surgeons of the Hand today and to assess how several elements of practice vary by surgeon location and experience. METHODS: An online survey consisting of 10 questions was sent electronically to members of the American Society of Surgeons of the Hand (N = 2,413). A brief description of the study and a link were sent to participants by the investigators. Results were anonymously uploaded to an online spreadsheet. RESULTS: 716 hand surgeons (30%) responded to the survey. Surgeons were nearly equally represented by region. A wide variation in surgeon experience was observed. A majority (65%) performed most of their surgery at an outpatient surgical center. Preoperative electrodiagnostic testing was used, at least occasionally, by 90% of surgeons. Approximately one-half did not administer preoperative antibiotics at the time of surgery. Intravenous sedation with local anesthesia was the most common practice (43%), followed by Bier block (18%). A mini-open incision was most commonly used (50%). A minority reported using an orthosis postoperatively (29%), and they rarely prescribed a course of postoperative therapy (12%). Postoperative pain management was variable, with hydrocodone and derivatives given most commonly (61%). International practitioners were much less likely to operate in an outpatient surgical center (45%) or use antibiotics (13%). Younger surgeons were more likely to use electrodiagnostic testing (96%) compared with the mean (90%). CONCLUSIONS: When compared with several previous similar studies, we noted a trend toward increased use of electrodiagnostic testing and decreased use of postoperative therapy and immobilization. TYPE OF STUDY/LEVEL OF EVIDENCE: Economic and decision analysis V.

Higher diagnostic yield with the combined sensory index in mild carpal tunnel syndrome.

OBJECTIVES: The combined sensory index (CSI), a sensitive composite score of 3 median sensory comparison studies, may still be underutilized in diagnosing mild cases of carpal tunnel syndrome (CTS). Our goal was to compare the effectiveness of the "standard" median digit 2 (D2) sensory study to a CSI algorithm in diagnosing mild CTS. METHODS: We retrospectively identified patients with typical CTS symptoms and signs. Electrodiagnostically normal patients and those having mild CTS diagnosed by D2 or CSI algorithm were separated into groups. RESULTS: Seventy-four patients were included, and 51 (68.9%) were diagnosed with mild CTS. Of the 51, 31 (60.8%) were diagnosed using the CSI algorithm, and 20 (39.2%) were diagnosed using D2 (P < 0.001). CONCLUSIONS: Our data suggest that the CSI algorithm is significantly more effective than the D2 to diagnose mild CTS. If mild CTS is diagnosed earlier, treatment can be initiated sooner and morbidity can likely prevented.

Requests of electrodiagnostic testing: consistency and agreement of referral diagnosis. What is changed in a primary outpatient EMG lab 16 years later?

The aims are to evaluate electrodiagnostic testing (EDX) requests and verify if presence, consistency and agreement of referral diagnosis could be predicted by patient demographic findings and referring physician typology, and if there were differences in respect to our previous study performed 16 years ago. The study concerns EDX requests referred to two electromyography labs during the year 2011. Differences between findings of general practitioners (GPs) versus specialists' requests and between this study with the previous were assessed. Multivariate logistic regression was performed to calculate odds ratio to assess the strength of association between presence, consistency and agreement of referral diagnosis with patient demographic findings and referring physician typology. We evaluated EDX requests of 1,586 patients (mean age 56 ± 16.7 years, 58.8 % women), 1,050 (66.2 %) were referred by GPs and 536 (33.8 %) by specialists. The suspected diagnosis was reported in 1,033 (65.1 %) requests, the overall consistency was 79.9 % and agreement was 71.9 %. Presence, consistency and agreement of referral diagnosis were predicted by physician's typology (specialist). Only if the suspected diagnosis was carpal tunnel syndrome, consistency and agreement were high regardless of doctor's typology. The physicians, especially GPs, who reported the referral diagnosis decreased during the past 16 years. A diagnostic test, including EDX, should be considered mainly if it fits into the best diagnostic strategy. The neurophysiologist should decide if EDX is useful, make the best decision on further management, and not submit patients to unnecessary and uncomfortable procedures. This choice of behaviour could be questionable and may lead to ethical and deontological problems.

Utility of minimum F-wave latencies compared with F-estimates and absolute reference values in S1 radiculopathies: are they still needed?

INTRODUCTION: The utility of F-waves in assessing radiculopathies is debated. The aim of this study is to determine the frequency of abnormal minimum tibial F-wave latencies compared to an F-estimate and an absolute reference value in patients with electromyography (EMG) confirmed S1 radiculopathies. METHODS: A retrospective review of F-waves in patients with an EMG-confirmed isolated S1 radiculopathy was performed. The minimum and mean latencies of 8 tibial F-waves were compared with the calculated F-estimate and to an absolute reference value, and the frequencies of abnormal responses were determined. RESULTS: Of the 50 patients with an S1 radiculopathy, 4% had prolongation of the minimum reproducible F-wave latency, and 8% had prolongation of the mean latency relative to the calculated F-estimate. CONCLUSIONS: The minimum and mean F-wave latencies are infrequently abnormal when compared with an estimated F-wave latency in S1 radiculopathies and are insensitive in the assessment of S1 nerve root injury.

Nasal potential difference measurements in diagnosis of cystic fibrosis: an international survey.

BACKGROUND: The role of nasal potential difference (NPD) measurement as a diagnostic test for cystic fibrosis (CF) is a subject of global controversy because of the lack of validation studies, clear reference values, and standardized protocols for diagnostic NPD. METHODS: To determine diagnostic NPD frequency, protocols, interpretation, and rater agreement, we surveyed the 18 NPD centres of the European Cystic Fibrosis Society Diagnostic Network Working Group. RESULTS: Fifteen centres reported performing 373 diagnostic NPDs in 2012. Most use the CFF-TDN-SOP (67%) and the chloride-free + isoproterenol response of the side with the largest response (47%) as diagnostic criteria and use centre-specific reference ranges. Rater agreement for five NPD tracings - in general - was good, but poor in tracings with different responses between the two nostrils. CONCLUSIONS: NPD is frequently used as a diagnostic and research tool for CF. Performance is highly standardized, centre-specific reference ranges are established, and rater agreement - in general - is good. Centre-independent diagnostic criteria and reference ranges must be defined by multicentre validation studies to improve standardized interpretation for diagnostic use.