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Shai N Gozani

Publications and source records attributed to Shai N Gozani.

13 recordsLinked to original sources
PubMed2006

Repeatability of nerve conduction measurements using automation.

OBJECTIVE: To quantify nerve conduction study (NCS) reproducibility utilizing an automated NCS system (NC-stat, NeuroMetrix, Inc.). METHOD: Healthy volunteers without neuropathic symptoms participated in the study. Their median, ulnar, peroneal, and tibial nerves were tested twice (7 days apart) by the same technician with an NC-stat instrument. Pre-fabricated electrode arrays specific to each nerve were used. Both motor responses (compound motor action potential [CMAP] and F-waves - all nerves) and sensory responses (sensory nerve action potentials [SNAP] - median and ulnar nerves only) were recorded following supramaximal stimuli. Automated algorithms determined all NCS parameters: distal motor latency (DML), mean F-wave latency (FWL), distal sensory latency (DSL), CMAP amplitude, and SNAP amplitude. Latency was adjusted for skin temperature deviation from reference. Pearson correlation coefficient (CC), intraclass correlation coefficient (ICC), coefficient of variance (CoV), and relative intertrial variation (RIV) were calculated. RESULTS: Fifteen subjects participated in either upper or lower extremity studies with nine participating in both. With the exception of CMAP amplitude, all parameters had CoV less than 0.06. Upper extremity amplitude parameters had CCs greater than 0.85. CCs for latencies were greater than 0.80 except for the median nerve FWL (CC = 0.69). For lower extremity nerves, ICCs were highest for mean FWL (>0.90), followed by DML (>0.82) and then CMAP (peroneal 0.33, tibial 0.73). The 10th to 90th RIV percentiles were bounded by +/-7% for F-wave latencies; +/- 9% for all DSLs; and +/- 11% for DML (except peroneal at 15%). CONCLUSIONS: The reproducibility of NCS parameters obtained with an automated NCS instrument compared favorably with traditional electromyography laboratories. F-wave latencies had the highest repeatability, followed by DML, DSL, SNAP and CMAP amplitude. Given their high reproducibility, automated NCS instrument may encourage wider utilization of NCS in clinical and research applications.

Action Potentials↗
PubMed2006

Factors influencing F-wave latency detection of lumbosacral root lesions using a detection theory based model.

OBJECTIVE: To evaluate the F-wave dilution hypothesis; which implies that absolute F-wave latencies obscure the much smaller delay associated with slow intra-lesion conduction, such is caused by nerve root compression in lumbosacral radiculopathy. A corollary objective is to determine how F-wave measurement and pathological factors influence diagnostic accuracy. METHODS: An analytical model is developed based on signal detection theory and a number of simplifying assumptions. Diagnostic accuracy, quantified by the area under the receiver operating characteristic (ROC) curve, is determined for various model realizations derived from the clinical and experimental neurophysiology literature. A preliminary experimental validation of model predictions is also performed. RESULTS: Absolute F-wave latency does not influence the accuracy of focal lesion detection. F-wave latency variance and lesion pathology are the determinant factors. F-wave latencies and distal latencies are estimated to have qualitatively similar detection characteristics, although distal latencies have quantitatively better diagnostic efficacy for comparable focal pathology. Preliminary experimental results support the modeled dependence of diagnostic accuracy on latency variance and lesion severity. CONCLUSIONS: Absolute F-wave latency does not dilute slow conduction within focal lesions, such as in lumbosacral radiculopathy. The dominant measurement factor is F-wave latency variance. SIGNIFICANCE: To maximize the diagnostic utility of F-wave latencies, focus must be placed on reducing latency variance, such as through correction for demographic covariates. This model calls into question the F-wave dilution hypothesis.

Adolescent↗
PubMed2006

NC-stat sensory nerve conduction studies in the median and ulnar nerves of symptomatic patients.

OBJECTIVE: This study evaluated validity and reliability of automated median and ulnar sensory nerve conduction study (NCS) measurements by the NC-stat. METHODS: Median and ulnar distal sensory latencies (DSL) and amplitudes (SNAP) were measured in sixty subjects with the NC-stat and by a neurologist (reference) using traditional instrumentation. The median-ulnar DSL differences (MUD) was calculated. Validity was quantified by the Pearson correlation. Reliability was evaluated by the intraclass correlation coefficient (ICC), Bland-Altman analysis, and inter-rater agreement of MUD abnormalities. RESULTS: As a result of differences in electrode placement, NC-stat and reference mean values had systematic differences. The correlation ranged from 0.70 (ulnar DSL) to 0.91 (median DSL). The ICC ranged from 0.69 (ulnar DSL) to 0.91 (median DSL). In Bland-Altman analysis of DSLs, NC-stat measurements had a bias of 0.56 ms (median) and 0.31 ms (ulnar) and precision of 0.31 and 0.30 ms. Inter-rater agreement for MUD abnormalities was 93.8% (raw) and 0.80 (Kappa). CONCLUSIONS: NC-stat validity and reliability metrics were similar to traditional NCS. Use of the NC-stat would require applicable reference ranges. SIGNIFICANCE: NC-stat median and ulnar NCS are valid and reliable. This device may be useful for increasing availability of NCS when clinically appropriate.

Action Potentials↗
PubMed2006

Diabetic nerve conduction abnormalities in the primary care setting.

BACKGROUND: Nerve conduction studies (NCS) are the most objective measure of nerve function, and their use is recommended in the clinical and epidemiological evaluation of diabetic polyneuropathy (DPN). The purpose of this study was to utilize automated NCS technology to characterize nerve conduction of patients with diabetes in primary care settings. METHODS: The Diabetes cohort was drawn from 28 community clinics. The Control cohort consisted of subjects without diabetes and without evidence of neuropathy. Bilateral peroneal NCS were performed with an automated NCS instrument (NC-stat, NeuroMetrix, Inc., Waltham, MA). Neuropathic symptoms were quantified using an abbreviated form of the NTSS-6 questionnaire. Risk factors for abnormal NCS were determined using multivariate regression modeling. RESULTS: Data were collected for 172 control subjects and 1,358 subjects with diabetes. Statistically significant differences in peroneal NCS were found. Of the Diabetes cohort, 75.1% had at least one NCS abnormality, and 53.2% had bilateral abnormalities. Of the asymptomatic patients, 45% had bilateral NCS abnormalities. By contrast, 40% of those with clinically significant symptoms lacked bilateral NCS abnormalities. Independent predictors for bilateral NCS abnormalities were age, height, weight, hemoglobin A1c (HbA1c), and duration of diabetes. Up to 16% of the variance in NCS measurements was explained by HbA1c, duration of diabetes, and several demographic variables. CONCLUSIONS: This study suggests that automated NCS can provide nerve conduction confirmation of DPN in primary care settings and has clinical utility. These findings have important implications for the clinical and epidemiological evaluation of DPN.

Adult↗
PubMed2006

Time-dependent changes in median nerve sensory amplitude after local anesthetic administration and tourniquet application.

Indirect visualization, as used in several newer mini-open and endoscopic carpal tunnel release (CTR) procedures, may increase the possibility of nerve injury in some cases. Intraoperative neural monitoring may be used to evaluate nerve location and integrity. In the study reported here, we assessed the feasibility of intraoperative neural monitoring by systematically exploring the effect of local anesthetic and tourniquet on median sensory amplitude. Results for 30 median nerves (7 symptomatic) showed that sensory amplitude decreased, on average, 54% with lidocaine injection, 15% with tourniquet application, and 47% with the combination. Sensory amplitudes of 9 of 10 nerves were still above 1.0 microV 15 minutes after anesthetic administration and tourniquet application. Study results demonstrate that intraoperative monitoring, using the amplitude of the median sensory nerve response, is viable under CTR conditions.

Action Potentials↗
PubMed2004

Time course and predictors of median nerve conduction after carpal tunnel release.

PURPOSE: To identify predictors of outcome and of electrophysiologic recovery in patients with carpal tunnel syndrome (CTS) treated by endoscopic carpal tunnel release using a nerve conduction testing system (NC-Stat; NEUROMetrix, Inc, Waltham, MA). METHODS: Validity of the automated nerve conduction testing system was shown by comparing presurgical distal motor latencies (DMLs) against a reference obtained by referral to an electromyography laboratory. The DML was evaluated in 48 patients with CTS. Measurements were obtained within 1 hour of surgery and at 2 weeks, 6 weeks, 3 months, and 6 months after carpal tunnel release. Presurgical and postsurgical DMLs were then compared and correlated with variables and possible predictors of outcome including age, body mass index, gender, and presurgical DMLs. RESULTS: The automated nerve conduction testing system DMLs matched those of reference electromyography/nerve conduction study values with high correlation. Sensitivity of the automated nerve conduction testing system when compared with a standardized CTS case definition was 89%, with a specificity of 95%. A significant correlation was found between the DML before release and the DML 1 hour after release. Moreover, maximal postsurgical DML improvement was highly dependent on the presurgical DML, with no improvement shown for the <4-ms group, mild improvement for the 4-to-6-ms group, and maximal improvement in the >6-ms group. Among the clinical variables of age, gender, and body mass index only age was mildly predictive of postrelease DML changes at 6 months. No other correlations between clinical variables and postsurgical DMLs were significant. In addition the predictive value of age was lost when combined with the presurgical DML in a multivariate analysis. CONCLUSIONS: Postsurgical changes in the median nerve DML were highly dependent on the prerelease latency. The sensitivity and specificity of a nerve conduction monitoring system in detecting and aiding in the diagnosis of CTS is useful in the long-term management of patients with CTS and can aid in determining the level of improvement in median nerve function after endoscopic carpal tunnel release.

Adult↗
PubMed2004

Median and ulnar nerve conduction measurements in patients with symptoms of diabetic peripheral neuropathy using the NC-stat system.

BACKGROUND: Diabetic peripheral neuropathy (DPN) is a common, disabling, and costly complication of diabetes mellitus. Although there are multiple methods for detecting and monitoring DPN, nerve conduction studies (NCS) are generally considered to be the most sensitive and reproducible. However, utilization of NCS in patients with diabetes is low, presumably because of limited access and economic issues. Advanced point-of-service NCS systems, already widely used in the assessment of entrapment neuropathies, may address these issues in the arena of diabetes. METHODS: Seventeen patients with diabetes and clinical evidence of neuropathy were enrolled in the study. NCS were performed using the NC-stat nerve conduction testing system (NEUROMetrix, Inc., Waltham, MA) and compared against results from a neurologist-supervised study using a standard electromyography system, which was considered the reference method. Results for ulnar and median distal motor latencies (DMLs) and F-waves, obtained by both methods, were compared with each other. The NC-stat measurements were also compared with a historical control population. RESULTS: A high correlation between the two methods of NCS assessment was demonstrated. The Pearson correlation coefficients between the NC-stat system and the reference measurements were 0.96 (DML) and 0.89 (F-wave latency) for the median nerve and 0.70 (DML) and 0.78 (F-wave latency) for the ulnar nerve. Significant differences were observed between the NC-stat and reference median (P < 0.001, paired t test) and ulnar (P < 0.05, paired t test) nerve DMLs. F-wave latencies did not demonstrate significant differences (P > 0.05, paired t test). The rate of abnormalities ranged from 17.7% for the median nerve DML to 26.7% for the ulnar nerve F-wave latency. The rate of upper extremity nerve involvement in DPN according to a case definition requiring both median and ulnar nerve abnormalities was 25.0%. The rate of median neuropathy at the wrist, which is the second most common neuropathy in individuals with diabetes, was 17.6%. CONCLUSIONS: NC-stat-based NCS of the median and ulnar nerves provide results similar to those obtained with traditional neurologist-supervised NCS using a standard electromyography system. The number of subjects meeting electrophysiological criteria for DPN, affecting the upper extremities, is similar to prior studies. The widespread availability of the NC-stat system may provide a robust and objective method for identifying DPN and other neuropathies in patients with diabetes.

Biosensing Techniques↗
PubMed2002

Detection of lumbosacral nerve root compression with a novel composite nerve conduction measurement.

STUDY DESIGN: Multivariate logistic regression techniques were used to develop a composite nerve conduction measurement that detects lumbosacral (L5, S1, or both) nerve root compression. OBJECTIVES: To evaluate the diagnostic efficacy of a composite nerve conduction measurement for detection of lumbosacral nerve root compression. SUMMARY OF BACKGROUND DATA: Nerve root involvement is characterized by clinical abnormalities and confirmed by radiologic and electrodiagnostic studies. Imaging studies visualize structural abnormalities; however, they are associated with high false-positive rates. Electrodiagnostic methods assess the physiologic integrity of the nerve roots. One form of electrodiagnostic testing, nerve conduction studies, is widely used for evaluation of musculoskeletal and neuromuscular complaints. Although similar clinical value is expected for the evaluation of nerve root compromise, prior applications of nerve conduction studies have yielded widely varying results. METHODS: Two groups of subjects were compared. The L5-S1 compression group was composed of 25 patients with magnetic resonance imaging-confirmed lumbosacral (L5, S1, or both) nerve root compression and symptoms in the appropriate segmental distribution. The majority of subjects (22) had at least one of the following findings on physical examination: positive straight-leg raise test, diminished ankle reflexes, sensory loss, or weakness. The control group consisted of 35 asymptomatic individuals with no history of radiculopathy or potentially confounding neuropathology. The posterior tibial and deep peroneal nerves were evaluated bilaterally in all study subjects using standard nerve conduction procedures, which consisted of the measurement of distal motor latencies and F-wave latencies that assess nerve root pathophysiology. A composite nerve conduction measurement was determined using multivariate logistic regression analysis. The efficacy of the composite measurement was assessed by receiver operating characteristic curve analysis and by the diagnostic sensitivity and specificity. RESULTS: Five F-wave latency parameters (peroneal mean F-wave latency, odds ratio = 0.42; peroneal seventh F-wave latency decile, odds ratio = 2.71; tibial mean F-wave latency, odds ratio = 8.90; tibial first F-wave latency decile, odds ratio = 0.47; tibial maximum F-wave latency, odds ratio = 0.44) were found to be predictive of nerve root compression. A composite nerve conduction measurement, NC composite, constructed from these five parameters (NC composite = exp(phi)/(1 + exp(phi)), phi = -31.2 + 1.0 * Per7 Decile - 0.88 * PerMean + 2.2 * TibMean - 0.88 * Tib1 Decile - 0.83 * TibMax) yielded an area under the receiver operating characteristic curve of 0.91. At a threshold of 0.20, NC composite had a diagnostic specificity of 84.3% and a sensitivity of 83.3%. CONCLUSION: This preliminary study suggests that a novel composite nerve conduction measurement, based on F-wave latency parameters, may be highly effective at detecting magnetic resonance imaging-confirmed lumbosacral nerve root compression. Because these measurements provide objective evidence of functional nerve root compromise and are noninvasive, they may be of diagnostic value to clinicians evaluating patients presenting with low back and leg pain.

Adult↗
PubMed2002

Noninvasive detection of fibrillation potentials in skeletal muscle.

The presence of spontaneous muscle activity was determined by analysis of the power spectra of computer-model-generated sequences of spontaneous activity and additive noise. The modeling results identified the frequency band of 100-300 Hz as the band of peak signal-to-noise ratio for the detection of fibrillation potentials. Animal experiments were conducted in which the left sciatic nerves of three rats were transected. Measurements were taken 14 days following surgery with Ag/AgCl gel electrodes on the skin surface. Data was recorded from the gastrocnemius muscle on both the normal and denervated side for all three rats. The normal data and the denervated data yielded no discernible difference in the time-domain. Spectral analysis, however, demonstrated a clear and quantifiable difference between denervated and normal muscle signals. The average difference between the denervated and normal power spectral densities for the frequency band from 100 Hz to 300 Hz was 3.43, 1.90, and 3.02 dB for the three rats. The additional energy observed in the signals recorded from denervated muscles suggests that the single fiber spontaneous muscle activity that occurs in denervated muscle can be noninvasively detected. The potential diagnostic utility of noninvasive fibrillation potential detection is discussed and suggestions for future experiments are made.

Action Potentials↗
PubMedDate not supplied

Utility of nerve conduction studies for carpal tunnel syndrome by family medicine, primary care, and internal medicine physicians.

INTRODUCTION: Nerve conduction studies (NCS) are increasingly being performed at the point-of-service by family medicine, primary care, and internal medicine (FM/PCP/IM) physicians. Carpal tunnel syndrome (CTS) is a common neuropathy often diagnosed with the aid of NCS. METHODS: A retrospective analysis of a point-of-service NCS data registry was conducted; 1190 patients who underwent NCS by 613 FM/PCP/IM physician practices, for evaluation of CTS were analyzed. Utility measures included demographic and electrophysiological characteristics of study population, adherence to evidence-based testing guidelines, and relevance of diagnostic outcomes. RESULTS: Tested patients tended to be over 40, female, and overweight or obese. The median nerve distal motor latency was 4.4 +/- 1.2 ms; 92.6% of studies met the testing guideline; 30.5% of tested limbs yielded normal results; 53.1% CTS; 5.4% ulnar neuropathy; and 11.0% nonspecific upper extremity neuropathy. DISCUSSION: This study demonstrated that point-of-service NCS by FM/PCP/IM physicians for CTS was applied to appropriate patient subpopulations, was performed in accordance with evidence-based testing parameters, and generated relevant diagnostic outcomes.

Adult↗