Reference values for nerve conduction studies in healthy newborns, infants and children in Philippine Children's Medical Center

@#<p style="text-align: justify;"><strong>BACKGROUND:</strong> Nerve conduction studies play a diagnostic role in the clinical evaluation of neuromuscular disorders in children. Reference ranges define the expected parameter values in disease-free children.</p><p style="text-align: justify;"><strong>OBJECTIVE:</strong> To propose reference values for sensory and motor nerve conduction and late responses in upper and lower limb peripheral nerves in Filipino children 5 years and below.</p><p style="text-align: justify;"><strong>METHODS</strong>: Sensory nerve conduction studies on median, ulnar, superficial peroneal, and sural nerves and motor nerve conduction and late response studies on median, ulnar, peroneal and posterior tribal nerves were done using standardized techniques among 100 healthy Filipino children.</p><p style="text-align: justify;"><strong>RESULTS:</strong> Subjects were stratified according to age groups. Reference values for the following parameters: (1) sensory conduction velocity and amplitude; (2) motor conduction velocity, amplitude and latency at distal sites;  (3) F-wave latency; and (4) H-reflex latency were summarized. These were expressed as mean ±standard deviation or median (range) for values that follow Gaussian and non-Gaussian distributions. The 5th and 95th percentile values were likewise reported. Age had direct correlation with various nerve conduction parameters. Height was directly correlated with F-wave parameters of median, ulnar and peroneal nerves but not posterior tribal nerve.</p><p style="text-align: justify;"><strong>CONCLUSIONS</strong>: Reference standards for nerve conduction studies of commonly tested nerves of Filipino children are presented. Values are comparable to reference ranges elsewhere except for the H-reflex latency which is higher in this study.</p>

Diagnostic Value of the Second Lumbrical-Interosseous Distal Motor Latency Comparison Test in Severe Carpal Tunnel Syndrome

OBJECTIVE: To examine the usefulness of the second lumbrical-interosseous (2L-INT) distal motor latency (DML) comparison test in localizing median neuropathy to the wrist in patients with absent median sensory and motor response in routine nerve conduction studies. METHODS: Electrodiagnostic results from 1,705 hands of patients with carpal tunnel syndrome (CTS) symptoms were reviewed retrospectively. All subjects were evaluated using routine nerve conduction studies: median sensory conduction recorded from digits 1 to 4, motor conduction from the abductor pollicis brevis muscle, and the 2L-INT DML comparison test. RESULTS: Four hundred and one hands from a total of 1,705 were classified as having severe CTS. Among the severe CTS group, 56 hands (14.0%) showed absent median sensory and motor response in a routine nerve conduction study, and, of those hands, 42 (75.0%) showed an abnormal 2L-INT response. CONCLUSION: The 2L-INT DML comparison test proved to be a valuable electrodiagnostic technique in localizing median mononeuropathy at the wrist, even in the most severe CTS patients.

Obesity Affects Median Nerve Conduction - A Study in Armed Forces Individuals.

Background: Obesity, a growing public health concern, is associated with various disorders. Studies have suggested obesity as an independent risk factor that influences the prevalence of carpal tunnel syndrome (CTS) among active workers. The present study is an attempt to establish relationship between median nerve conduction velocity and obesity in people who do not have any other contributory factor for CTS other than obesity. CTS is the commonest entrapment neuropathy where the median nerve is compressed. Methods: The study was conducted in 15 obese subjects with Body Mass Index (BMI)>30 (group III) and 15 overweight subjects with BMI between 25&29.9 (group II) and 15 control subjects with BMI <25 (group I). The subjects were personnel from armed forces. Their body density was estimated using hydro-densitometry and the body fat percentage was calculated from density. The distal motor latency (DML) and the sensory conduction velocity (SCV) across the wrist on stimulation of median nerve at wrist 3cm proximal to distal crease were assessed in all subjects. Results: The mean values of DML in group I, II, and III were 3.52±0.25 ms, 3.50±0.30 ms and 3.65±0.20 ms respectively. Mean value of SCV among these groups were 48.99±3.23 m/s, 49.32±3.35 m/s and 48.69±4.00 m/s. Conclusion: No relationship could be established between BMI and DML as well as BMI and SCV. The relationship between percentage body fat and DML and SCV also found to be statistically insignificant. However, there was a correlation between BMI and body fat percentage. Carpal tunnel syndrome is uncommon even in obese armed forces personnel, which might be due to their regular body and hand exercise thereby having increased tone in hand muscles.

Effect of body mass index on parameters of nerve conduction study in Indian population.

As the adipose tissue in epineurium is related to some extent to amount of body fat, it is possible that the amount of such fat may affect the nerve conduction. In this study, we have analyzed effect of Body Mass Index (BMI) on various parameters of nerve conduction study in one hundred seventy five healthy volunteers between ages of 18 and 66 years. BMI was determined and nerve conduction studies were performed prospectively in all the subjects using standardized techniques. Prolongation of distal motor latency (DML) was observed with increasing BMI except in motor Peroneal nerve. (In Median Nerve, P<0.05). F- Wave minimum latency was also found to be significantly prolonged in (P<0.05) in motor Tibial nerve. Higher BMI was found to be non-significantly associated with lower amplitude (both sensory and motor) except for peroneal nerve. Motor as well as sensory conduction velocity showed non-significant slowing along increasing BMI except sural and motor-sensory ulnar nerve in younger age group. This study demonstrated that various parameters of nerve conduction study can be affected by BMI. So, this biological factor has to be taken into consideration while interpreting nerve conduction studies

Normative data of upper limb nerve conduction in central India.

Nerve conduction study is an important tool to evaluate peripheral nerve abnormality. The primary purpose of this study was to provide normative electrophysiological data for commonly tested upper limb nerves in normal healthy adults. Nerve conduction studies were performed prospectively in upper limbs of 175 carefully screened healthy volunteers between the ages of 18 and 66 years using standardized techniques. There was no statistically significant difference found in conduction velocity and amplitude of motor median and ulnar nerves as well as sensory conduction velocity of median nerve. However, distal and F-minimum latencies of motor nerves, sensory amplitudes and conduction velocity of ulnar nerve was found to be significantly influenced by gender (P<0.05). This study established normative conduction parameters of the commonly tested nerves of upper limb for our clinical neurophysiology laboratory in Central India. This can be of use to evaluate the patients with peripheral nerve abnormalities who reside in this particular geographic set-up. Gender was shown to have an influence on sensory amplitude, distal motor and Fminimum latencies of median and ulnar nerves.