Effect of Hand Held Vibrating Tools on Nerve Conduction Study in Dental Residents.

BACKGROUND: Repetitive exposure to vibration has been shown to induce peripheral nerve dysfunction. Dentists are exposed to handheld vibrating tools in their daily clinical practice. Most of the studies are done in dentists who have symptoms such as paresthesia and numbness of the hands. Thus, we conducted the study to explore the effect of vibration on nerve conduction variables in apparently healthy asymptomatic dental residents. METHODS: This cross-sectional study enrolled 22 dental residents and age matched 22 medical residents as controls. Nerve conduction study was performed in median and ulnar nerves of both hands. RESULTS: Anthropometric and cardiorespiratory variables were comparable between the groups. There were no statistically significant differences between dental and medical residents in the sensory conduction variables (right median onset latency=2.05±0.27 vs 1.91±0.21, p value=0.07; right median amplitude =27.80±8.11 vs 29.55±7.04, p=0.45; right median conduction velocity = 59.54±7.05 vs 61.06±5.15, p= 0.42) and motor conduction variables (right median distal latency = 2.87±0.38 vs 2.87±0.38, p= 0.94; right median distal amplitude=10.71±2.19 vs 11.10±2.37, p=0.58; right median conduction velocity= 70.57±13.16 vs 68.53±7.73, p= 0.54) of median and ulnar nerves. Further, there was no significant difference between the dominant and non-dominant hands of dental residents. CONCLUSIONS: Hand held vibration tools did not alter nerve conduction study parameters of dental residents.

Effect of long term high altitude exposure on cardiovascular autonomic adjustment during rest and post-exercise recovery.

BACKGROUND: Despite the successful adaptation to high altitude, some differences do occur due to long term exposure to the hypoxic environment. The effect of long term high altitude exposure on cardiac autonomic adjustment during basal and post-exercise recovery is less known. Thus we aimed to study the differences in basal cardiac autonomic adjustment and its response to exercise in highlanders and to compare it with lowlanders. METHODS: The study was conducted on 29 healthy highlander males who were born and brought up at altitude of 3000 m and above from the sea level, their cardiac autonomic adjustment was compared with age, sex, physical activity and ethnicity-matched 29 healthy lowlanders using Heart Rate Variability (HRV) during rest and recovery from sub-maximal exercise (3 m step test). Intergroup comparison between the highlanders and lowlanders and intragroup comparison between the rest and the postexercise recovery conditions were done. RESULTS: Resting heart rate and HRV during rest was comparable between the groups. However, heart rate recovery after 3 min step test was faster in highlanders (p < 0.05) along with significantly higher LF power and total power during the recovery phase. Intragroup comparison of highlanders showed higher SDNN (p < 0.05) and lower LF/HF ratio (p < 0.05) during recovery phase compared to rest which was not significantly different in two phases in lowlanders. Further highlander showed complete recovery of RMSSD, NN50, pNN50 and HF power back to resting level within five minutes, whereas, these parameters failed to return back to resting level in lowlanders within the same time frame. CONCLUSION: Highlanders completely recovered back to their resting state within five minutes from cessation of step test with parasympathetic reactivation; however, recovery in lowlanders was delayed.

Visual Evoked Potentials in Primary Open Angle Glaucoma.

BACKGROUND AND AIMS: Visual evoked potentials (VEPs) assess the integrity of the visual pathways from the optic nerve to the occipital cortex. Optic disc cupping and visual field loss have been associated with prolongation of latency of VEP in primary open angle glaucoma (POAG). METHODS: Pattern reversal and flash VEP tests were done in consenting 20 primary open angle glaucoma eyes and 40 normal control eyes. RESULTS: In POAG cases, the refractive error [3.51 ± 1.88 versus 1.88 ± 1.11, D, p = 0.001], cup-disc ratio in percent [66.00 ± 16.98 versus 28.50 ± 5.80, p = 0.001], intraocular pressure [19.55 ± 2.08 versus 11.65 ± 1.64, mmHg, p = 0.001], and automated visual field pattern standard deviation [4.13 ± 6.96 versus 1.64 ± 0.45, dB, p = 0.001] were significantly more than in control. The visual acuity [0.41 ± 0.29 versus 1.00 ± 0.00, p = 0.001], foveal visual sensitivity [25.92 ± 6.88 versus 33.48 ± 1.75, dB, p = 0.001], and automated visual field mean deviation [-9.63 ± 10.58 versus 0.07 ± 1.54, dB, p = 0.001] were significantly less in cases than in control. Among VEP variables, pattern reversal latency N145 [149.00 ± 15.75 versus 137.52 ± 15.20, ms, p = 0.011], flash amplitude N75 [2.18 ± .57 versus 1.47 ± .38, µV, p = 0.001], and flash amplitude N145 [1.99 ± .39 versus 1.43 ± .38, µV, p = 0.001] were increased in cases. The pattern reversal amplitude N75 [1.97 ± .35 versus 2.47 ± .58, µV, p = 0.001], amplitude P100 [3.09 ± .46 versus 6.07 ± 1.44, µV, p = 0.001], and amplitude N145 [2.21 ± .58 versus 4.45 ± 1.99, µV, p = 0.001] were decreased in cases. CONCLUSIONS: POAG caused glaucomatous damage to optic pathway.

Nerve Conduction Study on Sural Nerve among Nepalese Tailors Using Mechanical Sewing Machine.

INTRODUCTION: The use of new technologies and innovations are out of access for people living in a developing country like Nepal. The mechanical sewing machine is still in existence at a large scale and dominant all over the country. Tailoring is one of the major occupations adopted by skilled people with lower socioeconomic status and education level. Sural nerves of both right and left legs are exposed to strenuous and chronic stress exerted by chronic paddling of mechanical sewing machine with legs. AIM: To evaluate the influence of chronic and strenuous paddling on right and left sural nerves. MATERIALS AND METHODS: The study recruited 30 healthy male tailors with median age {34(31-37.25)} years (study group), and, 30 healthy male volunteers with age {34(32-36.25)} years (control group). Anthropometric measurements (age, height, weight, BMI and length of both right and left legs) as well as cardio respiratory measurements [Systolic Blood Pressure (SBP), Dystolic Blood Pressure (DBP), Pules Rate (PR) and Respiratory Rate (RR)] were recorded for each subject. Standard nerve conduction techniques using constant measured distances were applied to evaluate sural nerve (sensory) in both legs of each individual. The differences in variables between the study and control groups were tested using Student's t-test for parametric variables and Mann-Whitney U test for nonparametric variables. A p-value of ≤ 0.05 was considered significant. RESULTS: Age, height, weight, body mass index and leg length were not significantly different between tailors and control groups. Cardio respiratory measurements (SBP, DBP, PR and RR) were also not significantly altered between both the groups. The sensory nerve conduction velocities (m/s) of the right {44.23(42.72-47.83) vs 50(46- 54)} and left sural nerves {45.97±5.86 vs 50.67±6.59} m/s were found significantly reduced in tailors in comparison to control group. Similarly amplitudes (µv) of right sural (20.75±5.42 vs 24.10±5.45) and left sural nerves {18.2(12.43-21.8) vs 32.0(26.5-35.25)} were significantly less in tailors in comparison to control group whereas, latencies (ms) of right sural {2.6(2.2-2.7) vs 2.0(2.0-2.250} and left sural nerve {2.4(2.07-2.72) vs 2.0(2.0-2.0)} were found significantly high in tailors as compared with control group. CONCLUSION: Operating mechanical sewing machine by paddling chronically and arduously could have attributed to abnormal nerve conduction study parameters due to vibration effect of the machine on right and left sural nerves. The results of present study follow the trend towards presymptomatic or asymptomatic neuropathy similar to subclinical neuropathy.

Vibration upshot of operating mechanical sewing machine: an insight into common peroneal nerve conduction study.

BACKGROUND: Most of the people associated with tailoring occupation in Nepal are still using mechanical sewing machine as an alternative of new technology for tailoring. Common peroneal nerves of both right and left legs are exposed to strenuous and chronic stress exerted by vibration and paddling of mechanical sewing machine. METHODS: The study included 30 healthy male tailors and 30 healthy male individuals. Anthropometric variables as well as cardio respiratory variables were determined for each subject. Standard Nerve Conduction Techniques using constant measured distances were applied to evaluate common peroneal nerve (motor) in both legs of each individual. Data were analyzed and compared between study and control groups using Man Whitney U test setting the significance level p ≤ 0.05. RESULTS: Anthropometric and cardio respiratory variables were not significantly altered between the study and control groups. The Compound muscle action potential (CMAP) latency of common peroneal nerves of both right [(11.29 ± 1.25 vs. 10.03 ± 1.37), P < 0.001] and left [(11.28 ± 1.38 vs. 10.05 ± 1.37), P < 0.01] legs was found to be significantly prolonged in study group as compared to control group. The Amp-CMAP of common peroneal nerves of both right [(4.57 ± 1.21 vs. 6.22 ± 1.72), P < 0.001] and left [(4.31 ± 1.55 vs. 6.25 ± 1.70), P < 0.001] legs was found significantly reduced in study group as compared to control group. Similarly, the motor nerve conduction velocity (MNCV) of common peroneal nerves of both right [(43.72 ± 3.25 vs. 47.49 ± 4.17), P < 0.001] and left [(42.51 ± 3.82 vs. 46.76 ± 4.51), P < 0.001] legs was also found to be significantly reduced in study group in comparison to control group. CONCLUSION: Operating mechanical sewing machine by paddling chronically and arduously could have attributed to abnormal nerve conduction study parameters due to vibration effect of the machine on right and left common peroneal nerves. The results of present study follow the trend towards presymptomatic or asymptomatic neuropathy similar to subclinical neuropathy.

Nerve Conduction and Heart Rate variability in Patients with Hypothyroidism at a Tertiary Care Centre in Eastern Nepal.

INTRODUCTION: Thyroid hormone effects on many organs including central and peripheral nervous systems. However, these hormones do not affect all systems/organs to a similar extent. Thus, we conducted this study to explore the effect of thyroid hormones on somatic nervous system assessed by Nerve conduction study and cardiac autonomic activity assessed by heart rate variability. METHODS: The study included newly diagnosed hypothyroid patients and healthy controls. In all subjects NCS were performed in median, ulnar, tibial and sural nerves using Nihonkohden machine Cardiac autonomic control was assessed using Short-term Heart Rate Variability and parameters were analyzed by Time Domain and Frequency Domain methods. RESULTS: Both the groups were comparable in term of age, Body Mass Index, Pulse Rate, Systolic Blood Pressure and Diastolic Blood Pressure. Sensory parameters of NCS showed significant decrease in left median nerve SNAP amplitude (38.24±10.23 Vs 31.59±14.06, P=0.048) and nerve conduction velocity of bilateral median nerve in hypothyroid patients. In motor parameters of NCS, onset latencies of bilateral median nerves and right ulnar nerve were significantly increased in hypothyroid patients. All Time Domain measures of HRV and Frequency Domain measures; LF Power, HF Power and Total Power were significantly decreased (P<0.05) in hypothyroid patients. These HRV parameters are indicators of parasympathetic activity. CONCLUSIONS: In newly diagnosed hypothyroid patients, especially median nerve functions (both sensory and motor) and parasympathetic activity were decreased. It reflects that in hypothyroidism both autonomic nervous system and other somatic nerves are not affected in a similar extent.

Nerve conduction studies in lower limb of elite Nepalese football players: an insight into neural adaptations.

BACKGROUND: The study was aimed to assess somatic neural alterations in lower limbs of elite Nepalese football players by comparing their nerve conduction parameters with non-athletic controls. METHODS: Players (N.=27, age 22.74±2.52 yrs.) with excellent cardio-respiratory fitness and presenting no signs of injuries, and sedentary controls (N.=29, age 23.41±2.95 yrs.) were recruited for the study. Standard nerve conduction techniques were applied to evaluate posterior tibial and sural nerves in the dominant and non-dominant limbs of each individual. Conduction velocity, onset latency, amplitude and duration of the motor and sensory evoked responses were recorded. RESULTS: The players had significantly lower resting mean heart rate, systolic and diastolic blood pressure than controls. Tibial compound muscle action potential (CMAP) showed higher amplitude as compared to controls; tibial proximal CMAP amplitude [(13.624±4.57) vs. (10.810±4.62) mV, P=0.035] of dominant leg, tibial proximal [(13.893±4.60) vs. (11.083±4.51) mV, P=0.045] and distal [(16.388±3.62) vs. (13.958±4.65) mV, P=0.049] amplitude of non-dominant leg. Likewise, players had significantly shorter tibial CMAPs duration of each lower limb compared with corresponding limb of controls. Sural nerve of non-dominant leg revealed shortened sensory nerve action potential duration [(1.729±0.25) vs. (1.904±0.289) ms, P=0.018]. CONCLUSIONS: Increased tibial CMAP amplitude and decreased CMAP duration in players suggest excitation of more number of motor units and higher synchronicity of muscle fibers' discharge than in controls respectively. Higher amplitude can also be attributed to increase in muscle fiber size and/or efficiency of neuromuscular transmission. Increased synchronicity indirectly reflects narrow range of conduction velocity among tibial neurons. The adaptive changes in somatic nerves need more crucial research for exact identification of sites and the structures responsible.

Mesopancreas: myth or reality?

CONTEXT: A recently published study hypothesized the concept of 'mesopancreas', defining it as a firm, well-vascularized structure extending from the posterior surface of the pancreatic head to behind the mesenteric vessels. OBJECTIVE: To verify and define mesopancreas from resection specimens obtained from fresh cadavers. DESIGN: Postmortem anatomical-pathological study. SETTING: Department of Surgery in conjunction with the Departments of Forensic Medicine and Pathology, Government Medical College and Hospital, Jabalpur, MP, India. PARTICIPANTS: Twenty fresh adult cadavers without any intra-abdominal injury or gross intra-abdominal pathology. INTERVENTIONS: Specimens containing the entire duodenum, pancreatic head and neck, gallbladder, cystic duct, common bile duct, superior mesenteric vessels, inferior vena cava and aorta were removed en-bloc. Gross and histopathological examinations of the specimens were carried out. MAIN OUTCOME MEASURES: To look for a fibrous sheath or fascia around the retropancreatic structure purported to be a mesopancreas. RESULTS: Loose areolar tissue, adipose tissue, peripheral nerve, nerve plexus, lymphatic and capillaries were found in the retropancreatic tissue, extending from the head, neck and uncinate process of pancreas to the aorto-caval groove but no fibrous sheath or fascia was found around these structures. CONCLUSIONS: The concept of 'mesopancreas' is anatomically unfounded.