To establish the cutoff value of cross-sectional area (CSA) of the median nerve at the wrist, for determination of electrophysiologically moderate and severe carpal tunnel syndrome (CTS).
The prospective study was conducted among patients suspected of having CTS. A total of 106 patients (185 symptomatic wrists) received nerve conduction study (NCS) and ultrasonography. To establish a cutoff value, various diagnostic properties were calculated across a range of the CSA.
A mean±standard deviation of CSA of the median nerve of normal and mild, moderate and severe CTS was 9.4±2.1, 12.0±2.7, 13.8±4.7, and 15.4±4.1 mm2, respectively. The positive relationship between CTS severities and CSA was observed (rs=0.56). A 14 mm2 CSA had sufficient power to rule in moderate and severe CTS, with a specificity of 91.4% and sensitivity of 42.3%. In addition, it showed a post-test probability (positive predictive value) of 86.3% as against a pre-test probability of 56.2%.
Patients who had ≥14 mm2 of median nerve CSA had very high probability of moderate to severe CTS.
Citations
To investigate the electrophysiological effects of focal vibration on the tendon and muscle belly in healthy people.
The miniaturized focal vibrator consisted of an unbalanced mass rotating offset and wireless controller. The parameters of vibratory stimulation were adjusted on a flat rigid surface as 65 µm at 70 Hz. Two consecutive tests on the different vibration sites were conducted in 10 healthy volunteers (test 1, the Achilles tendon; test 2, the muscle belly on the medial head of the gastrocnemius). The Hoffman (H)-reflex was measured 7 times during each test. The minimal H-reflex latency, maximal amplitude of H-reflex (Hmax), and maximal amplitude of the M-response (Mmax) were acquired. The ratio of Hmax and Mmax (HMR) and the vibratory inhibition index (VII: the ratio of the Hmax after vibration and Hmax before vibration) were calculated. The changes in parameters according to the time and site of stimulation were analyzed using the generalized estimating equation methods.
All subjects completed the two tests without serious adverse effects. The minimal H-reflex latency did not show significant changes over time (Wald test: χ2=11.62, p=0.07), and between the two sites (χ2=0.42, p=0.52). The changes in Hmax (χ2=53.74, p<0.01), HMR (χ2=20.49, p<0.01), and VII (χ2=13.16, p=0.02) were significant over time with the adjustment of sites. These parameters were reduced at all time points compared to the baseline, but the decrements reverted instantly after the cessation of stimulation. When adjusted over time, a 1.99-mV decrease in the Hmax (χ2=4.02, p=0.04) and a 9.02% decrease in the VII (χ2=4.54, p=0.03) were observed when the muscle belly was vibrated compared to the tendon.
The differential electrophysiological effects of focal vibration were verified. The muscle belly may be the more effective site for reducing the H-reflex compared to the tendon. This study provides the neurophysiological basis for a selective and safe rehabilitation program for spasticity management with focal vibration.
Citations
To delineate cervical radiculopathy that is found in combination with traumatic cervical spinal cord injury (SCI) and to determine whether attendant cervical radiculopathy affects the prognosis and functional outcome for SCI patients.
A total of 66 patients diagnosed with traumatic cervical SCI were selected for neurological assessment (using the International Standards for the Neurological Classification of Spinal Cord Injury [ISNCSCI]) and functional evaluation (based on the Korean version Modified Barthel Index [K-MBI] and Functional Independence Measure [FIM]) at admission and upon discharge. All of the subjects received a preliminary electrophysiological assessment, according to which they were divided into two groups as follows: those with cervical radiculopathy (the SCI/Rad group) and those without (the SCI group).
A total of 32 patients with cervical SCI (48.5%) had cervical radiculopathy. The initial ISNCSCI scores for sensory and motor, K-MBI, and total FIM did not significantly differ between the SCI group and the SCI/Rad group. However, at discharge, the ISNCSCI scores for motor, K-MBI, and FIM of the SCI/Rad group showed less improvement (5.44±8.08, 15.19±19.39 and 10.84±11.49, respectively) than those of the SCI group (10.76±9.86, 24.79±19.65 and 17.76±15.84, respectively) (p<0.05). In the SCI/Rad group, the number of involved levels of cervical radiculopathy was negatively correlated with the initial and follow-up motors score by ISNCSCI.
Cervical radiculopathy is not rare in patients with traumatic cervical SCI, and it can impede neurological and functional improvement. Therefore, detection of combined cervical radiculopathy by electrophysiological assessment is essential for accurate prognosis of cervical SCI patients in the rehabilitation unit.
Citations
Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominantly inherited disorder that affects peripheral nerves by repeated focal pressure. HNPP can be diagnosed by clinical findings, electrodiagnostic studies, histopathological features, and genetic analysis. Ultrasonography is increasingly used for the diagnosis of neuromuscular diseases; however, sonographic features of HNPP have not been clearly defined. We report the sonographic findings and comparative electrodiagnostic data in a 73-year-old woman with HNPP, confirmed by genetic analysis. The cross-sectional areas of peripheral nerves were enlarged at typical nerve entrapment sites, but enlargement at non-entrapment sites was uncommon. These sonographic features may be helpful for diagnosis of HNPP when electrodiagnostic studies are suspicious of HNPP and/or gene study is not compatible.
Citations
To ascertain the etiology of non-traumatic plexopathy and clarify the clinical, electrophysiological characteristics according to its etiology.
We performed a retrospective analysis of 63 non-traumatic plexopathy patients that had been diagnosed by nerve conduction studies (NCS) and needle electromyography (EMG). Clinical, electrophysiological, imaging findings were obtained from medical records.
We identified 36 cases with brachial plexopathy (BP) and 27 cases with lumbosacral plexopathy (LSP). The causes of plexopathy were neoplastic (36.1%), thoracic outlet syndrome (TOS) (25.0%), radiation induced (16.7%), neuralgic amyotrophy (8.3%), perioperative (5.6%), unknown (8.3%) in BP, while neoplastic (59.3%), radiation induced (22.2%), neuralgic amyotrophy (7.4%), psoas muscle abscess (3.7%), and unknown (7.4%) in LSP. In neoplastic plexopathy, pain presented as the first symptom in most patients (82.8%), with the lower trunk of the brachial plexus predominantly involved. In radiation induced plexopathy (RIP), pain was a common initial symptom, but the proportion was smaller (50%), and predominant involvements of bilateral lumbosacral plexus and whole trunk of brachial or lumbosacral plexus were characteristic. Myokymic discharges were noted in 41.7% patients with RIP. Abnormal NCS finding in the medial antebrachial cutaneous nerve was the most sensitive to diagnose TOS. Neuralgic amyotrophy of the brachial plexus showed upper trunk involvement in all cases.
By integrating anatomic, pathophysiologic knowledge with detailed clinical assessment and the results of ancillary studies, physicians can make an accurate diagnosis and prognosis.
Citations
Objective: To investigate the electrophysiologic and histopathologic changes of the prheral nerve from hyperthermal nerve injury and to observe the difference of these changes according to the level of temperature and the duration of heat application.
Method: The experimental rats (Sprague-Dawley) were divided into four groups according to the degree of temperature and the duration of heat application : Group 1, 43oC for 15 min; Group 2, 43oC for 30 min; Group 3, 45oC for 15 min; Group 4, 45oC for 30 min. A segment of 5 mm of the sciatic nerve was exposed and treated in vivo with local hyperthermia using a thermostatically controlled heating unit.
For the electrophysiologic examination, both sciatic nerve conduction study and needle electromyographic examination were performed immediately before, and at 1 day, 3 days, 1 week, 2 weeks, and 4 weeks after the hyperthermia. For the histopathologic study, a sciatic nerve biopsy was performed at 1 day, 1 week, 2 weeks, and 4 weeks after the hyperthermia and the changes were investigated under the light microscopic and electronmicroscopic examinations.
Results: In experimental groups, the compound muscle action potentials (CMAPs) showed a significant reduction compared to the control group (p＜0.05). Amplitudes of CMAPs following the heat application to the nerve were inversely related with the degree and duration of hyperthermia. A significant recovery of CMAPs was observed at 4 weeks after the hyperthermia in all experimental groups. The motor conduction latencies, however, did not show any significant changes. The needle electromyography of the gastrocnemius began to reveal fibrillation potentials on the 3rd day after the hyperthermia and continued to appear until the second week and then completely disappeared at 4 weeks after the hyperthermia. The histopathologic findings began to show the degeneration of axon and myelin within 24 hours and a remarkable regeneration at 4 weeks after the hyperthermia.
Conclusion: The results revealed that the hyperthermia of peripheral nerve within the range of 43∼45oC for 15∼30 min is likely to cause a significant acute, but not necessarily permanent nerve injury, and the severity of nerve injuries is related to the temperature and duration of heat applications. Whether the results can be clinically applied to human beings would require further exploration.
Local steroid injection in carpal tunnel syndrome(CTS) is widely practised for the relief of symptoms such as pain and paresthesias. We evaluated the effects of the injection with electrophysiologic changes and improvement in pain and paresthesias.
27 patients, 40 cases with carpal tunnel syndrome diagnosed clinically and electrophysiologically were injected with 40mg of triamcinolone acetonide. Patients were reevaluated with the visual analogue scale and electrophysiologic parameters after 2 to 4 weeks. Then we split up the patients into "excellent", "good" ,"poor" group by the degree of responses to the injections. In order to predict the injection effect, we analyzed several clinical and electrophysiologic factors: duration of symptoms, Phalen test, prolongation of distal motor latency of the median nerve, denervation evidence of the abductor pollicis brevis muscle.
Symptom relief was noted in the 89% of the cases[excellent(75%), good(14%)], and there was no statistically significant correlation between any of the above four factors and the degree of the symptom responses. Among the electrophysiologic parameters motor distal latency, motor residual latency, sensory onset and peak latency, median to radial sensory onset and peak latency difference reflected the clinical improvements(p＜0.05). But there was some cases that improved clinically but deteriorated electrophysiologically(2 cases in motor distal latency, 5 cases in motor residual latency, 1 case in sensory peak latency, none in sensory onset latency).
In conclusion we find that local steroid injection in CTS is an effective therapeutic modality for the symptom remission and it also showed changes in electrophysiologic parameters. And among these parameters sensory distal latency seems to be the most appropriate electrophysiologic parameter which best reflects the improvement of pain and paresthesias.
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