Brief Submotor-Threshold Electrical Stimulation Applied Synchronously Over Wrist Flexor and Extensor Muscles does Not Suppress Essential Tremor, Independent of Stimulation Frequency

Background

Electrical stimulation of muscles below motoneuron threshold has shown potential as a low-cost and minimally invasive treatment for Essential Tremor (ET). Prior studies have stimulated wrist flexor and extensor muscles synchronously with diverging results, calling for further investigation. Also, prior studies have only used a narrow range of stimulation parameters, so stimulation parameters have not been optimized. Our purpose was to further investigate synchronous submotor stimulation and identify the effect of stimulation frequency on tremor suppression.

Methods

We quantified the effect of brief, synchronous stimulation at 15 different frequencies from 10-150 Hz applied over wrist flexors and extensors on both tremor power and frequency in 20 ET patients. We compared tremor power and frequency from hand acceleration and sEMG between pre-, per-, and post-stimulation phases.

Results

Our stimulation paradigm did not result in significant tremor suppression or tremor frequency changes at any tested stimulation frequency, showing no significant interaction between phase and stimulation frequency for tremor power measured by either hand acceleration (p = 0.69) or sEMG (p = 0.07). Additionally, the effect of phase interacting with stimulation frequency on tremor frequency was statistically insignificant for acceleration (p = 0.64) and sEMG (p = 0.37).

Discussion

We conclude that brief synchronous submotor-threshold stimulation does not reduce tremor in ET patients, independent of stimulation frequency (from 10 to 150 Hz). Our results are consistent with the hypothesis that brief submotor-threshold stimulation suppresses tremor via reciprocal inhibition, which requires asynchronous stimulation. In contrast, it is hypothesized that synchronous stimulation might require longer stimulation durations to affect supraspinal tremor networks.

Highlights

We studied the effects of synchronous submotor electrical stimulation over wrist flexor and extensor muscles on Essential Tremor. Our results indicate that suppressing tremor with brief synchronous stimulation is ineffective. Based on recently hypothesized mechanisms of peripheral tremor suppression, we hypothesize that asynchronous stimulation or long-duration synchronous stimulation are more effective approaches to peripheral tremor suppression.

How to suture a wound

Rationale and key points This article explores how to suture a wound using several common techniques. The use of different suture techniques depends on various factors, including the type of wound, its location, skin thickness, wound tension and cosmetic considerations. » Nurses should have a comprehensive understanding of the relevant anatomy and underlying structures, and the expertise to determine that suturing, rather than other methods of wound closure, is appropriate in each case. » Nurses should work within their scope of practice and to agreed departmental protocols. » Nurses should audit and reflect on their practice to ensure that their suturing skills are maintained and improved. » Nurses should be aware of local procedures in the event of needle-stick injury. Reflective activity 'How to' articles can help update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. What factors would affect your decision to use sutures to close a wound rather than another method. 2. How you think this article will change your practice.

Assessment and management of patients with minor traumatic wounds

Patients with minor traumatic wounds are a common and universal presentation to emergency departments, and their assessment and management requires the use of cognitive and motor skills. Knowledge of anatomy and physiology, combined with decision-making skills, are essential for clinicians to undertake a thorough assessment, develop a care plan and provide effective wound management. This article discusses the importance of wound irrigation and debridement, as well as different methods available for wound closure. It is important that clinicians are competent in the motor skills required to perform these tasks to enable effective care delivery. Nurses should be aware of the latest research in the field and implement best practice in their clinical settings.

Comparison of suture types in the closure of scalp wounds

Innovation in practice can benefit patients and healthcare providers but must be evidence based. This article describes a quantitative study of whether absorbable sutures are as beneficial as non-absorbable sutures in the management of simple scalp lacerations in adults. The results suggest that absorbable sutures can provide the same cosmetic and functional results as non-absorbable sutures. Their use can also reduce patient returns and save money and resources.

Utility of zanamivir for chemoprophylaxis of concomitant influenza A and B in a complex continuing care population

OBJECTIVE

To describe compliance with and the safety and prophylactic efficacy of zanamivir among patients at risk of developing influenza-related complications after exposure to both influenza A and B viruses.

DESIGN

Nonrandomized trial using both historical and contemporaneous controls from ward populations within the same facility.

SETTING

A 547-bed urban hospital providing complex continuing care and rehabiltation.

PATIENTS

Fifty patients on a single ward concomitantly exposed to both influenza A and B during an influenza outbreak.

INTERVENTIONS

All patients were screened for symptoms of influenza and nasopharyngeal swabs were sent for viral culture prior to treatment (two oral inhalations [2 x 5 mg] twice daily for 5 days) or prophylaxis (two oral inhalations [2 x 5 mg] once daily for 14 days) with zanamivir. Patient symptoms, compliance, and drug tolerance were monitored daily. Demographic data, comorbidities, vaccination status, and functional status (Katz score) were collected for all patients.

RESULTS

The mean age of the patients was 70.6 years (standard deviation, +/- 16.4 years). Ninety-four percent had two or more comorbidities, 71% were dependent in two or more activities of daily living, 63% had been vaccinated for influenza, and 82% had received amantadine. Zanamivir was well tolerated, with 93% of the patients completing their course. The efficacy for preventing symptomatic infection was 82% and 91% (95% confidence interval, 62% to 98%) based on historical and contemporaneous controls, respectively.

CONCLUSION

These data suggest that zanamivir can be used safely and effectively as a prophylactic agent in the management of influenza outbreaks in a complex continuing care population with multiple comorbidities.

Copper-associated liver disease in childhood

BACKGROUND/AIMS

Indian childhood cirrhosis is associated with high liver copper concentrations and progressive liver disease with a high mortality. Early treatment with penicillamine was found to reduce mortality and reverse liver damage. We aimed to define the clinical features of copper-associated liver disease outwith the Indian subcontinent and encourage the earlier consideration of the syndrome in cryptogenic liver disease.

METHODS

Three European children presented between 10 and 29 months of age with abdominal distension, pyrexia and hepatosplenomegaly. Over 1-5 weeks their condition deteriorated rapidly due to liver failure. Two died within 2 months of onset and one received a successful liver transplant. In two cases consideration of the diagnosis occurred only on examination of the liver after orthotopic liver transplant or death. Light microscopy was used, with haematoxylin and eosin, reticulin and orcein stains. Tissue, plasma and water copper levels were measured by flame atomic absorption spectrometry.

RESULTS

All had micronodular cirrhosis and severe hepatocellular necrosis with Mallory bodies and copious-orcein positive material. Liver copper concentrations ranged from 1100-1310 micrograms/g dry weight. For two patients domestic water with high copper content had been used for the preparation of feeds. No environmental source of excess copper could be identified in the third case.

CONCLUSIONS

We suggest that the above condition, which is called Indian childhood cirrhosis in the Indian subcontinent and Copper Storage Disease elsewhere, would be better named 'Copper-Associated Liver Disease in Childhood', emphasising the need to consider this disorder in unexplained liver disease and to seek possible sources of excessive copper intake.

Pancreatitis in patients with organic acidemias

STUDY OBJECTIVE

The discovery of pancreatitis in two children with methylmalonic acidemia led us to review the experience with pancreatitis in a large number of patients with organic acidemias to determine whether pancreatitis is an important complication of these disorders.

DESIGN

Case series.

SETTING

Pediatric metabolism services at five tertiary care centers.

PATIENTS

Records of all patients with organic acidemias followed at the five institutions during the past 10 years were reviewed. Pancreatitis was recognized by symptoms and laboratory findings and confirmed by imaging studies, surgery, or autopsy. At three institutions all cases of pancreatitis in children younger than 10 years were reviewed.

MEASUREMENTS AND RESULTS

Nine children with pancreatitis (seven with acute and two with chronic cases) were identified among 108 children with branched-chain organic acidemias. They ranged in age from 13 months to 9 years. Five had methylmalonic acidemia, three had isovaleric acidemia, and one had maple syrup urine disease. There were three deaths; acute hemorrhagic pancreatitis occurred in two children, and chronic pancreatitis was found at autopsy in a third. All three patients with isovaleric acidemia and pancreatitis were identified after the occurrence of pancreatitis. The survey of pancreatitis at three institutions found 57 other patients (none with an inborn error) in addition to three patients with inborn errors included in this study.

CONCLUSIONS

Acute or chronic pancreatitis may complicate branched-chain organic acidemias and must be considered in the assessment of patients with these disorders who have acute clinical deterioration and vomiting, abdominal pain, encephalopathy or shock, or milder symptoms. Conversely, an inborn error of organic acid metabolism should be considered in children with pancreatitis of unknown origin.

Familial hypercholesterolaemia: pilot study to identify children at risk

AIMS

To evaluate a more effective method of identifying children with familial hypercholesterolaemia by screening a population at high risk.

METHODS

Domiciliary measurement of random cholesterol concentration was made in 200 children who were first or second degree relatives of subjects with premature onset coronary artery disease. Measurements were taken by a health visitor using a portable analyser.

RESULTS

Twelve new cases of familial hypercholesterolaemia were identified during the first nine months of the study. Random cholesterol concentrations were within the normal range (< 5.2 mmol/l) in 70.5% of samples tested. Forty two (21%) of patients tested had a borderline cholesterol (5.2-5.9 mmol/l) but 50% of these fell within the normal range when fasting capillary samples were analysed. Children with significant hypercholesterolaemia on random testing (concentrations of > 5.9 mmol/l) (8.5%) also had fasting venous blood assayed for high density lipoprotein (HDL) cholesterol and tri-glyceride in the laboratory. Results indicated that 6.5% of patients screened were at high risk of cardiovascular disease (ratio of total: HDL cholesterol of > 4.5), and 1% had a moderately increased risk (ratio 3.5-4.5).

CONCLUSIONS

Children with familial hypercholesterolaemia can be identified from a selected "high risk" population by measuring random capillary cholesterol concentration.

Cholinergic receptors in cognitive disorders

Cholinergic receptors (muscarinic subtypes M1 and M2, and putative nicotinic binding) have been examined in the hippocampus obtained at autopsy from a variety of patients with cognitive disorders (Alzheimer's, Parkinson's, and Huntington's diseases, Down's Syndrome and alcoholic dementia) and compared with neurologically normal controls and cases of Motor Neuron disease. In all of the disorders associated with a pre-synaptic cortical cholinergic deficit reflected by an extensive loss of choline acetyltransferase (Alzheimer's disease, Parkinson's disease and Down's Syndrome) there was a substantial reduction in the binding of (3H) nicotine to the nicotinic receptor. By contrast reductions in both muscarinic subtypes (M1 and M2) were apparent to only a moderate extent in Alzheimer's disease, whereas in Parkinson's disease binding was significantly increased (apparently not in relation to anti-cholinergic drug treatment) in the non-demented but not demented cases. A further abnormality detected in Alzheimer's disease but not the other disorders investigated was a decrease in an endogenous inhibitor of nicotinic binding, the identity of which is as yet unknown but which may be a candidate for a possible endogenous modulator of the nicotinic receptor. These observations suggest that in Alzheimer's disease not only muscarinic but also nicotinic receptor function should be considered in relation both to future therapeutic strategies and, in the search for a clinical marker which might be of diagnostic value, to potential probes of the cortical cholinergic system.

SCLC theory for a Gaussian trap distribution

A simplified one-carrier space charge limited conduction theory has been developed for a Gaussian trap distribution in. an insulator. It is shown that the distribution behaves much like a discrete trap level at low applied fields, although the current has a temperature dependent activation energy. At higher fields the current-voltage relation becomes superquadratic, but this does not account for the behaviour normally attributed to an exponential trap distribution.