Breaking News
January 19, 2019 - Newly developed risk score more effective at identifying type 1 diabetes
January 19, 2019 - Highly effective protocol to prepare cannabis samples for THC/CBD analysis
January 19, 2019 - Prinston Pharmaceutical Inc. Issues Voluntary Nationwide Recall of Irbesartan and Irbesartan HCTZ Tablets Due to Detection of a Trace Amount of Unexpected Impurity, N-Nitrosodiethylamine (NDEA) in the Products
January 19, 2019 - How does solid stress from brain tumors cause neuronal loss, neurologic dysfunction?
January 19, 2019 - $14.7 million partnership to supercharge vaccine development
January 19, 2019 - Ian Fotheringham receives Charles Tennant Memorial Lecture award
January 19, 2019 - Brain vital signs detect neurophysiological impairments in players with concussions
January 19, 2019 - Lack of job and poor housing conditions increased likelihood of people attending A&E
January 19, 2019 - Novel targeted drug delivery system improves conventional cancer treatments
January 19, 2019 - Rutgers study finds gene responsible for spread of prostate cancer
January 19, 2019 - Complications Higher Than Expected for Invasive Lung Tests
January 19, 2019 - 3-D printed implant promotes nerve cell growth to treat spinal cord injury
January 19, 2019 - Automated texts lead to improved outcomes after total knee or hip replacement surgery
January 19, 2019 - Poor cardiorespiratory fitness could increase risk of future heart attack, finds new study
January 19, 2019 - Drinking soft drinks while exercising in hot weather may increase risk of kidney disease
January 19, 2019 - Formlabs 3D prints anatomical models
January 19, 2019 - Heart-Healthy Living Also Wards Off Type 2 Diabetes
January 19, 2019 - Teaching Kids to Be Smart About Social Media (for Parents)
January 19, 2019 - Metabolite produced by gut microbiota from pomegranates reduces inflammatory bowel disease
January 19, 2019 - Researchers examine how spray from showers and toilets expose us to disease causing bacteria
January 19, 2019 - Behavioral experiments confirm that additional neurons improve brain function
January 19, 2019 - New study compares performance of real-time infectious disease forecasting models
January 19, 2019 - Obesity can be risk factor for developing renal cell carcinoma, confirms study
January 19, 2019 - New regulation designs on cigarette packs direct smokers’ attention to health warnings
January 19, 2019 - QIAGEN receives first companion diagnostic approval in Japan
January 19, 2019 - Study explores role of Dunning-Kruger effect in anti-vaccine attitudes
January 19, 2019 - Newly identified subset of immune cells may be key to fighting chronic inflammation
January 19, 2019 - New immune response regulators discovered
January 18, 2019 - Poor blood oxygenation during sleep predicts chance of heart-related death
January 18, 2019 - First international consensus on the diagnosis and management of fibromuscular dysplasia
January 18, 2019 - Rapid resistance gene sequencing technology can hasten identification of antibiotic-resistant bacteria
January 18, 2019 - Researchers develop artificial enzymatic pathway for synthesizing isoprenoids in E. coli
January 18, 2019 - Scientists advise caution in immunotherapy research
January 18, 2019 - How children across the world develop language
January 18, 2019 - Columbia Medical Student Receives McDonogh Scholarship
January 18, 2019 - Secretive ‘Rebate Trap’ Keeps Generic Drugs For Diabetes And Other Ills Out Of Reach
January 18, 2019 - Plant based diet could be the best option for the planet says commission
January 18, 2019 - New conservation practice could reduce nitrogen from agricultural drainage, study shows
January 18, 2019 - UIC researchers receive $1.7 million NCI grant to study Southeast Asian fruit
January 18, 2019 - New study determines the fate of DNA derived from genetically modified food
January 18, 2019 - Scientists develop new gene therapy that prevents axon destruction in mice
January 18, 2019 - Study finds critically low HPV vaccination rates among younger adolescents in the U.S.
January 18, 2019 - Brain cells involved in memory play key role in reducing future eating behavior
January 18, 2019 - Risk for Conversion of MS Varies With Different Therapies
January 18, 2019 - Investigational cream may help patients with inflammatory skin disease
January 18, 2019 - Medical school news office receives six writing awards | News Center
January 18, 2019 - County By County, Researchers Link Opioid Deaths To Drugmakers’ Marketing
January 18, 2019 - Research reveals risk for developing more than one mental health disorder
January 18, 2019 - Scientists discover a dramatic pattern of bone growth in female mice
January 18, 2019 - Study finds link between lengthy periods of undisturbed maternal sleep and stillbirths
January 18, 2019 - New nuclear medicine method could improve detection of primary and metastatic melanoma
January 18, 2019 - Combination therapy shows high efficacy in treating people with leishmaniasis and HIV
January 18, 2019 - Health Tip: Don’t Ignore Changes in Skin Color
January 18, 2019 - Dietary Recommendations for Healthy Children
January 18, 2019 - Eliminating the latent reservoir of HIV
January 18, 2019 - Pain From The Government Shutdown Spreads. This Time It’s Food Stamps
January 18, 2019 - Newly discovered regulatory mechanism helps control fat metabolism
January 18, 2019 - New rapid blood tests could speed up TB diagnosis, save the NHS money
January 18, 2019 - Researchers develop intelligent system for ‘tuning’ powered prosthetic knees
January 18, 2019 - Monoclonal antibody pembrolizumab prolongs survival in patients with squamous cell carcinoma
January 18, 2019 - New research detects mosquito known to transmit malaria for the first time in Ethiopia
January 18, 2019 - Researchers identify new genes linked to development of age-related macular degeneration
January 18, 2019 - Computerized method helps better protect pharma patents
January 18, 2019 - New guidelines to make swallowing safer for people in Australian nursing homes
January 18, 2019 - Lumex Instruments’ RA-915AM monitor installed at Hg treatment plant in Almadén, Spain
January 18, 2019 - ACCC survey finds multiple threats to growth of cancer programs
January 18, 2019 - Meeting the challenge of engaging men in HIV prevention and treatment
January 18, 2019 - Furloughed Feds’ Health Coverage Intact, But Shutdown Still Complicates Things
January 18, 2019 - Experts discuss various aspects on health risks posed by fumigated containers
January 18, 2019 - Researchers use gene-editing tool CRISPR/Cas9 to limit impact of parasitic diseases
January 18, 2019 - Alpha neurofeedback training could be a means of enhancing learning success
January 18, 2019 - Innovative ‘light’ method demonstrates positive results in fight against malignant tumors
January 18, 2019 - The cytoskeleton of neurons found to play role in Alzheimer’s disease
January 18, 2019 - New resource-based approach to improve HIV care in low- and middle-income countries
January 18, 2019 - Bedfont appoints Dr Jafar Jafari as first member of the Gastrolyzer Medical Advisory Board
January 18, 2019 - New study shows link between secondhand smoke and cardiac arrhythmia
January 18, 2019 - DZIF scientists reveal problems with available diagnostics for Zika and chikungunya virus
January 18, 2019 - Breast cancers more likely to metastasize in young women within 10 years of giving birth
January 18, 2019 - Over 5.6 million Americans exposed to high nitrate levels in drinking water
January 18, 2019 - Blood vessels can now be created perfectly in a petri dish
Direct electrical current can be delivered to nerves for blocking pain signals

Direct electrical current can be delivered to nerves for blocking pain signals

image_pdfDownload PDFimage_print

Using computer models and laboratory rats, Johns Hopkins researchers have demonstrated that “direct electrical current” can be delivered to nerves preferentially, blocking pain signals while leaving other sensations undisturbed.

The researchers say the experiments advance the search for improved implantable devices able to treat chronic pain that is due to peripheral nerve injury or disease.

“We have developed a potential new concept for neural implants that works differently than conventional electrical stimulators,” says Gene Fridman, Ph.D., M.S., assistant professor of otolaryngology-;head and neck surgery and biomedical engineering at the Johns Hopkins University School of Medicine. “We believe we are the first to investigate the idea of using this concept for implantable medical devices that use direct electrical current, long thought to be unsafe.”

Implantable spinal cord stimulators and peripheral nerve stimulators designed to interrupt nerve pain impulses were developed more than 30 years ago, but the devices work by interacting with sensory nerve cells, leading to numbness, tingling and other side effects.

In a report on the new findings, published online April 11 in Science Advances, the researchers say direct electrical current devices would allow for more precise, preferential targeting of the appropriate pain-transmitting nerve cells, making them more effective for pain suppression and reducing the side effects of conventional devices.

Traditionally, direct current -; or single-direction streaming electrical signaling -; has been considered unsafe for medical devices that deliver electrical stimulation in the body. The continual flow of electrical current results in chemical reactions at the site of the electrodes delivering the signal, causing gas bubbles, corrosion and toxic byproducts to form.

All modern implantable electrical stimulation devices use alternating current pulses instead, in which the electrical current switches back and forth very quickly in a circuit between positive and negative voltage. Such rapid pulses allow the devices to interact with the nervous system but don’t create the toxic chemical reactions.

In 2013, Fridman and his team reported on successful efforts to develop an ionic direct current system, which converts the “safe” pulses like those delivered in the conventional stimulator into direct ionic current that may potentially be applied to the body safely.

To find out if the modified system of direct ionic current could be safely used to preferentially target and silence pain-transmitting neurons, Fridman teamed up with pain researcher Yun Guan, M.D., Ph.D., an associate professor of anesthesiology, critical care medicine and neurological surgery at the Johns Hopkins University School of Medicine.

When nerve cells receive a signal of pain or other sensation, the signal opens sodium channels and floods the cell with positively charged sodium ions, which positively charge the neurons until the electrochemistry changes enough to inactivate the channels and close them.

This change in electrical charge of the neuron is what propagates and sends the signal to the spinal cord and then to the brain to register as a sensation, such as pain or pressure.

Each nerve in mammalian arms and legs contains multiple sensory neurons (nerve cells) transmitting pain and other sensations such as touch or feeling to the spinal cord. Fridman and Guan realized that the pain and “feeling” sensory neurons each contained different kinds of sodium channels and that it may be possible to block one kind of channel and not the others to prevent patients from feeling pain but not other sensations.

Fridman and Guan’s team first devised a computer model to try to predict what happens when researchers use direct current to block the pain signals or inhibit other sensory neurons. In the model they sent negatively charged direct current to the nerves to weaken their activity. The model showed that the sodium channels 1.6 in the feeling sensory neurons were blocked with 670 microamperes, but the pain neuron’s sodium channels 1.7 were blocked at only 290 microamperes. For comparison, holding a 9-volt battery to the tongue delivers approximately 2,000 microamperes, causing a small shock. This suggested to the researchers that it was theoretically possible to preferentially target one type of neuron over another, since the channels could be blocked at different levels of current.

Next, working with anesthetized rats, they sent direct ionic current into the sciatic nerve in the legs and, using neural recording electrodes, recorded whether this current inhibited the activity of individual or groups of neurons at the spinal cord.

In a series of experiments, they increased the current in two-minute increments from 0.1 to 0.2, 0.4 and 0.8 milliamperes. The current at 0.8 milliamperes completely blocked the response of the pain-transmitting neurons. Although signals from the feeling sensory neurons were reduced by 20 percent, they were still active and sending sensation signals to the spinal cord. After the current was stopped, the signal from the pain-transmitting neurons remained blocked for another two minutes, whereas the signal from the feeling sensory neurons quickly came back.

“Using direct current, we can inhibit the pain-transmitting neurons at much lower amplitudes than the feeling sensory neurons, allowing us to be preferential in how we target the nerve,” says Guan. “We also found that because the pain neurons take longer to come back on line, we may be able to conserve energy and not have to deliver this electrical current constantly to keep them blocked.”

Being able to deliver this current periodically rather than constantly would mean longer use of the neural implant before needing to recharge the battery, says Guan.

Guan cautions that more studies will be needed to verify safety and measure the strength and duration of pain relief before direct ionic current devices could be used for people.

Source:

https://www.hopkinsmedicine.org/news/media/releases/direct_electrical_current_used_to_preferentially_inhibit_pain_transmitting_neurons

Tagged with:

About author

Related Articles