Introduction
Anesthesia enables pain-free medical treatments and surgeries by entailing the administration of drugs to cause a reversible loss of feeling and consciousness. Neuromodulation, in contrast, is to modify inappropriate neural circuits and treat symptoms in situations including chronic pain, mobility difficulties, and neurological disorders. The intersection of anesthesia and neuromodulation is crucial in procedures involving the insertion or use of neuromodulation devices. Devices such as deep brain, spinal cord, and peripheral nerve stimulators require careful consideration and coordination between the anesthesia and neuromodulation teams to ensure safe and effective patient outcomes.
What Is Neuromodulation?
Therapeutic neuromodulation refers to a technique that uses targeted stimulation, such as electrical impulses or chemicals, to change the activity of nerves in specific body areas. It is similar to how a pacemaker corrects irregular heartbeats. This approach has revolutionized the treatment of chronic pain, starting with the implantation of a device. One common example is Spinal Cord Stimulation (SCS), where a thin wire is placed near the spinal cord and connected to a small device implanted under the skin. This apparatus controls pain signals by gently electrically stimulating the spine. Intrathecal pumps are a different approach that delivers medication directly to the spinal fluid, needing lower doses and minimizing side effects. Deep brain stimulation for Parkinson's disease, sacral nerve stimulation for pelvic diseases, vagal nerve stimulation for migraines, and cochlear implants to help restore hearing are all examples of neuromodulation therapies.
What Are the Significant Advancements in Neuromodulation?
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The use of devices to stimulate nerves and treat various illnesses has caused considerable developments in neuromodulation during the past 20 years.
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These developments include wireless systems, smaller devices, more reliable equipment, and improved targeting of specific areas in the nervous system.
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Neuromodulation is commonly used for chronic pain management and has become more popular due to better reimbursement and increased physician involvement.
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Studying the effectiveness of neuromodulation is challenging due to problems with bias, reproducibility, and difficulties in measuring pain in research animals.
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The dorsal root ganglion focuses electrical stimulation on pain developed in a rat. It was discovered that electrical stimulation reduced pain in them with and without injuries for both nerve-related pain and knee osteoarthritis.
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This highlights how well animal models can mimic human pain and how to target particular locations for stimulations successfully.
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Researchers must concentrate on selective stimulation, matching treatment intensity and duration, using injured models resembling human biology, and appropriately interpreting pain-related behavioral changes.
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Measuring pain behaviors in animals is subjective and can vary, making it challenging to apply animal data to human pain experiences directly.
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Developing electrodes for dorsal root ganglion placement still faces challenges when considering durability and size.
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The results counter the notion that electrical stimulation is most helpful for nerve-related pain and demonstrate its potential to reduce knee osteoarthritis discomfort.
What Are the Devices Used for Neuromodulation to Treat Migraine?
There are four different devices available for neuromodulation:
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E-TNS: This device is called Cefaly, placed externally, and stimulates the trigeminal nerve, which is involved in migraine headaches.
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nVNS: Gammacore is a noninvasive device that stimulates the vagal nerve, another nerve involved in migraines.
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sTMS: The sTMS mini is a device that uses a single-pulse transcranial magnetic stimulation to disrupt pain signals associated with migraines.
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REN: Nerivio is a remote electrical neuromodulator that works on nerves to alleviate migraine pain.
Although each device works differently, it aims to prevent or treat migraine episodes. These devices are relatively new treatment options that have become available in recent years.
How Pain Is Managed Using Neuromodulation?
Neuromodulation is a medical technique involving implanted devices to deliver electrical or chemical stimulation to specific parts of the nervous system. It has been used to treat various conditions, including chronic pain. Two common forms of neuromodulation for pain management are Deep Brain Stimulation (DBS) and Spinal Cord Stimulation (SCS).
DBS involves directly stimulating specific areas of the brain responsible for pain perception. It has been used for over 60 years to treat neuropathic pain that does not respond to medication. In some cases, DBS has shown favorable responses in patients with pain caused by stroke or spinal cord injury. It can also be used for atypical facial pain. However, the evidence supporting its use is limited and is typically considered a last-resort treatment.
SCS, on the other hand, involves stimulating the spinal cord to prevent pain signals from reaching the brain. It has been used since the late 1960s and has evolved. The most widely accepted theory for how SCS works is the gate control theory, which suggests that stimulation of non-painful signals "closes the gate" to transmitting painful signals. Other mechanisms of action have also been identified, including activation of inhibitory systems and modulation of neurotransmitter release. The use of SCS involves a trial phase and a permanent implant phase.
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During the trial phase, a temporary lead is inserted near the spinal cord, and the patient undergoes a trial period to assess the effectiveness of the stimulation.
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If the trial is successful, a permanent implant is done, where a permanent lead is placed and connected to an implanted device.
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SCS has a low risk of major complications but can have minor complications like a lead fracture or migration, infection, and pain at the implant site.
Even though SCS has a high initial cost, studies have shown that it is cost-effective compared to conventional medical management alone. It provides significant benefits regarding quality-adjusted life years compared to other pain treatments. DBS and SCS are techniques used to treat chronic pain when other treatments have not been successful. They involve stimulating specific brain or spinal cord areas to alleviate pain.
What Is the Anesthetic Management for a Patient With a Sacral Neuromodulation Device?
Sacral Nerve Stimulation (SNS) or sacral nerve neuromodulation is used for conditions like overactive bladder, urinating dysfunction, and fecal incontinence. It involves stimulating the nerves in the sacral area to improve these functions. The procedure typically involves a two-stage process:
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The first stage is with an initial evaluation period to test the effectiveness of the stimulation.
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In the second stage, a permanent stimulator is implanted if the evaluation succeeds.
During surgery unrelated to SNS, such as a lower body lift, the SNS device may need to be temporarily turned off or disconnected. This ensures the device does not interfere with the surgical procedure. Anesthesia for patients with SNS is similar to anesthesia for patients with spinal cord stimulators. Precautions are taken to minimize any interference or risks associated with the SNS device, such as avoiding monopolar electrocautery and using bipolar cautery instead.
The anesthesia team must know the patient's SNS device and its specific model to ensure appropriate care. Postoperative evaluation of the SNS device may be necessary, but it does not have to be done immediately after surgery. Overall, involving the anesthesia team early in the patient's care helps ensure a successful outcome.
Conclusion
A promising strategy for enhancing patient care and outcomes is using neuromodulation devices for anesthesia. These tools have proven effective in treating neurological diseases, mobility abnormalities, and chronic pain. Together, anesthesia professionals and the neuromodulation team can ensure that these tools are used safely and efficiently during surgical procedures.
