Patients with chronic intractable neuropathic pain often struggle to find relief from conventional treatments like medication therapy or exercise. Fortunately, advancements in neuromodulation technologies offer new treatment options.
Neuromodulation involves delivering electrical currents to nerve fibres responsible for pain, directly impacting the source of the neurological issue. While spinal cord stimulation has been widely used for patients with chronic pain in the trunk and limbs, recent developments in direct peripheral nerve stimulation show promising results for chronic neuropathic pain.
You might ask what a ‘peripheral nerve’ is. The peripheral nervous system is a network of nerves that runs throughout the head, neck, and body. It carries messages to and from the central nervous system (the brain and spinal cord).
One option for treating chronic neuropathic pain is Percutaneous Electrical Nerve Stimulation (PENS) of the peripheral nervous system.
The Potential of Peripheral Nerve Stimulation
Peripheral nerve stimulation is gaining traction due to its effectiveness in targeting specific pain areas. This approach is particularly useful for patients experiencing hyperalgesia (increased sensitivity to pain) and allodynia (pain from non-painful stimuli). By focusing on the peripheral nerves, this method can help manage pain without the need for, or potential risks of more invasive spinal cord interventions or surgeries.
What is PENS Therapy?
PENS therapy is a minimally invasive technique that delivers electrical stimulation directly to peripheral nerves through fine needles. This method induces analgesic effects and helps normalize central pain processing, offering relief for chronic peripheral neuropathic pain.
Benefits of PENS Therapy
Minimally Invasive: PENS therapy avoids the risks of surgery.
Non-Pharmacological: Ideal for patients seeking non-drug treatments for pain management.
Minimal Side Effects: Compared to long-term medication use, PENS has fewer side effects and complications.
Economic Value: It is cost-effective compared to more invasive treatments, providing significant savings for healthcare providers.
Effective Pain Relief: Patients may report significant pain reduction after undergoing PENS therapy.
Improved Functionality: By reducing pain, PENS can enhance a patient's ability to perform daily activities.
Repeatable Relief: PENS can be repeated every few months if needed, offering ongoing pain management without permanent implants.
When is PENS Therapy Appropriate?
PENS therapy is suitable for patients who:
Have not found pain relief from pharmacological treatments.
Are not candidates for permanent implanted devices.
Need targeted pain relief for specific areas, such as single peripheral nerves or their smaller nerve branches.
How PENS Therapy Works
PENS therapy involves the following steps:
Probe Placement: Fine probes are placed subcutaneously at the predetermined pain site. Ultrasound may be used to ensure accurate placement.
Electrical Stimulation: A combination of low and high-frequency electrical currents stimulates the release of natural pain-relieving chemicals like encephalin, β-endorphin, endomorphin, and dynorphin.
Duration and Frequency: Each session typically lasts about 30 minutes, and multiple sessions may be recommended for optimal results.
Probe Selection: Probes of varying lengths (20mm to 200mm) are chosen based on the size and location of the painful area.
Limitations
While PENS therapy can significantly reduce pain, it does not work for everyone, or all types of pain and it does not address the underlying cause of the condition. Therefore, PENS therapy is often used as part of a comprehensive pain management plan.
Conditions Treated by PENS
PENS is a versatile treatment option for various chronic pain conditions. By directly targeting the nerves responsible for transmitting pain signals, PENS can provide significant relief for several types of pain, including:
· Discrete Areas of Allodynia and Hyperalgesia
Allodynia refers to pain from stimuli that don’t usually provoke pain, while hyperalgesia is an increased sensitivity to painful stimuli. PENS therapy targets the nerves responsible for these abnormal pain responses, helping to alleviate discomfort in specific areas.
· Neuropathic Pain
This type of pain arises from damage to the nervous system and can be chronic and debilitating. PENS therapy can help manage conditions like diabetic neuropathy and post-herpetic neuralgia by modulating pain signals at the peripheral nerve level.
· Occipital Neuralgia
Characterized by piercing, throbbing, or electric-shock-like chronic pain in the upper neck, back of the head, and behind the ears, occipital neuralgia responds well to PENS by targeting the occipital nerves.
· Cluster Headache
These are severe headaches on one side of the head, often around the eye. PENS therapy can be used to stimulate nerves like the greater occipital nerve to reduce the frequency and severity of these headaches.
· Peripheral Neuralgia
Peripheral neuralgia involves pain due to damaged peripheral nerves. PENS therapy can alleviate pain by delivering electrical stimulation directly to the affected nerves, such as those in the limbs or torso.
· Trigeminal Neuralgia
Known for causing severe, electric-shock-like facial pain, trigeminal neuralgia could be managed with PENS therapy by targeting the more peripheral branches of the trigeminal nerve.
· Post-Hernia Repair Pain
Pain following hernia surgery can be persistent and severe. PENS therapy can help manage this pain by targeting the affected nerves in the surgical area.
· Neuropathic Chest Wall Pain
Pain in the chest wall due to nerve damage can be debilitating. PENS therapy provides relief by stimulating the specific nerves responsible for this pain.
· Stump Pain and Post-Mastectomy Pain
Pain in the residual limb (stump) following amputation and pain after mastectomy can be significantly alleviated with PENS therapy. This approach targets the specific nerves involved in transmitting pain from these areas.
· Intractable Facial Pain
Chronic facial pain that doesn’t respond to other treatments can be addressed with PENS therapy, which targets specific facial nerves to reduce pain. Some of the facial nerves that can be targeted include:
Supraorbital/Supratrochlear Nerve: These nerves are targeted for pain in the forehead and scalp.
Infraorbital Nerve: This nerve is targeted for pain in the midface, including the upper lip and cheeks.
Mental Nerve: Pain in the lower lip and chin can be managed by targeting the mental nerve.
Inferior Alveolar Nerve: This nerve is targeted for pain in the lower teeth and jaw.
Auriculotemporal Nerve: Pain around the temple and side of the head can be alleviated by targeting this nerve.
PENS therapy represents a significant advancement in the management of chronic neuropathic pain, offering a minimally invasive and cost-effective alternative to traditional treatments. By directly targeting peripheral nerves, PENS can provide substantial pain relief, improve patients' quality of life, and reduce the need for more invasive surgical procedures.
