Introduction
Rhizotomy is indicated in patients with neuropathic pain. The nerve fibers can be destructed by cutting them off using a surgical instrument or burning them with electric or chemical current. In rhizotomy, pain can be malignant (caused by cancer) or nonmalignant (not caused by cancer). Rhizotomy can treat patients with unilateral body cancer pain and occasionally bilateral body cancer pain. Outcomes, such as the sensory and motor autonomic deficit, should be considered beforehand.
What Are the Causes of Non-malignant Pain That Can Be Treated With Rhizotomy?
Nonmalignant pain has different causes; they are:
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Lumbar Facet Syndrome- In this, there is a dysfunction at the level of posterior facet joints of the spine.
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Chronic Discogenic Back Pain- Pain is caused due to a worn-out lumbar disc.
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Cervical Pain and Joint Pain- Pain is caused due to arthritis of the neck and other joints, respectively.
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Trigeminal Neuralgia- Neuropathic pain is caused by the trigeminal nerve (the fifth facial nerve).
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Cerebral Palsy- It is a motor disability in children, affecting their ability to move, maintain balance, and posture. Pain-inducing spasticity (increased muscle tone) is seen in these patients, which can be reduced by selective dorsal rhizotomy (a type of rhizotomy).
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Spinal Stenosis- There is a narrowing of spaces within the spine, thereby putting pressure on the nerves passing through.
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Sciatica- In this condition, the pain radiates along the path of the sciatic nerve.
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Occipital Neuralgia- Pain occurs due to injury or inflammation of the occipital nerve.
What Are the Tests Done Before Rhizotomy?
A careful screening is done to evaluate the patient; some of the routine tests done before the procedure are as follows:
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Magnetic Resonance Imaging (MRI)- It is a diagnostic and screening procedure that provides a three-dimensional image of the desired anatomical location or organ.
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Nerve Block Injection Test- This is done to locate the nerve causing pain.
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Facet Nerve Injection Test- It is a diagnostic test to locate the pain-hat facet.
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Discography- It is an imaging test used to evaluate back pain.
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X-Rays- This is similar to MRI, but the resultant images are only two-dimensional.
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Computed Tomographic (CT) Scans- It is also an imaging technique; however, the resultant images of a CT scan are more detailed when compared to MRI and X-rays.
What Are the Different Types of Rhizotomy?
After a thorough evaluation, the neurosurgeon determines the type of approach, and different techniques to perform rhizotomy which are listed below:
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Surgical Sectioning- In this procedure, the sensory nerves causing pain are identified and cut close to the spinal cord. After anesthetizing the patient, an incision is made at the location of the pain, followed by laminectomy (removal of parts of the vertebrae called laminae). Then, the dura mater (tough tissue) enclosing the spinal cord is opened, and the spinal cord is exposed. Next, stimulation confirms the dorsal nerve roots (sensory roots) which are then ablated. The closure of the dura mater follows this, then the laminae are fixed in place, and the skin incision is closed.
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Glycerol Rhizotomy- In this type, after the anesthetization, the surgeon uses a needle to deliver glycerine or glycerol (chemical) to destroy the root of the affected nerve.
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Radiofrequency Rhizotomy- It is similar to glycerol rhizotomy; but in this, instead of chemicals, a radiofrequency current is used to burn the roots.
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Balloon Rhizotomy- A cannula is inserted close to the damaged nerve, and a balloon catheter is passed through the cannula. The balloon is then inflated to compress and damage the nerve. Later, the balloon is deflated, and the catheter and cannula are removed.
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Endoscopic Rhizotomy- It is a minimally invasive technique and can be done with local anesthesia. An endoscope is inserted through the small incision using the tubular retractor system which helps the surgeon bypass healthy organs during nerve identification. Special instruments are used to snip the affected nerve, thereby reducing the chances of the nerve growing back.
Depending on the location where the rhizotomy is performed, it can be differentiated as follows:
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Selective Dorsal Rhizotomy- This is mostly done for sciatica and cerebral palsy patients, wherein selective ablation of the sensory root or dorsal ganglion of the damaged sciatic nerve blocks the pain signals without impairing muscle function.
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Percutaneous Rhizotomy- Percutaneous rhizotomy is used to treat trigeminal neuralgia. The logic behind the procedure is that the successful thermal lesioning (burning) of the gasserian ganglion (origin of the trigeminal nerve) using radiofrequency rhizotomy interrupts peripheral stimulus from reaching the central nervous system.
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Sacroiliac Joint Rhizotomy- It is performed in patients with sacroiliitis (inflammation of the sacroiliac joint) or groin pain. The ablation of L4-L5 dorsal rami S1-3 lateral branches of the sacroiliac joints is done using radiofrequency currents.
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Lumbar Facet Joint Rhizotomy- This is done in patients with spondylolisthesis (a medical condition caused due to slipping of one vertebra over the other) and lumbar facet syndrome where the medial branches of the lumbar dorsal rami are ablated using radiofrequency current.
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Cervical Rhizotomy- Cervical rhizotomy is done in patients with cervical spondylosis (arthritis in the neck spine due to age-related friction) or soft tissue injury. Ablation is done at the anterior lateral capsule of the cervical facet joint using radiofrequency currents.
What Are the Alternatives for Rhizotomy?
Doctors suggest effective pain management options before finalizing the surgical process. These include:
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Physical Therapy- A physical therapist helps to improve posture, strength, and flexibility through stretches, movement, and core exercises which can reduce pain.
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Acupuncture, Acupressure, and Massage Therapy- Tiny needles or hand pressure can reduce tension, relieve joint pain, and speed up recovery after an injury.
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Aquatic or Water Therapy- Water can counteract gravity, hence creating an ideal exercise environment to improve blood circulation.
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Nutrition or Lifestyle Changes- Obesity often exerts increased pressure on the spine. Studies have shown that smoking exacerbates back pain.
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Cupping- Suction cups against the skin can reduce or increase blood flow and reduce pain; however, more research is needed to understand the underlying mechanism.
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Osteopathic Manipulation- Specially trained physicians exert gentle pressure, resistance, and stretching to relieve pain and increase blood flow.
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Injections- Besides reducing pain, they also help identify the location of the pain. Corticosteroids are commonly administered and can be done as an outpatient procedure. A few examples include epidural steroid injection, facet joint injection, sacroiliac joint injection, and so on.
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Medication- Non-steroidal anti-inflammatory drugs are usually prescribed and they provide short-term pain relief.
What Are the Risks and Complications of Rhizotomy?
A small number of patients may experience the following complications, such as:
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Anesthesia Dolorosa- Loss of sensations and numbness in the nerve distribution area.
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Difficulty In Chewing- If the procedure involves trigeminal neuralgia, then one might experience difficulty chewing.
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Spinal Deformities- Excessive bending may occur when laminectomy is done in children.
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Meningitis- Meninges are the protective layers around the brain and spinal cord. Infection in these layers causes meningitis.
The risks associated with glycerol or glycerin rhizotomy include nausea, infection, bleeding, vomiting, a minor sensory change like numbness, and anesthetic complications. Radiofrequency rhizotomy has a greater risk of causing sensory changes like numbness than when compared with the chemical method.
What to Expect After the Surgery?
The patient's vitals must be carefully monitored if done under general anesthesia. The procedure might take only a few minutes but one might need to stay in the recovery room for a few hours. Swelling, pain, and bruising may be common. Temporary numbness can be expected in the region supplied by the damaged nerves. Non-steroidal anti-inflammatory drugs and ice packs are prescribed to reduce the soreness. Relief from pain may take up to three weeks following surgery.
Conclusion
Rhizotomy is a safe and efficacious method of pain relief and it can be repeated multiple times with no increase in morbidity. However, rhizotomy does not offer a 100% success rate, and a few patients may feel no significant pain relief or may experience a gradual return of the pain as the nerve grows back. In these patients, the clinical doctor may suggest a second rhizotomy. Depending on the origin of the pain, treatment options may include decompression surgery to remove the tissues that press on the nerve.
