What Are the Side Effects of a Rhizotomy?

Rhizotomy side effects range from mild, self-resolving soreness and temporary numbness to rarer but more serious complications like persistent altered sensation or, in the case of selective dorsal rhizotomy, long-term spinal changes. The specific risks depend heavily on which type of rhizotomy you are having and where in the body it targets. Because “rhizotomy” is really a family of procedures, from radiofrequency ablation of small spinal nerves to surgical cutting of nerve roots for cerebral palsy, the side-effect profile changes substantially with the technique and the anatomy involved.

Short-Term Effects That Usually Resolve on Their Own

Most people experience some degree of post-procedure discomfort regardless of which type of rhizotomy they undergo. For radiofrequency procedures targeting the spine, a burning or aching sensation at the treatment site is the most frequently reported short-term complaint. In one study of patients treated for chronic thoracic pain, about 18% developed transient burning pain or mild sensory loss, both of which resolved without intervention.¹ Localized swelling, mild bruising, and muscle soreness around the needle insertion site are also common in the first few days. These effects usually peak within 48 hours and taper off over one to two weeks.

A temporary flare in pain can catch people off guard. Before the treated nerve fully stops transmitting pain signals, the area around the lesion may feel more sensitive than it did before the procedure. This is not a sign that something has gone wrong. Applying ice and taking standard over-the-counter pain medication usually bridges the gap. For most spinal radiofrequency procedures, the short-term risk of serious complications like infection, hematoma, or nerve damage is low. One comparative study of sacroiliac joint rhizotomy found zero intraoperative or postoperative complications of this kind across all patients.²

Numbness and Altered Sensation

Sensory changes are the single most discussed side effect across nearly every form of rhizotomy. Because the entire point of the procedure is to disrupt a nerve’s ability to transmit signals, some degree of numbness in the treated area is essentially built into the process. In many spinal procedures, that numbness is limited to a small patch of skin overlying the targeted nerve and fades within weeks to months as surrounding nerves compensate.

Occasionally, the sensory changes go beyond simple numbness into territory that is harder to ignore. One case report described a woman who developed pain, numbness, and swelling in her buttock and thigh after radiofrequency ablation of lumbar medial branch nerves. She also experienced allodynia, a condition where normally painless touch becomes painful, over a broad area of her thigh. When the procedure was later performed on the opposite side, she developed similar numbness extending from her hip to her knee. In both cases the abnormal sensations eventually resolved, and imaging confirmed the needles had been placed correctly.³ Cases like this are unusual, but they illustrate that even with proper technique, nearby nerves can be affected.

Side Effects Specific to Trigeminal Rhizotomy

Rhizotomy for trigeminal neuralgia carries a different set of concerns because the trigeminal nerve controls sensation across the face and some of the muscles used for chewing. Facial numbness is by far the most common side effect. In a prospective study of patients who underwent radiofrequency rhizotomy for trigeminal neuralgia, about a third experienced facial numbness afterward.⁴ For many patients this is an acceptable trade-off for relief from severe facial pain, but it can affect everyday activities like eating, drinking, and applying makeup.

Chewing-muscle weakness is another concern. The same study found that about 14% of patients developed weakness in the masseter muscle, which is the primary muscle you use when biting down.⁴ In a larger series of patients with bilateral trigeminal neuralgia who underwent radiofrequency rhizotomy, masseter problems appeared in about 2% of procedures, while diminished corneal reflex occurred at a similar rate.⁵ A weakened corneal reflex is worth paying attention to because it means the eye on the affected side is less responsive to irritation, raising the risk of eye injury or infection. Keratitis, an inflammation of the cornea, appeared in about 1% of procedures in that series.⁵

Patients and clinicians also need to be aware of the rare possibility of facial asymmetry and meningitis, though these are considered extremely uncommon across all trigeminal procedures.⁶

Chemical Rhizotomy and How Its Side Effects Compare

Not all rhizotomies use heat. Some procedures inject chemicals like ethanol or glycerol directly onto the nerve to destroy it. The side-effect profiles of these chemical approaches overlap with radiofrequency methods but tend to skew toward more pronounced sensory loss. In a study comparing ethanol rhizotomy to radiofrequency rhizotomy for trigeminal neuralgia, about 30% of patients in the ethanol group developed complete numbness in the treated area, compared to none in the radiofrequency group. Loss of the corneal reflex was even more striking: nearly half of the ethanol patients lost some or all of it, while none in the radiofrequency group did. Masseter weakness, however, was nearly universal in both groups, affecting over 90% of patients regardless of technique.⁷

Phenol neurolysis, sometimes used for joint pain rather than facial pain, carries a similar pattern. In a comparison of phenol injections versus radiofrequency ablation for knee pain, the phenol group had significantly more post-treatment tingling and altered sensation. A small proportion of the phenol patients also experienced a paradoxical increase in pain afterward, while none of the radiofrequency patients did.⁸ The takeaway is that chemical methods, because they are harder to control precisely, tend to produce wider areas of nerve damage and correspondingly more sensory side effects.

Glycerol rhizotomy for trigeminal neuralgia occupies a middle ground. It generally causes some degree of facial numbness, and researchers have noted that the presence of numbness after the procedure actually predicts better pain relief. In a long-term study, patients who developed numbness after glycerol rhizotomy had significantly longer pain-free periods.⁹ That creates an uncomfortable trade-off: the side effect you would most like to avoid is the one most closely linked to treatment success.

Selective Dorsal Rhizotomy in Children with Cerebral Palsy

Selective dorsal rhizotomy, or SDR, is a fundamentally different procedure from the percutaneous methods described above. It is an open surgery, typically performed on children with cerebral palsy, in which specific sensory nerve rootlets in the lower spine are permanently cut to reduce muscle stiffness. Because of its surgical nature and the age of its patients, the side-effect profile is more complex.

A systematic review pooling data from over a thousand children found that the most common long-term complications were structural changes to the spine. About one in five children developed scoliosis, while roughly 18% developed increased lordosis (an exaggerated inward curve of the lower back). Spondylolysis, a stress fracture in a vertebra, appeared in close to 10%, and kyphosis in about 8%.¹⁰ These spinal changes can emerge months or years after the surgery, which means children who undergo SDR need long-term follow-up with spinal imaging.

The neurological side effects are different in character from those of percutaneous rhizotomy. Constipation affected about 14% of children, and urinary incontinence appeared in about 6%.¹⁰ A separate systematic review highlighted that bladder problems may affect a larger proportion of children, with one estimate putting permanent bladder dysfunction at close to 29%.¹¹ The discrepancy between those two estimates likely reflects differences in how bladder dysfunction was defined and measured across studies, but either way it is a real concern that families should discuss before proceeding.

One complication that is unique to SDR is the unmasking of weakness. Children with cerebral palsy often have spasticity that partially compensates for underlying muscle weakness. When that spasticity is reduced by the surgery, the weakness becomes apparent, and children may temporarily lose motor abilities they had before. Intensive physical therapy is considered essential after SDR to rebuild strength, and recovery timelines vary widely.¹¹

Anesthesia Dolorosa

The most feared complication of any rhizotomy involving sensory nerves is anesthesia dolorosa, a condition in which the area that has been made numb paradoxically becomes the source of severe, constant pain. The term literally means “painful numbness,” and it describes a form of nerve-injury pain that is extremely difficult to treat. In one retrospective analysis of patients who underwent spinal posterior rhizotomy for cancer pain, over half developed anesthesia dolorosa within about one to eight months of the procedure.¹² The authors concluded that the complication occurs more frequently than most textbooks acknowledge and recommended restricting posterior rhizotomy to patients with very limited life expectancy.

In trigeminal radiofrequency rhizotomy, the rate appears much lower. One large series put it at about 0.5% of procedures.⁵ The difference probably reflects the distinction between complete nerve root transection (cutting entirely through the nerve, which carries high risk) and the more targeted partial damage that radiofrequency methods produce. Still, even a small chance of anesthesia dolorosa weighs heavily in the decision-making process because the condition has no reliable cure.

Quality of Life After Rhizotomy

Side effects do not exist in a vacuum. What matters to most patients is how the procedure affects daily life over months and years. A study comparing partial sensory rhizotomy to microvascular decompression for trigeminal neuralgia found that five years after surgery, patients who had undergone the rhizotomy reported more complications that affected their quality of life. They were roughly three times more likely to experience anxiety, six times more likely to report persistent numbness, and about three times more likely to have ongoing burning sensations. The most dramatic difference was in difficulty eating, which was over 17 times more common in the rhizotomy group.¹³

Those numbers sound alarming, but context matters. Partial sensory rhizotomy for trigeminal neuralgia is generally offered to patients who are not good candidates for microvascular decompression, which is a more invasive open-skull surgery. Patients who undergo the rhizotomy tend to be older, sicker, or dealing with anatomical situations that make the alternative impractical. The comparison is useful not as a verdict against rhizotomy but as a reminder that the procedure trades one set of problems for another, and ongoing sensory side effects can ripple into psychological well-being.

For cervical procedures targeting occipital neuralgia, the picture is more encouraging. A series of patients who underwent partial posterior rhizotomy at the upper cervical levels found consistent long-term relief of severe occipital pain with minimal risk of vertigo, scalp numbness, or the kind of nerve-injury pain syndromes associated with more aggressive techniques.¹⁴ The procedure did not always address pain in the forehead or temple area, so the limitation was more about incomplete pain relief than about new problems.

Who Faces Higher Risk of Complications

Not everyone walks into a rhizotomy with the same likelihood of side effects. For selective dorsal rhizotomy in children, obesity is a strong predictor of surgical-site problems. Children with elevated body mass were over 24 times more likely to have prolonged wound healing and were significantly more likely to develop surgical site infections.¹⁵ Very young children (age five and under) were more prone to cerebrospinal fluid leaks, while children with more severe motor impairment required longer epidural pain management after the surgery.¹⁵

For radiofrequency procedures, the technical details of the lesion itself matter. Increasing the needle diameter, raising the temperature, or extending the treatment duration all produce larger areas of tissue damage. Moving from a smaller to a larger needle gauge can increase the lesion width by roughly 60%, and raising the temperature from moderate to high settings can more than double it.¹⁶ Larger lesions are more likely to catch nearby structures. At the same time, an older study of trigeminal rhizotomy found no clear relationship between the lesion temperature or duration and the likelihood of sensory changes, suggesting that individual anatomy and needle placement play a role that technical settings alone cannot predict.¹⁷

Does Rhizotomy Affect Spinal Stability

A natural worry for anyone undergoing lumbar rhizotomy is whether disrupting the nerves around the spine could destabilize it. The concern is not unfounded in theory: the medial branch nerves targeted by lumbar radiofrequency ablation also supply the small muscles that help stabilize the vertebrae. If those muscles weaken, might the vertebrae start to slip?

The available evidence is reassuring. An observational study of patients with existing degenerative spondylolisthesis (a condition where one vertebra has already begun sliding forward on the one below it) found that radiofrequency ablation did not accelerate the slippage. The rate of progression averaged about 1.3% per year, which matches the expected natural rate for that condition without any intervention.¹⁸ This is a single-center study, and it looked at patients who already had the condition, so the evidence is not definitive for all populations. But it suggests that the common lumbar radiofrequency procedure is not creating new structural problems.

The story is different for selective dorsal rhizotomy in children, where the surgical approach involves opening the spine and where spinal deformity is one of the most common long-term complications, as noted earlier. The structural risks of SDR are a product of both the surgery itself and the changes in muscle tone that follow, and they represent a genuinely different concern from the percutaneous procedures used for chronic pain in adults.

How Imaging Guidance Is Changing the Risk Profile

One reason side-effect rates vary so much across studies is that the technology used to guide the procedure has evolved. Older techniques relied on the practitioner’s feel and basic fluoroscopy. Newer approaches use neuronavigation, which gives a three-dimensional view of the anatomy in real time. A systematic review of neuronavigation-guided percutaneous trigeminal rhizotomies found that the technique appeared to improve pain-relief outcomes while lowering complication rates and reducing radiation exposure compared to conventional methods.¹⁹ Endoscopic guidance has also been adopted for sacroiliac joint procedures, with at least one comparative study reporting no complications in the navigation-assisted group.²

If you are considering a rhizotomy and want to minimize side-effect risk, asking your practitioner about the guidance method they use is a reasonable conversation to have. The technology does not eliminate complications, and the studies available are still relatively small. But the direction of the evidence favors more precise targeting, and the gap between older and newer methods may account for part of the wide range of complication rates reported in the literature.

1
Journal of Neurosurgery. The treatment of chronic thoracic segmental pain by radiofrequency percutaneous partial rhizotomy
2
PubMed Central. Navigation-Assisted Full-Endoscopic Radiofrequency Rhizotomy Versus Fluoroscopy-Guided Cooled Radiofrequency Ablation for Sacroiliac Joint Pain Treatment: Comparative Study
3
PubMed Central. Abnormal Paresthesias Associated With Radiofrequency Ablation of Lumbar Medial Branch Nerves: A Case Report
4
Frontiers in Pain Research. Patient satisfaction and pain relief following radiofrequency rhizotomy for trigeminal neuralgia: a prospective cohort study
5
PubMed. Management of bilateral trigeminal neuralgia with trigeminal radiofrequency rhizotomy: a treatment strategy for the life-long disease
6
IntechOpen. Interventional Treatment Options for Trigeminal Neuralgia
7
PubMed Central. A refined percutaneous rhizotomy with DSA-guided ethanol for the second-line treatment of trigeminal neuralgia
8
Korean Journal of Pain. Comparison of the efficacy of genicular nerve phenol neurolysis and radiofrequency ablation for pain management in patients with knee osteoarthritis
9
Journal of Neurosurgery. Percutaneous glycerol rhizotomy for trigeminal neuralgia in patients with multiple sclerosis: a long-term retrospective cohort study
10
PubMed. A systematic review of complications following selective dorsal rhizotomy in cerebral palsy
11
PubMed Central. Long‐term effects of selective dorsal rhizotomy in children with cerebral palsy: a systematic review
12
Pain. How frequent is anesthesia dolorosa following spinal posterior rhizotomy? A retrospective analysis of fifteen patients
13
PubMed Central. Impact of pain and postoperative complications on patient-reported outcome measures 5 years after microvascular decompression or partial sensory rhizotomy for trigeminal neuralgia
14
Journal of Neurosurgery. Treatment of occipital neuralgia by partial posterior rhizotomy at C1–3
15
PubMed. Predictors of postoperative complications after selective dorsal rhizotomy
16
Pain Medicine. Factors That Affect Radiofrequency Heat Lesion Size
17
PubMed. Quantitative analysis of lesion parameters in radiofrequency trigeminal rhizotomy
18
PubMed Central. Lumbar Spondylolisthesis Progression: What is the Effect of Lumbar Medial Branch Nerve Radiofrequency Ablation on Lumbar Spondylolisthesis Progression?
19
The Clinical Journal of Pain. Neuronavigation-guided Percutaneous Rhizotomies to Trigeminal Neuralgia: A Systematic Review