Sympathetic Nerve Blocks: How They Help With Complex Regional Pain Syndrome (CRPS)

Chronic nerve pain can be life-altering, especially when it stems from a condition as complex and misunderstood as Complex Regional Pain Syndrome (CRPS). Patients with CRPS often experience severe, persistent pain that is out of proportion to the original injury, along with changes to skin color, temperature, swelling, and mobility. For many, traditional pain medications and conservative therapies offer little relief.

One advanced treatment option that has helped many CRPS patients regain function and control over their pain is the sympathetic nerve block. This minimally invasive procedure targets the nervous system pathways involved in chronic pain, offering both diagnostic insight and meaningful nerve pain relief.

In this article, we’ll explain what CRPS is, how sympathetic nerve blocks work, and why they are a valuable option in modern CRPS treatment.

What Is Complex Regional Pain Syndrome (CRPS)?

CRPS is a chronic pain condition that usually develops after an injury, surgery, fracture, or even a minor trauma. While the original injury may heal, the pain persists and often worsens over time.

Key Features of CRPS

CRPS commonly affects an arm, hand, leg, or foot and may include:

• Severe burning or stabbing pain
• Sensitivity to touch or temperature
• Swelling and stiffness
• Skin color or temperature changes
• Excessive sweating in the affected area
• Muscle weakness or reduced range of motion

What makes CRPS particularly challenging is that the pain is often driven by abnormal nervous system activity rather than ongoing tissue damage.

The Role of the Sympathetic Nervous System in CRPS

To understand how sympathetic nerve blocks work, it helps to understand the sympathetic nervous system.

The sympathetic nervous system controls involuntary body functions such as:

• Blood vessel constriction
• Sweating
• Heart rate
• Stress responses

In CRPS, this system becomes overactive or dysregulated, sending abnormal pain signals to the affected limb. This process, called sympathetically maintained pain, can amplify pain intensity, disrupt circulation, and interfere with normal nerve function.

When the sympathetic nervous system is involved, standard pain treatments often fall short. This is where sympathetic nerve blocks come in.

What Is a Sympathetic Nerve Block?

A sympathetic nerve block is a targeted injection of local anesthetic, sometimes combined with steroids, near specific sympathetic nerve clusters. The goal is to temporarily interrupt abnormal pain signals and restore balance within the nervous system.

Depending on the location of CRPS, different nerve blocks may be used:

• Stellate ganglion block – for CRPS affecting the neck, arm, or hand
• Lumbar sympathetic block – for CRPS involving the leg or foot

These procedures are performed under imaging guidance to ensure precision and safety.

How Sympathetic Nerve Blocks Work: The Science Behind Pain Relief

Sympathetic nerve blocks work through several key mechanisms:

1. Interrupting Abnormal Pain Signaling

By anesthetizing the sympathetic nerves, the block disrupts pain signals traveling between the nervous system and the affected limb. This can significantly reduce pain intensity, sometimes immediately.

2. Improving Blood Flow

Overactive sympathetic nerves can cause blood vessels to constrict, leading to coldness, color changes, and poor circulation. Blocking these nerves allows blood vessels to dilate, improving oxygen delivery and tissue healing.

3. Resetting the Pain Pathway

In some patients, repeated nerve blocks help “reset” the nervous system, reducing hypersensitivity and breaking the cycle of chronic pain.

4. Reducing Central Sensitization

CRPS often involves central sensitization, where the brain becomes overly responsive to pain signals. Sympathetic nerve blocks may help calm this response when used early and appropriately.

Use Cases for Sympathetic Nerve Blocks in CRPS Treatment

Sympathetic nerve blocks are commonly used in CRPS for several important reasons:

Diagnostic Use

If a patient experiences significant pain relief after a block, it confirms that the sympathetic nervous system is contributing to their pain. This helps guide long-term treatment planning.

Therapeutic Pain Relief

For many patients, sympathetic nerve blocks provide meaningful nerve pain relief, allowing them to participate more effectively in physical therapy and daily activities.

Early Intervention

When used early in the course of CRPS, nerve blocks may prevent disease progression and reduce the risk of long-term disability.

Multimodal Treatment Plans

Sympathetic nerve blocks are often combined with:

• Physical therapy
• Occupational therapy
• Medications for nerve pain
• Behavioral and psychological support

This comprehensive approach addresses both the physical and neurological components of CRPS.

What to Expect During the Procedure

A sympathetic nerve block is typically performed in an outpatient setting and takes less than 30 minutes.

During the Procedure

• The patient lies comfortably on a procedure table
• Imaging guidance (fluoroscopy or ultrasound) is used
• The injection site is cleaned and numbed
• Medication is carefully injected near the targeted nerve cluster

Most patients experience minimal discomfort.

After the Procedure

• Temporary warmth or heaviness in the limb is common
• Pain relief may occur within minutes or hours
• Relief may last from days to weeks

A series of blocks may be recommended for optimal results.

Who Is a Good Candidate for Sympathetic Nerve Blocks?

Patients who may benefit include those who:

• Have a confirmed or suspected diagnosis of CRPS
• Experience burning, temperature-related, or color-changing pain
• Have pain that worsens with stress or emotional triggers
• Have not responded well to conservative treatments

A pain management specialist will determine candidacy through a comprehensive evaluation.

Why Early CRPS Treatment Matters

CRPS can progress if left untreated, leading to muscle wasting, joint stiffness, and long-term functional impairment. Early intervention, including sympathetic nerve blocks can:

• Reduce pain severity
• Improve mobility
• Prevent chronic disability
• Support faster recovery
• Improve overall quality of life

Prompt treatment is one of the most important predictors of success in CRPS management.

Sympathetic Nerve Blocks as Part of a Long-Term Strategy

While sympathetic nerve blocks are not a cure for CRPS, they are a powerful tool within a comprehensive pain management plan. For some patients, nerve blocks provide lasting relief; for others, they open the door to additional therapies that restore function and independence.

Pain management specialists tailor CRPS treatment to each individual, often combining interventional procedures with rehabilitative and supportive care to address both the symptoms and underlying nervous system dysfunction.

Final Thoughts

CRPS is a challenging condition, but advances in interventional pain management have expanded treatment options significantly. Sympathetic nerve blocks offer both diagnostic clarity and meaningful nerve pain relief, making them a cornerstone of modern CRPS treatment.

If you or a patient is struggling with chronic, unexplained limb pain following an injury or surgery, early evaluation by a pain management specialist may help prevent long-term complications and improve outcomes. At Greater Austin Pain Center, our experienced pain management team provides personalized, evidence-based treatments designed to help you move, work, and live more comfortably.

Schedule your consultation today at one of our convenient locations in Austin, Kyle, San Marcos, or Dripping Springs. Together, we can find safer, more effective solutions for lasting pain relief.