76 Complex Regional Pain Syndrome

Case 76 Complex Regional Pain Syndrome

Christopher P. Kellner and Christopher J. Winfree

Clinical Presentation

A 47-year-old woman is walking from one commuter train car to the next, when the sliding door closes on her right arm and shoulder, trapping her for 3 to 4 minutes; during this time, she begins to experience stabbing pain throughout her right arm.
She extricates herself, and later that day is evaluated in the Emergency Room, where no discernible injuries or neurologic deficits are discovered.
Because her pain persists weeks after her injury, she undergoes magnetic resonance imaging of her cervical spine, which only shows some mild, nonspecific degenerative changes.
She was treated with nonsteroidal anti-inflammatory drugs and short-acting opiates, which offered partial relief of her pain.

Questions

Based on the available information, what is the differential diagnosis for this patient’s pain?
What studies do you order?

Her electro-diagnostic studies were normal. On repeat examination a few months after injury, the patient has developed right upper extremity swelling from the shoulder to the forearm, and the entire arm is painful to touch and also to either active or passive movement.
What is the most likely diagnosis at this point?
Describe the initial, noninvasive treatment of this condition.
Describe the invasive treatments of this condition, for use when conservative measures fail.

The patient undergoes a comprehensive, multidisciplinary approach to treat her condition. Although she is able to tolerate physical therapy, her arm still greatly bothers her; she still has swelling and stiffness in the arm, and she cannot work. She has tried several medication trials without sufficient pain relief, and several anesthetic blocks were unhelpful. A psychological evaluation was unrevealing.
You now wish to employ spinal cord stimulation (SCS). Where will you place the electrodes?
What are the potential complications of SCS?
What are the outcomes for spinal cord stimulation in patients with complex regional pain syndrome (CRPS)?

Answers

Based on the available information, what is the differential diagnosis for this patient’s pain?

Cervical radiculopathy
Brachial plexopathy
Peripheral nerve damage
CRPS

What studies do you order?

Electromyography with nerve conduction studies (EMG/NCS) may help distinguish a peripheral nerve injury, cervical radiculopathy, and neuralgic amyotrophy.
This test should be performed a minimum of 3-weeks postinjury to permit appropriate denervational changes, if any, to occur in the affected muscles.

What is the most likely diagnosis at this point?

CRPS is a neuropathic pain syndrome that requires

Persistent pain beyond that expected from an initial noxious stimulus

Pain that exceeds the confines of a single peripheral nerve or nerve root distribution

Swelling, temperature changes, abnormal coloration, or vasomotor dysfunction in the affected region

Absence of another condition that could reasonably explain the findings 1

CRPS type I has no evidence of nerve injury, whereas in CRPS type II there is evidence of nerve injury, typically upon EMG/NCS.

With negative EMG findings, this patient has CRPS type I.
Describe the initial, noninvasive treatments for this condition.
- Effective treatment of CRPS requires a multidisciplinary, pain management-oriented approach.2
- Aggressive physical therapy enables recovery of function in the affected extremity and prevents disuse changes from occurring.
- Analgesics, typically the anticonvulsants, antidepressants, and opioids, provide pain relief to permit physical therapy (which would otherwise be too painful without them) to be undertaken.
- Psychological evaluation, and ongoing support if needed, is performed to determine whether any psychological amplifiers of pain exist, such as stress, behavioral problems, depression, disordered coping mechanisms, etc., and treat them if necessary.
Describe the invasive treatments for this condition, for use when conservative measures fail.
- If several weeks of the noninvasive multidisciplinary approach are insufficiently helpful, then the patient may be a candidate for anesthetic blocks to provide temporary pain relief.³
- If a more aggressive approach is required, then the patient becomes a candidate for SCS.³
You now wish to employ SCS. Where will you place the electrodes?
- The spinal cord stimulator array, either a percutaneous or a laminectomy paddle lead, may be placed in the dorsal epidural space from C2–C5, just off midline and eccentric to the right. C-arm radiography is used to determine the exact location (Fig. 76.1).
- In this location, the stimulator will administer electricity to the dorsal columns associated with the right upper extremity. Thus, the patient should experience stimulation paresthesias in the right arm, overlapping with the painful area.
- Ideally, this is performed in the awake patient to confirm overlap and limit unwanted stimulation paresthesias to other parts of the body such as trunk and leg.
What are the potential complications of SCS?
- Displaced electrodes (21.5%)
- Fractured electrode (5.9%)
- Infection (3.4%)
- Hardware malfunction (4.9%)
- Subcutaneous hematoma (4.4%)
- Discomfort over pulse generator (1.2%)
- Cerebrospinal fluid leak (0.5%)^4,5
What are the outcomes for spinal cord stimulation in patients with CRPS?
- A meta-analysis of 25 case series with a median follow-up of 33 months found that 67% of CRPS patients achieved 50% or more pain relief.⁶
- SCS is an appropriate and effective therapeutic option for patients with chronic benign pain refractory to medication.