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Complications of Percutaneous Cordotomy

Ibrahim Yegül MD

Ege University School of Medicine, Izmir, Turkey

Introduction

Cordotomy has been used for a long time for different types of pain. While being extremely effective in relieving pain due to peripheral somatic causes, it does not provide adequate relief in painful dysesthetic or deafferentation syndromes such as post-herpetic neuralgia, phantom limb pain or brachial plexus avulsion.

Percutaneous cordotomy is a procedure in which the spinal anterolateral ascending system for the transmission of nociception, known as the spinothalamic tract, is interrupted to relieve pain [1].

Anatomy

It is generally accepted that pain fibers coming from the lower body are located at the mediolateral aspect of the spinal cord while those coming from the upper body are located anteromedially [2] (Figure 58.1).

**Figure 58.1** Schematic representation of target (lateral spinothalamic tract) and its environs at the C1–C2 level. [2].

Indications

Cancer pain below the C4 dermatome level
Occasionally, bilateral cordotomies may be required and a contralateral procedure can be performed as a staged procedure no less than 1 week after the first [3].

Contraindications

Severe bleeding diathesis
Unstable cardiac function
Severe systemic infection
Midline pain (relative)
Severely reduced ventilator function (FEV1 < 12 ml kg^-1)
Inability of the patient to co-operate during the procedure
Patient who cannot stay in supine position for the required 30–40 minutes.

Technique

The patient is placed in the supine position on the CT table and the head is immobilized with a tape. It is important to place a small pillow under the patient’s neck for both the patient’s and interventionalist’s comfort (Figure 58.2).

**Figure 58.2** Use of a small “d” shaped pillow under the neck and head.

The entry point is prepped and draped in the usual sterile fashion. Care is taken not to cover the patient’s face (Figure 58.3).

**Figure 58.3** Local anesthetic infiltration needle is left inside and a lateral scout is taken to decide correct puncture point.

After infiltrating the skin between the first and the second cervical vertebrae, a 20G Crawford needle is introduced on the contralateral side to the pain under CT guidance. After the needle is advanced a few centimeters, a lateral scout view followed by axial images are obtained to check the depth and direction of the needle (Figure 58.4a–c). After confirming correct direction and depth, the needle is advanced. If the needle is directed too anteriorly, blood would be visualized in the needle as the anterior epidural region has rich vascularity. Also, it is not appropriate to direct the needle dorsally.

**Figure 58.4** The Crawford needle is at the C1–C2 interspace (a), lateral scout (b) and axial (c) images.

After the needle passes the dura, the flow of cerebrospinal fluid (CSF) is observed (Figure 58.5).

Ten milliliters of contrast medium, which consists of 7 ml iohexol (Omnipaque 350 mg/ml) and 3 ml normal saline, is injected into the subarachnoid space of the spinal canal to visualize the spinal cord (Figure 58.6a,b).

**Figure 58.6** Contrast agent is injecting with barbotage (a) and spinal cord became visualized (b).

Under CT guidance, the needle is positioned so that its tip is directed to the anterior portion of the spinal cord. An insulated electrode (Minta® Disposable RF Cordotomy Electrode, 2 mm active tip) is inserted through the needle to enter the spinal cord (Figure 58.7a–d). The electrode tip is stimulated with 2 Hz and 100 Hz current. The patients are questioned about sensory changes and observed for motor twitching during stimulation.

**Figure 58.7** Placing the electrode (a) and (b). The electrode is in the right target (c). The impedance reading (d).

When the patient feels the stimulation in the same location as their pain, the procedure to form the lesion can be started. A thermocouple monitored lesion is made using a temperature of 80° C, 10 seconds followed by 20 and 30 seconds (Figure 58.8).