Chordotomy is a pain surgery procedure used as ultima ratio (Latin : ultimus: “the last”; “the most distant”; “the utmost”; ratio: “reason”; “reasonable consideration”) in the treatment of refractory pain. The procedure is based on surgical transection of the pain pathway in the spinal cord, the so-called tractus spinothalamicus (anterior cord), and is thus one of the classic neuroablative procedures. Anterior cord transection is also known as anterolateral chordotomy. Early therapeutic success is very good and about 90% of patients experience improvement or resolution of their pain, but the number of pain-free patients drops to about 50-60% after one year. This effect is probably caused by the activation of other, alternative pain pathways.
Indications (areas of application)
- Malignant (malignant) tumor disease with severe tumor pain in trunk and extremities.
- Reduced life expectancy
Contraindications
Because the indications, due to the severity of the procedure and significant complications, are very narrow and a careful cost-benefit analysis is mandatory, the contraindications arise from the indications mentioned.
Before surgery
Before surgery, a detailed medical history must be taken and the patient must be informed about possible complications. Radiographic examination of the spine, in addition to thorough clinical inspection, ensures planning for surgery. Platelet aggregation inhibitors (prevent aggregation of blood platelets (thrombocytes); blood-thinning medications) should be discontinued approximately 5 days prior to surgery. This must be checked with the help of a blood test. To support wound healing, it is recommended that the patient stop nicotine consumption.
The procedure
Anterior cord transection is used to control pain on the contralateral (opposite) side of the body, as the pain pathways cross at segmental level to the opposite side (i.e., if the procedure is performed on the left side, painlessness is achieved on the right side of the body). In this regard, success is most successful with unilateral pain (pain on one side of the body). Most often, the surgery is performed on one side, but it can be performed on both sides. However, because the complication rate is very high with bilateral chordotomy, this procedure is rarely performed. Chordotomy is still performed either as an open surgery, or as a percutaneous puncture. Percutaneous puncture is performed on a supine patient. The surgical site is sterilely draped and the puncture site is initially anesthetized using local anesthesia. The choice of the puncture site depends on the pain symptoms. The painlessness achieved by chordotomy begins 3-5 spinal cord segments below the operated site. If pain in the legs, pelvis or abdomen is to be treated, the chordotomy is performed high thoracically in the area of segments Th2/ 3. For pain in the chest and arms, the chordotomy is placed in the cervical (neck) area C1/2. To locate the tractus spinothalamicus, two auxiliary techniques are available to the surgeon: First, fluoroscopy (“life” X-ray control) allows constant control of the position of the puncture probe; second, neurophysiological control by means of impedance measurements and stimulation of the nerve also allows precise localization of the target structure. Both procedures are obligatory when searching for the tractus spinothalamicus. A lumbar puncture needle is used, which is inserted into the spinal subarachnoid space from the lateral side. Impedance measurement can be used to distinguish tissues such as pia arachnoidea (spider skin), spinal cord tissue, or cerebrospinal fluid (CSF), as they all have different impedances. The pain pathway is transected by electrocoagulation or thermolesion at approximately 65-70 °C. High-frequency alternating current is used for a period of 20-30 seconds.
After surgery
After surgery, close monitoring of the patient is necessary. In addition to surgical follow-up, the focus immediately after surgery is on monitoring the patient’s cardiovascular system. Furthermore, the patient’s neurologic status must also be closely monitored to detect potential complications early.
Possible complications
- Respiratory disturbances (especially with bilateral surgery).
- Rectal disorders and micturition disorders (disorders of urination), also especially in bilateral surgery.
- Postchordotomy dysesthesia – sensory disturbances caused by the procedure.
- Injury to the pyramidal tract with weakness of the muscles (paralysis) on the side of the procedure (ipsilateral)