Cordotomy

Also known as: Open or closed cordotomy, unilateral or bilateral cordotomy

Definition: Cordotomy is a surgical procedure that disables selected sensory tracts contained within the spinal cord (interruption of the lateral spinothalamic tract). The procedure is commonly performed on patients experiencing severe pain as a result of cancer. Anterolateral cordotomy is effective in relieving unilateral, somatic pain while bilateral cordotomy may be required for visceral or bilateral limb pain. Cordotomy is usually done percutaneously (stereotactic technique) with fluoroscopic guidance while the patient is under local anesthesia. Open cordotomy is not recommended for patients with unstable medical conditions but may be required if percutaneous cordotomy is not feasible or a previous attempt has failed.

Cancers treated: This surgical technique addresses the management of cancer pain that does not respond to oral analgesics.

Why performed: Pain is experienced by up to 75 percent of patients with advanced cancer. Between 25 and 30 percent of these patients report the pain as severe or excruciating. In 2014 the journal Continuing Education in Anaesthesia, Critical Care & Pain researchers reported that up to 10 percent of adult cancer patients do not find adequate pain relief with optimized regimes of systemic analgesia. Intraspinal procedures are the last of a long treatment continuum that includes the following:

The extensive number of available drugs has resulted in adequate control of discomfort from most malignant cancers. For a small number of cancer patients, however, referral for anesthetic or neurosurgical procedures for pain management is still needed.

The optimal candidate for this operation should have unilateral, severe pain in the fifth cervical vertebra (C5) or lower dermatomes that is not treated adequately by less invasive methods. Cordotomy appears to be more effective in the treatment of intermittent shooting pains rather than distressing dysesthesias (burning, prickling pain, or aching). It is indicated for localized, not general, pain and is not usually indicated for pain in the upper torso because of the risk of respiratory complications.

Patient preparation: The procedure is usually done on an outpatient basis. Patients are instructed not to eat or drink anything for five hours prior to the procedure. In cases where open surgery is required, patients should not eat or drink for twenty-four hours prior to the surgery. In both cases, someone should drive the patient to and from the procedure and stay with the patient for at least eighteen to twenty-four hours afterward.

Steps of the procedure: The patient is placed in a supine position with the upper cervical spine in a horizontal position. The patient is given light intravenous sedation. Using local infiltration of anesthesia between the first and second cervical vertebrae, the physician introduces a cordotomy needle in the side of the neck on the side opposite that of the perceived pain. An image intensifier is used to define the point of the dural puncture. Once the needle has been introduced into the subarachnoid space of the spinal cord, a contrast medium is injected to visualize the surrounding anatomy. A special insulated electrode is inserted through the needle. With monitoring, the electrode is directed into the spinal cord.

An electrical cable line is attached to the electrode, and the tip is stimulated with an electrical current. During each stimulation, the patient is closely questioned about sensory changes and motor twitching. In this setting, portions of the spinothalamic tract are destroyed to result in a desired level of analgesia. Disturbances in temperature sensation are usually seen as a result of these cordotomy lesions.

The CT-guided cordotomy technique is similar to this traditional percutaneous method except that the cordotomy electrode needle is inserted with the patient in a computed tomography (CT) machine.

In selected cases, an open cordotomy is needed. The patient is completely anesthetized, placed in a prone position, and undergoes a traditional surgical exposure. A laminotomy is performed at the level of the first and second thoracic vertebrae (T1 and T2), and the spinal cord is directly visualized. Placement of the electrode is accomplished with C-arm fluoroscopy, and disruption of the spinothalamic tract is electrically monitored.

After the procedure: Postoperative care consists of observation for ipsilateral leg weakness, changes in bladder control, significantly lower medication requirements, and possible respiratory depression. Hospitalization is usually for one or two days.

Risks: The complication rate from unilateral cordotomy is low, with a mortality rate between 0.6 and 6.0 percent. Bowel incontinence and bladder dysfunction can be seen in 2 to 10 percent of patients. Although information relative to sexual function is difficult to obtain, reports of impotency are rare. Transient hypotension can occur in 2 to 8 percent of cases. Permanent muscle weakness with ataxia (difficulty in walking) can be a major concern in 1 to 6 percent of patients. Respiratory problems are mild and transient, but respiratory failure has been documented in 1 percent of patients. Postcordotomy dysesthetic syndromes (burning distress throughout the entire area that was made analgesic) can occur in 1 to 10 percent of patients. Their pathophysiologic mechanisms are unknown. Open surgical cordotomy seems to be less effective and certainly has a higher risk of complication than do percutaneous techniques.

Results: Cordotomies are performed to treat cancer pain, often from lung or gastrointestinal malignancies. The procedure has been rarely employed in the treatment of lumbar radiculopathy or peripheral neuropathy. The target sites are the lower body as opposed to the upper body in about two-thirds of patients. In the hands of experienced surgeons, the spinothalamic tract can be located in 95 percent of patients. Adequate levels of pain relief are found in as high as 95 percent of patients on discharge from the hospital. At last follow-up, the success rate drops to 84 percent. Review of the literature realistically suggests long-term success rates of 50 to 75 percent. Repeat cordotomies may be necessary in 10 percent of patients.

Bibliography

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Feizerfan, Alireza, and J. H. L. Antrobus. "Role of Percutaneous Cervical Cordotomy in Cancer Pain Management." Continuing Education in Anaesthesia, Critical Care & Pain 14.1 (2014): 23–26. Print.

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