Stereotactic Thalamotomy for Facial and Cancer-Related Pain

Stereotactic thalamotomy is a lesioning procedure; meaning it creates a small, precisely placed, permanent change in brain tissue, rather than implanting a device, used for a small number of patients with severe, disabling pain that has not responded to other treatments. It works on a similar general principle to MR-guided focused ultrasound (MRgFUS), described on our Movement Disorders pages: a specific, deep target is identified using stereotactic planning, and a controlled lesion is created at that target, rather than an implanted electrode delivering ongoing, adjustable stimulation.

Thalamotomy for pain is a specialized and much less commonly used procedure than spinal cord stimulation, and it is not appropriate for most patients with chronic pain. It is reserved mainly for two specific situations: severe facial pain that has not responded to other treatments, and severe cancer-related (oncologic) pain, particularly when a device-based option is not suitable or practical.

The target for thalamotomy is a small region of the thalamus; a deep brain structure involved in relaying and processing pain signals on their way to conscious awareness. Using stereotactic imaging and planning, the surgical team identifies the target precisely, and a small, controlled lesion is created there. The aim is to reduce the perceived severity and distress of pain, particularly the diffuse, difficult-to-localize suffering that severe facial or cancer-related pain can cause, which does not always respond well to treatments aimed at a specific nerve or pain pathway.

The lesion described above is most often created using a stereotactic radiofrequency probe, which requires a small opening in the skull. In some centers, the same target can instead be treated using MR-guided focused ultrasound (MRgFUS); the incisionless technique described in detail on our Movement Disorders pages for tremor, focusing ultrasound energy through the intact skull to create the lesion without any incision. As with MRgFUS for tremor, this requires a skull density ratio, measured on a CT scan beforehand, high enough for ultrasound energy to pass through the skull effectively, and is not suitable for every patient for this reason. Whether radiofrequency or MRgFUS thalamotomy is used depends on the equipment available, the skull density measurement, and the specific target and clinical situation, and is discussed individually rather than one technique being presented as better than the other.

Thalamotomy for pain is considered only after standard treatments have been tried without adequate relief, and only for specific pain patterns:

• Severe facial pain: including trigeminal neuropathic pain, post-herpetic facial pain, or other facial pain conditions that have not responded to medication, nerve-targeted procedures, or other treatments generally tried first
• Severe cancer-related (oncologic) pain: pain caused by cancer or its treatment that has not been adequately controlled by medication, including opioids at doses the patient can tolerate, particularly where the pain is widespread, affects both sides of the body, or is not well suited to a device-based or nerve-specific option

For pain confined to one side of the body below the neck, particularly in the context of cancer, other procedures such as percutaneous cordotomy are also used in some centers and may be discussed as an alternative or additional option, depending on the individual case.

A surgical evaluation for thalamotomy is generally considered only after appropriate medication, nerve-targeted treatments and, where relevant, a trial of device-based options have been tried without adequate relief, and only following assessment by a multidisciplinary pain team that confirms the pain pattern is one this procedure is intended to address.

• Detailed pain history and neurological examination
• Review of all treatments already tried, including medication doses and any procedures attempted
• Brain MRI for surgical planning
• Multidisciplinary pain team assessment, including consideration of overall prognosis and goals of care, which is particularly relevant when pain is related to cancer
• Discussion of realistic goals, given that this is a permanent procedure

The realistic goal of thalamotomy is a meaningful reduction in the severity and distress of otherwise unmanageable pain, improving comfort and quality of life. It is not presented as eliminating all pain sensation, and individual results vary. For patients with a limited life expectancy due to cancer, the goal is typically comfort and quality of remaining time, discussed openly and individually with the patient and their family.

Because thalamotomy creates a permanent lesion, it cannot be adjusted or reversed in the way that spinal cord stimulation can. Risks include the general risks of a stereotactic brain procedure, and the possibility of side effects related to the specific location of the lesion, which are discussed individually based on the exact target used. Pain relief may lessen over time in some patients, and the procedure does not address the underlying cause of pain, such as the cancer itself, only the perceived severity of the pain it causes.

Most patients are observed in hospital for a short period after the procedure. Because no device is implanted, there is no ongoing hardware to manage or replace, though follow-up continues to monitor pain control and any side effects, alongside the patient’s ongoing pain management and, where relevant, oncology care.