After amputation, most amputees will feel abnormal sensations at the site of the missing limb. These sensations can either be non-painful or painful. Physicians will initially manage phantom limb pain with medications and other alternative but non-invasive treatments. However, once the patient has exhausted all options but the pain remains excruciating, surgical options, like thalamotomy, can be considered.
Different post-amputation sensations
It’s important to note that most amputees will experience various abnormal sensations at the site of the missing limb. These sensations can either be non-painful (phantom limb sensation) or painful (phantom limb pain).
The former is distinguished by the feeling that the missing limb is present, while the latter is characterized by pain at the location of the amputated limb. The severity of phantom limb pain ranges from mild to severe, and many amputees report it has significantly affected their quality of life.
Onset and causes of phantom limb pain
Phantom limb pain occurs within days or years from amputation, depending on the patient. Some patients report feeling pain a week after surgery, while about 50% say they felt pain within 24 hours.
However, phantom limb pain is different from residual pain or stump pain. This type of pain is felt in the remaining part of the limb, particularly in the scar area. But similar to phantom limb pain, stump pain can also persist for years.
The treatment for stump pain is generally straightforward, as the cause of the pain is localized to a particular area. Meanwhile, phantom limb pain’s precise pathophysiology is still unclear. But recent studies increasingly suggest that psychological factors and the central and peripheral nervous systems all contribute to the onset of phantom limb pain.
With the help of these findings and previous surgical studies, a group of researchers could pinpoint the area of the brain that can bring relief to patients. The study was published in the Neurology International journal in November 2021.
The researchers studied the case of a 42-year-old woman with a below-elbow amputation on the left arm. She underwent amputation surgery a year before the study began, and she developed intense pain and a burning sensation throughout her left limb. Her physicians prescribed her conventional and narcotic medication, with no improvement in the pain.
To understand the source of the pain better, the researchers placed a deep brain stimulator on the right side directed to the ventral posteromedial nucleus. After examining the scan results, the researchers offered a stereotactic (minimally invasive) centro-median right-sided thalamotomy, and the patient gave her consent.
A thalamotomy is a surgical procedure used to treat tremors, such as those associated with Parkinson’s disease. It involves making an opening to the thalamus—a small structure in the brain that relays sensory and motor signals—to improve the brain’s overall function.
This isn’t the first time thalamotomy was used to treat phantom limb pain. The procedure was studied in 1982, 2018, and 2021. In the 2021 study, the researchers examined medial thalamotomy instead of central-median thalamotomy. They also used stereotactic radiosurgery, a relatively safe and effective method.
After the procedure, the patient felt immediate pain relief that persisted after one year. The researchers noted that the patient experienced a phantom limb sensation on her left elbow and arm in the last part of the surgery. This sensation was believed to be caused by a circuit located in the centro-median nucleus, which has extensive connections with the cortex and the striatal systems.
This finding is expected to spur further clinical studies into the potential role this nucleus can play in various clinical scenarios, including psychiatric conditions, Parkinson’s disease, and, of course, pain.
The researchers also noted that the results support the theory that phantom limb pain is related to changes in the brain, which occur during amputation. They also found that the degree of reorganization in the brain post-amputation is strongly associated with the degree of phantom limb pain.
The bottom line
There is no one-size-fits-all approach to managing phantom limb pain because of individual variations. It typically requires a multidisciplinary approach and comprehensive evaluation by your health care team. Surgical options are only offered to patients after all other options have failed.