What is Thalamic Pain Syndrome (Central Post-Stroke Pain)?
Thalamic pain syndrome is a painful condition that can happen after someone has a stroke. The pain is centered in one area, is nerve-related, and often changes with temperature. This could also lead them to feel pain more intensely than usual (hyperalgesia) or to feel pain from things that normally wouldn’t hurt at all (allodynia). Up to eight percent of stroke survivors might experience this kind of pain.
Unfortunately, recognizing this syndrome isn’t easy. It could take months or even years after a stroke before a person starts to feel this type of pain. This condition is also known as central post-stroke pain, or historically, it was called Dejerine–Roussy syndrome. While all thalamic pain syndromes will fit under the umbrella of “central post-stroke pains,” not all central post-stroke pains come from the thalamus. A more precise way to think of central post-stroke pain might be as pain that happens because of an injury to a part of the nervous system (the spinothalomic tract).
Thalamic pain syndrome, sometimes referred to as centralized neuropathic pain, is not yet well-studied. If a patient has a history of long-lasting, focused pain, and a history of stroke, doctors might suspect thalamic pain syndrome. Options for treatment are unfortunately limited and vary in their results. Some alternative approaches recommended for treatment might help alleviate the pain and improve quality of life. These could include medications for nerve pain, painkillers, or more invasive options like deep brain stimulation, surgery, or neuromodulation.
These treatments are complex, and often require a group of specialists, like a neurologist, a pain medicine specialist, or a neurosurgeon. As thalamic pain syndrome is quite persistent, doctors need to keep an eye out for this syndrome among stroke survivors who are complaining of nerve-related pain symptoms.
What Causes Thalamic Pain Syndrome (Central Post-Stroke Pain)?
Thalamic pain syndrome often occurs after a stroke. A specific type of stroke called a lacunar infarct results from damage to a small part of the brain called the thalamus. A larger-sized stroke might be labeled based on the main injured artery, such as the middle cerebral artery. Damage to the thalamus can also result from conditions like a lesion or an abscess, leading to problems with senses, similar to thalamic pain syndome.
Thalamic pain syndrome can occur after a stroke, regardless if the stroke was caused by a blockage (ischemic stroke) or bleeding (hemorrhagic stroke). The pain that comes after a stroke involving the thalamus is neuropathic, meaning it is related to nerve damage. Any harm done to the thalamus can lead to loss of senses on the opposite side of the body. When the route carrying signals from the spinal cord to the thalamus is damaged, it affects temperature regulation. Thalamic pain may happen immediately after a stroke, or it may occur months or even years later.
The thalamus serves like a switchboard in the brain – it receives all sensory information (except smell) and redirects it to the appropriate parts of the brain for processing. When our senses pick up information from our environment, these signals travel through our peripheral nervous system and arrive at the brain’s sensory processing center, the thalamus. From here, these signals are decoded and forwarded to the somatosensory cortex, the part of the brain that interprets the signals. But in thalamic pain syndrome, this system is damaged, which distorts or disrupts the interpretation of signals like touch, temperature, and pain.
In normal scenarios, touch should not cause pain unless it’s strong enough to damage tissues. However, when you have thalamic pain syndrome, your brain starts misinterpreting these ordinary sensory signals – regular touch may cause pain (allodynia), or potentially painful signals could be felt as more intense than they really are (hyperalgesia).
Thalamic pain syndrome falls under the category of centralized pain, meaning that the cause of the pain originates from the central nervous system. When the body’s pain-processing system stays unusually active, a state known as “wind-up” or “temporal summation”, it may cause an exaggeration of pain signals. People in this state often become hypersensitive to pain.
To diagnose thalamic pain syndrome, it’s essential to first rule out peripheral sources of pain. A stroke affecting certain areas of the brain, more specifically the ventral posterior nuclei of the thalamus, is commonly linked to centralized post-stroke pain. A fewer number of opiate receptors, which aid in managing pain, in the thalamus may enhance the perception of pain once it’s damaged. Chronic activation of microglial cells, the immune cells in the central nervous system, may be a cause of pain after a stroke.
It’s also observed that autonomic instability, a condition that affects the automatic functions of the body, may contribute to a lower skin temperature in the painful areas noted by patients with central post-stroke pain. Moreover, stress could worsen the pain.
Risk Factors and Frequency for Thalamic Pain Syndrome (Central Post-Stroke Pain)
Each year, there are 700,000 cases of cerebrovascular accidents (CVA), also known as strokes, in the United States. Among these strokes, around 56,000 cases result in a type of chronic pain called central post-stroke pain. This type of pain, which typically arises during the recovery phase after a stroke, can be linked to a subset of strokes called thalamic strokes, which account for 20% to 33% of cases. It exists in about 8% of all stroke patients and 11% of those over 80 years old. The pain may develop immediately or up to six years after the stroke, but usually begins within a month. Interestingly, not all people who have a stroke get this pain; it occurs in less than 40% of cases.
Both the most common type of stroke (ischemic, or caused by a clot) and thalamic pain syndromes share similar causes. Around 80% of cases for both result from ischemic strokes. A UK study in 2004 found that between 2000 and 6000 patients experienced post-stroke pain, with a rough estimate of 20,000 patients suffering overall.
Post-stroke pain can affect anyone—there are no significant differences between those with pain and those without when it comes to gender, previous stroke history, or demographics. But there may be a connection with age. Some studies show that patients who have post-stroke pain tend to be younger, by more than ten years, compared to those with only sensory deficits. However, not all studies agree on this point.
Chronic pain is a common aftermath of a stroke, with over 40% of patients meeting the diagnosis of central post-stroke pain four years after their stroke. However, only 7.3% of patients with chronic pain can link their pain to a stroke. Strokes affecting the right side of the brain are more likely to result in pain, as this hemisphere plays a crucial role in managing pain.
Signs and Symptoms of Thalamic Pain Syndrome (Central Post-Stroke Pain)
Thalamic pain syndrome, or central post-stroke pain, is a condition that is diagnosed based on a patient’s medical history and physical examination. This problem usually begins with numbness or tingling on the side opposite to where the stroke occurred. Over time, this sensation can turn into a burning feeling that affects half of the patient’s body. It’s important to note that the severity of the pain can vary throughout the day and can significantly affect a person’s life. Touching or applying pressure to the affected side of the body can make the pain worse.
Allodynia, characterized by a heightened pain response to mild pressure, is a common symptom of central post-stroke pain. Some patients might also feel more pain when exposed to cold, and around 40% of patients may experience hyperalgesia, which is an abnormal increase in pain sensation. Unexplained itching or a searing sensation might also occur after a stroke. These symptoms usually become more centralized or focused 12 weeks following the onset of symptoms. Cognitive disturbances, mood changes, sleep issues, and fatigue are associated with this condition as well.
A thorough neurological exam is a key part of assessing a patient after a stroke. Although general sensory examination findings may appear normal, patients with thalamic pain syndrome often have problems recognising differences in temperature. This dysfunction in the spinothalamic tract, the pathway that transmits pain and temperature sensations, is necessary for the development of central neuropathic pain. Thus, during an assessment, it’s important to examine muscle strength, balance, speech, and other potential effects of the stroke.
- Numbness or tingling on the opposite side of stroke
- Burning pain on the affected half of the body
- Pain severity can vary and worsen by touch or pressure
- Allodynia or pain from mild touch
- Abnormal pain response to cold
- Hyperalgesia or amplified pain sensations
- Unexplained itching or a searing sensation
During a physical examination, the area with reported pain may feel colder than unaffected areas. Patients may show impaired reactions to pinprick (sharp sensation) and temperature stimuli, while their sense of proprioception (body position) and vibration remains normal. If a patient retains their sense of pinprick and temperature, it’s less likely that the pain is due to central post-stroke pain. The exam may show that pain coordinates with areas of sensory loss. In cases of central post-stroke pain, temperature changes are more pathogenic (disease causing) than changes in pinprick sensation.
Testing for Thalamic Pain Syndrome (Central Post-Stroke Pain)
Central post-stroke pain is a condition that can occur after having a stroke, which is a serious medical event where blood flow to the brain gets interrupted or reduced. This pain typically affects the face and head and can present up to six months after either an ischemic or hemorrhagic stroke. Ischemic stroke happens when a blood clot blocks blood flow to the brain, and hemorrhagic stroke happens when a blood vessel in your brain leaks or bursts.
According to the International Classification of Headache Disorders 3rd edition, central post-stroke pain is diagnosed if you experience facial and head pain within six months following a stroke, and the pain cannot be explained by another source. For diagnosis, imaging tests such as magnetic resonance imaging (MRI) are required. This imaging test can show a vascular lesion at an appropriate site, which is an abnormality in your blood vessels where the stroke occurred. However, it’s possible for this pain to present later than six months after a stroke.
Imaging can help doctors confirm the history of a stroke and rule out other possible conditions that might be causing the pain. For example, an MRI can help in the understanding of a thalamic infarction, which is a term used to describe tissue death in the thalamus area of the brain due to limited blood flow after a stroke. The larger this infarction is, the greater the damage to the brain, and the worse the prognosis or outlook.
If your neurological symptoms are chronic (long-term), stable, and you have a confirmed history of a stroke that affected the thalamus, no additional evaluation may be necessary. However, if you have new neurological symptoms that suggest a stroke event, doctors may order an immediate CT scan of your head without contrast. This is a special type of X-ray that provides images of your brain.
If you’ve recently had a stroke, repeated CT or MRI tests might be necessary. These would help check for any changes to brain functions, signs of hemorrhagic conversion (where an ischemic stroke transforms into a hemorrhagic stroke), or worsening brain swelling. If seizures develop after the stroke, an electroencephalogram (EEG), which records electrical signals in your brain, may be necessary, along with consultation with a neurologist. If the patient doesn’t already have a known history of stroke and shows symptoms suggestive of thalamic pain syndrome, further evaluation for other conditions such as multiple sclerosis (MS) could be warranted. Diagnosis of MS would likely include an MRI of the brain and spinal cord with contrast.
Treatment Options for Thalamic Pain Syndrome (Central Post-Stroke Pain)
Chronic and centralized pain can be challenging to treat. Often, doctors will consider antidepressants, medications usually used for epilepsy (anticonvulsants), and painkillers (opioid analgesics). Some research suggests that a drug called amitriptyline, painkillers, and anticonvulsants, along with approaches such as transcranial magnetic stimulation (a procedure that uses magnetic fields to stimulate nerve cells in the brain) and acupuncture, can help in treating central post-stroke pain, which is pain that occurs after a stroke. However, these results are somewhat mixed.
Physical therapy is beneficial in recovery after a stroke. If pain continues to be a problem, other treatments such as deep brain stimulation (a procedure that sends electrical signals to the brain) or radiation therapy (use of high-energy radiation to relieve pain) can be considered. Cognitive-behavioral therapy, a type of talk therapy, can be helpful in preventing depression in stroke patients. Some cases have indicated that acupuncture can reduce post-stroke pain, and there have been promising results with a treatment known as cold water vestibular caloric stimulation that involves stimulating the inner ear with cold water.
Typically, the first step in managing central post-stroke pain is to reduce the pain linked with touch. Along with amitriptyline, other antidepressants such as trazodone and venlafaxine can be considered. Drugs like gabapentin, pregabalin, carbamazepine, phenytoin, and lamotrigine, usually used for epilepsy, can also be used. Other treatments, including painkillers, drugs lowering blood pressure (like clonidine or beta-blockers), and anesthetics (like lidocaine or propofol) have also been studied.
Research suggests that lamotrigine might be the most effective anticonvulsant for treating central post-stroke pain. Amitriptyline seems particularly effective in patients with spinal cord injury and depression. There’s mixed evidence about the efficiency of pregabalin and gabapentin. Although studies have not directly evaluated a drug called duloxetine for central post-stroke pain, it has shown promise for pain related to multiple sclerosis. Other treatments that showed similar results include cannabinoids and the addition of a heart medication called mexiletine to antidepressants.
Interestingly, intravenous infusion of lidocaine seems to provide pain relief up to 45 minutes in patients with central post-stroke pain. An aesthetic block, an injection that numbs a specific area, can also provide short-term relief. Furthermore, infusing ketamine, a medication primarily used for starting and maintaining anesthesia, can effectively reduce pain, and electrical stimulation of the Gasserian ganglion, a cluster of nerve cells responsible for feeling in the face, can provide relief in patients with facial pain after a stroke.
Transcranial magnetic stimulation, which uses magnetic fields to stimulate nerve cells, could also be a potential treatment. A study showed that it might offer modest improvement in pain at four weeks following the treatment. Deep brain stimulation and motor cortex stimulation, which involve sending signals to the brain via a device implanted in the body, might also help, though results vary between patients.
Spinal cord stimulators, devices that send electrical signals to the spine, can improve pain in about half of patients with central post-stroke pain. However, a procedure known as thalamotomy, which involves removing part of the brain to treat involuntary movements or pain, might be conducted to alleviate the source of pain. It should be noted that the effect of pain relief by spinal cord stimulation decreases over time and is therefore not a permanent solution.
What else can Thalamic Pain Syndrome (Central Post-Stroke Pain) be?
Thalamic pain syndrome can be mistaken for various other health conditions. In many cases, if a patient’s medical history and physical symptoms suggest central post-stroke pain, these other conditions become less likely. Physicians should consider the following conditions that have similar symptoms when diagnosing thalamic pain syndrome:
- Centralized pain syndrome
- Chronic pain syndrome
- Complex regional pain syndrome
- Idiopathic peripheral neuropathy (unexplained nerve disease)
- Lateral medullary infarction (a type of stroke)
- Multiple sclerosis (a neurological disease)
- Syringomyelia (a rare, fluid-filled cyst in the spinal cord)
- Brain mass
What to expect with Thalamic Pain Syndrome (Central Post-Stroke Pain)
The outlook is usually not favorable after a stroke. About 5% of stroke patients deal with medium to intense pain after experiencing a cerebral infarction, which is a type of stroke where blood flow in the brain is blocked. The pain can settle in and continue without much change in its nature or severity. Treatment options to manage this pain are limited, and their success can vary greatly. Sometimes, the pain might sadly remain persistent, despite the best efforts to control it.
Recognizing pain soon after a stroke along with starting treatment can improve chances of a better outcome. However, this does not necessarily guarantee the complete disappearance of pain. About half of the patients have stated to experience some relief in pain with medication.
In a study, a meaningful number of patients have shown significant or complete relief from stroke-related pain after starting antidepressant therapy. Yet, typically, most patients continue to experience some level of discomfort. Among patients who suffer sensory changes after a stroke, like changes in their sense of touch or feeling sensations, around 18% will experience pain particularly to cold and warm stimuli.
Following a cerebrovascular infarct (another term for stroke), patients who report having pain and sensory deficits (problems in sensing things) are much more prone to developing allodynia or dysesthesia, conditions where normal touch feels painful or sensations are distorted, respectively. Only a small percentage (3%) of stroke patients with only sensory deficits experienced allodynia, but for patients reporting post-stroke pain, a large majority (88%) had allodynia.
Possible Complications When Diagnosed with Thalamic Pain Syndrome (Central Post-Stroke Pain)
Persistent pain after surviving a stroke can lower a patient’s quality of life, often leading to higher rates of depression. This is not unique to patients suffering thalamic pain syndrome; it’s common across all stroke victims. In addition to pain and depression, stroke survivors often have to manage other medical complications. These can vary but frequently include frequent trips, urinary tract infections, and chest infections like pneumonia.
Other common issues after having a stroke include the development of pressure sores and a heightened risk of falling into depression. Studies reveal that around 29 percent of patients suffer from depression after a stroke. More alarmingly, the chances of major depression significantly rises within the first two years post-stroke.
Stroke survivors with depression often have worsened outcomes and higher mortality rates. On the other hand, managing and overcoming depression can lead to improved conditions post-stroke.
Further research has also shown that rates of suicide attempts and successes unfortunately tend to double following a stroke.
When caring for stroke patients, it’s crucial to understand their physical disability, any previous health conditions such as depression, any existing cognitive impairment, and their family and social support systems. Apart from these conditions, post-stroke fatigue is also a common complaint among patients and should be addressed. Its prevalence varies widely, with anywhere between 23 to 75 percent of stroke patients reporting feelings of severe tiredness.
Common Issues:
- Persistent pain
- Increased rates of depression
- Frequent falls
- Urinary Tract Infections
- Chest Infections
- Pressure Sores
- High risks of major depression within the first two years
- Raised rates of suicide attempts and successes
- Post-stroke fatigue
Preventing Thalamic Pain Syndrome (Central Post-Stroke Pain)
If you’ve had a stroke and are feeling pain afterwards, it’s important to see your regular doctor. This pain could be a sign of a condition known as thalamic pain syndrome or central post-stroke pain. This happens when a stroke disrupts certain brain pathways that are involved in feeling temperature, leading to symptoms like burning or tingling pain and a heightened sensitivity to changes in temperature.
Strokes can sometimes lead to long-term or chronic pain. This pain can cause difficulties sleeping, can lead to feelings of depression, and can reduce your independence. Another symptom of chronic pain after a stroke is allodynia, which is experiencing pain from things that normally wouldn’t cause pain, and hyperalgesia, which is heightened pain in response to painful stimuli.
It’s important to note that treating thalamic pain can be complex and may require a specialist’s help. There’s no one-size-fits-all solution when it comes to treating this kind of pain. The main goal of treatment should be to enhance your quality of life.
