Definition

Central post-stroke pain (CPSP), formerly known as thalamic pain syndrome, is a chronic complex disabling pain syndrome characterized by pain and temperature sensation abnormalities after a cerebrovascular accident, infarct, or hemorrhage. It was first described, with pathophysiologic correlation to a lesion in the thalamus, in 1906 by Dejerine and Roussy as a “severe persistent, paroxysmal, often intolerant pain on the hemiplegic side, not yielding to analgesic treatment” [1]. There were previous descriptions of pain after a central lesion by Edinger [2] and others earlier in the 19th century.

The disease affects up to 8% of patients with stroke and, in one study, 9% of hemorrhagic stroke patients with thalamic lesions [3–5]. Pain onset in stroke patients occurs weeks to months after a cerebrovascular accident [5]. CPSP is considered a persistent central neuropathic pain that follows an ischemic or hemorrhagic stroke without a peripheral cause. Although the pathogenesis remains unclear, there appears to be involvement not only of the thalamus as initially studied by Dejerine but of the spinothalamic pathway because of the pain and temperature sensitivity [6,7]. Interestingly, not all patients with lesions along the spinothalamic pathway have CPSP [8,9]. Many CPSP patients have many lesions noted on magnetic resonance imaging that are unrelated to the pain [10].

Predictors as to those at risk are unclear, but in one study controls with thalamic stroke without thalamic pain had lesions mainly in the more anterolateral nuclei. Thalamic pain patients were noted to have lesions mainly in lateral and posterior thalamic nuclei on magnetic resonance imaging [11]. In one study at 16 months, patients with higher pain intensity were female [12].

Symptoms

CPSP is characterized by mild hemiplegia, hemihypoesthesia, hyperpathia with burning sensation, hemiataxia, astereognosis, dyskinesias (especially choreoathetosis), and positive or negative pain sensations that occur for hours to continuously in the entire half the body, arm, leg, foot, or hand [13,14]. Patients describe pain sensations as burning, cold, stabbing, sharp, aching, pricking, squeezing, shooting, tingling, or heavy when they are exposed to changes in temperature measured by a thermal probe, monofilament for tactile stimuli, and brushing with a stiff brush typically used for oil painting [15]. Particularly excruciating are the sensory abnormalities, especially the thermal sensations that can include burning, scalding, or burning and freezing in addition to other vague descriptions of positive and negative sensory abnormalities. Symptoms can be constant or intermittent, described as burning by some CPSP patients, and triggered by touching of an item, being touched, or changes in temperature [14]. Because of the variable onset and symptom constellation, patients are often misdiagnosed [16].

Physical Examination

It is important in considering the diagnosis of CPSP to perform a thorough musculoskeletal and neurologic physical examination to rule out other causes of pain. Physical findings in patients with CPSP may include mild or more severe hemiplegia, hyperesthesia, or hypoesthesia. Patients may have impaired pinprick, temperature, and touch sensation, whereas vibration and joint proprioception are less commonly affected [10].

In a prospective study of 207 stroke patients, 87 subjects (16 with CPSP and 71 with no pain) with abnormal sensation were observed. The CPSP group was noted to have more abnormal sensibility to cold and warm stimuli compared with nonpain subjects with abnormal sensation. The 16 CPSP patients had evoked dysesthesia or allodynia (sensation of pain by stimuli that are usually nonpainful) [5].

Functional Limitations

Strokes that cause CPSP are typically associated with only mild hemiplegia, though some patients can have moderate or severe hemiplegia and the functional limitations that accompany these. The pain of CPSP can often be a much more severe cause of functional limitation, at times to the point of being incapacitating.

Diagnostic Studies

Brain imaging of patients with CPSP will typically show a lesion in the spinothalamic pathway, but not all patients with such lesions will have CPSP [8,9].

Historically, CPSP has been resistant to both medical and surgical management. Despite the severe impact on quality of life for patients with CPSP, there is limited scientific evidence of its treatment [17].