Summary:
Central post stroke pain is an often under-recognised and subsequently inadequately treated pain condution. Along with CRPS and spasticity/shoulder issues, its is one of the most common painful afflictions following a CVA.
ICD-11 diagnosis:
Chronic neuropathic pain of Chronic central post-stroke pain subtype
Epidemiology:
Up to 10% of ischaemic stroke patients experience some aspect of chronic PSP
Onset can occur 1-3 months after stroke - with majority having symptoms by six months
Definition:
Central post-stroke pain (CPSP) describes the symptom of pain arising after a stroke that is secondary to lesion within the central nervous system
In CPSP, the lesion involves some portion of the central pain pathways and the damage creates the sensation of pain with minimal or no stimulation of peripheral pain receptors
Patients commonly experience hyperaesthesia - which may be allodynic or hyperalgesic. Spontaneous pain may also be experienced.
CPSP still remains a diagnosis of exclusion
Anatomical pathology:
Lesions of the spinothalamic tract
Lesions of the thalamus
Lesions of the medullary tract (particularly with facial pain)
Primary lesions of the sensory cortex are rarely involved
Risk factors:
Depression, greater stroke severity, younger age, and smoking
Pathophysiology:
It is suspected that in most cases there is incomplete lesion, or partial repair of a lesion, leading to loss of inhibition with compensatory overactivation within the thalamus leading to spontaneous pain or allodynia
There is likely an endogenous opioid role also. It has been found that patients with CPSP have a deficit in opioid binding. It is unclear the full effects of this finding.
Treatment:
Summary -
1st - Pregabalin (most evidence - helps QOL more than pain score. Side effects ++)
2nd - Amitriptyline (but watch seizures)
3rd - Carbamazepine (watch aplastic anaemia/SJS)
Consider Duloxetine if mood concerns also.
Pregabalin - Most studied. Placebo controlled double blind study of 2019 patients did not significantly reduce mean pain score but improved sleep, anxiety and other QOL measures. HOWEVER 70% of patients experienced dizziness, somnolence, oedema or weight gain.
Gabapentin - Evidence is scarce
Carbamazepine - Second line - though risks of stevens-johnson syndrome and aplastic anaemia. Less efficacious compared to amitriptyline
Amitriptyline - Safe and effective up to a dose of 75 mg daily. Only a small study though and side effects ++. Can lower seizure threshold.
SSRI/SNRI - Only fluvoxamine has been studied that reduced pain if started within the first year, but not after that time. Other types have not been studied.
Methyprednisolone (acutely) - Has been shown to help and reduce pain scores when started within a day or so of pain onset.
Non-pharmacological therapies:
Deep brain stimulation - Has been helpful in other conditions. In a 2005 study with 45 patients 53% had permanent implantation and 58% of those achieved long term pain relief.
Repetitive transcranial magnetic stimulation - Appears to be more effective in patients with milder symptoms but small studies in Japan have shown some benefit.
References:
1. Treister, A. K., Hatch, M. N., Cramer, S. C., & Chang, E. Y. (2017). Demystifying poststroke pain: from etiology to treatment. PM&R, 9(1), 63-75.
2. Plecash, Chebini, A., Ip, A., Lai, J. J., Mattar, A. A., Randhawa, J., & Field, T. S. (2019). Updates in the Treatment of Post-Stroke Pain. Current Neurology and Neuroscience Reports, 19(11), 1–11. https://doi.org/10.1007/s11910-019-1003-2
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