Central Post-Stroke Pain

Central post-stroke pain is chronic neuropathic pain from a lesion of the central somatosensory tracts after stroke, with altered temperature and pain sensation in the affected area. It occurs in about 8% of stroke survivors (up to 35% after lateral medullary stroke), starting from days to months, sometimes years, after stroke. Lesions can be thalamic, brainstem or cortical.

Pathophysiology. Damage to the spinothalamic tract and thalamocortical network leads to disinhibition and hyperexcitability of central pain neurons.

Constant burning, aching, freezing, lancinating or squeezing pain in a body area corresponding to the lesion (half of the body or part of it), with allodynia (touch, cold), hyperalgesia, dysaesthesia, and sensory loss to temperature and pinprick. Pain is not due to spasticity or shoulder problems.

Clinical, based on pain in the territory of sensory loss after stroke, with imaging showing a lesion consistent with the territory. Quantitative sensory testing shows impaired temperature and pain thresholds. Exclude other causes of post-stroke pain: shoulder subluxation, spasticity, complex regional pain syndrome, headache, musculoskeletal pain and depression.

Differential diagnosis.

• Spasticity related pain, complex regional pain syndrome and hemiplegic shoulder pain.
• Peripheral neuropathy, radiculopathy and depression related pain.
• Recurrent stroke.

First line drugs.

• Amitriptyline 10 to 25 mg at night, increased gradually to 75 mg (caution in older adults and arrhythmia, and avoid early after stroke if cardiac risk).
• Lamotrigine 25 mg daily, increased slowly over 6 weeks to 200 to 400 mg daily (risk of rash).

Second line. Pregabalin 75 mg twice daily, increased to 300 mg twice daily, or gabapentin 300 mg daily, increased to 1800 to 2400 mg daily in divided doses (adjust to eGFR). Duloxetine 60 mg daily and carbamazepine 100 to 200 mg twice daily in selected cases.

Further options. Intravenous lidocaine 5 mg/kg over 30 to 60 minutes in specialist settings, topical agents, repetitive transcranial magnetic stimulation of the motor cortex, and motor cortex stimulation or deep brain stimulation in refractory cases. Opioids offer limited benefit.

Supportive. Treat depression and sleep disturbance, physiotherapy, cognitive behavioural therapy and patient education.

Monitoring. Pain scores, function, adverse effects and mood.

Referral and escalation. Refer to pain services, and neurology, for refractory pain.

Special groups. In older adults, start low and titrate slowly because of sedation and falls.