Central pain: an overview

Abstract

Central pain is a particular form of neuropathic pain. Due to lesions in the spinothalamocortical pathways, ectopic neuronal discharges can occur into different neurons of the spinal cord and brain. Functional MRI, and positron emission tomography might be able to visualize ongoing pain activity which is, sometimes the consequence of spinothalamocortical lesions. Sometimes the patient experiences a burning ice-like sensation. This is more frequent in spinal cord lesions than in brain injuries. Some adrenergic, gabergic neurotransmitters, glycine, prostanoids and glutamate may play a role in pain transmission. These transmitters can induce changes in the neuronal membrane potential. Consequently, amitriptyline as an adrenergic reuptake inhibitor and the sodium channel blockers are the drugs of first-choice. A test procedure with placebo, opioids, lignocaine, propofol and ketamine might give some insight into advanced drug treatment. If oral or transdermal drug delivery is not indicated or ineffective, the intrathecal administration route can be attempted with baclofen, clonidine, opioids and midazolam. Invasive electrostimulation is the last treatment option. Thalamic stimulation can be tried in spinal cord injuries, and sensory motor cortex stimulation is sometimes the last resort for brain lesions associated with pain.