Traumatic Brain Injury
This article focuses on chronic pain following traumatic brain injury. See open access article by Irvine et al.
Global incidence of TBI is 106 per 100,000 people.
|Loss of consciousness||<30 min||30 min - 24 h||> 24 h|
|Amnesia||<24 h||1-7 d||>7 d|
|Glasgow Coma Score||13-15||9-12||1-9|
|Structural Imaging||Normal||Abnormal, transient changes||Abnormal, lasting changes|
Among 23 studies with 4200 patients, 51.5% had chronic pain, 57.8% of those had post-traumatic headache (some studies up to 81%). Headache at the time of injury was 71%, and by one year this had dropped to 41%. 12% had CRPS with severe TBI. Post-traumatic stress disorder can occur.
- Descending regulation of pain.
- Lower pressure pain thresholds, decreased conditioned pain modulation (similar to post-stroke, post-surgical, fibromyalgia), reduced firing LC, dysregulation PAG output.
- Treatment alpha-2 agonists, selective serotonin-NA reuptake inhibitors.
- Ascending pathways. STT (post thalamic stroke pain), demonstrated on diffusion tensor tractography.
- Treatment deep brain and motor cortex stimulation, or target posterior limb capsule.
- Dopamine & Substantia Nigra. Injury to substantia nigra and other dopaminergic centres.
- Treatment levodopa.
- Axonal damage.
All of these areas are potential mechanisms for persistent post-traumatic headache, not cervical pain.