After evaluating a patient today who presented to my clinic with CRPS in his foot, which was spreading to his contra-lateral foot, I went to the literature to assess why CRPS spreads.
After a quick search on Google Scholar, I was pleased to find an article published in the Journal of Neural Transmission (honestly the first time I ever heard of this journal) on the spreading on CRPS. In summary, this article has the following conclusions about the spontaneous spreading of CRPS which I found interesting…:
1. Out of 185 subjects studied over a 6 year period, 48% had multiple affected limbs. This is speculated to result out of adaptation of the CNS in an attempt to adapt to the altered condition by remodeling or neuronal plasticity.
2. The syndrome started in 1 limb in 88% of patients, 2 limbs in 11% of patients and 4 limbs in 1% patients.
3. CRPS spread in 78 patients. The severity of the CRPS did not vary greatly once spread.
4. Out of those who had spreading CRPS, 53% had spreading to the contra-lateral limbs and 32% in limbs. In 15% of cases, the spread was in a diagonal pattern (i.e. from L leg to R arm). So individuals with spontaneous spread to the contralateral limbs were 2.3x more likely for spread than ipsilateal and 25x more likely than diagonal spread.
5. The mechanism of ipsilateral spontanous spread is unclear.
6. Patients with multiple-CRPS, were significantly younger than those with single- CRPS. This may be due to genetic factors/predisposition for this syndrome.
7. Contralateral spreading of CRPS is thought to possibly arise via altered spinal processing of incoming sensory information in the spinal cord and brainstem. Spinal glial cells and pro-inflammatory cytokines may be important factors in this. Its spread probably involves different supraspinal mechanisms and noxious stimuli activate bilateral regions of the brain associated with descending pain pathways.
8. There is little data on ipsilateral spreading of symptoms but the authors speculate that glial mediated changes at one segement of the spinal cord reach other segments by axonal transport via descending or ascending fibre tracts.
van Rijn MA, Marinus J, Putter H, et al. Spreading of complex regional pain syndrome: not a random process. J Neural Transm 2011.