Central pathways, especially primary sensorimotor areas, exhibits the potential to intensify and modulate the quality of cramping in phantom limb pain, as per the findings of a study and case report published in 'Experimental Brain Research'.

Phantom limb pain is a condition in a substantial number of amputees with varying characteristics of pain and restriction. A forearm amputee was reported with constant phantom pain in hand, in whom it regularly elicit the rare phenomenon of referred cramping phantom pain by touching the face. 

To clarify the underlying mechanisms, it followed the cramp during an axillary blockade of the brachial plexus. During the blockade, both phantom pain and the referred cramp were abolished, while a referred sensation of “being touched at the phantom” persisted. Furthermore, to identify the cortical substrate, elicited the cramp during functional magnetic imaging. Imaging revealed that referred cramping phantom limb pain was associated with brain activation of the hand representation in the primary sensorimotor cortex. 

The results and findings supported the hypothesis which formerly said that in this case, the cramping phantom limb pain, is associated with substantial brain activation in the hand area of the deafferented sensorimotor cortex. But, this alone is not adequate to elicit referred cramping phantom limb pain. The peripheral inputs, from the arm nerves affected by the amputation and from the skin in the face at which the involved cramp is evoked revealed that these may be the preconditions for referred cramping phantom limb pain to occur.