Abstract: Nociceptive stimuli to the orofacial region are typically
received by the peripheral terminal of trigeminal ganglion (TG) neurons,
and noxious orofacial information is subsequently conveyed to the trigeminal
spinal subnucleus caudalis and the upper cervical spinal cord (C1-C2).
This information is further transmitted to the cortical somatosensory
regions and limbic system via the thalamus, which then leads to the perception
of pain. It is a well-established fact that the presence of abnormal pain
in the orofacial region is etiologically associated with neuroplastic changes
that may occur at any point in the pain transmission pathway from the
peripheral to the central nervous system (CNS). Recently, several studies
have reported that functional plastic changes in a large number of cells,
including TG neurons, glial cells (satellite cells, microglia, and astrocytes),
and immune cells (macrophages and neutrophils), contribute to the sensitization
and disinhibition of neurons in the peripheral and CNS, which
results in orofacial pain hypersensitivity.
Keywords; orofacial pain, spinal trigeminal nucleus, trigeminal ganglion,
upper cervical spinal cord