Paragangliomas (PG) are rare tumors originating from neural crest cells, arising at various locations along the chain of the sympathetic nervous system as well as the branchiomeric
Horigome, "Developmental morphology of branchiomeric
nerves in a cat shark, Scyliorhinus torazame, with special reference to rhombomeres, cephalic mesoderm, and distribution patterns of cephalic crest cells," Zoological Science, vol.
A classification system for extra-adrenal pheochromocytoma proposed by Glenner and Grimley (10) in 1974 divided the tumors into four groups based on location: branchiomeric
, intravagal, aortico sympathetic, and visceroautonomic.
According to the WHO classification, they are tumors belonging to the group of parasympathetic (non-chromaffin) branchiomeric
paragangliomas, known as chemodectomas (1).
In vertebrates, the cranial nerves display a branchiomeric
pattern that depends in part on the segmental nature of the rhombencephalon and neural crest cells that derive from this region of the brain (Hunt et al., 1991), whereas spinal nerves are in general metamerically arranged with somites.
The embryological origin is also quite compared in this investigation line, because, muscles of a branchiomeric
origin, many times respond differently from the other striated muscles of a myotomic origin.
The phylogeny of the muscles of facial expression and the facial nerve is somewhat less easily understood than that of other muscles of branchiomeric
These segmentally and symmetrically distributed paraganglia may be classified according to their anatomic distribution as branchiomeric
, intravagal, aorticosympathetic, and visceral autonomic.
Paragangliomas are made up of cells that originate in the branchiomeric
paraganglionic system and that develop in close relationship to the laryngeal arteries.
With the exception of endodermal heterotopia of the atrioventricular node, primary cardiac tumors rarely cause sudden death. Among benign primary cardiac tumors, paraganglioma, a neuroendocrine neoplasm that arises from the extra-adrenal paraganglia of the autonomic nervous system, accounts for less than 1%.[2,3] The sites of origin in the heart parallel the anatomic distribution of visceral autonomic paraganglionic tissue, chiefly arising from the roof of the atria and atrial septum and from the branchiomeric
In those cases in which the latter method of stimulation was employed, the trigeminal nerves were bilaterally transected to reduce movement caused by volume conduction of electrical current from the stimulating electrode to the nuclei of the branchiomeric