Synonyms: hypophyseal canal, craniopharyngeal duct, transsphenoidal canal.
Prevalence: very rare.
Definition: Persistence of the craniopharyngeal canal is a rare basal skull congenital defect with a range from small canals (in 0.42% of the asymptomatic population  ) to large basal cephalocele with major craniofacial defects. Craniopharyngeal canal represents a remnant of the stem of Rathke’s pouch that goes through the sphenoidal synchondrosis between the presphenoid and postsphenoid by a vertical conduct in the basisphenoid, extending from the floor of the sella turcica to the undersurface of this bone and connecting the pituitary fossa with the nasopharynx cavity.
Etiology: unknown, some authors have reported maternal use of anticonvulsants  .
Embryology: The adenohypophyseal primordium is induced by the adjacent floor of the forebrain from which the neurohypophysis will develop. The primordium is situated immediately external to the oropharyngeal membrane and becomes a pocket, the adenohypophyseal pouch, at 24 days of gestation. The basement membrane of the pouch appears to be in contact with that of the diencephalon, but cells soon become visible between the two membranes and the pouch becomes discontinuous at its apex. Then over the apex, the floor of the forebrain form an evagination, the stem of the pouch becomes narrowed and loses its connection with the roof of the mouth during the sixth week of embryonic development. The craniopharyngeal canal is a channel formed during osteogenesis and which may persist as a passage through the sphenoid bone. It indicates approximately the course of the former stem of the adenohypophyseal pouch  .
This traditional explanation of the origin of adenohypophysis from ectoderm near the stomadeum has been challenged  . In birds, there is evidence to suggest that the cells that form Rathke´s pouch are of neuroectodermal origin, arising from the ventral neural ridge  ,  . Pearse et al advanced the view that this would link the adenohypophysis with other structures derived from the neural crest and make it an integral part of the amine-precursor-uptake-decarboxylation (APUD) system.
Associated anomalies: Arachnoid cyst, cystic pituitary adenoma, anencephaly, holoprosencephaly  , craniopharyngioma  , Rathke´s cleft cyst  , cephalocele  , meningohydroencephalocele  and other anomalies of the skull base.
Prenatal diagnosis: Non-reported before. <![endif]>
Prognosis: it depends on the size of the canal and the associated anomalies. It has been reported upper airways obstruction during infancy, cerebrospinal fluid rhinorrhea, meningitis, sinusitis, panhypopituitarism, accidental removing of the hypophysis mimicking a midline nasal polyp, neurological symptoms, hydrocephaly  .
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