Sternberg′s canal as a cause of encephalocele within the lateral recess of the sphenoid sinus: A report of two cases

Abstract

Background:Intrasphenoidal encephaloceles are extremely rare findings. Sternberg's canal is a lateral craniopharyngeal canal resulting from incomplete fusion of the greater wings of the sphenoid bone with the basisphenoid. It acts as a weak spot of the skull base, which may lead to develop a temporal lobe encephalocele protruding into the lateral recess of the sphenoid sinus (SS).Case Description:We present two cases of intrasphenoidal encephalocele due to persistence of the lateral craniopharyngeal canal. The first case presented with cerebrospinal fluid (CSF) rhinorrhea and the second one was referred to the neurosurgical department with CSF rhinorrhea and meningitis. Radiological investigations consisted of computed tomography (CT) scan, CT cisternography and magnetic resonance images in both cases. These imaging studies identified a herniated temporal lobe through a bony defect which communicates the middle cranial fossa with the lateral recess of the SS. Both patients underwent a transcranial repair of the encephalocele because of the previous failure of the endoscopic surgery. There was no complication related to the surgical procedure and no recurrence of CSF leakage occurred 2 and 3 years after surgery, respectively.Conclusion:Encephalocele within the lateral recess of the SS is a rare entity which must be suspected in patients who present with spontaneous CSF rhinorrhea. Congenital intrasphenoidal encephaloceles, which are located medial to the foramen rotundum, seem to be due to persistence of the Sternberg's canal. Transcranial approach is a good option when a transnasal approach had failed previously.

A modification of endoscopic endonasal approach for management of encephaloceles in sphenoid sinus lateral recess

“…The first center to ossify is between foramen rotundum (FR) and foramen oval (FO) at 9 weeks of intrauterine life [18,28]. Non-fusion due to defective ossification and synchondroses can lead to osteodural defects in skull base through several mechanisms [29][30][31][32][33][34][35][36][37].…”

Spontaneous Skull Base Meningoencephaloceles and Cerebrospinal Fluid Fistulas

“…In contrast, it has been postulated that impaired CSF absorption may act as the inciting event and cause an empty sella, compression of the pituitary gland, subtle endocrine dysfunction, and, therefore, obesity. Whether obesity is the result of a spontaneous CSF fistula or the primary cause remains controversial (5,11,13,16,19,20,23,30,31). However, an additional factor, such as an underlying anatomic abnormality of the arachnoid villi, must be present to account for the low incidence of spontaneous CSF fistulas among the general population (16,18,19,23).…”

“…The most plausible mechanism for the development of CSF fistulas in the lateral sphenoid recess is a combination of pneumatization of the lateral recess, a flattened skull base in the sphenoid sinus recess, and prominent arachnoid granulations. When an associated meningoencephalocele is present, herniations of the temporal lobe may be seen (5,8,16,17,21,22,24,25,30,38,40).…”

“…On the other hand, the lateral recess of the sphenoid sinus undergoes extensive lateral pneumatization lateral to the foramen rotundum and into the pterygoid process, the greater wing of the sphenoid bone, or both, a process that occurs in as many as 27% of all adults (Fig 6) (8,16,18,24,28,30,38,39). Although formation of a spontaneous CSF fistula in the lateral sphenoid recess has been postulated to result from a persistent lateral craniopharyngeal, or Sternberg, canal (a congenital defect that results from incomplete fusion of the basisphenoid with the greater sphenoid wing and is situated along the course of the internal carotid artery, medial to the superior orbital fissure and foramen rotundum), its location in anatomic studies is inconsistent ( Fig 3).…”

Abordaje endoscópico transpterigoideo y reparación de base de cráneo tras resección de meningoencefalocele esfenoidal. Nuestra experiencia

“…En el caso de una meningitis y en el del absceso cerebral, la vía endoscópica de abordaje fue transetmoidoesfenoidal 8 estando las lesiones situadas en el RLE. La persistencia de la fís-tula de líquido cefalorraquídeo fue descrita en 6 casos tratados por vías diferentes a la TP (3 transesfenoidales, 3 transetmoidoesfenoidales) 2,8,12,26 . Los 6 casos fueron reparados con resolución completa de la fístula (3 casos con obliteración del seno esfenoidal 2,26 y 3 con cirugía endoscópica de revisión 8,12 ).…”