Nasal dermal sinuses — New concepts and explanations

Abstract

Utilizing a series of 13 consecutive patients with nasal dermal sinus‐cyst (NDSC) as a basis for study, this area of embryopathology was reexamined in light of the known and also the speculative knowledge available. Four of these patients had NDSC that involved the intracranial cavity and these served as a basis for correlating preoperative radiologic findings with what was actually found at the time of surgery. In so doing, we have been able to show that the pathogenesis of these lesions is consistent and the predictability of their intracranial involvement is based on this consistency. The repeated penetration through the prenasal space and into the foramen cecum is accompanied by a characteristic deformity of the base of the skull that is entirely recognizable radiographically. A protocol of findings has been developed, therefore, that allows the surgeon to be forewarned regarding the depths to which NDSC extends, and as such to design the surgical procedure to fit the lesion. The more basic findings for this study relate to the demonstration in human embryos of an anatomic reason why intracranial dermal cysts grow in the manner in which they do, i.e., in the substance of the falx cerebri; and even more basically, with additional human embryo studies we have been able to demonstrate a neuroectodermal pathway through the prenasal space, thus definitively confirming previous speculated embryomorphologic information. By corroborating the placement of the dermal displacement in the prenasal space, we have speculated that the NDSC is often but one disorder in a spectrum of aberrations which involves not only dermal and neural displacement, but also cranial floor deformities.

Congenital Brain and Spinal Cord Malformations and Their Associated Cutaneous Markers

“…Like spinal DSTs, cranial DSTs can produce symptoms by (1) serving as a portal of entry for bacteria and producing meningitis, subdural empyema, or brain abscess; (2) causing aseptic meningitis through the desquamation of epithelial debris from the tract and/ or associated dermoid or epidermoid cysts; and (3) causing intracranial hypertension and/or focal brain compression through the progressive enlargement of an intracranial dermoid or epidermoid cyst. Cranial DSTs are recognized as midline pits or dimples located between the glabella and nasal tip 33 (Fig 12A) or in the parieto-occipital region (Fig 13A) but are not found between these areas. Although subcutaneous dermoid and epidermoid cysts may arise at the anterior fontanelle, they do not extend intracranially.…”

“…A subcutaneous tract extends to the skull base between the nasal bone and nasal cartilage. 33 An associated dermoid or epidermoid cyst or a small heterotopic mass of astrocytes and even neurons (called a nasal glioma) may be present within the tract. Although 70% to 90% of these tracts end extracranially, 10% to 30% extend to a variable extent intracranially through the skull base at the foramen cecum (Fig 12B).…”

“…Although 70% to 90% of these tracts end extracranially, 10% to 30% extend to a variable extent intracranially through the skull base at the foramen cecum (Fig 12B). 33,34 Computed tomography (CT) and MRI provide complementary information in the detection of frontonasal DSTs. CT may reveal bony defects within the foramen cecum or intracranial calcifications, whereas MRI may detect the soft tissue components of the tract and/or intracranial dermoid or epidermoid cysts.…”

The Presentation and Management of Nasal Dermoid

“…In 1893, Bland-Sutton presented the superficial sequestration theory. 1 During the fourth to sixth weeks of embryonic development, the medial nasal processes begin to fuse. According to this theory, epithelial entrapment during the fusion of medial nasal processes could lead to formation of a cyst or a sinus.…”

“…Unlike other craniofacial dermoids, the nasal lesions can present as a cyst, a sinus, or a fistula and may have an intracranial extension. 1 The incidence is estimated at 1:20 000 to 1:40 000 births. 2,3 Pathogenesis involves the incomplete obliteration of neuroectoderm in the developing frontonasal region.…”