Symptomatic large parietal foramina

Repair of Congenital Enlarged Parietal Foramina With Porous Polyethylene Implants

Enlarged biparietal foramina is an autosomal dominant disorder that is caused by a failure of completion of ossification within the parietal bones. Enlarged parietal foramina measuring more than a few millimeters are uncommon. Even though spontaneous regression has been described, closure is rarely complete, and depending on the size of the resulting defect, an unprotected brain is a concern. There are few reports on the surgical management of persistent enlarged biparietal foramina. This is the first report describing our experience with a custom porous polyethylene implant.

Foramina parietalia permagna: familial and radiological evaluation of two cases and review of literature

PURPOSE

Foramina parietalia permagna is a variable intramembranous ossification defect of the parietal bones. Foramina parietalia permagna have an autosomal dominant inheritance, and it is showed that mutations in chromosome 5 and 11 are causing this anomaly. Enlarged parietal foramina occurs extremely rare. They are usually asymptomatic, but occasional headache, vomiting, pain over unprotected cerebral cortex, and seizures may be experienced by the patients. In the literature, some associated congenital bony defects, soft tissue pathologies, underlying neuronal deficits, and vascular variations have been described.

METHODS

We report two cases of foramina parietal permagna with their pedigrees and genetic analysis.

RESULTS

In case 1, cytogenetic analysis revealed a mutation of the ALX4 gene and all of the members of the family diagnosed with FPP. MRI revealed inferior vermian cerebellar hypoplasia. Surgery was not considered. In case 2, cytogenetic analysis could not be obtained because of financial reasons. Cranial MRI revealed hypoplastic right transverse sinus and sigmoid sinus, with a persistent parafalcine sinus. Surgery was not considered.

CONCLUSION

Despite of its rarity, genetic background and some important associated anomalies make foramina parietalia permagna more than an uncommon insignificant genetic disorder.

Enlarged parietal foramina: a review of genetics, prognosis, radiology, and treatment

INTRODUCTION

Enlarged parietal foramina are variable ossification defects in the parietal bones that present as symmetric radiolucencies on skull radiographs. In contrast to the normal small parietal foramina, enlarged parietal foramina are a hereditary condition and genes associated with it have been identified.

METHODS

A literature review was performed to discuss the many known findings related to enlarged parietal foramina.

CONCLUSIONS

Even though they remain asymptomatic in the majority of cases, they may be associated with other pathologies and occasionally become symptomatic. This article provides a comprehensive review of the current knowledge of enlarged parietal foramina.

Acquired encephalocele attributable to tuberculous osteitis: case report

OBJECTIVE

There are many forms of calvarial tuberculosis. In this case report, extensive calvarial tuberculosis caused a large cranial defect and occlusion of the sigmoid sinus in a 10-year-old child. This resulted in a transient increase of the intracranial pressure and formation of an acquired encephalocele.

CLINICAL PRESENTATION

A 10-year-old boy presented with an acquired, infected encephalocele and features of tuberculous mastoiditis. Computed tomographic and magnetic resonance imaging scans demonstrated evidence of left occipital encephalocele with left mastoiditis, extradural granulations, bone destruction, and complete occlusion of the left sigmoid sinus.

INTERVENTION

The encephalocele was surgically excised and combined with left mastoidectomy. Although no mycobacterium had been demonstrated in the excised lesion, the presence of active tuberculous infection in the mastoid led to the conclusion that the bone destruction leading to encephalocele was secondary to the calvarial tuberculosis. The patient received antituberculous treatment with clinical improvement.

CONCLUSION

This is the first report of calvarial tuberculosis causing a cranial defect and venous sinus thrombosis and resulting in an acquired encephalocele. Surgical excision combined with medical treatment was curative.

A novel locus for parietal foramina maps to chromosome 4q21-q23

Parietal foramina [PFM], inherited usually in an autosomal dominant mode, is an extremely rare developmental defect characterized by a symmetrical, oval hole in the parietal bone. It can be present as either an isolated or a syndromic feature. PFM types 1 and 2 (PFM1 and PFM2) have been found to be caused by mutations in the MSX2 and ALX4 genes, located to chromosomes 5 and 11, respectively. After exclusion of both the above loci in a large Chinese pedigree with autosomal dominant PFM, a genome-wide search revealed a linkage of the PFM to markers at the 4q21-q23 region. The maximum LOD score from two-point linkage analysis is 3.87 for marker D4S2961. Analysis of co-segregated haplotype localized the region to a 20-cM interval that flanks D4S392 and D4S2945. Therefore, we concluded that the PFM in the family is a new PFM locus. Although three genes, BMPR1B, PP1 and IBSP, are located to 4q21-q25 and their functions are related to bone morphogenesis, no mutations were identified by sequencing analysis of their exons.

Surgical management of foramina parietalia permagna

Enlarged parietal foramina are rare congenital skull defects identified on physical examination and confirmed radiographically. They are round or oval defects situated on each parietal bone approximately 1 cm from the midline and 2 to 3 cm superior to the lambdoid suture. Although small parietal foramina are common variants in up to 60% to 70% of normal skulls, large parietal foramina ranging from 5 mm to multiple centimeters are less common, with a prevalence of 1:15,000 to 1:25,000. We present a case series of four patients with large persistent parietal foramina managed surgically for the correction of this deformity. Two infants were treated with autologous calvarial bone grafts, and two were treated with a mesh plating system and hydroxyapatite. No patient developed any perioperative complications. No perioperative or delayed infections occurred in our patient population. The mean postoperative follow-up was 36 months. One patient required a second procedure with methylmethacrylate because of late bone graft failure, whereas the others were successfully treated by the initial procedure. Foramina parietalia permagna, otherwise known as fenestrae parietals symmetricae, enlarged parietal foramina, giant parietal foramina, or Catlin marks, are a rare clinical entity. A spontaneous decrease in the size of these defects with growth of the infant has been reported, but this closure is usually incomplete. Surgical intervention of persistent large foramina protects the child against potential injury to the underlying brain. We advocate cranioplasty for active young children and those at risk for injury (i.e., seizure disorder) to decrease the risk for potential intracranial injury.

Functional haploinsufficiency of the human homeobox gene MSX2 causes defects in skull ossification

The genetic analysis of congenital skull malformations provides insight into normal mechanisms of calvarial osteogenesis. Enlarged parietal foramina (PFM) are oval defects of the parietal bones caused by deficient ossification around the parietal notch, which is normally obliterated during the fifth fetal month. PFM are usually asymptomatic, but may be associated with headache, scalp defects and structural or vascular malformations of the brain. Inheritance is frequently autosomal dominant, but no causative mutations have been identified in non-syndromic cases. We describe here heterozygous mutations of the homeobox gene MSX2 (located on 5q34-q35) in three unrelated families with PFM. One is a deletion of approximately 206 kb including the entire gene and the others are intragenic mutations of the DNA-binding homeodomain (RK159-160del and R172H) that predict disruption of critical intramolecular and DNA contacts. Mouse Msx2 protein with either of the homeodomain mutations exhibited more than 85% reduction in binding to an optimal Msx2 DNA-binding site. Our findings contrast with the only described MSX2 homeodomain mutation (P148H), associated with craniosynostosis, that binds with enhanced affinity to the same target. This demonstrates that MSX2 dosage is critical for human skull development and suggests that PFM and craniosynostosis result, respectively, from loss and gain of activity in an MSX2-mediated pathway of calvarial osteogenic differentiation.

The calvarium

The calvarium is a crucial structure that can manifest a great deal of pathology. The plain film remains the main imaging modality, although CT and MRI are becoming increasingly important. We discuss its anatomy, normal variants, congenital and developmental anomalies, hematologic disease, idiopathic disorders, neoplasms, metabolic disease, trauma, and the postoperative skull. Whenever possible, we emphasize CT and MRI.