Dyssegmental dysplasia, Silverman-Handmaker type: A challenging antenatal diagnosis in a dizygotic twin pregnancy.

BACKGROUND: Dyssegmental dysplasia Silverman-Handmaker (DDSH; MIM 224410) type is an extremely rare skeletal dysplasia caused by functional null mutations in the perlecan gene. Less than forty cases are reported in the literature, of which only four were prenatally detected. METHODS: We report on a dizygotic twin pregnancy from consanguineous parents for which one of the twins presented prenatally with severe micromelia, limb bowing and scoliosis, and postnatally with clinical and radiological features compatible with a diagnosis of dyssegmental dysplasia. Molecular studies were undertaken to confirm the clinical diagnosis of DDSH. RESULTS: Molecular analysis results revealed a novel homozygous variant in the HSPG2 gene (MIM 142461), NM_005529.6(HSPG2):c.4029 + 1G>A, consistent with a diagnosis of DDSH. CONCLUSION: To the best of our knowledge, the current report is only the seventh molecularly confirmed case of DDSH.

Twin Reversed Arterial Perfusion Sequence (TRAPS): An Illustrative Series of 13 Cases.

Twin reversed-arterial-perfusion sequence (TRAPS) is a rare and severe complication of monochorionic twin pregnancies. It usually occurs in the setting of monochorionic placentation, when the heart of a normal appearing twin serves as the pump for one or more dysmorphic twins whose head, thoracic organs, and upper extremities do not fully develop or do not develop at all and thus lack cardiac activity. Anomalous vascular placental architecture causes a shift in arterial flow towards the acardiac twin(s). The exact physiopathologic mechanisms that lead to this devastating phenomenon are not well known. We reviewed the maternal history and the surgical pathology reports of the fetuses and placentas of 13 different cases of TRAPS that were collected in a 23-year study period at a single institution. Herein we summarize the characteristic findings and illustrate specific mechanical feto-placental circulation issues that appear to be instrumental in the development of TRAPS.

Are Fassier-Duval rods at risk of migration in patients undergoing spine magnetic resonance imaging?

BACKGROUND: The Fassier-Duval (FD) rod is a stainless-steel device widely used to correct bone deformities and reduce the risk of fractures in patients with osteogenesis imperfecta (OI). Since these are telescopic expandable rods, there has been a reluctance to perform magnetic resonance imaging (MRI) in patients with OI secondary to a theoretical risk of migration during the MRI scans. The primary aim of this study was to assess the risk of migration of FD rods in patients who underwent MRI of the spine. The secondary aims are to assess the heating effects and artifact of these implants. METHODS: We retrospectively reviewed our database for all patients with OI who had undergone FD rodding and subsequent MRI evaluation for craniofacial and spinal disorders. Ten patients were eligible to be included in the study. The MRI examination was performed in all patients using a1.5 T magnet. The radiographic images pre-MRI and post-MRI were evaluated and compared to assess whether or not migration of implants had occurred. Patients' charts and MRI logbooks were reviewed to assess the heating effects based on patient-reported events during or immediately after the MRI. In addition, the scans were reviewed to evaluate peri-implant soft tissues to assess for changes that might indicate such effect. Artifact was judged to be present if it interfered with the evaluation of any portion of spinal anatomy of clinical interest. RESULTS: Ten patients underwent 19 FD roddings. The indications for MRI in these patients were basilar invagination, basilar impression, platybasia, and complex scoliosis. None of the implants have shown any migration, heating effect, or artifact. CONCLUSIONS: FD rods are safe and pose no risk of migration, heating effects, or artifact when undergoing an MRI of the spine using a 1.5 T magnet. With the introduction of magnet strengths higher than 1.5 T, further testing should be performed. LEVEL OF EVIDENCE: Level IV.

Cranial base abnormalities in osteogenesis imperfecta: phenotypic and genotypic determinants.

Cranial base abnormalities are an important complication of osteogenesis imperfecta (OI), a hereditary bone fragility disorder that in most patients is caused by mutations affecting collagen type I. To elucidate which clinical characteristics are associated with the occurrence of cranial base abnormalities in OI, we compared cephalometric results of 187 OI patients (median age 12.0 years, range 3.4 to 47 years; 96 female) with those of 191 healthy subjects and related findings to clinical descriptors of the disease. Overall, 41 patients (22%) had at least one unambiguously abnormal skull base measure. Multivariate logistic regression analysis in patients with OI types I, III, and IV (n = 169) revealed that height Z-score [odds ratio (OR) = 0.53, 95% confidence interval (CI) 0.43-0.66, p < .001]--but not age, gender, scleral hue, lumbar spine areal bone mineral density, or a history of bisphosphonate treatment--was a significant independent determinant of skull base abnormalities. Among patients with a height Z-score below -3, 48% had a skull base abnormality regardless of whether they had received bisphosphonate treatment in the first year of life or not. Genotype-phenotype correlations were evaluated in patients with detectable mutations in COL1A1 or COL1A2, the genes coding for collagen type I (n = 140). Skull base abnormalities were present in 6% of patients with haploinsufficiency (frameshift or nonsense) mutations, in 43% of patients with helical glycine substitutions caused by COL1A1 mutations, in 32% of patients with helical glycine substitutions owing to COL1A2 mutations, and in 17% of patients with splice-site mutations affecting either COL1A1 or COL1A2. However, multivariate logistic regression analysis showed that height Z-score but not the type of collagen type I mutation was independently associated with the prevalence of skull base abnormalities. In conclusion, this study shows that clinical severity of OI, as expressed by the height Z-score, was the strongest predictor of skull base abnormalities. We did not find evidence for the hypothesis that bisphosphonate treatment protects against skull base abnormalities.

Ganglioneuromas of the sacrum-a report of two cases with radiologic-pathologic correlation.

Ganglioneuromas are rare, benign, well-differentiated, slow-growing tumors, composed of ganglion cells and Schwann cells. Ganglioneuromas are derived from the neural crest cells and can arise anywhere from the base of the skull to the pelvis. We present and discuss the clinicopathologic and radiographic features of two patients with ganglioneuroma arising from the sacrum, a rare anatomic location.