Fronto-cerebellar fiber tractography in pediatric patients following posterior fossa tumor surgery

Objective

Fronto-cerebellar association fibers (FCF) are involved in neurocognitive regulatory circuitry. This may also be relevant for cerebellar mutism syndrome (CMS) as a complication following posterior fossa tumor removal in children. In the present study, we investigated FCF by diffusion tensor imaging in affected children and controls.

Methods

Diffusion-weighted MR imaging at 3 T (GE) allowed tractography of FCF using a fiber tracking algorithm software (Brainlab 2.6) in 29 patients after posterior fossa tumor removal and in 10 healthy peers. Fiber tract volumes were assessed and fiber signals were evaluated in a semiquantitative manner along the anatomical course.

Results

Volumes of FCF revealed significant diminished values in pediatric patients with symptoms of CMS (19.3?±?11.7 cm³) when compared with patients without symptoms of CMS (26.9?±?11.9 cm³) and with healthy peers (36.5?±?13.82 cm³). In medulloblastoma patients, the volume of FCF was also significantly reduced in patients with symptoms of CMS despite having the same antitumor therapy. In semiquantitative analysis of the fiber tract signals, differences were observed in the superior cerebellar peduncles and midline cerebellar structures in patients with symptoms of CMS.

Conclusion

Using DTI, which allows the visualization of fronto-cerebellar fiber tracts, lower FCF tract volumes and diminished fiber signal intensities at the level of the superior cerebellar peduncles and in midline cerebellar structures were identified in patients with postoperative symptoms of CMS. Our study refers to the role of a neural circuitry between frontal lobes and the cerebellum being involved in neurocognitive impairment after posterior fossa tumor treatment in children.     

The growth of the foramen magnum in Crouzon syndrome

Background

Though the craniovertebral junction is often abnormal in children with Crouzon’s syndrome, no study had measured accurately the size of their foramen magnum (FM).

Patients and methods

We compared the FM size (area, diameters) on computed tomography examination in 21 children with a genetically confirmed Crouzon’s syndrome prior to any surgery and in 23 control children without craniofacial abnormalities. We extrapolated the growth pattern in both groups.

Results

We found a statistically significant smaller FM area (p?=?0.0228), FM sagittal diameter (p?=?0.0287), and FM sagittal posterior diameter (p?=?0.0023) in children with Crouzon’s syndrome. No differences were detected with regard to the transversal diameter. Hydrocephalus in children with Crouzon’s syndrome was associated with a small FM area (p?=?0.05), small sagittal diameter (p?=?0.023), small sagittal posterior diameter (p?=?0.0173), and reduced transversal diameter (p?=?0.03985). No association of the aforementioned findings was found with the position of the cerebellar tonsils or the lambdoid suture functional state (open or fused). Comparable results were observed among the two genetic forms (exon 8 or 10 mutations). Concerning the growth pattern, a first phase of rapid increase and a second phase of slow increase could be recognized in all the measurements in both populations, though with some significant differences.

Discussion and conclusions

The growth of FM follows a biphasic pattern in both Crouzon’s and control children. The sagittal diameter and the global size of the FM are mostly affected in children with Crouzon’s syndrome. The small FM, especially its posterior part, is likely to play a key role in the physiopathology of hydrocephalus.     

A systematic review of the results of surgery and radiotherapy on tumor control for pediatric craniopharyngioma

Objective

Craniopharyngiomas are rare tumors with bimodal incidence in the pediatric and adult age groups. Treatment strategies range from aggressive resection to planned limited resection combined with adjuvant therapies. Currently there is no consensus for standard of care for pediatric craniopharyngioma.

Materials and methods

We performed a systematic review of the published literature on pediatric craniopharyngioma. Patients were grouped based on extent of resection into gross total resection (GTR), subtotal resection (STR), and biopsy procedures. These groups were compared with respect to tumor control. Chi square was used to compare rates of recurrence. Kaplan–Meier was used to generate progression-free survival (PFS) estimates. Cox proportional hazard modeling was used to evaluate risk of progression. Each extent of resection group was also subdivided based on adjuvant therapy and compared.

Results

A total of 109 studies described extent of resection resulting in a cohort of 531 patients. Recurrence data were available for 377 patients. There was no difference in 1- or 5-year PFS between the groups who underwent GTR and STR combined with radiation (XRT; log-rank; p?=?0.76; 1-year PFS 89 vs 84 %; 5-year PFS 77 vs 73 %, respectively). One-year PFS was 84 % for STR+XRT compared to 76 % for STR alone while 5-year PFS was 73 % for STR+XRT compared to 43 % for STR alone (log-rank; p?=?0.003).

Conclusion

Although there are limitations of a systematic review of retrospective data, our results suggest that STR+XRT of pediatric craniopharyngioma is associated with similar rates of tumor control as GTR.     

Symptomatic Cerebral Vasospasm Following Resection of a Medulloblastoma in a Child

Background

Vasospasm may occur following intracranial tumor resection but is uncommon following resection of tumors in the posterior fossa.

Methods

Case report.

Results

Here, we report an unusual pediatric case of symptomatic cerebral vasospasm following resection of a posterior fossa medulloblastoma in a 10-year-old child. CT angiogram and serial Transcranial Doppler (TCD) studies confirmed the presence of vasospasm and response to hemodynamic augmentation therapy, resulting in favorable outcome.

Conclusion

This case illustrates an unusual complication of posterior fossa tumor resection, and the potential utility of TCD studies in the detection and management of vasospasm in pediatric neurocritical care.     

Prognosis of pediatric high-grade gliomas with temozolomide treatment: a retrospective, multicenter study

Purpose

We analyzed the usefulness of initial or recurrent treatment of temozolomide (TMZ) in pediatric high-grade gliomas (HGGs).

Methods

Between 2002 and 2010, we performed surgery on 35 patients with 17 glioblastomas, 14 anaplastic astrocytomas, 3 anaplastic oligodendrogliomas, and 1 anaplastic oligoastrocytoma. The male-to-female ratio was 21:14, and the median age was 13?years (range, 3–18?years). The mean follow-up period was 15.9 (±1.8) months. As the TMZ treatment, 22 patients received the initial treatment and 13 patients at recurrence. We analyzed the prognostic significance of TMZ treatment, tumor location, extent of removal, pathology, and recurrence pattern.

Results

The median progression-free survival (PFS) and overall survival (OS) were 9.7 (±1.4) and 17.8 (±2.5) months, respectively. Based on univariate analysis, the median PFS was 9.9 (±1.6) months in the tumors located in the cerebral hemisphere and 5.6 (±1.3) months in the diencephalon (p?=?0.03). Median PFS was 12.5 (±1.7) months in the initial treatment and 6.8 (±0.8) months in the recurrent treatment (p?=?0.03). The median OS was 14.9 (±2.3) months in glioblastomas and 24.4 (±4.1) months in tumors with an anaplastic pathology (p?=?0.01). The median OS was 12.1 (±3.7) months in patients with cerebrospinal fluid (CSF) dissemination and 18.2 (±2.9) months in patients without CSF dissemination (p?=?0.02). Grades 3 and 4 treatment-related toxicity occurred in 7.7–9?% of the patients.

Conclusions

Initial or recurrent TMZ treatment in pediatric HGGs was safe and tolerable. Initial treatment showed improved PFS compared to recurrent treatment, and both showed similar OS.     

Syringobulbia associated with posterior fossa meningioma: a review of the literature

Purpose

Syringomyelia can be defined as a degenerative, progressive and chronic spinal cord disease. Its association with tumors of the posterior cranial fossa (PCF) is a rare condition.

Methods

The authors report a rare case of syringobulbia consequent to a meningioma originating from PCF in a 17-year-old female, discussing the pathogenetic mechanism of development and the resolution of the syrinx cavity after surgical procedure.

Results

The postoperative period was uneventful without complications. At 6-month follow-up, MRI revealed complete tumor removal with resolution of the syrinx cavity.

Conclusions

In cases of syringomyelia and tonsillar herniation associated with PCF meningioma, the tumor resection allows to eliminate the mass effect and increases the size of the posterior fossa with the progressive ascent of the cerebellar tonsils and the consequent reduction of their downward movement with systolic pulsation. The re-establishment of a normal anatomical condition led to the gradual disappearance of syrinx and hydrocephalus.     

Does optic nerve sheath diameter on MRI decrease with clinically improved pediatric hydrocephalus?

Introduction

Serial change in ventricular size is recognized as an imperfect indicator of ongoing hydrocephalus in children. Potentially, other radiographic features may be useful in determining the success of hydrocephalus interventions. In this study, optic nerve sheath diameter (ONSD), optic nerve tortuosity, and optic disk bulging were assessed as indicators of hydrocephalus control in children who underwent endoscopic third ventriculostomy (ETV) or posterior fossa tumor resection.

Methods

Sixteen children underwent ETV or tumor resection for treatment of hydrocephalus. T2-weighted axial magnetic resonance images of the orbit were obtained, and the ONSD was measured posterior to the optic globe, pre- and post-intervention. Evidence of optic disk bulging and optic nerve tortuosity was also assessed. Ventricular size was estimated using the frontal and occipital horn ratio (FOR).

Results

There was a significant reduction in the ONSD post-ETV (n?=?9) and after tumor resection (n?=?7). Average preoperative ONSD was 6.21 versus 5.71 mm postoperatively (p?=?0.0017).There was also an 88 % (p?=?0.011) and 60 % (p?=?0.23) reduction in optic disk bulging and tortuosity, respectively. The FOR normalized in the tumor resection group but not the ETV group. After intervention, all patients showed improvement in signs and symptoms of hydrocephalus.

Conclusion

In our study population, ONSD decreased in response to measures to reduce hydrocephalus. Optic disk bulging also appears to resolve. Serial reduction in ONSD, and optic disk bulging may be indicators of improved hydrocephalus following pediatric neurosurgical interventions.     

External drainage with an Ommaya reservoir for perioperative hydrocephalus in children with posterior fossa tumors

Purpose

This study aims to evaluate an external drainage using an Ommaya reservoir for relieving perioperative hydrocephalus and reducing postoperative complications in children with posterior fossa tumors.

Methods

We retrospectively analyzed the data from 48 children with posterior fossa tumors who underwent tumor resection between May 2006 and June 2012. An Ommaya reservoir was placed in the right lateral ventricle forehead for continuous perioperative drainage of cerebrospinal fluid (CSF).

Results

Tumors were successfully removed from all patients. Intracranial infection occurred in nine patients and was controlled by antibiotic treatment. Preoperative obstruction and obstructive hydrocephalus were relieved, and the need for a shunt or endoscopic third ventriculostomy was avoided. One patient who underwent a second surgical procedure had intracranial infection, hydrocephalus, and occipital pseudomeningocele. After continuous drainage and anti-infective treatment, hydrocephalus and intracranial infection were effectively controlled.

Conclusions

Using an Ommaya reservoir for perioperative external ventricular CSF drainage enabled tumors to be wholly and safely removed. Restoring CSF circulation provided an effective means of controlling and preventing hydrocephalus secondary to posterior fossa tumors in children.     

Differential vulnerability of white matter structures to experimental infantile hydrocephalus detected by diffusion tensor imaging

Purpose

The differential vulnerability of white matter (WM) to acute and chronic infantile hydrocephalus and the related effects of early and late reservoir treatment are unknown, but diffusion tensor imaging (DTI) could provide this information. Thus, we characterized WM integrity using DTI in a clinically relevant model.

Methods

Obstructive hydrocephalus was induced in 2-week-old felines by intracisternal kaolin injection. Ventricular reservoirs were placed 1 (early) or 2 (late) weeks post-kaolin and tapped frequently based solely on neurological deficit. Hydrocephalic and age-matched control animals were sacrificed 12 weeks postreservoir. WM integrity was evaluated in the optic system, corpus callosum, and internal capsule prereservoir and every 3 weeks using DTI. Analyses were grouped as acute (<6 weeks) or chronic (≥6 weeks).

Results

In the corpus callosum during acute stages, fractional anisotropy (FA) decreased significantly with early and late reservoir placement (p?=?0.0008 and 0.0008, respectively), and diffusivity increased significantly in early (axial, radial, and mean diffusivity, p?=?0.0026, 0.0012, and 0.0002, respectively) and late (radial and mean diffusivity, p?=?0.01 and 0.0038, respectively) groups. Chronically, the corpus callosum was thinned and not detectable by DTI. FA was significantly lower in the optic chiasm and tracts (p?=?0.0496 and 0.0052, respectively) with late but not early reservoir placement. In the internal capsule, FA in both reservoir groups increased significantly with age (p?Conclusions All hydrocephalic animals treated with intermittent ventricular reservoir tapping demonstrated progressive ventriculomegaly. Both reservoir groups demonstrated WM integrity loss, with the CC the most vulnerable and the optic system the most resilient.     

Results of posterior cranial vault remodeling for plagiocephaly and brachycephaly by the meander technique

Objective

Several techniques to remodel the posterior calvarium in order to increase intracranial volume (ICV) and to improve cosmetic appearance are reported. This study presents the results of meander technique in patients with brachycephaly and posterior plagiocephaly.

Methods

During December 2011 and July 2013, a total of 12 children (median age: 15 months) underwent posterior cranial vault remodeling by the meander technique (brachycephaly, n?=?6; posterior plagiocephaly, n?=?6). The available pre- and postoperative MRIs were assessed with regard to ICV, cranial index (CI) and asymmetry index (AI) as well as the position of the cerebellar tonsils.

Results

No intra- or postoperative complications were observed. Blood transfusions were necessary in nine of 12 patients. A significant increase of the ICV from 1,178.4?±?134.5 to 1,293.0?±?137.5 cm³ (p?p?p?p?p?p?Conclusion The presented surgical technique is considered to be safe. The technique is capable to significantly increase ICV and improve cosmetic appearance of the remodeled calvarium. Further evidence that posterior cranial vault remodeling influences the position of the cerebellar tonsils is added by the results of the study.     

Brain volume and shape in infants with deformational plagiocephaly

Purpose

Infants with deformational plagiocephaly (DP) have been shown to exhibit developmental delays relative to unaffected infants. Although the mechanisms accounting for these delays are unknown, one hypothesis focuses on underlying differences in brain development. In this study, we used MRI to examine brain volume and shape in infants with and without DP.

Methods

Participants included 20 infants with DP (mean age?=?7.9?months, SD?=?1.2; n?=?12 male) and 21 controls (mean age?=?7.9?months, SD?=?1.3; n?=?11 male). Measures included volumes of the total brain and cerebellum; midsagittal areas of the corpus callosum and cerebellar vermis; and linear distance measures used to quantify the shape of selected brain structures. We also evaluated the association between shape measures and developmental scores on the Bayley Scales of Infant and Toddler Development-III (BSID-III).

Results

Brain volume did not distinguish cases and controls (p?=?.214–.976). However, cases exhibited greater asymmetry and flattening of the posterior brain (p?p?=?.035), shortening of the corpus callosum (p?=?.012), and differences in the orientation of the corpus callosum (p?=?.005). Asymmetry and flattening of brain structures were associated with worse developmental outcomes on the BSID-III.

Conclusions

Infants with DP show differences in brain shape, consistent with the skull deformity characteristic of this condition, and shape measures were associated with infant development. Longitudinal studies, beginning in the neonatal period, are needed to clarify whether developmental effects precede or follow brain deformation.     

Brain stem tumors in children and adolescents: single institutional experience

Purpose

Pediatric brain stem tumors (BsT) are a heterogeneous group of diseases. Our aim was to analyze our experience to find out prognostic factors.

Method

A retrospective study with BsT patients was performed. Imaging characteristics, extension of surgery, pathology, and adjuvant therapy were analyzed and correlated with overall survival (OS) and progression-free survival (PFS) as outcome measures.

Result

Since 1980 to 2010, we analyzed 65 BsT patients, 41 of them girls (63 %), median age of 8 years (range 13.9?months to 17.6 years). Twenty-two patients (33.8 %) had diffuse intrinsic pontine gliomas (DIPG) and 43 (66.2 %) presented with focal BsT. Histology was available in 42 patients; the most frequent is low-grade glioma in 24/42 patients (57 %). DIPG’s histology (obtained usually at necropsy) confirmed five high-grade gliomas. After median follow-up of 49.3 months (0.5–175 months), 20/22 DIPG patients have died (90.9 %), while 27/43 with focal tumors were alive (62.8 %). Variables related to outcome were histology (better for low-grade glioma (LGG) OS p?<?0.001), surgery (better if operated OS p?<?0.001), and adjuvant therapy (worse if given, PFS p?=?0.001, OS p?=?0.024). The outcome for DIPG was dismal, median OS/EFS of 14.2/9.4 months, significantly worse than focal BsT (p?=?0.000), while OS/EFS was 122.8/87.2 months for focal intrinsic, 88.2/47.1 months for exophytic, and 124.4/54 months for cervico–medullary tumors: no differences were found among them, except the histology (OS p?<?0.001 for low-grade vs high-grade tumors).

Conclusion

BsT in children comprised two different groups: diffuse (DIPG) and focal gliomas. The DIPGs continue having a dismal prognosis, needing new approaches, while focal tumors including LGG have better prognosis.     

Torticollis as a first sign of posterior fossa and cervical spinal cord tumors in children

Background

Torticollis, despite being well-known neurological manifestation, is often underestimated as a first symptom of the abnormalities of posterior cranial cavity and cervical spinal cord.

Objectives

The purpose of this study is to analyze the occurrence of acquired torticollis in children as a herald sign of the tumors of the cervical spinal cord or of the posterior fossa.

Methods

Clinical records of 54 cases treated for the tumor of the cervical spinal cord or posterior fossa (including congenital ones) were retrospectively reviewed. The following data were calculated: the occurrence of the torticollis as a first sign of tumors, the duration time from the onset of the symptoms to diagnosis, the concurrence of other pathological symptoms, and the diminishing of symptoms of the torticollis following treatment.

Results

In 12/54 (22.2 %) torticollis was first sign of central nervous system tumor and in all of them preceded other neurological symptoms. The time from the onset of torticollis to establishing diagnosis ranged from 2 to 52 weeks (9.6 weeks on average). Eleven of twelve patients were treated surgically—in 10 of them, torticollis disappeared in the postoperative course.

Conclusions

Torticollis may be a herald sign of the tumor of the cervical spinal cord or the posterior fossa. Those pathologies should be considered in the differential diagnosis of the torticollis, particularly if accompanied by other symptoms of the focal pathology of central nervous system. Awareness of this fact may shorten the time to establish the proper diagnosis. Torticollis necessitates exclusion of the posterior fossa and spinal cord tumor.     

Neuroendoscopic biopsy of pediatric brain tumors with small ventricle

Purpose

Intraventricular endoscopic procedures to resect or biopsy peri- or intraventricular tumors may have not been used in patients with small ventricles due to the presumed difficulties with ventricular cannulation and the perceived risk of morbidity. The purpose of this study is to review the feasibility and safety of neuroendoscopic procedures in the biopsy of pediatric brain tumors with a small ventricle.

Methods

Between January 2006 and January 2013, 72 children were identified with brain tumors confirmed by transventricular endoscopic biopsy. Patients were divided into non-hydrocephalus and hydrocephalus groups, and the ratio of the two groups was 20:52.

Results

In 20 pediatric brain tumors with small ventricle, the targeted lesion was successfully approached under the guidance of neuronavigation. Navigational tracking was especially helpful in entering small ventricles and in approaching the third ventricle through the narrow foramen of Monro. The histopathologic diagnosis was established in all 20 patients: nine germinomas, three mixed germ cell tumors, two pilomyxoid astrocytomas, and two pilocytic astrocytomas. The tumor biopsy sites were the suprasellar area (n?=?10), pineal area (n?=?4), lateral ventricular wall (n?=?4), and mammillary body (n?=?1). There were no major morbidities related to the endoscopic procedure.

Conclusion

Neuroendoscopic biopsy or resection of peri- or intraventricular tumors in pediatric patients without hydrocephalus is feasible. Navigation-guided neuroendoscopic procedures improved the accuracy of the neuroendoscopic approach and minimized brain trauma. The absence of ventriculomegaly in patients with brain tumor may not serve as a contraindication to neuroendoscopic tumor biopsy.     

Diffuse intrinsic pontine glioma in children and adolescents: a single-center experience

Background

Patients with diffuse intrinsic pontine glioma (DIPG) have a very poor prognosis. Only radiotherapy (XRT) has proven to be effective in delaying the disease progression. Several chemotherapy schedules have been applied so far, but none demonstrated significant improvements in progression and survival.

Methods

We retrospectively analyzed the clinical data of children diagnosed with DIPG at our center (Pediatric Hospital “Regina Margherita,” Turin, Italy) between 1999 and 2013. Progression-free survival (PFS) and overall survival (OS) were used to describe the outcomes.

Results

Twenty-four children were included in our report. Patients diagnosed before March 2003 (n?=?12) were treated with XRT and vincristine (VCR); the remaining 12 patients received XRT and temozolomide (TMZ). Progression-free survival was 18.8 % at 1 year (SE?=?7.6 %), while overall survival was 44.1 % at 1 year (SE?=?9.9 %). Median PFS was 8.1 months, whereas median OS was 11.2 months. No statistically significant difference in PFS or OS was evidenced between the two treatment groups.

Conclusion

Radiotherapy followed by VCR or TMZ allows obtaining results that are in line with previous reports, with no advantages over other similar treatment schedules. DIPGs are challenging tumors with a dismal outcome. Further research and newer therapies are urgently needed in order to achieve improvements in survival.     

Chiari I malformation after cranial radiation therapy in childhood: a dynamic process associated with changes in clival growth

Object

The small posterior fossa is believed to be relevant to the development of Chiari I malformation (CMI). In this study, we evaluated children with supratentorial tumors developing CMI after radiation therapy (RT) that involved the skull base. Changes in clivus and supraocciput growth rate were correlated with tonsillar herniation.

Methods

Ten children who underwent RT for supratentorial tumors at St. Jude Children's Research Hospital (1994–2008) developed CMI on follow-up magnetic resonance imaging (MRI). Four other patients with supratentorial tumor and CMI who did not receive RT were identified. Length of the supraocciput, basisphenoid, and basichondrium and extent of tonsillar herniation were measured on serial midsagittal MRI.

Results

Over the median follow-up of 85.5 months, basisphenoid annual growth rate was significantly lower in children receiving RT for suprasellar tumor (n?=?8) than those who did not (p?=?0.04). Growth of clivus and basisphenoid was significantly lower in the first 12 months after RT in children who received RT for suprasellar tumor (p?=?0.03 and p?=?0.04, respectively). In these patients, tonsillar herniation increased over 24 months after RT, reaching maximal descent at a mean of 20.2 months; this resolved as clival growth returned to normal. No patient was symptomatic.

Conclusions

In these children, restriction of clival growth occurred after RT for suprasellar tumors. Changes in clival growth were associated with changes in the extent of tonsillar herniation. This supports the importance of the small posterior fossa and reduced clival length in the etiology of CMI.

     

Childhood central nervous system tumors at MAHAK’s Pediatric Cancer Treatment and Research Center (MPCTRC), Tehran,Iran

Purpose

As central nervous system (CNS) tumors account for second most common childhood malignancies and the first cause of mortality in children with cancer, improving treatment modalities can lead to increase the health care of patients. In this study, we examined the prevalence of childhood brain tumors in patients who referred to MAHAK’s Pediatric Cancer Treatment and Research Center (MPCTRC) for treatment.

Methods

A retrospective review of all children less than 15 years old with a CNS histologically proven tumor, who presented to MPCTRC from April 2007 to April 2010, was performed. Data was analyzed by SPSS version 19 with Kolmogorov–Smirnov and Chi-square tests.

Results

There were 198 (124 boys) children eligible for the study. The majority of the tumors were infratentorial (n?=?134), and the rest were supratentorial (n?=?60) and spinal (n?=?4) cases. The median age was 6.11?±?3.65 years old. Medulloblastoma (n?=?66), low-grade glioma (n?=?52), and high-grade glioma (n?=?40) were the most common tumors. The mean duration of follow-up was 21 months. At the time of this analysis, there were 105 (53 %) children alive, 82 (41.4 %) deaths, and 11 (5.6 %) lost for follow-up. The survival rate was 51.68?±?5.22 %.

Conclusions

In contrast of high rate of death in this study, other general characteristics can serve as benchmark for improving our care for children with brain tumors in Iran.     

Normative data for fetal cisterna magna length measurement between 18 and 24 weeks of pregnancy

Purpose

The aim of this study was to determine normative data for fetal cisterna magna length (CML) measurement in a Brazilian population.

Methods

This was a retrospective cross-sectional study on 3,862 normal singleton pregnancies between the 18th and 24th weeks of pregnancy. Fetal CML was measured in the axial plane of the fetal head, at lateral ventricle level, including the cavum septum pellucidum, thalamus, third ventricle, and transverse cerebellar diameter. The anteroposterior measurement was made between the posterior border of the cerebellar vermis and the internal face of the occipital bone. To assess the correlation between CML and gestational age (GA), polynomial equations were calculated, with adjustments using determination coefficient (R ²).

Results

The mean CML ranged from 4.29?±?0.93 mm at 18 to 18?+?6 weeks to 5.58?±?1.23 mm at 24 to 24?+?6 weeks of pregnancy. There was a good correlation between CML and GA, best represented by a linear equation: CML?=?0.535?+?0.208*GA (R ²?=?0.084).

Conclusion

We established normative data for fetal CML in the second trimester of pregnancy, in a large Brazilian population.