Differential Diagnosis of Intracranial Cystic Lesions at Head US: Correlation with CT and MR Imaging

Connatal cyst in a preterm twin infant with maternal comorbidities

BACKGROUND

Connatal cysts are rare but recognized periventricular cysts that represent anatomic variants and are associated with good neurological outcomes. These cysts can be differentiated from cysts that portend graver prognoses by their location in relation to the ventricles, size, laterality, and temporal resolution.

PATIENT PRESENTATION

We describe a preterm twin infant born to a mother with diabetes and cardiovascular disease who was found to have connatal cysts on head ultrasound at 3 days of age. These cysts were present again on head ultrasound at 12 days of age and on brain magnetic resonance imaging at 27 days of age. The infant had a normal neurological examination in the neonatal period and on follow-up at 3 and 6 months of age. Repeated head ultrasound at 3 months of age demonstrated near resolution of the cysts.

CONCLUSION

Connatal cysts are normal anatomic variants which clinicians should be able to distinguish from similar appearing cysts with less favorable outcomes. Although the etiology of connatal cysts remains unknown, this case raises the possibility of maternal comorbidities or perinatal hypoperfusion playing a role in their formation.

Blake's pouch cyst and Werdnig-Hoffmann disease: Report of a new association and review of the literature

Background:

We report a case of a neonate with proximal spinal muscular atrophy (SMA) type 1 (also known as Werdnig-Hoffmann disease or severe infantile acute SMA) associated with a Blake's pouch cyst; a malformation that is currently classified within the spectrum of Dandy-Walker complex. The association of the two conditions has not been previously reported in the English literature. A comprehensive review of the pertinent literature is presented.

Case Description:

A male neonate was noted to have paucity of movement of the four limbs with difficulty of breathing and poor feeding soon after birth. Respiratory distress with tachypnea, necessitated endotracheal intubation and mechanical ventilation. Pregnancy was uneventful except for decreased fetal movements reported by the mother during the third trimester. Neurological examination revealed generalized hypotonia with decreased muscle power of all limbs, nonelicitable deep tendon jerks, and occasional tongue fasciculations. Molecular genetic evaluation revealed a homozygous deletion of both exons 7 and 8 of the survival motor neuron 1 (SMN1) gene, and exon 5 of the neuronal apoptosis inhibitory protein (NAIP) gene on the long arm of chromosome 5 consistent with Werdnig-Hoffmann disease (SMA type 1). At the age of 5 months, a full anterior fontanelle and abnormal increase of the occipito-frontal circumference were noted. Computed tomographic (CT) scan and magnetic resonance imaging (MRI) of the brain revealed a tetraventricular hydrocephalus and features of Blake's pouch cyst of the fourth ventricle.

Conclusions:

This case represents a previously unreported association of Blake's pouch cyst and SMA type 1.

Unilateral Type II Schizencephaly

Schizencephaly is a rare developmental disorder of the brain that is characterized by abnormal clefts within the cerebral hemispheres. Infants with this disorder commonly have developmental delay, delay in speech and language, partial or complete paralysis, poor muscle tone, and seizures. The manifestations and severity of the disease are related to the size and location of the clefts. The authors report a case of type II (open-lipped) schizencephaly diagnosed in the second trimester by sonography. Early prenatal diagnosis of fetal type II (open-lipped) schizencephaly allows time for patient counseling and discussion of options and preparation.

State-of-the-art cranial sonography: Part 2, pitfalls and variants

OBJECTIVE

In the first part of this article, modern cranial sonography techniques and interpretation were discussed, emphasizing ways in which the application of modern imaging technology and techniques are able to enhance detection of pathologic abnormalities on cranial sonography.

CONCLUSION

In this part of the article, we will describe pitfalls and variants that may be confused with pathologic abnormalities. Emphasis will be placed on recognizing normal variations and distinguishing them from pathologic abnormalities that may require additional imaging or clinical follow-up.

Magnetic resonance imaging of fetal developmental anomalies

Fetal developmental anomalies consist of central nervous system malformations, brain injury, and tumors. Overlap is often seen especially between malformation and injury because malformation may be genetically determined or related to external causative agent, whereas brain injury may be, on one hand, caused by malformation as with intracranial vascular malformation and, on another, can cause brain malformation when cerebral insult occurs during organogenesis and histogenesis. The goal of this review was not to describe by magnetic resonance imaging (MRI) all fetal developmental anomalies encountered in utero; it is most likely to focus on fetal brain anomalies that either are most commonly seen in fetal tertiary care facility or are extremely challenging for MRI. Consequently, the potential of advanced MR techniques such as proton MR spectroscopy and diffusion tensor imaging is also described especially when a challenge is highlighted. This review is therefore organized in subchapters as follows. The first section gives the place of MRI in prenatal development and cites the standard protocol and the advanced techniques. The rules of fetal brain MRI, the challenge and pitfalls, and the selection of MRI cases follow as 3 subchapters. Also, abnormalities are described as 3 separate subchapters entitled ventriculomegalies (hydrocephalus), malformations, and brain injury.

Newborn frontal horn cysts: cause for concern?

OBJECTIVE

To document the incidence, natural history and compare neurodevelopmental outcome of newborns with and without frontal horn cysts (FHC).

STUDY DESIGN

This was a case-control study. Newborns with and without FHC were identified and matched for demographics and worst cranial ultrasound scan (CUS) findings. Neurodevelopmental outcome was assessed at 18 to 24 months.

RESULT

A total of 30 FHC cases were identified from medical imaging database. Twenty-five cases occurred in preterm 32 weeks gestation with an incidence of 1% (25 of 2340). The diagnosis was made on the initial CUS in 28 cases. The cyst size and number varied from 1 to 18 mm and 1 to 6 respectively with no change noted on repeat CUS during hospital stay. Neurodevelopmental outcomes were not statistically significantly different between the groups.

CONCLUSION

FHC are not uncommon in the newborn period. They appear to be benign with no impact on neurodevelopmental outcome. This information is vital for counseling parents of infants with FHC.

Outcomes of preterm neonates with frontal horn cysts: a retrospective study

Isolated paraventricular frontal horn cysts are sometimes encountered on cranial ultrasound examinations of preterm neonates. The etiology and clinical significance of these lesions are unclear. The authors aimed to identify antenatal/intrapartum risk factors associated with the occurrence of these cysts and to assess developmental outcomes of preterm neonates with isolated frontal horn cysts. A retrospective cohort study with matched control design was used. A total of 28 cases were matched for gestation with 56 controls. No antenatal/intrapartum factors were associated with these cysts. At corrected age of 1 year, there was no difference in the mean general quotient between cases and controls (97.75 ± 17.28 vs 94.94 ± 9.86; P = .410). In all, 1 case and no controls had a diagnosis of cerebral palsy and 1 case and 3 controls had general quotients less than 80. The authors conclude that isolated paraventricular frontal horn cysts are benign, with no effect on neurodevelopment.

Infant craniospinal ultrasonography: beyond hemorrhage and hydrocephalus

Ultrasonography is widely used for screening for neonatal intracranial hemorrhage, hydrocephalus, and cord tethering in young infants. Proper interpretation of infant cranial and spinal ultrasound examinations requires not only familiarity with the appearances of these disorders, but also recognition of imaging artifacts capable of mimicking pathology and awareness of developmental variants and conditions that occupy a borderline position along the spectrum from normal to abnormal. This article will review the current understanding of the ultrasonographic characteristics and clinical relevance of these imaging artifacts, developmental variants, and quasi-pathologic conditions to avoid diagnostic pitfalls and guide appropriate patient management.

Routine TORCH screening is not warranted in neonates with subependymal cysts

BACKGROUND

Congenital infections are associated with a wide variety of clinical symptoms, including subependymal cysts (SEC).

OBJECTIVE

To determine the co-occurrence of SEC and congenital infections, as diagnosed by TORCH serologic tests and/or cytomegalovirus (CMV) urine culture.

METHODS

We performed a retrospective study of all neonates admitted to our neonatal intensive care unit from 1998 to 2009 in whom SEC were detected on cranial ultrasound and TORCH serologic tests and/or CMV urine cultures were performed.

RESULTS

Fifty-nine neonates fulfilled the inclusion criteria. TORCH serologic tests were performed in 69% (41/59) of cases. Urine CMV culture was performed in 68% (40/59) of cases. None of the neonates tested positive for IgM Toxoplasma gondii, Rubella and Herpes simplex virus. Positive CMV IgM titers and/or a positive urine CMV culture were detected in 2% (1/59) of neonates.

CONCLUSION

The co-occurrence of TORCH congenital infections in infants with SEC is rare. Routine TORCH screening in neonates with SEC does not seem warranted.

Fetal magnetic resonance imaging of acquired and developmental brain anomalies

During the last decade, increasing interest in magnetic resonance imaging has emerged for the evaluation of fetal abnormalities detected on ultrasound. The advent of single-shot rapid acquisition sequences has greatly facilitated our ability to obtain detailed imaging information of the fetal brain. To date, fetal magnetic resonance imaging has shown to have an important role in the investigation of cerebral abnormalities suspected by sonography, and in the detection of subtle brain anomalies associated with high-risk pregnancies. Magnetic resonance imaging has proved to be a useful adjunct to sonography during the prenatal period of development, especially for the detection of acquired disorders.

Cavum veli interpositi cyst: prenatal diagnosis and postnatal outcome

OBJECTIVE

The cavum veli interpositi (CVI) is a space within the double-layered tela choroidea of the third ventricle. Occasionally, this space is fluid-filled and sonographically visible as an interhemispheric anechoic cyst. Because of its rarity, the incidence of CVI cyst is undetermined and the outcome of affected individuals has been found to be variable. The aim of this study was to report our experience of the sonographic findings and outcome of fetuses affected by CVI cysts.

METHODS

In five fetuses with a CVI cyst, we performed targeted prenatal ultrasound scans of intracranial structures and a detailed anatomical survey to rule out associated malformations. Follow-up consisted of neurological examination and neurosonography.

RESULTS

The CVI cyst appeared as a well-defined anechoic lesion without adjacent mass effect. In all fetuses the cyst was single and in two cases it enlarged slightly during pregnancy. The cyst was isolated in three fetuses and associated with borderline ventriculomegaly in two. A single umbilical artery was the only associated extracranial anomaly and this was detected in only one fetus. Neurosonography confirmed the presence of CVI cysts in all cases after delivery. During postnatal follow-up (range 10-48 months), the cyst regressed in one case within 1 month after delivery while the size of the others remained stable. No infant developed psychomotor disorders.

CONCLUSIONS

Prenatal sonographic diagnosis of CVI cysts is feasible. Its finding in isolation is consistent with favorable postnatal outcome.

Brain imaging findings in very preterm infants throughout the neonatal period: part I. Incidences and evolution of lesions, comparison between ultrasound and MRI

This study describes the incidence and evolution of brain imaging findings in very preterm infants (GA<32 weeks), assessed with sequential cranial ultrasound (cUS) throughout the neonatal period and MRI around term age. The accuracy of both tools is compared for findings obtained around term. Periventricular echodensities and intraventricular haemorrhage were the most frequent cUS findings during admission. Frequent findings on both cUS and MRI around term included ventricular dilatation, widened extracerebral spaces, and decreased cortical complexity. MRI additionally showed punctate white matter lesions and diffuse and excessive high signal intensity, but did not depict lenticulostriate vasculopathy and calcifications, and was less reliable for germinolytic and plexus cysts. cUS detected most abnormalities that have been associated with abnormal neurodevelopmental outcome.

Spectrum of choroid plexus lesions in children

OBJECTIVE

The aim of this article is to review the embryology of the choroid plexus and the spectrum of disorders involving the choroid plexus in children and to illustrate their radiologic features.

CONCLUSION

The choroid plexus is an important part of the CNS that can be the primary or secondary location for many congenital abnormalities or pathologic conditions such as neoplasms, infections, inflammatory processes, cysts, and vascular malformations.

From fossil to fetus: nonhemorrhagic germinal matrix echodensity caused by mineralizing vasculitis--hypothesis of fossilizing germinolysis and gliosis

Subventricular echodensities medioventral to the caudate nucleus near the caudothalamic groove are regular ultrasonographic findings in preterm infants with germinal matrix hemorrhages. The transformation into pseudocysts is termed germinolysis. Interestingly, identical ultrasonographic findings are rarely even reported for near-term infants. We examined 5 cases of near-term infants presenting with various localized subventricular echodensities after various noncerebral infections (intra-amniotic infection, gastroenteritis of unidentified pathogens, septic wound, and a twin pair with rotavirus gastroenteritis), suggesting an inflammatory or ischemic rather than a hemorrhagic etiology. With high-resolution ultrasonography, these lesions showed similar characteristics: all were space-occupying, homogeneous, echodense, and ultimately transformed into pseudocysts. Additionally, Doppler ultrasonography showed linear perivascular echodensities in the basal ganglia of one infant. All infants were also examined by cerebral magnetic resonance imaging (MRI) including T2*-weighted gradient-echo sequences so that subventricular hemorrhages could be excluded in 4 infants. One of these 4 infants died unexpectedly at home. Brain autopsy revealed nonhemorrhagic germinal matrix pseudocysts with gliotic walls. Based on our findings and the original literature, we favored an ischemic infarction of the strongly vascularized and highly metabolic germinal matrix as cause of this germinolysis and gliosis. We postulated that the infarction was the result of an obstructive and possibly mineralizing, or even fossilizing vasculopathy due to an inflammatory response. The precise pathogenesis of the suspected immune-mediated vasculitis remains unknown. We concluded that cerebral ultrasonography should be performed in infants with noncerebral infection and that it should be complemented by MRI in cases of subventricular echodensities to prove or to exclude a germinal matrix hemorrhage.

Hydranencephaly in neonates

Hydranencephaly is characterized by severe dysgenesis of the cerebral hemispheres, with relative preservation of the thalamus, cerebellum and brainstem. Modern neurological imaging techniques have demonstrated that the affected regions are usually localized within the territories of the middle cerebral arteries. Evoked potentials have confirmed the imaging findings. This article reports on two neonates with hydranencephaly who presented with normal appearance. Neurological images were characterized by marked reduction of the total brain cortex, which was replaced by fluid. Evoked potentials demonstrated preserved auditory evoked potentials but a total absence of visual evoked potentials. These diagnostic techniques provided efficient and precise information concerning the extent of intracranial dysgenesis.

Intraaxial brain masses: MR imaging-based diagnostic strategy--initial experience

PURPOSE

To develop and retrospectively determine the accuracy of a magnetic resonance (MR) imaging strategy to differentiate intraaxial brain masses, with histologic findings or clinical diagnosis as the reference standard.

MATERIALS AND METHODS

The study was HIPAA compliant and was approved by the institutional review board. A waiver of informed consent was obtained. A strategy was developed on the basis of conventional MR imaging, diffusion-weighted MR imaging, perfusion MR imaging, and proton MR spectroscopy to classify intraaxial masses as low-grade primary neoplasms, high-grade primary neoplasms, metastatic neoplasms, abscesses, lymphomas, tumefactive demyelinating lesions (TDLs), or encephalitis. The strategy was evaluated by using data from 111 patients (46 women, 65 men; mean age, 48.9 years) with imaging results available on a departmental picture archiving and communication system from a 5-year search period. Bayesian statistics of the strategy elements and three clinical tasks were calculated.

RESULTS

Search results identified 44 patients with high-grade and 14 with low-grade primary neoplasms, 24 with abscesses, 12 with lymphoma, 11 with TDLs, five with metastases, and one with encephalitis who had undergone conventional and advanced MR imaging. However, only 40 patients (25 women, 15 men; mean age, 45 years) had undergone all studies and had data to allow completion of the entire strategy. Accuracy, sensitivity, and specificity of the strategy, respectively, were 90%, 97%, and 67% for discrimination of neoplastic from nonneoplastic diseases, 90%, 88%, and 100% for discrimination of high-grade from low-grade neoplasms, and 85%, 84%, and 87% for discrimination of high-grade neoplasms and lymphoma from low-grade neoplasms and nonneoplastic diseases.

CONCLUSION

An integrated MR imaging-based strategy, which is accurate in differentiation of several intraaxial brain masses, was proposed.