Gastroschisis and septo-optic-pituitary dysplasia: Is there an association?

AIM

There are several case reports describing patients with both optic nerve hypoplasia/septo-optic-pituitary dysplasia (ONH/SOD) and gastroschisis (GS). Our aim was to investigate whether ONH/SOD is associated with GS.

METHODS

A retrospective population-based study was undertaken using the Population Research Data Repository at the Manitoba Center for Health Policy in Manitoba, Canada to investigate if any patient with ONH/SOD also had GS. In addition, Winnipeg's Surgical Database of Outcomes and Management (WiSDOM), a hospital-based paediatric surgical database, was searched to ascertain if any of the patients with GS also have ONH/SOD.

RESULTS

Cases were 124 patients with ONH/SOD diagnosed during 1990-2019. None had GS. The surgical database had 188 patients from Manitoba with GS during 1991-2019. None had ONH/SOD.

CONCLUSION

There does not appear to be an association between ONH/SOD and GS in our cohorts of patients with these two disorders.

Ophthalmic and Neuroimaging Associations In Optic Nerve Hypoplasia/Septo-Optic-Pituitary Dysplasia

BACKGROUND

Optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) are neurodevelopmental disorders associated with congenital visual impairment. Our aim was to investigate associations between several ophthalmic and neuroimaging features in patients with ONH/SOD.

METHODS

A retrospective chart and neuroimaging review was performed in patients with ONH/SOD. Ophthalmic signs (e.g., monocular best-corrected visual acuity [BCVA], nystagmus, and strabismus) and neuroimaging data were extracted and their associations were investigated.

RESULTS

There were 128 patients (70 males) with ONH/SOD who had neuroimaging. Their mean age at the end of the study was 13.2 (SD: 7.5) years. Ophthalmic data were available on 102 patients (58 males). BCVA varied from normal to no light perception. There were statistically significant associations between: (A) Reduced optic nerve or chiasm size on neuroimaging and more severely impaired BCVA and (B) laterality of the reduced optic nerve or chiasm size on neuroimaging and laterality of: (1) The eye with reduced BCVA, (2) small optic disc size, and (3) RAPD, if present (p ≤ 0.0002 each). The presence of symmetrically small optic nerves on MRI was significantly more common in patients with nystagmus than when nystagmus was absent (N = 96, 75% vs. 38.6%, p < 0.0001). The presence of neuronal migration disorders, their type and laterality were not associated with BCVA and laterality of the reduced BCVA.

CONCLUSION

The functional and structural associations in ONH are consistent with the impaired visual function that results from the hypoplastic anterior visual pathways. However, these associations were not perfectly concordant making prediction of adult BCVA challenging in these patients.

Risk factors in children with optic nerve hypoplasia and septo-optic dysplasia

AIM

To identify the risk factors for optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD).

METHOD

A retrospective, population-based study with case-control design was undertaken using the Population Research Data Repository at the Manitoba Center for Health Policy in Manitoba, Canada. Cases were 111 patients (63 males, 48 females; age range 1-35 years [mean 11 years 6 months, SD 7 years 2 months]) with ONH and SOD diagnosed from 1990 to 2019, matched to 555 unrelated population-based controls (315 males, 240 females; age range 1-35 years [mean 11 years 6 months, SD 7 years 2 months]) on year of birth, sex, and area of residence. Additionally, 75 cases (46 males, 29 females; age range 2-35 years [mean 12 years 6 months, SD 7 years 2 months]) with ONH and SOD were matched one-on-one with sibling controls (40 males, 35 females; age range 0-33 years [mean 11 years 7 months, SD 7 years 10 months], the rest did not have siblings). Several antenatal maternal risk factors associated with ONH and SOD were tested for their association with case and control group membership using adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from a multivariate conditional logistic regression model. The outcome was the risk of developing ONH and SOD.

RESULTS

Maternal age at conception (OR = 0.91, 95% CI = 0.86-0.96), primigravida (OR = 3.39, 95% CI = 1.92-6.01), and smoking (OR = 2.86, 95% CI = 1.61-5.05) were independently associated with ONH and SOD in the cohort matched to unrelated controls (p < 0.001). In the sibling cohort, smoking was an important risk factor (OR = 3.65, 95% CI = 1.2-11.1, p = 0.02).

INTERPRETATION

Unmodifiable and modifiable antenatal maternal risk factors are associated with ONH and SOD. Our investigation suggests that several risk factors reported in previous studies may have been due to confounding bias and that maternal smoking during pregnancy is the main modifiable risk factor associated with ONH and SOD.

WHAT THIS PAPER ADDS

Historically, many antenatal risk factors have been associated with optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD). Population-based data with matched controls for potential confounding bias are lacking. Young maternal age at conception, primigravida, and smoking during pregnancy are the main risk factors for ONH and SOD using a population-based, case-control design.

James Sharpe's Contributions to Neurology and Neuro-ophthalmology: A Posthumous Tribute 10 Years On

Dr. Sharpe was a leading eye movement researcher who had also been the editor of this journal. We wish to mark the 10th anniversary of his death by providing a sense of what he had achieved through some examples of his research.

Visual Acuity Outcomes in Children With Optic Nerve Hypoplasia and Septo-Optic-Pituitary Dysplasia

BACKGROUND

To investigate best-corrected visual acuity (BCVA) outcomes in patients with optic nerve hypoplasia (ONH)/septo-optic-pituitary dysplasia (SOD). Our primary hypothesis was that BCVA in patients with ONH/SOD does not change significantly over time.

METHODS

A chart review was undertaken in patients with a confirmed diagnosis of ONH/SOD. Demographic and clinical ophthalmologic data were extracted. Quantitative BCVA data were investigated across clinic visits after converting acuities to the logarithm of the minimum angle of resolution (logMAR).

RESULTS

There were 102 patients (56 males). Median age at the end of the study was 12.7 years. Median duration of follow-up was 4.5 years. BCVA significantly worsened slightly in the most affected eyes (0.056 average increase in logMAR/year, 95% confidence interval [CI]: 0.037 to 0.075) and significantly improved mildly in the lesser or equally affected eyes (0.014 average decrease in logMAR/year, 95% CI: 0.009 to 0.019) (P < 0.0001).

CONCLUSIONS

Although the overall BCVA data showed a statistically significant change with time, the actual changes were small and are of doubtful meaningful clinical significance (less than one line change on a Snellen chart). Our data suggest that ONH/SOD are nonprogressive neurodevelopmental disorders. The mild worsening of BCVA in the most affected eyes may be caused by amblyopia, whereas the small improvement in the lesser or equally affected eyes may be caused by developmental maturation. In addition, the changes in BCVA may also be due to increasing reliability of visual assessments with increasing age.

Neuroimaging Features in Children with Optic Nerve Hypoplasia and Septo-Optic-Pituitary Dysplasia

BACKGROUND

Optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) are common causes of congenital visual impairment. Our primary aim was to investigate the prevalence of abnormal neuroimaging features in patients with these disorders in Manitoba, Canada, and compare them with published reports.

METHODS

A retrospective neuroimaging review was performed in patients resident in Manitoba with ONH/SOD.

RESULTS

There were 128 patients (M = 70) with ONH/SOD who had neuroimaging. Their mean age (SD) at the end of the study was 13.2 (7.5) years. Males were significantly more likely to have bilateral ONH and a small optic chiasm size, while females were more likely to have a left ONH and a small left optic chiasm size on neuroimaging (p = 0.049). ONH and small optic chiasm size were seen in most patients on neuroimaging. Absent septum pellucidum was noted in 40%, small pituitary gland size in 28%, neuronal migration disorders (NMD) in 20% (>1 type and bilateral in 13 cases), corpus callosum abnormalities were present in 9%, while olfactory bulbs-tracts and olfactory sulci were absent in 8.6% of cases. Unilateral ONH was not significantly associated with other structural brain abnormalities, while NMD were significantly associated with other midline brain abnormalities including a symmetrically small optic chiasm size.

CONCLUSION

The prevalence of structural neuroimaging abnormalities in our cohort with ONH/SOD was generally in the same range reported in other studies with corpus callosum abnormalities being relatively less common in our study. Bilateral NMD were relatively common among patients with NMD. The association between sex and ONH laterality requires further study.

Selected Ophthalmological Features in Children with Septo-Optic Dysplasia and Optic Nerve Hypoplasia

Septo-optic dysplasia (SOD) and optic nerve hypoplasia (ONH) cause congenital visual impairment. Their aetiology is mostly unknown. Our aim was to investigate the prevalence of selected ophthalmological features in patients with these disorders. A chart review was performed on patients with SOD/ONH. Ophthalmological data were extracted. There were 102 patients (56 males). The median age at the end of the study was 12.7 years. Best-corrected visual acuity ranged from normal to no light perception. Bilateral ONH was more common than unilateral ONH. Strabismus (85%) and to a lesser extent nystagmus (52%) were both very common in our cohort. Patients with esotropia had worse visual acuity than those who had exotropia. The presence of nystagmus was more likely in cases with bilateral ONH. Therefore, patients with SOD/ONH may have normal visual acuity. Many have strabismus, which may cause amblyopia thereby further decreasing visual acuity. Nystagmus occurs commonly and its presence typically indicates bilateral ONH.

Assessing Children with Poor Coordination Can Be Tricky - A Review on Ataxia and Ataxia Mimickers and a Study of Three Children with Severe Epilepsy

While ataxia is a relatively common presenting feature in pediatric patients, it represents only one possible cause of uncoordinated movements. Other possible causes of uncoordinated movements include ingestion of toxic substances, musculoskeletal diseases, psychogenic disorders, extrapyramidal movement disorders, peripheral neuropathies, spasticity from any cause, and epilepsy. Therefore, primary health care providers must recognize and exclude other etiologies of uncoordinated movements before attaching the label “ataxia” to any patient presenting with poor coordination. Once the presence of ataxia is confirmed, the cause should be investigated. As ataxia may be vestibular, sensory, or cerebellar in origin, medical practitioners must evaluate the diverse symptoms and signs to effectively differentiate the various types of ataxia. Three case studies are presented to illustrate the complexity associated with the assessment of ataxia. Each case will discuss a pediatric patient who displays cerebellar ataxia as a concurrent feature of a gene-specific developmental and epileptic encephalopathy. These cases will provide an example of how ataxia may be differentiated from other causes of uncoordinated movements related to epilepsy and anti-seizure medications, namely: nonconvulsive seizures, postictal state, and medication side effects or toxicity. The assessment of poor balance can be challenging at times; however, with knowledge of the differential diagnosis of poor balance, medical practitioners will be able to confidently determine the presence of true ataxia from various ataxia mimickers, thereby allowing for timely and accurate diagnosis, and appropriate management.

Cerebellar radiological abnormalities in children with neurofibromatosis type 1: part 1 - clinical and neuroimaging findings

Background

Many children with neurofibromatosis type 1 (NF1) have focal abnormal signal intensities (FASI) on brain MRI, whose full clinical impact and natural history have not been studied systematically. Our aims are to describe the clinical and neuroradiological features in children with NF1 and cerebellar FASI, and report on the natural history of FASI that display atypical features such as enhancement and mass effect.

Method

A retrospective review of the hospital charts and brain MRIs was performed on children from Manitoba diagnosed between 1999 and 2008 with NF1, who also had cerebellar FASI on MRI.

Results

Fifty patients (mean age: 16.1y, minimum-maximum: 6.4 - 30y, 27 M) were identified. Mean duration of follow up was 10.1y. Developmental delay, learning disabilities, tumors, and visual signs occurred commonly. Cerebellar signs were not reported. Mean age of the patients at baseline MRI was 7.8 (SD: 4.5) years. FASI occurred in several brain locations and were rarely confined to the cerebellum. FASI displayed mass effect and enhancement infrequently but were associated with malignancy only once. The number of FASI at baseline MRI was significantly less in patients with attention deficient hyperactivity disorder and more if a first degree relative had NF1 or if they had decreased visual acuity.

Discussion

Patients with NF1 and cerebellar FASI do not have motor or consistent non-motor (e.g. developmental delay or learning disabilities) cerebellar features. The number of FASI may correlate with some clinical features. FASI may display enhancement and mass effect but they rarely become malignant.

Cerebellar radiological abnormalities in children with neurofibromatosis type 1: part 2 - a neuroimaging natural history study with clinical correlations

Background

Focal abnormal signal intensities (FASI) on brain MRI occur commonly in patients with neurofibromatosis type 1 (NF1). The natural history of cerebellar FASI and their correlation with clinical features have not been studied comprehensively. Our aims are to describe the natural history of cerebellar FASI on repeat MRI scans and correlate the findings with the clinical features in children with NF1 and cerebellar FASI.

Method

A retrospective review of 226 brain MRI scans and hospital charts was performed in 50 patients with cerebellar FASI, who were diagnosed with NF1 during their childhood between 1999 and 2008.

Results

Mean age at the end of the study period was 16.1 years. There were 27 males. Mean duration of clinical follow up was 10.1 years. Mean duration between the first and the last MRI was 6.6 years (n = 36, SD: 2.8 years). FASI were rarely confined to the cerebellum. The number of FASI was highest in early childhood and decreased significantly on subsequent MRI scans in most brain regions with the exception of the cerebrum, where a fewer number of patients with a smaller number of FASI were seen. Four patterns of change in FASI size over time were determined, none correlated with the clinical features.

Conclusions

In patients with NF1, the natural history of FASI including their number, age at onset, rate of size changes, and resolution if any, varies by brain region. FASI patterns of change over time showed no clinical correlate.

Eyelid Retraction in Isolated Unilateral Congenital Blepharoptosis

Isolated unilateral congenital ptosis is encountered relatively infrequently in clinical practice. It typically consists of a unilateral droopy eyelid, weak levator palpebrae superioris muscle function, lid lag, and an absent upper lid crease with no other abnormalities on examination. We present a four-and-a-half-year-old girl with isolated and mild unilateral congenital ptosis who unexpectedly demonstrated a static upper eyelid on downgaze in conjunction with a well-formed upper lid skin crease. We attribute this uncommon sign in congenital ptosis to stiffness and presumed fibrosis of the levator muscle. Examining the function of the eyelids in all directions of gaze is important in patients with abnormalities of lid position, since additional useful information can be gleaned about the status of the levator muscle including, aberrant regeneration or fibrosis.

Genetics and genotype-phenotype correlations in early onset epileptic encephalopathy with burst suppression

OBJECTIVE

We sought to identify genetic causes of early onset epileptic encephalopathies with burst suppression (Ohtahara syndrome and early myoclonic encephalopathy) and evaluate genotype-phenotype correlations.

METHODS

We enrolled 33 patients with a referral diagnosis of Ohtahara syndrome or early myoclonic encephalopathy without malformations of cortical development. We performed detailed phenotypic assessment including seizure presentation, electroencephalography, and magnetic resonance imaging. We confirmed burst suppression in 28 of 33 patients. Research-based exome sequencing was performed for patients without a previously identified molecular diagnosis from clinical evaluation or a research-based epilepsy gene panel.

RESULTS

In 17 of 28 (61%) patients with confirmed early burst suppression, we identified variants predicted to be pathogenic in KCNQ2 (n = 10), STXBP1 (n = 2), SCN2A (n = 2), PNPO (n = 1), PIGA (n = 1), and SEPSECS (n = 1). In 3 of 5 (60%) patients without confirmed early burst suppression, we identified variants predicted to be pathogenic in STXBP1 (n = 2) and SCN2A (n = 1). The patient with the homozygous PNPO variant had a low cerebrospinal fluid pyridoxal-5-phosphate level. Otherwise, no early laboratory or clinical features distinguished the cases associated with pathogenic variants in specific genes from each other or from those with no prior genetic cause identified.

INTERPRETATION

We characterize the genetic landscape of epileptic encephalopathy with burst suppression, without brain malformations, and demonstrate feasibility of genetic diagnosis with clinically available testing in >60% of our cohort, with KCNQ2 implicated in one-third. This electroclinical syndrome is associated with pathogenic variation in SEPSECS. Ann Neurol 2017;81:419-429.

Can Latent Class Analysis Be Used to Improve the Diagnostic Process in Pediatric Patients with Chronic Ataxia?

Chronic ataxia is a relatively common symptom in children. There are numerous causes of chronic ataxia, making it difficult to derive a diagnosis in a timely manner. We hypothesized that the efficiency of the diagnostic process can be improved with systematic analysis of clinical features in pediatric patients with chronic ataxia. Our aim was to improve the efficiency of the diagnostic process in pediatric patients with chronic ataxia. A cohort of 184 patients, aged 0-16 years with chronic ataxia who received medical care at Winnipeg Children's Hospital during 1991-2008, was ascertained retrospectively from several hospital databases. Clinical details were extracted from hospital charts. The data were compared among the more common diseases using univariate analysis to identify pertinent clinical features that could potentially improve the efficiency of the diagnostic process. Latent class analysis was then conducted to detect unique patterns of clinical features and to determine whether these patterns could be associated with chronic ataxia diagnoses. Two models each with three classes were chosen based on statistical criteria and clinical knowledge for best fit. Each class represented a specific pattern of presenting symptoms or other clinical features. The three classes corresponded to a plausible and shorter list of possible diagnoses. For example, developmental delay and hypotonia correlated best with Angelman syndrome. Specific patterns of presenting symptoms or other clinical features can potentially aid in the initial assessment and diagnosis of pediatric patients with chronic ataxia. This will likely improve the efficiency of the diagnostic process.

Infantile-onset saccade initiation delay (congenital ocular motor apraxia)

Infantile-onset saccade initiation delay, also known as congenital ocular motor apraxia, typically presents in early infancy with horizontal head thrusts once head control is achieved. Defective initiation of horizontal saccades and saccade hypometria with normal saccadic velocity are characteristic findings. Isolated impairment of vertical saccades is rare. Impaired smooth ocular pursuit may be seen. Other relatively common features include developmental delay, hypotonia, ataxia, or clumsiness. Brain MRI may be normal or show a diverse range of abnormalities, most commonly involving the cerebellum. Defective slow phases of the optokinetic response are commonly associated with brain MRI abnormalities. Isolated defect of vertical saccade initiation may indicate supratentorial brain abnormalities on MRI. Joubert syndrome, a developmental midbrain-hindbrain malformation, and ataxia telangiectasia are both commonly associated with defective volitional and reflexive saccade initiation, saccade hypometria, and head thrusts. Both horizontal and vertical saccades are impaired in these two disorders.

Neuro-Ophthalmological Findings in Children and Adolescents with Chronic Ataxia

Chronic ataxia is a challenging problem in paediatric neurology. It is caused by a multitude of disorders that at least initially have similar or non-specific phenotype. Some of these disorders have associated neuro-ophthalmological signs (N-OS). The aims of this study are to describe the N-OS and their frequencies in general and by disease aetiology in paediatric patients with chronic ataxia. The authors identified 184 patients under age 17 years with chronic ataxia (>2 months duration or recurrent) during 1991-2008 from multiple sources. Diagnoses and N-OS were ascertained following charts review. Mean age (SD) was 15 (7.7) years. Median duration of follow-up was 6.4 years. There were 214 N-OS in 115 patients (median = 2, range = 1-5 N-OS/patient). Strabismus was present in 29.3% of patients, nystagmus 27.7%, impaired smooth pursuit 23.4%, hypometric saccades 10.3%, decreased visual acuity 9.2%, abnormal optic discs 8.7%, abnormal pupillary examination 2.7%, hypermetric saccades 2.2%, impaired ductions 1.6%, and abnormal visual fields in 1.1% of patients. N-OS were reported most commonly among patients with the following disorders (commonest N-OS): hypoxic-ischaemic encephalopathy following birth (strabismus), episodic ataxia (nystagmus), neuronal ceroid lipofuscinosis (abnormal optic discs), neuronal migration disorder (strabismus), ischaemic stroke (nystagmus), Joubert syndrome-related disorders (strabismus), leukodystrophy (nystagmus), Friedreich ataxia (hypometric saccades, impaired smooth pursuit, nystagmus), mitochondrial disease (strabismus, nystagmus), ataxia telangiectasia (impaired smooth pursuit), and Angelman syndrome (strabismus). N-OS occur commonly in children with chronic ataxia. Although non-specific, they vary with disease aetiology, potentially aiding in the assessment of these patients.

Lissencephaly with brainstem and cerebellar hypoplasia and congenital cataracts

Classical lissencephaly may be associated with cerebellar hypoplasia and when significant cerebellar abnormalities occur, defects in proteins encoded by TUBA1A, RELN, and very-low-density lipoprotein receptor (VLDLR) genes have been reported. We present a neonate with a severe neurologic phenotype associated with hypotonia, oropharyngeal incoordination that required a gastric tube for feeding, intractable epilepsy, and congenital cataracts. Her brain magnetic resonance imaging (MRI) showed classical lissencephaly, ventriculomegaly, absent corpus callosum, globular and vertical hippocampi, and severe cerebellar and brainstem hypoplasia. She died at 6 weeks of age. No specific molecular diagnosis was made. This likely represents a previously undescribed genetic lissencephaly syndrome.

Novel diffusion tensor imaging findings in Krabbe disease

BACKGROUND

Krabbe disease is a lysosomal disorder that primarily affects myelin. Diffusion tensor imaging (DTI) provides quantitative information about the white matter organization and integrity. Radial diffusivity (RD) reflects myelin injury selectively.

PURPOSE

To report on quantitative DTI findings (including axial diffusivity (AD) and RD, not previously reported) in two children with Krabbe disease compared to controls.

METHODS

A quantitative region of interest (ROI) based DTI analysis was performed for the patients and age- and gender-matched controls. Fractional anisotropy (FA), mean diffusivity, AD and RD values as well as variation ratios between the patients' and controls' values were calculated for nine brain regions.

RESULTS

Two boys with Krabbe disease were included in this study. DTI data were acquired at the ages of 6.25 years and 6.5 months. For all regions, FA ratios were negative, while RD and MD ratios positive. The most elevated variation ratios were found for RD. Variation ratios were greater in the centrum semiovale, corpus callosum, and middle cerebellar peduncles than in other anatomical regions, especially in the older patient in comparison with the younger patient. The AD ratios, however, were much lower and close to zero.

CONCLUSIONS

DTI allows a quantitative evaluation of white matter damage in Krabbe disease. RD seems to be the most sensitive DTI parameter in agreement with the histopathological findings in Krabbe disease, a primary myelin disorder. This may be important in the early detection of the onset of demyelination.

The epidemiology of intermittent and chronic ataxia in children in Manitoba, Canada

AIM

To determine the epidemiology of chronic ataxia in children in Manitoba, Canada.

METHOD

A retrospective study using multiple sources and disease codes identified children (age 0-16y) with chronic ataxia (>2mo duration or recurrent episodes of ataxia) seen at Winnipeg Children's Hospital from 1991 to 2008. Patients with isolated peripheral nerve diseases, vestibular disorders, or brain tumors were excluded.

RESULTS

We identified 184 patients (males=females; mean age 15y, SD 7y 8mo) with chronic ataxia. Median age at the presenting symptom onset was 1 year 3 months and at ataxia onset 3 years 1 month. Median duration of follow-up was 6 years 5 months. During the study period, the crude incidence rate was 5.77 in 10,000; the crude prevalence rate was 6.59 in 10,000; and the crude mortality rate 0.446 in 10,000. The most common presenting symptoms were developmental delay, ataxia, or seizures. The most common diagnoses (known in 129) were Angelman syndrome (n=16), ataxia telangiectasia (n=13), mitochondrial disease (n=9), Friedreich ataxia (n=7), stroke (n=7), and familial/genetic episodic ataxia (n=7).

INTERPRETATION

Chronic ataxia is a relatively common early-presenting symptom in childhood. A specific diagnosis is possible in 70% of patients after extensive investigations. The mortality rate is relatively low and the disease burden is high with significant comorbidities including developmental delay and epilepsy.

Arterial ischemic stroke in an adolescent with presumed perinatal ischemic stroke

The risk of recurrent ischemic stroke after presumed perinatal stroke and the risk factors for such recurrence are rarely reported. Here, we present an adolescent with a history of presumed perinatal stroke who presented with arterial ischemic stroke recurrence at the age of 15 years. Hereditary thrombophilia screening performed at the time of his stroke recurrence demonstrated protein S deficiency. No evidence-based consensus guidelines on thrombophilia screening in children with presumed perinatal stroke exist, nor has the role of secondary prophylaxis been addressed. There is a risk of stroke recurrence after presumed perinatal stroke, and routine thrombophilia screening may identify those children who are at higher risk for recurrence and who might therefore benefit from secondary prophylaxis. Clear guidelines should be developed to standardize investigations and management of children with presumed perinatal ischemic stroke.

Posterior fossa decompression and the cerebellum in Chiari type II malformation: a preliminary MRI study

OBJECTIVES

Chiari type II malformation (CII) is a congenital deformity of the hindbrain. The posterior fossa and cerebellum are small in CII. The cerebellar atrophy is associated with cognitive and motor deficits. Brainstem compression occurs in some patients with CII for whom posterior fossa decompression may be life saving. The aim was to determine whether posterior fossa decompression can prevent or reduce the cerebellar atrophy in CII.

METHODS

Cerebellar volumes and their tissue types (gray matter, white matter, and CSF volumes) from brain MRI were compared among four CII patients, aged 9.5 to 16.5 years, who had had posterior fossa decompression in infancy, 28 CII patients who had not had posterior fossa decompression, and ten age-matched normal controls. Parametric and non-parametric tests investigated group differences.

RESULTS

Compared to controls, mean cerebellar volume was significantly smaller in CII patients (p<0.0001). Mean CSF volume within the cerebellar fissures and fourth ventricle was significantly smaller in patients without posterior fossa decompression compared to the CII patients who had the decompression, p=0.043. Mean CSF volume of the latter group was similar to the controls. Other cerebellar volumetric measurements did not differ between the CII groups.

CONCLUSIONS

Posterior fossa decompression normalizes CSF spaces within the posterior fossa in CII but does not prevent the cerebellar atrophy. The author proposes that surgical expansion of the posterior fossa should be considered in infants with CII who have a significantly small posterior fossa, to prevent or reduce the deficits associated with the cerebellar atrophy.

Anomalous development of brain structure and function in spina bifida myelomeningocele

Spina bifida myelomeningocele (SBM) is a specific type of neural tube defect whereby the open neural tube at the level of the spinal cord alters brain development during early stages of gestation. Some structural anomalies are virtually unique to individuals with SBM, including a complex pattern of cerebellar dysplasia known as the Chiari II malformation. Other structural anomalies are not necessarily unique to SBM, including altered development of the corpus callosum and posterior fossa. Within SBM, tremendous heterogeneity is reflected in the degree to which brain structures are atypical in qualitative appearance and quantitative measures of morphometry. Hallmark structural features of SBM include overall reductions in posterior fossa and cerebellum size and volume. Studies of the corpus callosum have shown complex patterns of agenesis or hypoplasia along its rostral-caudal axis, with rostrum and splenium regions particularly susceptible to agenesis. Studies of cortical regions have demonstrated complex patterns of thickening, thinning, and gyrification. Diffusion tensor imaging studies have reported compromised integrity of some specific white matter pathways. Given equally complex ocular motor, motor, and cognitive phenotypes consisting of relative strengths and weaknesses that seem to align with altered structural development, studies of SBM provide new insights to our current understanding of brain structure-function associations.

Upper limb cerebellar motor function in children with spina bifida

PURPOSE

To investigate upper limb cerebellar motor function in children with spina bifida myelomeningocele (SBM) and in typically developing controls.

METHODS

Participants with SBM, who had either upper level spinal lesions (n = 23) or lower level spinal lesions (n = 65), and controls (n = 37) completed four upper limb motor function tasks (posture, rebound, limb dysmetria, and diadochokinesis) under four different physical and cognitive challenge conditions. Functional independence was assessed by parental questionnaire.

RESULTS

Fewer SBM participants were able to complete the posture task, and they were less likely than controls to obtain a perfect rebound score. Participants with SBM showed impaired performance in either time, accuracy, or both, on the limb dysmetria and diadochokinesis tasks but responded like controls to physical and cognitive challenges.

CONCLUSIONS

Because upper limb motor performance predicted aspects of functional independence, we conclude that upper limb impairments in children with SBM are significant and have direct implications for the level of independent functioning in children with SBM.

Recurrent posterior circulation stroke in an infant with basilar artery aneurysm

Arterial ischemic stroke involving the posterior circulation is uncommon in children. The underlying etiologies and risk factors predisposing to posterior circulation stroke include vasculopathies, intracranial trauma, cardiac disease, infection, and hematologic disorders. However, in many children with posterior circulation stroke, the underlying mechanisms are poorly understood. We describe a 14-month-old infant with recurrent arterial ischemic stroke involving the posterior circulation secondary to an aneurysm of the basilar artery.

Early-onset neurodegenerative disease of the cerebellum and motor axons

We describe a novel hereditary neurodegenerative disease of infancy affecting an Aboriginal family from northern Manitoba, Canada. The parents are nonconsanguineous, without a family history of neurodegenerative diseases. Four of 10 siblings (three males and one female) presented with neurologic abnormalities including arthrogryposis, seizures, and severe developmental delay shortly after birth. In two children, cerebellar atrophy and mild cerebral atrophy were documented on neuroimaging. Two children, a boy who died at age 40 months and a girl who died at age 22 months, underwent muscle biopsies at 3 weeks and 4 months of age, respectively. The biopsies revealed fiber-size variability in the boy, and grouped atrophy with fiber-type grouping in the girl. Two boys who died at ages 7.5 and 37 months underwent autopsies that indicated severe atrophy of the cerebellar hemispheres (especially the inferior lobules and vermis), hypomyelination of white-matter fascicles in the striatum, severe atrophy of corticospinal tracts in the brainstem and spinal cord, and atrophy of the anterior spinal roots. In the spinal cord, motor neuron cell bodies and the posterior columns were spared. This clinical entity likely represents a novel neurodegenerative disease of the cerebellum and long motor axons.

Ketogenic diet in Alpers-Huttenlocher syndrome

We report on a young girl with Alpers-Huttenlocher syndrome, as confirmed by mitochondrial polymerase gamma sequencing, who was treated with the classic (4 parts fat:1 part each of carbohydrate and protein) ketogenic diet after she presented with epilepsia partialis continua. She improved clinically, and her electroencephalogram improved dramatically. This is the first detailed report on the efficacy of the ketogenic diet in treating the epileptic encephalopathy of Alpers-Huttenlocher syndrome. We present a literature review of the utility of a ketogenic diet in mitochondrial disorders, and speculations as to why the diet may be helpful in Alpers-Huttenlocher syndrome.

Visual fixation in Chiari type II malformation

Chiari type II malformation is a congenital deformity of the hindbrain. Square wave jerks are horizontal involuntary saccades that interrupt fixation. Cerebellar disorders may be associated with frequent square wave jerks or saccadic oscillations such as ocular flutter. The effects of Chiari type II malformation on visual fixation are unknown. We recorded eye movements using an eye tracker in 21 participants with Chiari type II malformation, aged 8 to 19 years while they fixated a target for 1 minute. Thirty-eight age-matched healthy participants served as controls. Square wave jerks' parameters were similar in the 2 groups. Saccadic oscillations were not seen. Chiari type II malformation is not associated with pathological square wave jerks or abnormal saccadic oscillations. The congenital nature of this deformity may permit compensation that preserves stable visual fixation. Alternatively, the deformity of Chiari type II malformation may spare parts of the cerebellum that usually cause fixation instability when damaged.

Square wave jerks in children and adolescents

Square wave jerks are involuntary, horizontal, saccadic intrusions that interrupt fixation. Each square wave jerk consists of an initial saccade that moves the fovea away from the intended position of fixation, followed by a second saccade in the opposite direction, which refoveates the fixation position. Square wave jerks reportedly occur in 24-60% of healthy adults. No previous study of square wave jerks in children and adolescents is available. We recorded eye movements using an infrared eye tracker in 38 participants aged 8-19 years while they fixated on a visual target for 1 minute. The frequency of square wave jerks, and the durations, amplitudes, and peak velocities of their saccades, were calculated and correlated with age. Ninety percent of participants had square wave jerks. Their median frequency was 3 per minute (range, 1-18), median duration was 249 milliseconds, the median amplitude of their saccades was 0.81 degrees, and the median peak velocity was 60 degrees/second. No parameter of square wave jerks correlated with age. The prevalence of square wave jerks is high in children and adolescents. This finding may be a feature of the less mature brain, and may reflect an inability to suppress unwanted supranuclear triggers for saccades.

The vestibulo-ocular reflex during active head motion in children and adolescents

BACKGROUND

Little information is available on the performance and maturity of the vestibulo-ocular reflex (VOR) in children and adolescents during active head motion as encountered during normal locomotion. We investigated the active VOR performance in children and adolescents to determine its norm and variation with age.

METHODS

We recorded the angular active VOR using an infrared eye tracker and a magnetic head tracker in 38 children, aged 8-19 years. Participants made sinusoidal head-on-body rotations in yaw (left-right) and pitch (up-down) at frequencies of about 0.5 and 2 Hz in the dark.

RESULTS

Mean VOR gains, the ratios of eye to head velocities, were close to unity and were significantly higher at 2 Hz than at 0.5 Hz. VOR gains did not vary with age.

CONCLUSION

The angular VOR during active head motion is functionally mature in children 8 years or older at 0.5 and 2 Hz head rotations.

Smooth ocular pursuit in Chiari type II malformation

Chiari type II malformation (CII) is a congenital anomaly of the cerebellum and brainstem, both important structures for processing smooth ocular pursuit. CII is associated with myelomeningocele and hydrocephalus. We investigated the effects of CII on smooth pursuit (SP) eye movements, and determined the effects of spinal lesion level, number of shunt revisions, nystagmus, and brain dysmorphology on SP. SP was recorded using an infrared eye tracker in 21 participants with CII (11 males, 10 females; age range 8-19y, mean 14y 3mo [SD 3y 2mo]). Thirty-eight healthy children (21 males, 17 females) constituted the comparison group. Participants followed a visual target moving sinusoidally at +/- 10 degrees amplitude, horizontally and vertically at 0.25 or 0.5Hz. SP gains, the ratio of eye to target velocities, were abnormal in the CII group with nystagmus (n= 8). The number of shunt revisions (range 0-10), brain dysmorphology, or spinal lesion level (n= 15 for lower and n= 6 for upper spinal lesion level) did not correlate with SP gains. SP is impaired in children with CII and nystagmus. Abnormal pursuit might be related to the CII dysgenesis or to effects of hydrocephalus. The lack of effect of shunt revisions and abnormal tracking in participants with nystagmus provide evidence that it is related primarily to the cerebellar and brainstem malformation.

Saccadic adaptation in Chiari type II malformation

BACKGROUND

Saccadic adaptation corrects errors in saccadic amplitude. Experimentally-induced saccadic adaptation provides a method for studying motor learning. The cerebellum is a major participant in saccadic adaptation. Chiari type II malformation (CII) is a developmental deformity of the cerebellum and brainstem that is associated with spina bifida. We investigated the effects of CII on saccadic adaptation.

METHOD

We measured eye movements using an infrared eye tracker in 21 subjects with CII (CII group) and 39 typically developing children (control group), aged 8-19 years. Saccadic adaptation was induced experimentally using targets that stepped horizontally 120 to the right and then stepped backward 3 degrees during saccades.

RESULTS

Saccadic adaptation was achieved at the end of the adaptation phase in participants in each group. Saccadic amplitude gain decreased by 6.9% in the CII group and 9.3% in the control group. The groups did not differ significantly (p = 0.27). Amplitude gain reduction was significantly less in the CII participants who had multiple shunt revisions. Regression analyses revealed no effects of spinal lesion level, presence of nystagmus, or cerebellar vermis dysmorphology on saccadic adaptation.

CONCLUSION

The neural circuits involved in saccadic adaptation appear to be functionally intact in CII.

Saccadic adaptation in children

Saccades are fast-orienting eye movements. Saccadic adaptation, a form of motor learning, is a corrective change in the amplitude of saccades in response to error. The aim of the study was to ascertain whether saccadic adaptation occurs in typically developing children. We recorded saccades with an infrared eye tracker in 39 children, aged 8 to 19 years, at baseline to 12-degree horizontal target steps and after an adaptive task. During the adaptive task, a saccadic hypometric error was induced. This task consisted of 200 12-degree target steps that stepped backward 3 degrees during the initial saccade and without the participants' awareness. The initial saccade triggered the back-step. This paradigm required a corrective reduction of the amplitude of the initial saccades in response to the induced error. Saccadic adaptation was achieved in 26 participants, whose mean saccadic amplitudes decreased by 13% (P < .05). Saccadic adaptation was not influenced by age. We conclude that children as young as 8 years old have established functions of the neural circuits responsible for the motor learning required for saccadic adaptation.

Cerebellar vermis morphology in children with spina bifida and Chiari type II malformation

OBJECTIVE

Posterior fossa size and cerebellar weight and volume are reduced in Chiari type II malformation (CII). This is assumed to affect the cerebellum uniformly. We quantified the presumed reduction in vermis size on magnetic resonance imaging (MRI).

METHODS

A midsagittal brain MRI slice was selected from each of 68 participants with CII (mean age 13 years). Control participants were 28 typically developing children (mean age 14.1 years). Midsagittal surface areas occupied by the intracranial fossa, posterior fossa, vermis, and its lobules were measured.

CONCLUSIONS

Mean posterior fossa area was significantly smaller (P<0.003), although mean vermis area was significantly larger (P<0.0001), in participants with CII than in control participants. This expansion involved vermis lobules I-V and VI-VII areas (P<0.0001). The midsagittal vermis was expanded and not reduced in size in participants with CII. This is attributed to compressive displacement of midline structures within the confines of a small posterior fossa.

Saccades in children

Saccades are necessary for optimal vision. Little is known about saccades in children. We recorded saccades using an infrared eye tracker in 39 children, aged 8-19 years. Participants made saccades to visual targets that stepped 10 degrees or 15 degrees horizontally and 5 degrees or 10 degrees vertically at unpredictable time intervals. Saccadic latency decreased significantly with increasing age, while saccadic gain and peak velocity did not vary with age. Saccadic gains and peak velocities in children are similar to reported adult values. This implies maturity of the neural circuits responsible for making saccades accurate and fast. Saccade latency decreases as the brain matures.

Saccades in children with spina bifida and Chiari type II malformation

BACKGROUND

Saccades are essential for optimal visual function. Chiari type II malformation (CII) is a congenital anomaly of the cerebellum and brainstem, associated with spina bifida.

OBJECTIVE

To investigate the effects of CII on saccades and correlate saccadic parameters with brain MRI measurements.

METHODS

Saccades were recorded in 21 participants with CII, aged 8 to 19, using an infrared eye tracker. Thirty-nine typically developing children served as controls. Participants made saccades to horizontal and vertical target steps. Nineteen participants with CII had MRI. Regression analyses were used to investigate the effects of spinal lesion level, number of shunt revisions, presence of nystagmus, and midsagittal MRI measurements on saccades.

RESULTS

Saccadic amplitude gains, asymptotic peak velocities, and latencies did not differ between the control and CII groups (p > 0.01). No significant differences were found between saccadic gains, asymptotic peak velocities or latencies, and spinal lesion level, number of shunt revisions, presence of nystagmus, or MRI measurements.

CONCLUSIONS

Saccades were normal in most participants with Chiari II malformation (CII). Neural coding of saccades is robust and is typically not affected by the anatomic deformity of CII.

Smooth pursuit eye movements in children

Smooth pursuit eye movements consists of slow eye movements that approximate the velocity of the eyes to that of a small moving target, so that target image is kept at or near the fovea. Little information on smooth pursuit is available in children. We used an infrared eye tracker to record smooth pursuit in 38 typically developing children, aged 8-19 years. Participants followed a visual target moving sinusoidally at +/-10 degrees amplitude, horizontally and vertically at 0.25 or 0.5 Hz. The mean horizontal smooth pursuit gains, the ratio of eye to target velocities, were 0.84 at 0.25 Hz and 0.73 at 0.5 Hz. Mean vertical smooth pursuit gains were 0.68 at 0.25 Hz and 0.45 at 0.5 Hz. Smooth pursuit gains were significantly lower for vertical in comparison to horizontal tracking, and for 0.5 Hz in comparison to 0.25 Hz tracking (P<0.0001). Smooth pursuit gains increased with age (P<0.01, Pearson's correlation tests), with horizontal gains attaining reported adult values by mid adolescence. Vertical gains had large variability among participants. The median phase, the time interval between eye and target velocities, varied between 39 and 86 ms. Phase was not influenced by age. We conclude that smooth pursuit gains are lower in children than gains reported in adults. Vertical pursuit gain is significantly lower than horizontal pursuit gain. Gains improve with age and approach adult values in mid adolescence. Children have larger phases than reported adults values indicating that prediction in the smooth pursuit system is less mature in children.

Pontocerebellar hypoplasia type 1: new leads for an earlier diagnosis

Pontocerebellar hypoplasia type 1 is a rare disease characterized by pontocerebellar hypoplasia and anterior horn cell degeneration. The oldest reported child died at the age of 26 months. Two siblings were diagnosed with pontocerebellar hypoplasia type 1 after the death of the second sibling at 40 months of age from respiratory failure and the unexpected finding of anterior horn cell degeneration on her autopsy. The older sibling was a boy who was labeled as having cerebral palsy. He died at 14 months of age from pneumonia following a clinical course similar to his sister's, who was born 5 years after his death. Both siblings had significant global developmental delay with axial and peripheral hypotonia initially. Peripheral hypertonia with brisk reflexes developed later but were absent prior to death. Extensive investigations in the second sibling ruled out known metabolic (including congenital disorders of glycosylation) and mitochondrial diseases using skin fibroblast cultures and enzyme analysis. Genetic testing for Friedreich's ataxia; neuropathy, ataxia, and retinitis pigmentosa (NARP); spinal muscular atrophy; and spinocerebellar ataxia type 1, 2, 3, 6, 7, and 8 gene abnormalities was negative. The elecroretinogram showed a previously unreported finding of abnormal and progressive rod/cone response. Our cases provide clinical and previously unreported electroretinographic evidence for neurodegeneration in pontocerebellar hypoplasia type 1 and call for the expansion of the disease phenotype.

New insights into the neuropathogenesis of molybdenum cofactor deficiency

BACKGROUND

Molybdenum cofactor deficiency (MOCOD) is a rare, progressive neurodegenerative disorder caused by sulphite oxidase enzyme deficiency. The neuropathological findings are consistent with a toxic insult to the brain that causes severe neuronal loss, reactive astrogliosis and spongiosis. The mechanisms responsible for these changes are unknown.

METHODS

The case is a male infant with MOCOD who died at nine months of age from pneumonia. At autopsy, a complete neuropathological examination was performed including conventional immunohistochemical staining. In addition, brain sections were stained cytochemically with shikata and orcein which stain for disulphide bonds. The elemental composition of cortical cells was then analyzed in the scanning electron microscope using backscatter electron imaging and energy dispersive X-ray spectrometry.

RESULTS

Neurons demonstrated cytoplasmic staining with shikata and orcein cytochemically when compared to control sections. Energy dispersive X-ray spectrometry analysis of these neurons confirmed the presence of excess sulphur and unexpectedly revealed excess magnesium accumulation. None of these findings was found in an age-matched control.

CONCLUSIONS

In MOCOD we found abnormal accumulation of sulphur and magnesium in neurons. It is postulated that sulphur-containing compound(s) that are formed as a result of MOCOD cause excitotoxic neuronal injury in the presence of excess magnesium.

The cerebellum: it's about time! But timing is not everything--new insights into the role of the cerebellum in timing motor and cognitive tasks

Converging evidence from different research studies supports a role for the cerebellum in timing neural processes. The cerebellum is part of a distributed system for motor control. The timing hypothesis provides a specific functional role for the unique contribution of the cerebellum. The timing capabilities of the cerebellum appear to extend beyond motor control into tasks focusing on perceptual processing that require the precise representation of temporal information and sensorimotor learning. Behavioral and modeling studies suggest that the cerebellar timing system is best characterized as providing a near-infinite set of interval-type timers rather than as a single clock with pacemaker or oscillatory properties, but this is controversial. In addition to learning precisely timed motor responses, the cerebellum is involved in on-line processing using feed-forward systems for which sensory input is used prior to movement execution to improve movement accuracy. This would be a mechanism for triggering accurate "time." The cerebellum continues to fascinate scientists, and although survival is possible without the cerebellum, the resultant quality of life is significantly compromised with clumsiness, ataxia, hypotonia, dysarthria, slowing of various cognitive perceptual processes, and impaired fine motor and ocular-motor coordination. The last three decades have seen the development of research that has focused on how the cerebellum functions. Further neurophysiologic research in cerebellar cortical neurotransmission is likely to further our understanding of the cerebellar contribution to timing sensorimotor processes.

Should children with Bell's palsy be treated with corticosteroids? A systematic review

The objective of this study was to evaluate the effect of corticosteroids in the treatment of pediatric Bell's palsy. A systematic review of trials that included pediatric (< 16 years old) cases with Bell's palsy and involved the use of steroids was conducted. Eight trials were identified, five of which were randomized, and prednisone was used in six trials, whereas corticotropin was used in the other two. The methods of randomization and allocation concealment of the treatments used were rarely reported. Only one trial was done exclusively in children; none of the other seven trials analyzed the pediatric cases separately. Four trials reported some benefit from steroids. The pediatric trial did not provide evidence for benefit from corticosteroids. There was substantial heterogeneity in the population and interventions used; hence a meta-analysis was not done. Based on this systematic review, we do not recommend the routine use of steroids in children with Bell's palsy.

Idiopathic "benign" intracranial hypertension: case series and review

Idiopathic "benign" intracranial hypertension is an uncommon but important cause of headache that can lead to visual loss. This study was undertaken to review our experience in the diagnosis and management of idiopathic intracranial hypertension, giving special attention to treatments used. A retrospective chart review was conducted on 32 patients diagnosed with idiopathic intracranial hypertension between 1984 and 1995. Subjects included 23 females and ranged in age from 2 to 17.5 years. Headache was the most common symptom, followed by nausea and vomiting, double vision, and visual loss. Papilledema was the most common sign. Others were VIth cranial nerve palsy and compromised visual acuity at or within 3 months of presentation. Management included administration of acetazolamide or corticosteroids, lumboperitoneal shunt, optic nerve fenestration, and repeat lumbar puncture. Treatment combinations were used in 40% of cases. During follow-up, headache, papilledema, and decreased visual acuity persisted for longer than 10 months in a significant number of patients. We conclude that idiopathic intracranial hypertension causes significant short- and long-term morbidity with no proven effective treatment available. A prospective study is needed to establish the indications for treatment and the efficacy of the treatments used.

Peripheral and autonomic nervous system involvement in chronic GM2-gangliosidosis

GM2-gangliosidosis (McKusick 268800 and 272800) is a rare hereditary, progressive disorder of ganglioside metabolism caused by deficiency of lysosomal beta-hexosaminidase (EC 3.2.1.52) activity. It is characterized by severe central nervous system involvement. Involvement of the peripheral and autonomic nervous system has been suspected but rarely documented in published case reports in the chronic form of the disease. Four patients, aged 24-29 years, with chronic GM2-gangliosidosis were examined prospectively for evidence of peripheral and autonomic nervous system dysfunction. All had nerve conduction studies, sympathetic skin responses and cardiac monitoring during the head tilt-table test. Three patients had objective evidence of autonomic dysfunction with abnormal sympathetic nervous skin responses and axonal sensorimotor polyneuropathy. None of the patients had evidence of significant cardiovascular autonomic dysfunction on the head tilt-table test. The peripheral and autonomic nervous system may be involved in patients with chronic GM2-gangliosidosis. In some cases, this may be clinically significant. On the other hand, cardiovascular autonomic instability is apparently not a significant problem in young adult patients with the disease.

Is the prophylactic use of antiepileptic drugs in Sturge-Weber syndrome justified?

Sturge-Weber syndrome (SWS) is a rare neurocutaneous syndrome. Epilepsy is one of its most common features and is usually the first neurological manifestation. Adequate control of epilepsy assumes major importance in SWS as the early onset of seizures and severe seizures are associated with developmental regression and hemiparesis. Recent advances in neuroimaging have helped in making preclinical and early diagnosis in SWS. The author proposes treating newly diagnosed patients with severe SWS with antiepileptic drugs (AEDs) before the onset of epilepsy. This may help prevent the development of hemiplegia and the developmental problems that may ensue.