Neuro-ophthalmological evaluation of patients with myelomeningocele and Chiari malformations

Prevalence of neurological involvement and malformative/systemic syndromes in A- and V-pattern strabismus

PURPOSE

To evaluate the prevalence of neurological involvement and malformative/systemic syndromes in A- and V-patterns with respect to other kinds of infantile concomitant strabismus.

METHODS

A retrospective comparative study of 14,006 consecutive patients examined in the Pediatric Ophthalmology and Strabismus Unit at the Catholic University of Rome between January 2002 and February 2010 was carried out. A total of 2.72% (385) of patients presented with concomitant constant infantile strabismus associated with A- and V- patterns (study group; mean age 8 years; range: 8 months - 37 years; male 211, female 174). Another 377 consecutive patients affected by infantile concomitant strabismus without A- or V- patterns were used as controls (control group; mean age 9 years, range: 1-34 years; male 194, female 183). All patients underwent a complete ophthalmologic and orthoptic examination with ocular motility evaluation and prism cover test or the Hirschberg test in primary, up and down gaze positions, as well as cycloplegic retinoscopy. The angle of deviation was evaluated at near (33 cm) and distance fixation (6 m) with full correction of refraction.

RESULTS

Neurological involvement and malformative/systemic syndromes were observed in 30.4% of the study group and in 19.8% of patients in the control group (P < 0.001). Patients with A-pattern showed a greater prevalence of neurological impairment, hydrocephalus and meningomyelocele, while those affected by V-pattern exhibited a greater prevalence of craniosynostosis and malformative syndromes.

CONCLUSIONS

Neurological involvement and malformative/systemic syndromes seem to be more evident in patients presenting with A- and V-pattern strabismus.

Vestibular evoked myogenic potentials in children affected by myelomeningocele

PURPOSE

The aim of the present study is to establish if the vestibular evoked myogenic potentials (VEMPs) could be used as a clinical test for the evaluation of vestibular function in children affected by myelomeningocele (MMC).

MATERIALS AND METHODS

Fifteen children, aged between 3 and 17 years, who had been affected by MMC were investigated. Data obtained from these children were compared with normal data from healthy children of the same age. Electromyographic activity of sternocleidomastoid muscle was recorded, while children were laid supine and asked to raise their head off the bed in order to activate their neck flexors bilaterally. The saccular receptors were acoustically stimulated with a logon of 500 Hz at an intensity of 130 dB peSPL presented monaurally through earphones. In each recording, we analyzed latencies and amplitudes of the p13-and n23 waves and the amplitude ratio between the two ears.

RESULTS

VEMPs were detected to be normal in 13 patients. In particular, the mean p13 and mean n23 latencies were 15.7 (±1.4) and 21.7 (±1.1) ms, respectively; the mean amplitude value was 84.7 (±36.6), while the mean amplitude ratio was 17.4 (±12). A comparison of latencies and amplitude ratios between the children and healthy control group did not reveal any significant difference. On the contrary, a comparison of amplitude values between the two groups showed significant differences.

CONCLUSION

In conclusion, vestibulocollic reflex is normal in patients affected by MMC, and VEMPs could represent a valid and noninvasive technique eligible to investigate the vestibular functions in these children.

Cerebellar motor function in spina bifida meningomyelocele

Spina bifida meningomyelocele (SBM), a congenital neurodevelopmental disorder, involves dysmorphology of the cerebellum, and its most obvious manifestations are motor deficits. This paper reviews cerebellar neuropathology and motor function across several motor systems well studied in SBM in relation to current models of cerebellar motor and timing function. Children and adults with SBM have widespread motor deficits in trunk, upper limbs, eyes, and speech articulators that are broadly congruent with those observed in adults with cerebellar lesions. The structure and function of the cerebellum are correlated with a range of motor functions. While motor learning is generally preserved in SBM, those motor functions requiring predictive signals and precise calibration of the temporal features of movement are impaired, resulting in deficits in smooth movement coordination as well as in the classical cerebellar triad of dysmetria, ataxia, and dysarthria. That motor function in individuals with SBM is disordered in a manner phenotypically similar to that in adult cerebellar lesions, and appears to involve similar deficits in predictive cerebellar motor control, suggests that age-based cerebellar motor plasticity is limited in individuals with this neurodevelopmental disorder.

The cerebellar dysplasia of Chiari II malformation as revealed by eye movements

INTRODUCTION

Chiari type II malformation (CII) is a developmental deformity of the hindbrain. We have previously reported that many patients with CII have impaired smooth pursuit, while few make inaccurate saccades or have an abnormal vestibuloocular reflex. In contrast, saccadic adaptation and visual fixation are normal. In this report, we correlate results from several eye movement studies with neuroimaging in CII. We present a model for structural changes within the cerebellum in CII.

METHODS

Saccades, smooth pursuit, the vestibulo-ocular reflex, and visual fixation were recorded in 21 patients with CII, aged 8-19 years and 39 age-matched controls, using an infrared eye tracker. Qualitative and quantitative MRI data were correlated with eye movements in 19 CII patients and 28 controls.

RESULTS

Nine patients with CII had abnormal eye movements. Smooth pursuit gain was subnormal in eight, saccadic accuracy abnormal in four, and vestibulo-ocular reflex gain abnormal in three. None had fixation instability. Patients with CII had a significantly smaller cerebellar volume than controls, and those with normal eye motion had an expanded midsagittal vermis compared to controls. However, patients with abnormal eye movements had a smaller (non-expanded) midsagittal vermis area, posterior fossa area and medial cerebellar volumes than CII patients with normal eye movements.

CONCLUSIONS

The deformity of CII affects the structure and function of the cerebellum selectively and differently in those with abnormal eye movements. We propose that the vermis can expand when compressed within a small posterior fossa in some CII patients, thus sparing its ocular motor functions.

Nonsurgical treatment for esotropia secondary to Arnold-Chiari I malformation: A case report

A 14-year-old girl with diplopia and esotropia secondary to Arnold-Chiari I malformation was surgically treated with Arnold-Chiari I malformation decompression (suboccipital craniectomy), C1 and partial C2 laminectomy, and duraplasty. The residual esotropia was treated with compensatory prisms and vision therapy more than 1 year after Arnold-Chiari malformation surgery. The esotropia was resolved after approximately 3.5 months of treatment. Five years later, the patient continued to maintain fusion without compensatory prism.

Longterm oculomotor and visual function in spina bifida cystica: a population-based study

PURPOSE

To document and describe the development from birth of visual and oculomotor functions in a group of children with spina bifida cystica (myelomeningocele and myeloschisis [MMC]). The emphasis in this study is on findings at 12-14 year follow-up.

METHODS

Twenty children aged 12-14 years with myelomeningocele and Chiari-related malformations were examined by an orthoptist and a paediatric ophthalmologist. A further child who did not wish to participate actively in the study is also reported. Visual acuity for near and distance, refractometer readings in cycloplegia, the presence of ocular motility disorders and nystagmus were recorded. Accommodation, convergence, colour vision and stereo acuity were assessed and the fundus and media were examined.

RESULTS

Six children (29%) in the study group had subnormal vision, although no child was visually impaired. Eleven (52%) showed manifest strabismus and 17 (81%) had a significant refractive error. Near visual acuity was normal in nearly all the children, but accommodation was defective in 10. Nine children had nystagmus and two had optic atrophy. No visual field defects were found.

CONCLUSIONS

The high incidence of ocular disturbances in children with spina bifida highlights the importance of regular ophthalmological investigation and follow-up.

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.

Peripersonal spatial attention in children with spina bifida: associations between horizontal and vertical line bisection and congenital malformations of the corpus callosum, midbrain, and posterior cortex

Horizontal and vertical line bisection was studied in 129 children and adolescents between 8 and 19 years of age, one group (n=32) of typically developing controls and one group (n=97) with spina bifida (SBM), a neurodevelopmental disorder associated with dysmorphology of the corpus callosum, posterior cortex, and midbrain. For each participant, structural brain MRIs were analyzed qualitatively to identify beaking of the midbrain tectum and corpus callosum agenesis and hypoplasia and quantitatively by segmentation and volumetric analyses of regional cortical white and gray matter. Each group showed the line length effect, whereby greater estimation errors are made with longer lines. The group with SBM differed from controls in terms of both accuracy and variability of line bisection. Children with SBM showed pseudoneglect, attending more than controls to left hemispace. The extent of rightward bisection bias was unrelated to right posterior brain volumes, although an intact corpus callosum during development moderated and normalized the exaggerated leftward line bisection bias. More children with SBM than controls attended to inferior hemispace. A normal midbrain and greater posterior cortex volume during development moderated and normalized the downward bias. Children with SBM showed more intra-subject variability than controls. Line bisection in children with SBM reflects three deficits: an exaggerated attentional bias to left hemispace, an abnormal attentional bias to inferior hemispace; and a larger zone of subjective uncertainty in bisection judgments.

Does posterior fossa decompression improve oculomotor and vestibulo-ocular manifestations in Chiari 1 malformation?

BACKGROUND

Oculomotor and vestibulo-ocular manifestations are associated with Chiari 1 malformation. Reports of the results of decompression of CM1 in resolution of these manifestations are limited.

METHODS

A retrospective review of case notes were undertaken from Jan 1998 to March 2003 of all the cases undergoing posterior fossa decompressions by the senior author. Forty patients were identified of which 12 had oculomotor and vestibulo-ocular manifestations.

RESULTS

Oculomotor and vestibulo-ocular symptoms were present in seven patients and eleven patients had clinical signs. There were only 2 patients who had symptoms and no objective findings. There was complete resolution of oculomotor and vestibulo-ocular manifestations in 8/12 patients and partial improvement in another one, leading to improvement in 9/12 patients. The mean time span to complete resolution was 15.5 months (range 3-71 months).

CONCLUSION

Posterior fossa decompression appears to be highly effective in causing complete resolution of disabling oculomotor and vestibule-ocular manifestations in most cases of CM1.

Isolated comitant esotropia and Chiari I malformation

PURPOSE

To report four patients with isolated comitant esotropia and Chiari I malformation and discuss the most appropriate management.

METHODS

Case reports and literature review.

RESULTS

All four patients (5, 14, 16, and 37 years of age) presented with an isolated comitant esotropia that led to the diagnosis of Chiari I malformation. The first two patients underwent uncomplicated neurosurgical decompression of their malformation, followed by complete resolution of their esotropia. The third patient underwent strabismus surgery and experienced initial resolution of the esotropia, but eventual recurrence resulted in the strabismus surgery being repeated 5 years later. The fourth patient had strabismus surgery with resolution of the esotropia but only 2 months of follow-up.

CONCLUSION

Although management of patients with Chiari I malformation and severe neurologic findings typically includes surgical decompression, management is less straightforward in cases with subtle findings or in which ocular findings are isolated. The decision to perform neurosurgical decompression or strabismus surgery should still be made on a case-by-case basis, with the understanding that strabismus surgery may provide only temporary ocular alignment.

Oculographic and clinical characterization of thirty-seven children with anomalous head postures, nystagmus, and strabismus: the basis of a clinical algorithm

BACKGROUND AND PURPOSE

We studied children with nystagmus who also had anomalous head postures and strabismus to determine the etiology of the conditions and present a diagnostic clinical algorithm.

METHODS

The patients for this study were among the 560 patients evaluated in the ocular motor neurophysiology laboratory between the years 1991 and 1997. Clinical characteristics, infrared oculography data, and medical and surgical treatments were entered into a database for analysis. Oculography was performed on all patients according to a standard protocol, and data were stored and analyzed off-line. Etiology of anomalous head posture was determined with both clinical and oculography information.

RESULTS

Thirty-seven children are the subjects of this report. The etiology of anomalous head posture was a "gaze null" due to congenital nystagmus in 23 (62%) patients, an "adduction null" due to manifest latent nystagmus in 12 (32%) patients, spasmus nutans in 1 (3%) patient, and strabismus in 1 (3%) patient. The patients' ages ranged from 9 months to 12 years and averaged 4.4 years. Sixty-nine percent were male patients. Nineteen (63%) of 30 patients had abnormal recognition (linear optotype) acuity in at least 1 eye on monocular cover; the recognition remained abnormal in 5 (17%) of 30 patients under binocular conditions. Thirty percent of patients had amblyopia, 16% had some structural disease of the eyes, 22% had some systemic syndrome or abnormality, 57% had a significant refractive error, and 27% had some ability to fuse.

CONCLUSIONS

The major etiology for anomalous head posture in these patients was to adopt a gaze null due to congenital nystagmus (62% of patients) regardless of the direction of their anomalous head posture or type of strabismus. Moving the fixing eye as the first step for the anomalous head posture, combined with moving the nonfixing eye for the resulting strabismus may help treat these patients.

Intact binocular function and absent ocular torsion in children with alternating skew on lateral gaze

BACKGROUND

A form of skew deviation, called alternating skew on lateral gaze, resembles bilateral superior oblique overaction. Oblique muscle overaction has been recently speculated to result from loss of fusion with subsequent "free-wheeling" of the torsional control mechanisms of the eyes, causing sensory intorsion or extorsion with attendant superior or inferior oblique muscle overaction, respectively. We wanted to investigate whether loss of fusion plays a role in the pathogenesis of alternating skew on lateral gaze.

SUBJECTS AND METHODS

We examined seven consecutive patients with posterior fossa tumors, enrolled in a multi-disciplinary pediatric neuro-oncology program, who displayed alternating skew on lateral gaze. All patients underwent a thorough ophthalmologic evaluation.

RESULTS

Visual acuities in the study patients ranged from 20/20 to 20/40. Five of the seven patients were orthotropic, and showed 40 sec of arc stereopsis. Three patients showed associated downbeat nystagmus. No ocular torsion was found in any of the five patients who showed normal stereopsis upon inspection of fundus landmarks on indirect ophthalmoscopy.

CONCLUSION

Patients with alternating skew on lateral gaze often have normal binocular vision and stereopsis, and lack ocular intorsion so typical of superior oblique overaction. Alternating skew on lateral gaze is neurologically mediated, with no role for defective fusion in its pathogenesis.

On infantile esotropia with nystagmus in abduction

Infantile esotropia with nystagmus in abduction is characterized by early onset, jerk nystagmus in abduction, and dissociated vertical deviation, among other features. Electro-oculographic tracings present easily recognizable patterns both in saccadic and pursuit movements. Visual evoked responses are asymmetric in most cases and optokinetic nystagmus is invariably asymmetric. Visual cortex maldevelopment seems to play a major pathogenic role. Recent findings in myelomeningocele and in patients with posterior fossa tumors suggest that pathological alterations in this area may tend to induce similar anomalies in electro-oculographic and optokinetic nystagmus recordings. Posterior fossa damage or impairment is therefore suspected to be a possible causative factor in the development of infantile esotropia with nystagmus in abduction.

The prevalence of neurologic dysfunction in children with strabismus who have superior oblique overaction

BACKGROUND

Children with certain neurologic diseases (hydrocephalus, meningomyelocele, or cerebral palsy) have been reported to manifest a high frequency of A-pattern strabismus and superior oblique overaction. However, it is not generally recognized whether children with strabismus who have superior oblique overaction are more likely to have concurrent neurologic diseases than those without superior oblique overaction. In this study, the authors examine this issue.

METHODS

The authors retrospectively reviewed the medical records of all patients (n = 168) with overdepression of the downturned eye in adduction, who were examined between October 1989 and March 1992. A randomly selected population of children with strabismus who did not have overdepression of the eye on infraduction and adduction served as controls (n = 98). Patients with simulating or confounding conditions such as pseudo-superior oblique overaction, inferior rectus skew deviation (alternating skew on lateral gaze), and restrictive or paralytic strabismus, and who were older than 20 years of age, were excluded.

RESULTS

One hundred twelve patients with true superior oblique overaction were analyzed. Of these 112 patients, 45 (40.2%) had concurrent neurologic abnormalities, compared with less than one fifth (17.3%) of control subjects (17 of 98) (P < or = 0.001).

CONCLUSIONS

Children with strabismus who have superior oblique overaction were found to have higher prevalence of concurrent neurologic diseases than control subjects. Superior oblique overaction may represent a clinical marker for an associated neurologic dysfunction, possibly representing a form of skew deviation in some cases.

Oscillopsia and horizontal nystagmus with accelerating slow phases following lumbar puncture in the Arnold-Chiari malformation

Oscillopsia and nystagmus began in a woman 2 weeks after an inadvertent lumbar puncture during anesthesia for childbirth. Examination showed horizontal-torsional jerk nystagmus in all positions of gaze. Magnetic-search-coil oculography revealed accelerating slow phases, with an increase in nystagmus amplitude in darkness. Magnetic resonance images showed type 1 Arnold-Chiari malformation. Three months after occipital decompressive surgery, nystagmus had almost disappeared. Accelerating slow phases should not be considered diagnostic of congenital nystagmus, especially with an onset of oscillopsia in adult life; imaging should be considered to exclude treatable hindbrain anomalies. Lumbar puncture in patients with the Arnold-Chiari malformation may accentuate craniospinal pressure dissociation and precipitate neurological signs.

Ophthalmic assessment of physically disabled children attending a rehabilitation centre

A retrospective analysis was conducted of 397 children, ranging in age from 2 to 19 years, attending the Regency Park Centre for Young Disabled in Adelaide. The disorders represented included cerebral palsy, head injury, spina bifida, severe speech and/or language disorders, muscular dystrophy and a number of less common conditions. The incidence of significant ophthalmic abnormalities in this population was 51%, with the highest incidence being 69 and 62% among children with head injury and cerebral palsy, respectively. Children with severe speech and language disorders had an incidence of 24%. Overall, routine examinations revealed previously unsuspected significant eye abnormalities in 31% of the children. A complete ophthalmic examination should be part of the evaluation of all physically disabled children to ensure early identification and treatment of abnormalities, and to optimize rehabilitation.

Alternating skew on lateral gaze. Neuroanatomic pathway and relationship to superior oblique overaction

BACKGROUND

Previous studies of patients with heterogeneous, often diffuse neurologic disorders concluded that the neurologic substrate for alternating skew on lateral gaze may be localized at the level of the brain stem tegmentum or the cervico-medullary junction, or both. The localized nature of brain tumors offers an opportunity to further investigate the anatomic localization for this as well as other conditions.

METHODS

To test the hypothesis that cervico-medullary and cerebellar lesions are responsible for alternating skew on lateral gaze, the authors investigated a series of 50 children with brain tumors, 39 of whom showed neuro-ophthalmologic abnormalities on clinical testing. Seven children had alternating skew on lateral gaze.

RESULTS

All seven children with alternating skew on lateral gaze showed neoplastic involvement at the level of the cervico-medullary junction and/or the cerebellum on critical analysis of neuro-imaging studies.

CONCLUSION

The authors conclude that the neuroanatomic substrate for alternating skew on lateral gaze is localized at the level of the cervico-medullary junction and/or the cerebellum. Knowing that (1) alternating skew on lateral gaze closely mimics superior oblique overaction clinically, (2) superior oblique overaction is frequently found in patients with myelomeningocele, and (3) myelomeningocele is uniformly associated with Arnold-Chiari type II which includes cerebellar and cervico-medullary region abnormalities, the authors propose that alternating skew on lateral gaze and superior oblique overaction associated with myelomeningocele have similar neuroanatomic pathways.

Neuro-ophthalmological findings in relation to CNS lesions in patients with myelomeningocele

Twenty-eight patients (14 male, 14 female; aged four to 34 years) with myelomeningocele were studied. Magnetic resonance imaging was used to determine the correlation between disturbances of ocular motility and the degree of hydrocephalus, tectal plate deformity and dislocation of the cerebellum and medulla oblongata. All patients had Chiari malformations. Strabismus and spontaneous nystagmus were strongly related mainly to the degree of hydrocephalus and to some extent to the amount of lower brainstem deformities. Ocular motility defects with regard to oblique muscle functions and horizontal and vertical gaze and saccadic control often correlated with lower brainstem lesions. Convergence defects correlated with deformities of the upper brainstem. However, these correlations were not valid in the individual patient; some had no strabismus and normal ocular motility, in spite of advanced hydrocephalus and Chiari malformations.