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Biomedical subjects

G W Cibis

Publications and source records attributed to G W Cibis.

At least 19 recordsLinked to original sources
PubMed2000

Electroretinography is necessary for spasmus nutans diagnosis.

The purpose of the present study was to determine whether that which clinically appeared to be spasmus nutans could actually represent retinal sensory deficits diagnosable by electroretinography. Eight patients clinically thought to have spasmus nutans underwent electroretinography according to international standards. Five had normal electroretinograms and represented cases of true spasmus nutans. Three patients had abnormal electroretinograms, indicating that they did not have spasmus nutans. The clinical findings used to diagnose spasmus nutans can be simulated by retinal dystrophies. A normal electroretinogram is needed to confirm the diagnosis of spasmus nutans.

Case-Control Studies↗
PubMed2000

Clinical and electroretinographic findings in fetal alcohol syndrome.

PURPOSE: Fetal exposure to alcohol is a serious public health problem and is associated with anomalies of the eye ground, as well as neurodevelopmental delay, growth delay, and characteristic facial features. Our purpose is to report the incidence of abnormal electroretinogram (ERG) results in children with fetal alcohol syndrome and raise awareness of the diagnosis of fetal alcohol syndrome in ophthalmology. METHODS: A retrospective review was performed on the records of 11 children with the diagnosis of fetal alcohol syndrome. The results of the ophthalmologic examination, magnetic resonance imaging, visual acuity test, and ERG are reported. RESULTS: The magnetic resonance imaging results were abnormal in all subjects tested. The ophthalmology examination showed optic nerve hypoplasia in 91% of the subjects. Visual acuity was reduced in all but one subject. The ERG results were abnormal, showing reduced b-wave amplitude, increased a- and b-wave implicit time, reduced Rmax, and increased log (k). The scotopic ERG was more severely affected than the photopic ERG. CONCLUSIONS: Prenatal alcohol exposure can lead to changes in retinal function as evidenced by an abnormal ERG response. The ERG can therefore be a tool with which to identify suspected alcohol embryopathy.

Abnormalities, Multiple↗
PubMed1999

ERG phenotype of a dystrophin mutation in heterozygous female carriers of Duchenne muscular dystrophy.

PURPOSE: Mutations in the dystrophin gene result in Duchenne muscular dystrophy (DMD). DMD is associated with an abnormal electroretinogram (ERG) if the mutation disrupts the translation of retinal dystrophin (Dp260). Our aim was to determine if incomplete ERG abnormalities would be associated with heterozygous carriers of dystrophin gene mutations. METHODS: Ganzfeld ERGs were obtained under scotopic and photopic testing conditions from a family which includes the heterozygous maternal grandmother, the heterozygous mother, and her children, two affected boys and dizygotic twin sibs, an unaffected male and heterozygous female. Southern blot analyses were done to characterise the dystrophin mutation. RESULTS: The dystrophin gene was found to contain a deletion encompassing exon 50. The ERGs in the two affected boys were abnormal, consistent with the DMD ERG phenotype. Serial ERGs of the heterozygous females were abnormal; however, they were less severely affected than the DMD boys. The ERG of the female sib showed a greater abnormality than her mother and maternal grandmother. The unaffected twin had a normal ERG. CONCLUSIONS: The ERG shows abnormalities associated with carrier status in this family with a single exon deletion. A large study of confirmed obligate carriers is planned to clarify further the value of the ERG in detecting female heterozygous carriers of dystrophin gene mutations.

Adult↗
PubMed1998

Comitant strabismus.

Proprioceptive receptors have long been known anatomically to be present in extraocular muscles, specifically at the myotendinous junction. Their function in regulating smooth pursuits is experimentally demonstrated. The clinical significance of this for strabismus is still unknown. Esotropia surgery before resolution of moderate amblyopia is not detrimental. Botulinum toxin injections will correct infantile esotropia but require more anesthesia sessions overall than does conventional surgery, increasing cost. Late-onset comitant esotropia is usually refractive in nature and rarely neurologic. Comitant esodeviation is also prevalent in children with known neurologic insults. In both situations, it is the associated neurologic signs that point to the underlying neurologic cause. Posterior fixation suture will correct a high accommodative convergence/accommodation ratio esotropia. Exotropia negatively affects patients' quality of life. Surgical outcomes differ in patients whose angle of deviation increases with 1 hour of occlusion testing at extreme distances ("outdoor sensitivity"). Recession resection influences the distance and near angles of deviation equally whereas bilateral lateral rectus resection influences the distance deviation more than the near. Spray administration of cycloplegic agents to closed eyelids has been shown to be as effective as administration of eye drops. The spray is much better tolerated by patients and easier to administer. Photorefraction, although not yet effective as a screening tool, is useful to document alignment and refractive errors.

Administration, Topical↗
PubMed1997

A deletion polymorphism due to Alu-Alu recombination in intron 2 of the retinoblastoma gene: association with human gliomas.

The retinoblastoma gene (RB) encodes a tumor suppressor that is inactivated in a number of different types of cancer. We searched for gross alterations of this gene in tumors of the central nervous system by using Southern blot hybridization. A common alteration was found in several tumors and was mapped to the region around exon 2. Nucleotide sequencing showed that the alteration was caused by a 799-bp deletion in intron 2 of the RB gene and was probably due to homologous recombination between two Alu repeats. Deletions of this type have not been found previously in the RB gene. The deletion turned out to be a polymorphism with an allele frequency estimated at 2.2% in 185 patients without cancer. The deletion was found in five of 48 patients with brain tumors (allele frequency of 5.2%). This difference is not statistically significant (P = 0.149, Fisher's exact test). Confining the analysis only to glioma brain tumors revealed a statistically significant difference compared with the cancer-free patient controls (P = 0.027, Fisher's exact test). Further study is needed to determine if the deletion is a weak brain cancer-predisposing mutation or a harmless polymorphism. Finding this mutation in a tumor and the germline DNA of a retinoblastoma patient could lead to incorrect estimation of the heritability of a tumor.

Base Sequence↗
PubMed1996

Discordant Duane's retraction syndrome in monozygotic twins.

PURPOSE: To evaluate whether differences in the intrauterine environment caused discordant Duane's retraction syndrome in monozygotic twins. METHODS: Pathology records were reviewed to determine monozygosity. RESULTS: Discordant Duane's retraction syndrome was present in twin boys with identical genetic foundations who had different intrauterine environments. The placenta indicated areas of anastomosis between the two umbilical cords suggestive of twin-to-twin transfusion that resulted in a visible growth discordance. CONCLUSIONS: Intrauterine environment influences ocular development, and twin-to-twin transfusion may cause Duane's retraction syndrome.

Diseases in Twins↗
PubMed1995

Abnormal electroretinogram associated with developmental brain anomalies.

PURPOSE: We have encountered abnormal ERGs associated with optic nerve hypoplasia, macular, optic nerve and chorioretinal colobomata and developmental brain anomalies. Brain anomalies include cortical dysgenesis, lissencephaly, porencephaly, cerebellar and corpus callosum hypoplasia. We describe six exemplar cases. METHODS: Scotopic and photopic ERGs adherent to international standards were performed as well as photopic ERGs to long-duration stimuli. CT or MRI studies were also done. The ERGs were compared to age-matched normal control subjects. RESULTS: ERG changes include reduced amplitude b-waves to blue and red stimuli under scotopic testing conditions. Implicit times were often delayed. The photopic responses also showed reduced amplitude a- and b-waves with implicit time delays. The long-duration photopic ERG done in one case shows attenuation of both ON- and OFF-responses. CONCLUSIONS: Common underlying developmental genetic or environmental unifying casualties are speculated to be at fault in causing these cases of associated retinal and brain abnormalities. No single etiology is expected. Multiple potential causes acting early in embryogenesis effecting neuronal induction, migration and differentiation are theorized. These occur at a time when brain and retinal cells are sufficiently undifferentiated to be similarly effected. We call these cases examples of Brain Retina Neuroembryodysgenesis (BRNED). Homeobox and PAX genes with global neuronal developmental influences are gene candidates to unify the observed disruption of brain and retinal cell development. The ERG can provide a valuable clinical addition in understanding and ultimately classifying these disorders.

Brain↗
PubMed1994

Optic nerve hypoplasia in association with brain anomalies and an abnormal electroretinogram.

Abnormal electroretinograms (decreased amplitude and prolonged implicit time > 2 standard deviations) in several patients with optic nerve hypoplasia (ONH) and developmental brain anomalies led us to study the electroretinogram (ERG) in 34 consecutive cases of ONH presenting to our practice. Ages of the subjects were between 7 months and 13 years (mean, 4 years). ERGs were recorded from each eye by means of a contact lens electrode and ganzfeld stimuli. Rod-dominated dark-adapted responses were recorded as well as cone-dominated light-adapted responses. When clinically indicated, brain imaging by either computed tomography (CT) or magnetic resonance imaging (MRI) was performed. The ERG was abnormal in 12 (35%) of the children, including five (42%) with unilateral ONH. Imaging studies of the brain in 12 children with ONH and an abnormal ERG disclosed brain malformations in nine (75%) of them compared to five (23%) in the group with ONH and a normal ERG. An abnormal ERG associated with ONH and brain malformations may represent retinal or transsynaptic degeneration beyond the ganglion cell layer and implies a shared causative mechanism.

Adolescent↗
PubMed1994

Retinal signal transmission in Duchenne muscular dystrophy: evidence for dysfunction in the photoreceptor/depolarizing bipolar cell pathway.

There have been reports of abnormal retinal neurotransmission determined by electroretinography in boys with Duchenne and Becker muscular dystrophy. Dystrophin may play a role in transmitting signals between photoreceptors and the excitatory synapse of the ON-bipolar cell. These electroretinographic changes appeared to be limited to the rod ON-pathway but we felt there was also similar abnormality in the cone ON-pathway. We used long-duration stimuli to separate ON-(depolarizing bipolar cell) and OFF (hyperpolarizing bipolar cell) contributions to the cone-dominated ERG to better understand how the retina functions in boys with Duchenne muscular dystrophy. We recorded the electroretinograms of 11 boys with Duchenne muscular dystrophy and found abnormal signal transmission at the level of the photoreceptor and ON-bipolar cell in both the rod and cone generated responses. The OFF-bipolar cell that responds to the offset of the stimulus continues to function normally. The results support our hypothesis that retinal dystrophin plays a role in receptor function or controlling ion channels at the level of the photoreceptor and depolarizing bipolar cell.

Adolescent↗
PubMed1993

The effects of dystrophin gene mutations on the ERG in mice and humans.

PURPOSE: The authors' earlier findings of a negative electroretinogram (ERG) in a boy with Duchenne muscular dystrophy (DMD) led them to investigate dystrophin gene deletions and ERGs in five boys with DMD. The authors wanted to determined whether there were similar ERG findings in an animal model for DMD, the mdx mouse. METHODS: Ganzfeld ERGs were recorded in five boys with DMD after a complete ophthalmic examination. The dystrophin gene was analyzed by Southern blot hybridization. ERGs were recorded in anesthetized mdx and control mice with a modified Grass photostimulator (Grass Instrument Company, Quincy, MA). RESULTS: Ophthalmic examinations in all five boys had normal findings, yet an abnormal negative ERG was recorded for each subject. The subjects' gene deletions were variable, ranging from large deletions to no detectable deletions. The ERGs of the mdx mice were normal and did not differ significantly from those of the control mice. CONCLUSIONS: The authors believe the unique ERG recorded for the human subjects is a manifestation of DMD associated with defects at the dystrophin gene locus and represents a new clinical entity. The ERG of the mdx mouse may be spared for several reasons, including milder effects of the mouse gene defect, differences in muscle and retinal gene product, or species differences in the biochemical role of dystrophin. The ERG shows promise of becoming a noninvasive diagnostic tool for DMD and its milder allelic forms.

Animals↗
PubMed1992

Familial total ophthalmoplegia with iris transillumination (a neurocristopathy).

A family with total (internal and external) ophthalmoplegia had associated iris transillumination. No abnormal visual-evoked response brain lateralization indicative of albinism was found. On the basis of avian chimera experiments showing iris muscles to be derived from neural crest cells, we proposed a neurocristopathic theory to explain all clinical findings in this family.

Female↗
PubMed1992

Incidence of inadvertent perforation in strabismus surgery.

We conducted a prospective study for over 2 years to determine the incidence of perforations following strabismus surgery. All eyes were examined by indirect ophthalmoscopy and indentation immediately after surgery in an attempt to identify perforation sites. No cryotherapy or treatment was done. None of the 10 perforations identified was associated with retinal detachment or endophthalmitis. The incidence of perforations was 2.8% on a per-case basis and under 1% on a per-muscle basis.

Adolescent↗
PubMed1990

Bilateral choroidal neonatal neuroblastoma.

We treated a bilateral, well-differentiated neuroblastoma of the choroid in a patient who had congenital abdominal neuroblastoma. Although orbital metastasis of neuroblastoma is common, intraocular metastasis is not. In our patient, there was no amplification of the N-myc oncogene in the tumor of either eye. This is consistent with early-stage primary neuroblastoma. Histologically, the tumors were identical in each eye and well differentiated with Homer Wright rosettes; most neuroblastoma metastases have few rosettes and are composed of more undifferentiated, anaplastic cells. We believe that our patient had bilateral primary tumors and not metastatic tumors.

Choroid Neoplasms↗