PubMed Health⌕ Search

Biomedical subjects

L Tychsen

Publications and source records attributed to L Tychsen.

46 records · Page 3Linked to original sources
PubMedDate not supplied

Disjunctive optokinetic nystagmus in a naturally esotropic macaque monkey: interaction between nasotemporal asymmetries of versional eye movement and convergence.

OBJECTIVE: To assess the interaction between versional and vergence eye movements in normal and strabismic monkeys. METHODS: Horizontal optokinetic nystagmus (OKN) and vergence were measured using the magnetic scleral search coil technique in a normal adult monkey and a strabismic monkey who had naturally occurring early-onset esotropia. Mean eye velocity and vergence angles were calculated during the slow phases of OKN. RESULTS: The strabismic monkey had a nasotemporal asymmetry of OKN favoring nasally directed motion in each eye. During monocular optokinetic stimulation, mean eye velocities were substantially greater for the adducting as compared to the abducting eye. The velocity of the abducting eye was between 55 and 80% of the velocity of the adducting eye (p < 0.01). As a consequence of the disjunctive movements, the eyes converged an average of 4 +/- 2.8 degrees during OKN. Saccadic analysis documented normal lateral rectus function in each eye. Neither an OKN asymmetry nor disjunctive OKN was observed in the normal monkey. CONCLUSION: Disjunctive OKN in the esotropic monkey suggests that the cerebral maldevelopment responsible for nasally biased OKN also contributes to nasal biases in vergence pathways.

Animals↗
PubMedDate not supplied

Retinal detachment in a child as the first sign of leukemic relapse: histopathology, MRI findings, treatment, and tumor-free follow up.

Improved leukemia therapies in children have brought about prolonged remissions with extramedullary relapses being reported in sites other than the most common (bone marrow, testes, brain, and spinal cord). A 3-1/2 year-old boy with a history of acute lymphocytic leukemia presented with total retinal detachment in one eye. Painful glaucoma unresponsive to medical therapy necessitated enucleation. Histopathologic examination documented the presence of a dense leukemic cellular infiltrate replacing a totally detached, necrotic retina. Tumor cells also were present in the optic nerve. The child had remained free of leukemia for 3 years after systemic and intrathecal chemotherapy, supplemented by craniospinal radiation. This represents the first case of relapse of acute lymphocytic leukemia presenting solely as a retinal detachment. Our case also underscores the point that the treatment of leukemia after an isolated ocular relapse can be associated with a favorable outcome.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Prevalence of intracranial lesions in children initially diagnosed with disconjugate nystagmus (spasmus nutans)

A small number of children who develop disconjugate nystagmus, torticollis, and head titubation (spasmus nutans) have been found to have optic chiasm or third ventricle gliomas. However, the prevalence of glioma or other developmental abnormalities in this disorder is unknown because no large series of spasmus nutans cases has previously been reported. A reviewer of the records of 67 consecutive children initially diagnosed with spasmus nutans and followed for an average of 3.3 years at the St Louis Children's Hospital revealed the following: 61% had a history of prematurity, developmental delay, or other systemic abnormality; strabismus, most commonly infantile esotropia, developed in 55%; 43% had neuroimaging studies; and 0% had evidence of a glioma or showed signs of tumor on follow-up examinations. From this consecutive patient series, we estimate the prevalence of tumor in spasmus nutans to be less than 1.4%. Without other evidence of an intracranial mass lesion, neuroimaging of infants initially diagnosed with spasmus nutans may not be immediately warranted.

Brain Neoplasms↗
PubMedDate not supplied

Neuroanatomic abnormalities of primary visual cortex in macaque monkeys with infantile esotropia: preliminary results.

To explore the structural basis for visuomotor deficits in infantile esotropia, we examined binocular connections and metabolic activity in the primary visual cortex of two strabismic macaque monkeys. The animals were documented to have onset of natural esotropia in early infancy. Behavioral testing showed that the animals had normal visual acuity in both eyes and the ocular motor deficits that characterize strabismus with onset in infancy. The neuronal tracer substance biotinylated-dextran-amine was injected into ocular dominance columns (ODC) in area V-1 (striate cortex), revealing a paucity of binocular connections between right-eye and left-eye ODCs. The metabolic label cytochrome-oxidase was used to stain neighboring right-eye and left-eye ODCs, revealing inequalities in metabolic activity compatible with interocular suppression. These results show that infantile esotropes have abnormalities of visual cortex structure that correlate with abnormalities in binocular behaviors.

Animals↗
PubMedDate not supplied

Incomplete presentations in a series of 37 children with Kawasaki disease: the role of the pediatric ophthalmologist.

BACKGROUND: Kawasaki disease (KD) is an acute and sometimes fatal febrile vasculitis of childhood, the presenting signs of which include conjunctival vessel dilatation and iridocyclitis. Consultation with a pediatric ophthalmologist is helpful for early recognition of the disease, especially in identifying "incomplete" cases, ie, those which lack all of the classical, systemic signs. METHODS: After encountering a case of incomplete KD in which diagnosis was delayed, we reviewed the hospital records of 37 children with KD to establish how often the disease manifested "incompletely," and how often pediatricians consulted pediatric ophthalmologists to help in its early diagnosis. RESULTS: Forty-five percent of the children eventually diagnosed with KD lacked the complete diagnostic criteria of KD when admitted to the hospital, and diagnosis and treatment therefore were delayed. Coronary artery aneurysms, a complication that might have less serious consequences if treated earlier, developed in 24% of these patients. Although 67% presented to their pediatrician with bilateral conjunctival injection and/or iridocyclitis, pediatricians requested ophthalmologic consultation for only 5% of them. CONCLUSIONS: Our review of these cases indicates that the eye findings in KD could play a role in earlier diagnosis and treatment. Pediatric ophthalmologists and pediatricians should be more aware of their combined responsibilities for expedient recognition of KD.

Adolescent↗
PubMedDate not supplied

Latent fixation nystagmus and nasotemporal asymmetries of motion visually evoked potentials in naturally strabismic primate.

PURPOSE: To determine whether macaque monkeys who had onset of natural, alternating esotropia in early infancy have the eye movement abnormalities and motion visually evoked potential (VEP) abnormalities observed in human infantile esotropes. METHODS: Recordings were obtained of horizontal pursuit eye movements and fixation nystagmus under conditions of monocular viewing. Motion VEPs in response to horizontal motion were recorded with the animals sedated to reduce the possibility of eye movement artifact. RESULTS: The strabismic monkeys had a naso-temporal asymmetry of horizontal pursuit favoring nasally directed motion when viewing with either eye. When fixating stationary targets, latent nystagmus was apparent; the eyes drifted conjugately and the slow phase of the nystagmus was always nasally directed with respect to the fixating eye. Motion VEPs were characterized by a strong horizontal asymmetry with the directional bias inverted approximately 180 deg in the two eyes. These eye movement and motion VEP asymmetries were not observed in a normal macaque. CONCLUSIONS: Macaque monkeys who have infantile esotropia possess asymmetries of horizontal pursuit and motion VEPs like those documented in strabismic humans. Macaques with infantile esotropia appear to be an appropriate animal model for study of neural mechanisms in strabismus.

Animals↗
PubMedDate not supplied

Prevalence of uveitis in an outpatient juvenile arthritis clinic: onset of uveitis more than a decade after onset of arthritis.

PURPOSE: To determine the prevalence and severity of uveitis in an outpatient pediatric arthritis clinic in the midwestern United States during the 1990s. METHODS: The prevalence and clinical characteristics of uveitis were studied retrospectively for all children diagnosed with arthritis at Shriner's Hospital for Crippled Children and followed by the pediatric rheumatology and ophthalmology units of the St Louis Children's Hospital between 1992 and 1995. RESULTS: Seven children (9%) developed uveitis in a population of 78 patients with juvenile arthritis. Six of the seven children were female, and all six females had anti-nuclear antibody (ANA)-positive, juvenile rheumatoid arthritis (JRA). The prevalence of anterior uveitis in females with ANA-positive, pauciarticular JRA was 20%, and in polyarticular JRA, 17%. One of the girls with uveitis had combined JRA and sarcoidosis; the boy with uveitis had juvenile spondylitis. Arthritis preceded the onset of uveitis in each child by 1 to 13 years (average, 6.4 years). Progression of the uveitis in three of the children resulted in band keratopathy and cataract, causing significant visual loss in two (i.e., in 29% of the children who developed uveitis). CONCLUSION: The prevalence and ocular morbidity of uveitis in juvenile arthritis appears to have remained relatively stable over the last 2 decades. Onset of the uveitis in several of the children in our study population occurred more than a decade after the diagnosis of arthritis. Girls with ANA-positive JRA and boys with juvenile spondylitis may need to be followed by periodic slit-lamp examination for longer periods than recommended previously.

Adolescent↗
PubMedDate not supplied

Spectrum of pediatric dacryocystitis: medical and surgical management of 54 cases.

BACKGROUND: Dacryocystitis in infants and older children is a serious complication of congenital or acquired nasolacrimal duct obstruction. To define the modes of presentation and treatment strategies of this disorder better, we reviewed the clinical courses of 54 children treated for dacryocystitis at St Louis Children's Hospital. METHODS: Clinical, neuroradiologic, and laboratory data were collated for all cases of dacryocystitis treated from 1990 to 1995. Average follow up of the children in this consecutive series was 1.75 years (range, 4 months to 5 years). RESULTS: Of the 54 patients, 36 (67%) had chronic low-grade dacryocystitis, which was treated with nasolacrimal duct probing on an outpatient basis. The remaining 18 patients (33%) had acute dacryocystitis, which was treated with a combined medical/surgical strategy. Medical treatment consisted of hospital admission for administration of intravenous antibiotics followed by inpatient surgery, which varied according to the age of the patient and the clinical history: 1) Acute dacryocystitis in neonates was treated surgically by nasolacrimal duct probing and nasal endoscopy for excision of intranasal duct cyst; 2) Acute dacryocystitis with periorbital cellulitis was treated surgically by nasolacrimal duct probing; 3) Acute dacryocystitis due to facial trauma was treated surgically by dacryocystorhinostomy and stent placement; and 4) Acute dacryocystitis complicated by orbital abscess was treated by inferior orbitotomy for orbital abscess drainage, simultaneous nasolacrimal duct probing, and stent placement. CONCLUSION: Dacryocystitis in the pediatric population may present in either chronic or acute forms. An effective and safe treatment for acute dacryocystitis is hospital admission, both for administering intravenous antibiotics and monitoring to rule out orbital cellulitis or abscess formation. Intravenous antibiotic therapy is followed within a day or two by surgery tailored to the clinical history. In the majority of both chronic and acute cases, nasolacrimal duct probing appears to be an effective treatment strategy.

Abscess↗