Optic pathway tumors in children: the effect of neurofibromatosis type 1 on clinical manifestations and natural history.

OBJECTIVE: To distinguish the clinical manifestations and natural history of optic pathway tumors (OPT) associated with neurofibromatosis type 1 (NF-1 OPT) from that of OPT not associated with NF-1 (non-NF-1 OPT). METHODS: Two groups of children with OPT were compared: (1) 17 children with NF-1 OPT who were followed prospectively, and (2) 19 children with non-NF-1 OPT who were identified retrospectively by a review of medical records. RESULTS: Precocious puberty was a common initial sign in the children with NF-1 OPT (5/17), and was not found in any patients without NF-1. In contrast, children with non-NF-1 OPT had symptoms attributable to increased intracranial pressure (12/19 and nystagmus (5/19); these symptoms were not found in any patient with NF-1. Decreased visual acuity at the time of diagnosis was common in both groups. There was no significant difference between the children with NF-1 OPT and those with non-NF-1 OPT as to age at diagnosis or sex distribution. Optic nerve involvement was more common in NF-1 (p < 0.001). Both isolated and bilateral optic nerve tumors were found exclusively in children with NF-1, whereas chiasmal (p = 0.016) and optic tract involvement (p = 0.001) were more common in those with non-NF-1 OPT. Radiographic evidence of hydrocephalus was found in none of the children with NF-1 OPT compared with 79% of the non-NF-1 OPT group. Progressive disease was seen in 12% of patients with NF-1 OPT compared with 63% of those with non-NF-1 OPT. CONCLUSIONS: Differences exist between NF-1 OPT and non-NF-1 OPT both at the time of diagnosis and during follow-up. Optic pathway tumors caused by NF-1 and non-NF-1 OPT have different biologic properties that distinguish both their initial clinical manifestations and their natural history.

Precocious puberty in children with neurofibromatosis type 1.

We undertook a comprehensive study of children with neurofibromatosis type 1 (NF-1) cared for in a large multidisciplinary clinic to determine the prevalence of precocious puberty and its relationship to optic pathway tumors (OPTs). Precocious puberty was diagnosed in 7 of 219 children with NF-1 (5 boys and 2 girls) examined between Jan. 1, 1985, and April 20, 1993. All seven children had OPTs involving the optic chiasm; they represented 39% of children with NF-1 and chiasmal tumors (95% confidence interval, 17% to 64%). Eleven prepubertal children (aged 2 to 10 years) with NF-1 and OPTs, and age- and sex-matched NF-1 control subjects without OPTs, underwent luteinizing hormone-releasing hormone (LH-RH) stimulation tests. Two boys with OPTs had pubertal luteinizing hormone (LH) responses, and testosterone levels > 10 ng/dl. Basal LH levels were also elevated in these two boys when tested with a very sensitive immunochemiluminometric assay. None of the children without an OPT had either a pubertal response to LH-RH or an elevated basal LH level. We conclude that precocious puberty in children with NF-1 is found exclusively in those who have OPTs involving the optic chiasm; it is a common complication in those children. With the use of a highly sensitive LH assay, biochemical evidence of hypothalamic-pituitary-gonadal axis activation may be demonstrated, even without provocative testing.

Natural history of optic pathway tumors in children with neurofibromatosis type 1: a longitudinal study.

To assess the natural history of optic pathway tumors (OPT) in children with neurofibromatosis type 1 (NF-1), from January 1985 through May 1993 we performed a prospective, longitudinal study of OPT in an unselected population of children with NF-1. Of 227 children with NF-1 seen in a specialty clinic, 176 (77%) underwent neuroimaging. Children in whom tumors were identified were followed closely by both repeated neuroimaging and ophthalmologic examinations to detect tumor growth or visual deterioration. Thirty-three children (19%) were found to have OPT at a median age of 4.2 years. The median age of children who had ophthalmologic complaints was significantly lower than that of children who had no such complaints (1.9 vs 5.3 years; p < 0.001). Although eight tumors were discovered because of ophthalmologic complaints or evidence of precocious puberty, 25 children (76%) were free of symptoms at the time of diagnosis. Twenty-one children (64%) had normal ophthalmologic findings at diagnosis; six children, all with chiasmal tumors, had previously unrecognized decreased visual acuity. Only three children (9%) had evidence of either tumor growth or deteriorating vision after diagnosis; the median duration of neuroimaging follow-up was 2.4 years (range, 0.2 to 7.2 years) and of ophthalmologic examinations 3.4 years (range, 0.2 to 8.1 years). All symptomatic OPT were diagnosed before 6 years of age. We conclude that OPT rarely progress during the next few years in children with NF-1 once the OPT have been discovered. The utility of screening neuroimaging for OPT in symptom-free children with NF-1 appears very limited.

Emergence of optic pathway gliomas in children with neurofibromatosis type 1 after normal neuroimaging results.

We report the appearance of gliomas of the optic nerve or chiasm in four young children with neurofibromatosis type 1 whose previous neuroimaging studies showed no abnormalities; the age range of the children was 1 year 8 months to 5 years 9 months at the time the tumors were detected. Normal neuroimaging findings in an infant or young child with neurofibromatosis type 1 does not provide assurance that the optic nerves and chiasm will remain healthy.

Clinical application of ultrasonography in the diagnosis of intussusception.

Sixty-five consecutive patients seen in a pediatric emergency department, in whom the diagnosis of intussusception was considered, had an ultrasound examination of the abdomen before a barium enema. The mean age of the patients was 1.7 years (range 2 weeks to 5 years). Intussusception was detected by ultrasonography in all 20 cases proved by barium enema. There were three false-positive ultrasound results (sensitivity = 100%, confidence interval (Cl) = 86% to 100%; specificity = 93%, Cl = 86% to 96%). Normal findings on ultrasonography correlated with a negative barium enema results in 42 of 42 cases (negative predictive value = 100%, Cl = 94% to 100%). No intussusception was missed by ultrasonography. To determine which patients would most benefit from ultrasonography, we divided patients into either a high-risk group (81% with intussusception) or a low-risk group (14% with intussusception) on the basis of clinical symptoms (p less than 0.01). If each high-risk child had a barium enema and each low-risk child had an ultrasound study as their initial diagnostic test, 89% of the patients in this study would have undergone only one examination. We conclude that ultrasonography can be used as a rapid, sensitive screening procedure in the diagnosis or exclusion of childhood intussusception. Children considered at low risk of having intussusception on the basis of clinical symptoms should initially have an ultrasound examination; patients at high risk should have an immediate barium enema.

Optic gliomas in children with neurofibromatosis type 1.

To determine the frequency and natural history of tumors of the optic nerves and chiasm in patients with neurofibromatosis type 1, we obtained computed tomographic scans of 65 children who had no known visual or ocular abnormalities before their initial evaluation. Optic gliomas were detected in 10 children (15%). The median age of children with gliomas was 4.3 years (mean 5.8 years, range 9 months to 21 years). Three children (30%) had isolated, unilateral tumors, three (30%) had bilateral tumors, and four (40%) had involvement of the optic chiasm and of one or both nerves. Definite abnormalities of vision were found in only two children (20%). Five additional children were referred to the clinic after evaluation of ophthalmologic complaints led to the diagnosis of neurofibromatosis type 1: three had unilateral exophthalmos and two had plexiform neurofibromas of the eyelid with associated glaucoma. Ipsilateral optic gliomas were found in all five children; one child also had a contralateral tumor. Optic gliomas are commonly identified in young children with neurofibromatosis type 1 who have no ocular or visual abnormalities. Optic nerve gliomas may be associated with plexiform neurofibromas of the eyelid and glaucoma.

Complex carbohydrate intolerance: diagnostic pitfalls and approach to management.

Complex carbohydrate intolerance occurred in three of 105 patients with protracted diarrhea of infancy. Nosocomial gastroenteritis complicated a primary disorder of carbohydrate absorption (primary glucose galactose malabsorption, two; primary sucrase isomaltase deficiency, one) in all patients. Their course was characterized by protracted diarrhea, variable degrees of villus atrophy on intestinal biopsy tissue, and negative caloric balance requiring intravenous alimentation for periods varying from 6 to 16 weeks. Dietary management required rigid exclusion of all offending carbohydrates from the diet. Delay in the diagnosis of primary carbohydrate intolerance varied from 2 weeks to 6 months. Complex carbohydrate intolerance may be more common than has been reported, and should be considered in all infants with protracted diarrhea of infancy when there is persistent carbohydrate intolerance.