Visual loss in tuberous sclerosis

Neuro-ophthalmic manifestations of the phakomatoses

PURPOSE OF REVIEW

The phakomatoses are a group of inherited disorders with variable clinical manifestations that are characterized by brain, cutaneous, ocular and other distinct lesions in multiple organs. Correctly recognizing the neuro-ophthalmic signs and symptoms can lead to early diagnosis and treatment. The group is composed of neurofibromatosis (type 1 and 2), tuberous sclerosis complex, von Hippel-Lindau, ataxia-telangiectasia and Sturge-Weber syndromes. However, more than 60 syndromes have been described in the medical literature. This review provides an update on the diagnosis and management of phakomatoses with a focus on their clinical neuro-ophthalmic manifestations.

RECENT FINDINGS

Phakomatoses are a group of inherited syndromes with variable clinical manifestations that are characterized by brain, cutaneous, ocular and other distinct lesions in multiple organs. Recent advances in diagnostic and treatment options that have contributed to prompt recognition and management of these disorders are discussed with an emphasis on the beneficial effects on vision.

SUMMARY

Phakomatoses, also known as neuro-oculo-cutaneous syndromes, are inherited disorders with characteristic lesions in multiple organs. Because of their frequent ocular involvement thorough ophthalmologic and neuro-ophthalmic evaluation is critical in this patient population in order to prevent vision loss and life-threatening complications that are often associated with these disorders.

Neuro-ophthalmological manifestations of tuberous sclerosis: current perspectives

Tuberous sclerosis complex (TSC) is a complex, multi-system disorder with a well-described underlying genetic etiology. While retinal findings are common in TSC and important in establishing the diagnosis, TSC also has many potential neuro-ophthalmology manifestations. The neuro-ophthalmology manifestations of TSC can have a significant impact on visual function and are sometimes a sign of serious neurological disease. The purpose of this review is to describe the neuro-ophthalmological manifestations of TSC. These manifestations include optic nerve hamartomas, elevated intracranial pressure, cranial nerve palsies, cortical visual impairment, visual field deficits, and ocular toxicity from vigabatrin treatment of infantile spasms. It is important to be aware of potential neuro-ophthalmological manifestations in these patients in order to detect signs of vision- or life-threatening disease and to optimize visual function and quality-of-life.

Papilledema: the vexing issues

Papilledema has long been recognized as a valuable sign of increased intracranial pressure (ICP). But because papilledema is based on interruption of the energy-dependent process of axoplasmic flow, it appears late after a rise in ICP. Papilledema is usually present in chronically high ICP but sometimes asymmetrically in the 2 eyes and rarely in 1 eye only. Distinguishing it from other optic neuropathies that produce elevated optic discs is challenging, especially in the chronic phase, when visual function may be impaired. Papilledema is often an unrecognized cause of optic disc edema in inflammatory and compressive meningeal disorders that interfere with cerebrospinal fluid (CSF) passage through the arachnoid granulations. Its detection is particularly critical in patients with noncompliant ventricles or extraventricular blockage of cerebrospinal flow because imaging may fail to disclose conventional signs of high ICP. Therefore, patients with indwelling CSF shunts, tuberous sclerosis, chronic granulomatous meningitis, or meningiomatosis should be periodically examined for papilledema so that timely ICP-lowering measures can be instituted to preserve vision.

Papilledema in obstructive hydrocephalus caused by giant cell astrocytoma of tuberous sclerosis

A 5-year-old girl with progressive hemiparesis and headache was found by brain imaging to have a large tumor centered at the foramen of Monro, blocking cerebrospinal outflow and producing massive lateral ventriculomegaly. Total excision of the mass led to a pathologic diagnosis of giant cell astrocytoma. Dermatologic abnormalities had been detected shortly after birth but were unexplained. Abdominal imaging disclosed renal cysts, and ophthalmologic examination disclosed papilledema and retinal plaques. On this basis, a diagnosis of tuberous sclerosis (TS) was finally made. Two months after surgery, papilledema had resolved, and visual function appeared to be normal. Although the patient apparently escaped visual loss, other reports affirm that giant cell astrocytoma, a common tumor in TS, may go undetected for long enough to produce irreversible optic neuropathy from chronic papilledema. Because patients with TS may not report visual loss, they should undergo periodic ophthalmologic screening.

Leucocoria na infância: diagnóstico diferencial por ultra-sonografia, tomografia computadorizada e ressonância magnética

Leucocoria é um reflexo pupilar anormal à luz incidente, em geral relacionado a uma anormalidade intra-ocular, ocorrendo freqüentemente em crianças. A avaliação da criança com leucocoria deve ser feita principalmente para excluir o diagnóstico de retinoblastoma (causa da metade dos casos). Os autores apresentam os aspectos clínicos e de imagem essenciais ao diagnóstico das causas mais comuns de leucocoria.

Visual performance in specific syndromes associated with intellectual disability

PURPOSE

To report visual performance in adults with specific causes of intellectual disability (ID) and to compare the test results to published reports.

METHODS

In a large-scale multicenter epidemiologic study of sensory impairments in 1598 adults with ID, the authors performed ocular assessments in 1539 persons. They compared the test results of those with five specific genetic disorders (Angelman syndrome, Prader-Willi syndrome, fragile X syndrome, Williams-Beuren syndrome, and tuberous sclerosis).

RESULTS

An overrepresentation of strabismus, low vision, and refractive errors was found. Apart from fragile X syndrome and Prader-Willi syndrome (with in general mild to moderate ID), the other syndrome groups contained one or more subjects with visual impairment or blindness. A number of them had never been seen by an ophthalmologist.

CONCLUSIONS

The authors confirm a number of ocular features previously reported by other studies and suggest some additional ocular features. They found increased frequencies of treatable ophthalmologic conditions in the subgroups. Because reliable ocular assessment is feasible for 85% of persons with ID, the results are an incentive to address visual functioning in people with ID in order to correct ocular problems and maximize their possibilities.

Biological behavior and tumorigenesis of subependymal giant cell astrocytomas

In spite of the benign nature of subependymal giant cell astrocytomas (SEGAs), some show massive hemorrhage, rapid growth, and tumor recurrence. This led us to investigate the biological behavior, cell dynamics, and tumorigenesis of SEGAs. All patients (4 men and 3 women; age range, 6-27 years; mean, 13.6 years) had features of tuberous sclerosis complex and obstructive hydrocephalus. One patient had intratumoral bleeding. In two patients, sequential neuroimaging showed a subependymal nodule growing to become a SEGA. All underwent surgical resection without radiation therapy. One tumor recurred and was treated surgically. There were no postoperative deaths. The presence of cytologic atypia, mitoses and vascular proliferation had no implication in terms of the clinical course. MIB-1 labeling indices were low (mean, 0.9), indicating low proliferative potential. Unexpectedly, bcl-2 staining was sparse and bax staining predominated in majority of cases. However, the mean value of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling index was low. Immunohistochemically, tumors were positive for both glial and neuronal markers. In the majority of our cases, the expression of p53 was low. Only one tumor was focally positive for tuberin. SEGAs have low proliferative potential and apoptotic activity, and exhibit features of mixed glial-neuronal differentiation. In contrast to p53, tuberin is suggested to be the tumor suppressor in this tumor.

Neuro-ophthalmology of the phacomatoses

The phacomatoses are a group of disorders that feature multiple hamartomas of the central and peripheral nervous system, eye, skin, and viscera. Most of these disorders have a well-defined Mendelian pattern of inheritance because of a mutation in a single gene which has been identified. In other instances, no clear patterns of inheritance or genetic susceptibility have been recognized. The combination of ocular and central nervous system manifestations in patients with phacomatoses makes neuro-ophthalmologic evaluation particularly important in diagnosis and management. This review provides an overview of the phacomatoses with emphasis on recent reports of significance to neuro-ophthalmology.