Electrophysiological Evidences of Visual Field Alterations in Children Exposed to Vigabatrin Early in Life

Pharmacotherapy for Seizures in Tuberous Sclerosis Complex

Epilepsy is one of the main symptoms affecting the lives of individuals with tuberous sclerosis complex (TSC), causing a high rate of morbidity. Individuals with TSC can present with various types of seizures, epilepsies, and epilepsy syndromes that can coexist or appear in relation to age. Focal epilepsy is the most frequent epilepsy type with two developmental and epileptic encephalopathies: infantile spasms syndrome and Lennox-Gastaut syndrome. Active screening and early management of epilepsy is recommended in individuals with TSC to limit its consequences and its impact on quality of life, cognitive outcome and the economic burden of the disease. The progress in the knowledge of the mechanisms underlying epilepsy in TSC has paved the way for new concepts in the management of epilepsy related to TSC. In addition, we are moving from traditional "reactive" and therapeutic choices with current antiseizure medications used after the onset of seizures, to a proactive approach, aimed at predicting and preventing epileptogenesis and the onset of epilepsy with vigabatrin, and to personalized treatments with mechanistic therapies, namely mechanistic/mammalian target of rapamycin inhibitors. Indeed, epilepsy linked to TSC is one of the only epilepsies for which a predictive and preventive approach can delay seizure onset and improve seizure response. However, the efficacy of such interventions on long-term cognitive and psychiatric outcomes is still under investigation.

What can visual electrophysiology tell about possible visual-field defects in paediatric patients

Recognising a potential visual-field (VF) defect in paediatric patients might be challenging, especially in children before the age of 5 years and those with developmental delay or intellectual disability. Visual electrophysiological testing is an objective and non-invasive technique for evaluation of visual function in paediatric patients, which can characterise the location of dysfunction and differentiate between disorders of the retina, optic nerve and visual pathway. The recording of electroretinography (ERG) and visual-evoked potentials (VEP) is possible from early days of life and requires no subjective input from the patient. As the origins of ERG and VEP tests are known, the pattern of electrophysiological changes can provide information about the VF of a child unable to perform accurate perimetry. This review summarises previously published electrophysiological findings in several common types of VF defects that can be found in paediatric patients (generalised VF defect, peripheral VF loss, central scotoma, bi-temporal hemianopia, altitudinal VF defect, quadrantanopia and homonymous hemianopia). It also shares experience on using electrophysiological testing as additional functional evidence to other tests in the clinical challenge of diagnosing or excluding VF defects in complex paediatric patients. Each type of VF defect is illustrated with one or two clinical cases.

OPTICAL COHERENCE TOMOGRAPHY AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY PARAMETERS IN PATIENTS WITH PHACOMATOSIS

PURPOSE

To compare the retinal vasculature characteristics between eyes of patients with and without phacomatosis.

METHODS

Case-control observational study with retinal vasculature evaluation by optical coherence tomography and optical coherence tomography angiography of the macula and disk.

RESULTS

The study included 80 eyes. Neurofibromatosis Type 1 patients presented with a higher central macular thickness (P = 0.007), a lower optical disk nervous fiber layer (P = 0.006), a lower perimeter, area, and circularity of the foveal avascular zone (P < 0.05), a higher vascular density of macular avascular layer (AMVD) (P = 0.004), and a lower papillary vascular density of superficial capillary plexus (SPVD) (P = 0.048). Patients with tuberous sclerosis presented with an increase in central macular thickness (P = 0.024) and in vascular densities (P < 0.05) [except for macular vascular density of deep capillary plexus (PMVD), AMVD, and SPVD]. Patients with Sturge-Weber syndrome showed a decrease in optical disk nervous fiber layer (P < 0.001), subfoveal choroid thickness (P = 0.011), macular vascular density of superficial capillary plexus (SMVD) (P = 0.036), and SPVD (P < 0.001).

CONCLUSION

Phacomatosis patients showed statistically significant differences of retinal vasculature characteristics, compared to eyes without pathology. Further studies are needed to determine when and if these parameters change with the course of the disease and if they can be used as biomarkers for disease severity or progression.

Evaluation of inner retinal layers with optic coherence tomography in vigabatrin-exposed patients

In order to reveal the underlying retinal pathology leading to dysfunction in vigabatrin-exposed patients, we aimed to evaluate the inner retinal layers encompassing ganglion cell complex (GCC) layer and inner plexiform layer with new generation optic coherence tomography (OCT). Fourteen patients with epilepsy and exposure to vigabatrin and 12 clinically normal individuals, constituting the control group, were included. Retinal images were obtained using spectral-domain OCT (Optovue RTVue Fourier domain). Nasal and superior quadrants of retinal nerve fiber layer (RNFL) were found to be significantly lower in the patient group compared to the controls (p < 0.01). No significant difference was shown in the thickness of GCC layer (p > 0.05). Foveal thickness was significantly higher in the patient group (p: 0.006), but no significant difference was found in perifoveal and parafoveal regions between groups (p > 0.05). The thickness of RNFL was found to be lower in vigabatrin-exposed patients without any reduction in GCC layer in the macular region. However, foveal thickness was found to be significantly higher compared to perifoveal and parafoveal macular regions in vigabatrin-exposed patients. In conclusion, OCT revealed reduced thickness of RNFL without any reduction in ganglion cell layer in our study. The objective quantitative assessment of OCT is a practical noninvasive method and it can have role in future monitoring of these patients.

An Update on the Ophthalmologic Features in the Phakomatoses

Neurofibromatosis type 1, tuberous sclerosis complex, and Von Hippel-Lindau disease, historically classified as the phakomatoses, are hereditary multisystem disorders characterized by the presence of hamartoma, which carry the risk of malignant transformation. The alteration of tumor suppressor genes seems to be at the basis of their pathophysiogenetic mechanism. Lisch and choroidal nodules in neurofibromatosis type 1, retinal astrocytomas in tuberous sclerosis complex, and retinal capillary hemangioma in Von Hippel-Lindau disease are the principal ophthalmic hamartomatous manifestations. The advent of novel imaging techniques such as near infrared reflectance and optical coherence tomography has provided unprecedented insight on the choroidal and retinal features of these diseases. These methods have improved early diagnosis and the ongoing surveillance in these conditions. Among an array of treatment modalities, antivascular endothelial growth factor therapy has been used in the management of retinal hamartomas but results have been varied. This review is an update on the pathophysiogenetic mechanisms, ophthalmic manifestations, and novel treatment strategies in the phakomatoses with emphasis on the role of imaging techniques.