Visual electrophysiology in children with tumours affecting the visual pathway. Case reports

Area of Science:

• Ophthalmology
• Pediatric Neurology
• Neuroscience

Background:

• Pediatric orbital, suprasellar, and postchiasmal tumors can cause visual loss.
• Assessing visual pathway function in children with these tumors is crucial for diagnosis and management.

Observation:

• Visual electrophysiology, including pattern electroretinography (PERG) and pattern visual evoked potentials (PVEP), was used in 9 children (8-14 years) with various tumors.
• Tests were performed using full and half-field pattern-reversal stimulation.
• Ophthalmologic and neuroimaging findings were correlated with electrophysiological results.

Findings:

• PERG P50 attenuation indicated central retinal dysfunction in orbital rhabdomyosarcoma.
• PVEP P100 delay suggested optic nerve dysfunction in retrobulbar chondrosarcoma and optic nerve glioma.
• PVEP P100 asymmetry identified crossed fiber dysfunction in hypothalamic germinoma and uncrossed pathway dysfunction in postchiasmal tumors.
• Normal PERG and PVEP results helped exclude retinal or chiasmal dysfunction in specific cases (pleomorphic adenoma, arachnoidal cyst).

Implications:

• PERG and PVEP findings aid in localizing visual pathway dysfunction in pediatric tumors.
• Electrophysiology provides valuable insights into the origin of visual loss, whether retinal, optic nerve, chiasmal, or postchiasmal.
• Follow-up electrophysiological testing can monitor the progression of visual dysfunction.