Visual Snow - Two Adolescents with a New Syndrome Different from Migraine or Epilepsy

Background: Visual Snow is a recently described distinct disorder with overlapping symptoms but different from migraine or epilepsy. The comorbidity with migraine is high.

Methods: We report two adolescents with a suspected epilepsy diagnosis and pathological EEG findings.

Results: This 11-year-old girl reports continuous colored dots (pink, green) within her visual field. In bright light, she has difficulties to identify objects (photophobia). She has paroxysms seeing after-images, prongs or unreal objects. At night she is blinded by lamps (nyctalopia) and loses orientation. In a situation with many sensory stimuli, as in a supermarket, her reaction is impaired. This led to the diagnosis of epilepsy with visual symptoms and impaired awareness. She suffers from chronic headache with eye pain but without nausea. Symptoms began in early childhood. The 13-year-old boy had a focal visual seizure evolving to bilateral tonic-clonic at the age of 12 years. Suddenly it got dark, objects seemed to move, and he felt as if he was compressed. Within the next 6 weeks, he had 7 seizures. At the same time, he began to have persistent visual phenomena with colored and black dots and patterns in his visual field, sometimes seeing flashes or prongs. He heard sounds repetitively. His parents reported “blackouts”, when he was not able to react immediately. Both patients did not go to school for many months, as they were not able to read and comprehend. They withdrew from social contacts. The boy had a reduction of his impairment after 12–18 months. Both benefitted from a therapy of their headache. Both had epileptiform activity with photic stimulation with asymmetric amplitudes r>l.

Discussion: Both patients fulfill the diagnostic criteria for Visual snow: • Visual snow: dynamic, continuous, tiny dots in the entire visual field lasting longer than 3 months. • Presence of at least two additional visual symptoms of the four following categories: Palinopsia, enhanced entoptic phenomena, Photophobia, Nyctalopia • Symptoms are not consistent with typical migraine visual aura • Symptoms are not better explained by another disorder. The syndrome is well characterized with typical findings but without a confirming test. Pathophysiology is unclear, there is no proven therapy. Patients benefit from treating their migraine, common comorbidity. EEG findings after photic stimulation, as in our patients, have not been reported. We discuss them in the context of published FDG-PET-studies with hypermetabolism in the right lingual gyrus.

Conclusion: Persistent visual symptoms with severe impairment of daily life activities are typical findings in the visual snow syndrome. Making the correct diagnosis can be of relevant relief for the patients.

Reference

1. Puledda F, Schankin C, Digre K, Goadsby PJ. Visual snow syndrome: what we know so far. Curr Opin Neurol 2018;31(1):52–58

No conflict of interest has been declared by the author(s).