Some patients with visual snow (VS) reported a benefit from noninvasive vagal nerve stimulation (nVNS), according to study findings presented at the 2022 American Headache Society (AHS) Annual Scientific Meeting, held from June 9-12, in Denver, Colorado, and virtually.
VS presents as continuous tiny dots or pixelations in the entire visual field accompanied by 2 or more symptoms of palinopsia, enhanced entopic phenomena, photophobia, or nyctalopia. Currently, there are no validated tools for quantifying VS symptomology or associated disability nor are there established treatments.
Researchers at the Mayo Clinic utilized the theory of cortical hyperexcitability as a mechanism for VS, making nVNS a potential treatment. In this retrospective case series, 3 patients trialed nVNS by performing 2 2-minute stimulations 3 times per day using a gammaCore™ device for 10 to 12 weeks. To evaluate VS symptoms, patients recorded specific symptoms on an 11-point scale for a total score of 60 points. The patients also recorded the number of days they experienced VS symptoms and headache.
The patients were a 67-year-old man (patient 1), a 38-year-old woman (patient 2), and a 48-year-old man (patient 3). All patients reported constant VS symptoms. Patients 2 and 3 had no obvious inciting VS event whereas Patient 1 awoke from anesthesia with VS. Patients 1 and 3 had episodic migraine and migraine with visual aura, respectively.
In an attempt to reduce VS symptoms, patient 1 had used benzodiazepines, serotonin reuptake inhibitors, tricyclic antidepressants, anticonvulsants, diuretics, magnesium, effervescent tabs, and pulse transcranial magnetic stimulation and patient 2 had used amitriptyline.
During the nVNS treatment, total VS symptoms scale score decreased from 40 to 37 points in patient 1, 40 to 20 points in patient 2, and 41 to 27 points in patient 3.
Patients 1 and 2, who reported a 3- and 20-point change in their VS symptoms, respectively, rated their change in symptoms as “better, and a definite improvement that has made a real and worthwhile difference.” Conversely, patient 3 who reported a 14-point change, also reported “no change” to their symptoms, however, the patient’s reaction to treatment may have been confounded by a depressive episode not related with the nVNS device.
The patients reported transient neck tightness during nVNS use.
These data were limited by the small sample size and nVNS should be evaluated among a larger cohort to corroborate findings.
The study authors concluded that response to nVNS was mixed. “Our symptom scale score helped to standardize recording of VS symptoms but changes in the overall symptom scale score did not consistently match the global impression of change,” the researchers stated. The overall decrease in reported VS symptoms likely indicated that nVNS should be investigated further.
Arca KN, VanderPluym J. Noninvasive vagus nerve stimulation for the treatment of visual snow. Presented at: AHS 2022 Annual Scientific Meeting; June 9-12, 2022; Denver, Colorado. Poster 183.