Diabetic retinopathy (DR) may be an indirect marker of striatopallidal microangiography in people with diabetes, according to research published in Parkinsonism & Related Disorders. The study also shows that DR severity may be associated with an increased risk, or worse prognosis, for patients who develop hyperkinetic disorders. 

Available evidence demonstrates that glycemic fluctuations trigger vascular-mediated dysfunction in both the retinal and striatopallidal regions in patients with diabetes, associated with variable hyperkinetic disorders. Investigators conducted a systematic review to examine the association between DR and hyperkinetic disorders of the diabetic striatopathy spectrum. In total, 461 citations were identified; 147 were eligible for review. Of these articles, 9 (6.12%) reported information on DR. 

They included 13 cases of hyperkinetic disorders in people with diabetes with reported retinopathy. Of the 13 cases, DR was present in 9 (69.23%); 2 of these patients had severe, bilateral, proliferative retinopathy, 1 had moderate-to-severe, nonproliferative DR, and 1 patient had nonproliferative retinopathy. 


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In patients with poorly controlled diabetes, glycemic fluctuations preceded symptom worsening or imaging abnormalities in 10 cases (76.92%). In 9 patients, insulin was either initiated or increased as an aggressive hyperglycemia control measure. 

In terms of imaging, striato-pallidal magnetic resonance imaging (MRI) abnormalities were characterized by unilaterally predominant T1-weighted hyperintensity in 11 patients, unilaterally predominant T1-weighted hypointensity in 1 patient, and bilateral T1-weighted hypointensity in 1 patient with DUSPS. T2-weighted MRI abnormalities were hyperintense in 12 patients. 

Among the 9 patients with retinopathy, investigators identified variable responses to treatment with haloperidol, pimozide, or olanzapine. Of the 2 patients with severe proliferative retinopathy, 1 was treated with deep brain stimulation of the thalamic ventralis oralis nucleus, and 1 was followed by chronic levodopa-resistant parkinsonism for up to 3 years. Of the 4 patients with no retinopathy, hyperkinetic disorder was either controlled with haloperidol therapy or resolved spontaneously within 6 weeks. 

Study limitations include the small number of initial articles available for review, representing underreporting and increasing the chance of identifying an association between retinopathy and hyperkinetic disorders, as well as the relative rarity of hyperkinetic disorders compared with retinopathy. 

“Early detection of retinopathy could identify patients in which avoiding glycemic fluctuations may prevent the development of hyperkinetic disorders,” the researchers concluded. 

Reference

Lizarraga JK, Chunga N, Yannuzzi NA, Flynn Jr. HW, Singer C, Lang AE. The retina as a window to the basal ganglia: Systematic review of the potential link between retinopathy and hyperkinetic disorders in diabetes. Published online October 13, 2020. Parkinsonism Relat Dis. doi: 10.1016/j.parkreldis.2020.10.025