Is optic nerve sheath diameter diagnostic in methanol intoxication?

Background And Aim: Methyl alcohol intoxication causes severe morbidity and mortality, especially in developing countries. Formic acid is formed as a result of methanol metabolism. Formic acid accumulation and inhibition of adenosine triphosphate synthesis result in ophthalmic issues. This study aimed to demonstrate that the optic nerve sheath diameter (ONSD) measurement is an accurate prognostic marker and can be helpful in the diagnosis of methanol intoxication.

Materials And Methods: This prospective study was conducted with 52 patients who were admitted to the emergency department after alcohol consumption and agreed to participate in the study. Age, gender, comorbid diseases, vital signs, ONSD ultrasonography measurements, hospitalization and discharge status, in-hospital mortality status, dialysis need, presence of visual impairment, blood gas parameters, respiratory status, time since alcohol intake, ethanol levels, urea levels, and creatinine levels were analyzed.

Results: ROC curve analysis was performed to evaluate the predictive power of ONSD to diagnose methanol intoxication. The area under the curve was 0.857 for the cut-off value of 5.05 mm (95 % CI: 0.728-0.985; p < 0.001), with a sensitivity of 80.8 % and a specificity of 100 %. In the regression analysis performed to determine the prognostic value of the parameters in estimating mortality in methanol intoxication cases, an increase in ONSD (OR: 3.619; 95 % CI: 0.057-0.199; p = 0.001), an increase in lactate levels (OR: 5.653; 95 % CI: 0.040-0.085; p < 0.001), and increased duration after alcohol intake (OR: 2558; 95 % CI: 0.004-0.034; p = 0.014) were identified as independent predictors of mortality, but pH, HCO, and base deficit levels were not significant predictors.

Conclusions: We believe that ONSD can be helpful for the differential diagnosis and prognosis of patients with suspected methanol toxicity who presented with alcohol intake.