Relationship between idiopathic peripheral facial paralysis and homocysteine levels in adult patients

Objective: The aim of this study is to evaluate the levels of Homocysteine (Hcy) in adult patients with Idiopathic Peripheral Facial Palsy (IPFP) at the time of admission and after treatment, and to investigate the effect of these levels on the disease's risk factors, severity, and prognosis. Materials and Methods: This study is a prospective case-control study. A total of 80 patients diagnosed with IPFP and presenting with acute facial paralysis between December 2023 and December 2024 at the Afyonkarahisar University of Health Sciences, Faculty of Medicine, ENT outpatient clinic, and 80 control subjects who were matched for demographic characteristics and chronic diseases, and who visited the Internal Medicine outpatient clinic for check-up without a history of facial paralysis, were included in the study. The demographic characteristics of the patients (age, sex, BMI, presence of chronic diseases), and the House-Brackmann Scale (HBS) were recorded. Serum biochemistry (liver and kidney function tests), B12, and folic acid levels were measured for both the patient and control groups. Additionally, blood samples were taken to measure homocysteine (Hcy) levels in both groups. The patient group was followed up for 8 weeks, with weekly evaluations of changes in HBS stages. Blood samples were also taken from the patient group 1 month after the onset of symptoms to recheck Hcy levels. Results: The patient group consisted of 46 males and 34 females (total of 80 patients), with a mean age of 50.46 years and a BMI of 30.1. The control group consisted of 42 males and 38 females (total of 80 people), with a mean age of 49.65 years and a BMI of 29.7. Age, gender, and BMI were similar between the two groups. Among the 80 patients, 45 had right-sided paralysis, and 35 had left-sided paralysis. Thirty-one patients presented with HBS Stage III, 20 with Stage IV, 15 with Stage V, 12 with Stage II, and 2 with Stage VI. No statistical difference was found between the side and severity of the paralysis. There was no significant difference between the B12 levels of the two groups (control group: mean ± SD 495.63 ± 329.57 pg/ml, patient group: mean ± SD 457.30 ± 309.86 pg/ml, p=0.409). Folic acid levels were statistically lower, while the baseline homocysteine (Hcy) levels were significantly higher in the patient group (folic acid levels: patient group mean ± SD 7.57 ± 4.17 ng/ml, control group 8.86 ± 4.40 ng/ml, p=0.034; Hcy levels: patient group mean ± SD 14.88 ± 5.37 μmol/l, control group 11.44 ± 3.00 μmol/l, p<0.001). One month after admission, the Hcy levels in the patient group were significantly lower compared to baseline levels (p<0.001), while there was no significant difference in the Hcy levels between the patient and control groups ix (p=0.327) (1-month Hcy levels: mean ± SD 11.33 ± 4.11 μmol/l). Age, sex, BMI, smoking, and hypertension (HT) did not affect the development of IPFP (p>0.05), whereas the presence of diabetes mellitus (DM) and high Hcy levels were identified as risk factors for the development of IPFP (p<0.05). However, the presence of DM and high Hcy levels did not have an impact on the initial HBS score, recovery time, or post-treatment HBS score (p>0.05). The average recovery time of IPFP patients was 5.05 ± 1.42 weeks. Seventy-three patients (91.3%) recovered to HBS Stage I or II, while 7 patients (8.8%) recovered to HBS Stage III. There was no statistically significant difference in baseline Hcy levels between the subgroup receiving vitamin supplementation and the subgroup not receiving it (baseline Hcy levels: mean ± SD; vitamin supplementation subgroup 15.21 ± 5.99 μmol/l, no supplementation subgroup 14.54 ± 4.72 μmol/l, p=0.821). In both subgroups, there was a significant reduction in Hcy levels at the 1-month follow-up compared to baseline (1-month Hcy levels: vitamin supplementation subgroup mean ± SD 10.13 ± 3.32 μmol/l, p<0.001; no supplementation subgroup 12.54 ± 4.50 μmol/l, p<0.05). The average recovery time was 5.10 ± 1.43 weeks for the vitamin supplementation group and 5.00 ± 1.43 weeks for the non-supplementation group, with no statistically significant difference between the subgroups (p>0.05). Post-treatment HBS stages were similar between the two subgroups, and no significant statistical difference was observed (p>0.05). Conclusion: We found that Hcy levels were significantly higher in the acute phase of IPFP compared to the control group, and that Hcy levels in the recovery phase decreased to levels similar to those of the control group. We also identified the presence of DM and high Hcy levels as risk factors for the development of IPFP. However, there was no correlation between the baseline HBS score, recovery time, and post-treatment HBS score with the presence of DM or high Hcy levels. The oxidative stress and neurotoxic effects of elevated Hcy may contribute to the development of IPFP by causing facial nerve damage. This issue requires multicenter, long-term follow-up studies with larger patient populations to be clarified. Keywords: Facial nerve, facial paralysis, Bell's palsy, homocysteine