Subcortical Brain Abnormalities and Clinical Relevance in Patients With Hemifacial Spasm

Abstract

Purpose: Hemifacial spasm (HFS), a rare neuromuscular movement disorder, is characterized by unilateral, irregular, and paroxysmal facial muscle contractions. To explore the central neural mechanisms of HFS, we conducted vertex-wise shape analyses to investigate volume and shape alterations of subcortical structures, which could help to better understand the abnormality in distinct subcortical regions and determine alternative biomarkers of HFS. Methods: Thirty patients with HFS and 30 age- and sex-matched healthy controls provided written informed consent. T1-weighted structural magnetic resonance imaging (MRI) data were collected from all participants. Vertex-wise shape analyses were performed to assess the volume and shape alterations of subcortical structures following HFS. Post hoc correlations with spasm severity and measures of mood dysfunction were applied to characterize subcortical brain alterations. Results: Compared with healthy controls, patients with HFS showed increased volume in the right caudate specifically. Furthermore, patients exhibited significant shape atrophy in the anterior medial aspect of left pallidum, together with shape expansion in the anterior ventrolateral aspect of right caudate head. In addition, shape alteration in right caudate was positively correlated with both anxiety and depression severity in patients with HFS. Conclusions: This is the first study to employ vertex-wise shape analysis to investigate subcortical brain abnormalities in patients with HFS. Our findings provide compelling evidence for subcortical brain alterations specific to HFS, and further may shed light on the pathophysiology of HFS and apply to the translational medicine.

Keywords: affective symptoms; hemifacial spasm; orofacial muscle contractions; subcortical brain abnormalities; translational medicine.

Figure 1

Bar graph showing the mean volumes of subcortical structures at left hemisphere (A) and right hemisphere (B) in patients with HFS (shown in red) and healthy controls (shown in green). HFS, hemifacial spasm; Error bars, mean ± standard deviation; Accu, accumbens; Amyg, amygdala; Caud, caudate; Hipp, hippocampus; Pall, pallidum; Puta, putamen; Thal, thalamus. ^*P < 0.05.

Figure 2

Results of vertex-wise shape analysis for left pallidum. The red-yellow colors indicate shape atrophy in anterior medial aspect of the left pallidum following patients with HFS compared to healthy controls (P < 0.05, FWE corrected). Blue models represent the original left pallidum structure. The color bar indicates P values.

Figure 3

Results of vertex-wise shape analysis for right caudate. The red-yellow colors indicate shape expansion in anterior ventrolateral aspect of the right caudate head in patients with HFS compared with healthy controls (P < 0.05, FWE corrected). Blue models represent the original right caudate structure. The color bar indicates P values.

Figure 4

Shape alterations in right caudate was positively correlated with anxiety symptom (shown in red-filled triangle; ρ = 0.861, P < 0.001, Bonferroni corrected) and depression symptom (shown in blue-filled upside-down triangle; ρ = 0.723, P < 0.001, Bonferroni corrected) in patients with HFS. Curved dashed lines indicate 95% confidence intervals. The vertex index of anterior ventrolateral aspect of the right caudate head represented shape alterations in patients with HFS. The anxiety symptom was measured by Hamilton Anxiety Scale, and Hamilton Depression Scale was performed to assess patients' depression symptom.