眼瞼痙攣（1）総論 眼瞼痙攣の病態生理と手術治療アップデート

The Pathophysiology and Surgical Treatment of Blepharospasm: An Update

はじめに

　眼瞼痙攣は局所性ジストニアの1つであり，不随意な閉瞼と努力性開瞼を特徴とする。PubMedで検索を行うと，1857年にMackenzieが痙攣患者に対してクロロフォルム吸入を行い，症状を軽減させた報告 1）が最初のようであるが，16世紀の初期フランドル派画家ブリューゲルはMeige症候群と思われる顔貌を描いている 2）。

　患者は初期には瞬目の増加や目を閉じたくなる症状を自覚し，緩徐に進行することが多い。病状の進行期には持続的な閉瞼を生じることもあり，仕事・生活・学業に深刻な影響を及ぼす 3）。症状は緊張・不安・疲労によって誘発または増悪し，感覚的トリックと呼ばれる特定の動作（顔や瞼への接触，会話，歌唱など）によって緩和される 4）。眼瞼痙攣は50～70歳の中高年患者に多く見られ，発症率は男性より女性で高い 5）。

　本態性，薬剤性，症候性に分類されることがあるが，本稿では本態性を中心に病態生理，診断基準・評価法，手術治療について，近年のアップデートを歴史とともに述べる。

　Blepharospasm is a focal dystonia characterized by involuntary eyelid closure and effortful eye opening. Its etiology is considered multifactorial. Environmental and modifying factors such as psychological stress, urban lifestyle, ocular surface disorders, and head trauma may increase susceptibility to blepharospasm, and abnormalities of sensorimotor integration within widespread neural networks (including the basal ganglia, thalamocortical circuits, cerebellar involvement, and brainstem blink reflex pathways) are believed to lower the threshold for spasms. Dysregulation of several neurotransmitter systems, particularly dopaminergic hypersensitivity, cholinergic overactivity, and impaired GABAergic inhibition may further amplify abnormal motor output. Botulinum toxin injection remains the first-line therapy for blepharospasm, providing symptom relief in the majority of patients; however, long-term management often requires repeated injections and adjunctive measures such as optical filters or mechanical devices. For botulinum toxin-refractory cases, surgical approaches including orbicularis oculi myectomy, frontalis suspension for associated apraxia of lid opening, Müllerʼs muscle desensitization procedures, and, more rarely, superselective facial neurectomy have been reported to improve functional eyelid opening and the patientsʼ quality of life. Deep brain stimulation of the globus pallidus internus (GPi) or the bilateral subthalamic nucleus (STN) is an option in selected cranial dystonia or Meige syndrome cases. Individualized multimodal treatment remains essential, because over-resection and ocular surface complications must be avoided.