Hemifacial Spasm
Hemifacial spasm is a movement disorder characterized by involuntary, recurrent contractions of the muscles supplied by the seventh cranial (facial) nerve on one side of the face. It usually starts around the eyelid and spreads over time to the lower face. In most cases it is caused by a blood vessel compressing the facial nerve. Botulinum toxin injection and microvascular decompression (MVD) are the main treatment options.
마지막 업데이트: 2026-06-07
Definition
Hemifacial spasm is a chronic movement disorder characterized by involuntary, intermittent, tonic (sustained) and clonic (rhythmic, tremor-like) contractions of the facial muscles supplied by the seventh cranial nerve (the facial nerve) on one side of the face. It typically begins in the muscle around the eye (orbicularis oculi) and, as the disorder progresses, can spread to the muscles around the mouth, the cheek and the neck. Bilateral involvement is very rare and suggests another underlying cause.
Causes
In the great majority of cases the cause is pulsatile compression (neurovascular compression) of the facial nerve by a blood vessel at its root exit zone from the brainstem (most often the anterior inferior cerebellar artery; less commonly the posterior inferior cerebellar artery or vertebral artery). Chronic compression leads to abnormal transmission between nerve fibres and involuntary muscle contractions. Less commonly there are secondary causes: cerebellopontine angle tumours (facial or vestibular schwannoma, meningioma, epidermoid cyst), brainstem lesions, multiple sclerosis and abnormal nerve regeneration after a previous facial palsy (Bell's palsy).
Symptoms
The contractions are one-sided and usually begin with involuntary twitching/closure of the eyelid; over time they spread to the muscles around the mouth, the cheek and the neck. The contractions may be both sustained (tonic) and rhythmic (clonic), come in intermittent episodes and, unlike trigeminal neuralgia, occur without a specific trigger (spontaneously); they usually decrease or disappear during sleep. Stress, fatigue, lack of sleep and facial movements (talking, laughing, chewing) can increase the contractions. Frequent eye closure can interrupt vision, making reading and driving difficult; the visible contractions can lead to social anxiety and depression.
Diagnosis
Diagnosis is primarily clinical; one-sided involuntary facial contractions that begin around the eye, spread to the lower face, are spontaneous and decrease during sleep are typical. Contrast-enhanced brain MRI with thin-section sequences such as FIESTA/CISS is needed both to show the neurovascular contact and to exclude secondary causes (cerebellopontine angle tumours, brainstem lesions, multiple sclerosis, vascular malformation). MR/CT angiography can help assess the vascular anatomy for surgical planning. A 'lateral spread' response on electromyography is a finding that supports abnormal nerve transmission. The differential diagnosis includes blepharospasm (bilateral eye-closure dystonia), facial myokymia, tic disorders and psychogenic spasm.
Medical (Conservative) Treatment and Botulinum Toxin
Oral medications (carbamazepine, baclofen, gabapentin, clonazepam) have limited efficacy in hemifacial spasm and are usually not the first choice. Botulinum toxin injection is an effective first-line treatment, particularly in older patients, those at high surgical risk or those who prefer not to undergo surgery. The toxin, applied to the affected facial muscles, temporarily blocks the nerve impulse to the muscle and reduces the contractions. Its effect begins within a few weeks and usually lasts a few months, so the injections need to be repeated at intervals. Side effects such as temporary drooping of the eyelid, double vision and facial asymmetry can occur; these are usually transient.
Surgical Treatment: Microvascular Decompression (MVD)
Microvascular decompression (MVD) is the cause-directed surgical treatment for hemifacial spasm and can provide a lasting solution. Through a retrosigmoid approach the posterior fossa is opened, the root exit zone of the facial nerve from the brainstem is examined under the microscope, the vessel compressing the nerve is identified and a soft spacer (for example a Teflon pad) is placed between the nerve and the vessel to relieve the compression. MVD is preferred in patients who do not respond to medication and botulinum toxin or who want a lasting solution and are suitable for surgery (usually younger patients without significant other illnesses). Possible side effects include temporary facial weakness, hearing loss and cerebrospinal fluid leak. In secondary hemifacial spasm, treatment is directed at the underlying cause (for example a tumour). Gamma Knife radiosurgery is not a routinely recommended method in this condition.
Prognosis
Without treatment, hemifacial spasm usually follows a progressive course and spontaneous remission is rare. With botulinum toxin, symptoms can be effectively controlled in most patients; however, because the effect is temporary, the injections need to be repeated regularly. Microvascular decompression can provide lasting improvement in suitable patients, although recurrence may occur in a small number of cases. The choice of treatment is individualized according to the patient's age, general health, imaging findings and preferences. Outcomes vary from person to person and cannot be guaranteed in advance.
참고 문헌
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:1871-1872.
- Wang A, Jankovic J. Hemifacial spasm: clinical findings and treatment. Muscle Nerve. 1998;21(12):1740-1747.
- Barker FG 2nd, Jannetta PJ, Bissonette DJ, Shields PT, Larkins MV, Jho HD. Microvascular decompression for hemifacial spasm. J Neurosurg. 1995;82(2):201-210.
이 항목은 일반적인 안내 목적이며 의사의 진료를 대신하지 않습니다. 진단과 치료 결정은 개인별로 이루어집니다.