Hemifacial spasms ( HFS ) is a rare neuromuscular disease characterized by irregular muscular contraction (spasm) on one side (hemi-) of the face (-facial). The facial muscles are controlled by the facial nerve (seventh cranial nerve), which originates from the brain stem and comes out of the skull below the ear where it is separated into five main branches.
The disease takes two forms: typical and atypical. In a typical form, twitches usually begin in the lower eyelids of the oculi orbicular muscles. Over time, it spreads throughout the lid, then into the orbicularis oris muscles around the lips, and the buccinator muscle in the cheekbone area. The reverse process of twitching occurs in atypical haemifacial spasms; begin to twitch in the orbicularis oris muscles around the lips, and the buccinator muscles in the cheekbone area in the lower face, then continue into the oculi orbicularis muscles in the petals as time passes. The most common forms are typical, and atypical forms are seen only in about 2-3% of patients with hemifacial spasms. The incidence of hemifacial seizures is about 0.8 per 100,000 people.
This disorder occurs in men and women, although it affects middle-aged or elderly women more often. Hemifacial spasm is much more common in some Asian populations. This may be caused by facial nerve injury, tumors, or may not have a clear cause. Individuals with seizures on both sides of the face are very rare.
Video Hemifacial spasm
Tanda & amp; Gejala
The first sign of haemifacial spasm is usually muscle movement in the patient's eyelids and around the eyes. It can vary in intensity. Twitching intermittent eyelids, which can result in the forced closing of the eyes which gradually spread to the lower muscles of the face (typical shape - See Figure). In the form of atypical seizures begin in the area of ​​the cheekbone and spread to the eyelid. In the end, all the muscles on that side are affected, most of the time. This sometimes causes the mouth to be pulled sideways. Experts associate hemifacial spasms with facial nerve injuries, Bell's palsy and tumors. Although the most common cause is the blood vessels suppress the facial nerve in the place where the patient's brain stem is released, sometimes no known cause. When the affected individual is younger than 40, the doctor suspects an underlying cause such as multiple sclerosis.
Maps Hemifacial spasm
Cause
Three theories exist to explain facial nerve dysfunction found in haemifacial spasm. The first proposed theory is the ephaptic transmission, which is a crossing of electrical activity from one demyelinated neuron to another producing the wrong synapse. The second theory involves the abnormal activity of the axon in the final zone of the facial nerve root secondary to damage of press/demyelination.
The third theory or "Kindling Theory" involves an increase in the facial nerve stimulation because of feedback from damaged facial nerves.
It is generally accepted as a compression of the facial nerve by the vessels of the posterior circulation. In detail severe cranial nerve compression by the dolichoectatic vertebral artery (distorted, dilated, and elongated) is accepted to be a common cause of hemifacial spasms. Less than 1% of cases are caused by tumors. Hemifacial spasm is much more common in some Asian populations.
Some families with hemifacial spasms have been reported, suggesting a genetic or predisposing etiology in some cases. There appears to be an autosomal dominant pattern of inheritance in families with low penetration, and except for younger age at onset, clinical features overlap with idiopathic cases. Evaluation of single nucleotide polymorphisms in genes associated with vascular changes led to compression of blood vessles showing no association with hemifacial spasm. Clarifying the role of genetic susceptibility in hemifacial spasms may help to better understand the pathogenesis of this disease.
Diagnosis
There are several tests performed to diagnose hemifacial seizures. Diagnosis of hemifacial seizure cases begins with a complete neurologic examination, including Electromyography (EMG - a test that measures and records the electrical activity generated in the muscles at rest and in response to muscle contraction), magnetic resonance imaging (MRI - a test that uses magnetic waves to create an image structures inside the head), Computed tomography (CT scan - the type of x-rays that computers use to create structural images inside the head), and Angiography (x-ray vein examination) when they are filled with contrast material).
Studies have shown that the most effective method of hemifacial spasm screening is MRI. In one study only 25% of CT scans showed abnormalities in hemifacial spasm patients, while more than half of MRI imaging showed vascular anomalies. MRI imaging should be an initial screening procedure in the assessment of patients with hemifacial spasm.
Prevention
There is no known way to prevent hemifacial spasms.
Maintenance & amp; Side Effects
Mild cases of hemifacial spasms can be managed by sedation or carbamazepine (anticonvulsant drugs). Microorganic decompression and botulinum toxin injection are the primary treatments currently used for hemifacial spasms.
Microvascular Decompression
Microvascular decompression seems to be the most popular surgical treatment today. Microvascular decompression reduces the pressure on the facial nerve, which is the cause of most cases of hemifacial spasm. Very good for good results are reported in 80% or more cases with a recurrence rate of 10%. In this series approximately 10% have previously failed operations. Serious complications can follow micro decompression surgery, even when performed by an experienced surgeon. These include cerebellar or swelling hematoma, brainstem infarction, cerebral infarction (ischemic stroke caused by blood vessels that supply blood to the brain), subdural hematoma and intracerebral infarction (blockage of blood flow to the brain). Death or permanent disability (hearing loss) can occur in 2% of patients from hemifacial spasms.
Botulinum Toxin
Botulinum toxin is safe and effective in the treatment of hemifacial spasms. Success rates range from 76-100%, but repeated injections may be needed every 3 to 6 months. Injection is given as an outpatient or office procedure. While side effects occur, this is never permanent. Repeated injections over the years have remained very effective. While toxins are expensive, the cost of even a long injection of injections is better than the cost of surgery. Patients with HFS should be offered a number of treatment options. Very mild cases or those who are reluctant to undergo surgery or Botulinum toxin injection may be offered medical treatment, sometimes as a temporary measure. In young and fit patients microsurgical decompression and Botulinum injections should be discussed as an alternative procedure. In most cases, and especially in the elderly and unfit, Botulinum toxin injection is the first-choice treatment. Imaging procedures should be performed in all cases of unusual haemifacial spasms and when surgery is contemplated. Patients with hemifacial spasms prove to decrease sweat after botulinum toxin injection. It was first observed in 1993 by Khalaf Bushara and David Park. This is the first demonstration of non-muscle use of BTX-A. Bushara further demonstrates the efficacy of botulinum toxin in treating hyperhidrosis (excessive sweating). BTX-A is then approved for excessive underarm armor treatment. This is technically known as severe primary axillary hyperhidrosis - excessive underarm sweating with unknown causes that can not be managed by topical agents (see focal hyperhidrosis).
Epidemiology
The incidence of hemifacial seizures is about 0.8 per 100,000 people. Hemifacial spasms are more common in women over 40 years of age. Estimates of prevalence for women were 14.5 per 100,000 and 7.4 per 100,000 in men. The prevalence for hemifacial spasms increases with age, reaching 39.7 per 100,000 for those aged 70 years and older. One study divided 214 hemifacial patients based on the cause of the disease. Patients with compression of the facial nerve at the end of the brainstem as primary haemifacial spasms and patients with facial paralysis or nerve lesions due to tumor, demyelinization, trauma or infection as secondary haemative spasms. The study found that 77% of hemifacial spasms were due to primary haemifacial spasms and 23% caused by secondary hemifacial spasm. The study also found both sets of patients to share the same age at onset, men with female ratios, and similarly affected sides. Another study with 2,050 patients presented with hemifacial spasm between 1986 and 2009, only 9 cases caused by cerebellopontine angle syndrome, an incidence of 0.44%.
History
The earliest descriptions of the hemifacial spasm were with Shultze in 1875 and Gowers in 1899. The etiology of hemifacial seizures and the location of the disorder has been debated for more than a century. Surgical treatment for hemifacial spasms in the early 20th century included neurolysis (nerve tissue destruction), facial nerve stretching (seventh cranial nerve), and high-pressure irrigation of the nerve with lactate solution. The current medical regimen involved the injection of nerves with ethanol, electrical stimulation, the application of toxic compounds (silver nitrate, zinc, arsenic, bromide) as well as drugs such as Dilantin or other anticonvulsants.
Additional advances in understanding etiology and improving care for hemifacial spasm did not occur until the mid-seventies. In 1977, 47 cases of hemifacial spasm experienced facial nerve microvascular decompression using an operating microscope. The results illustrate the conflicts of blood vessels (or cholesteatomas) located in the facial nerve exit zone in all cases. The root exit zone is where central axial glial insulation of nerve endings and axillary peripheral nerve myelination begin. Biopsy of the root exit zone shows degeneration of axons, deformed axes and myelin axes. The experimental results reinforce the theory that facial nerve vascular compression is a major cause of haemifacial spasm, and proposes a specific region of the facial nerve in which the effects of old compression results in neural dysfunction.
References
Further reading
- "Hemifacial Spasm Information Page". National Institute of Neurological Disorders and Stroke. October 11, 2011 . Retrieved January 6, 2012 .
External links
- Kastial Nerve Disorder Center.
Source of the article : Wikipedia
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