What is Hemifacial Spasm?
Hemifacial spasm (HFS) is a condition that causes unexpected, uncontrollable twitching of facial muscles on one side of the face. This happens due to abnormal spontaneous activity in the facial nerve on the same side. The facial nerve is the seventh cranial nerve, which controls the muscles responsible for facial expressions.
HFS falls into the category of peripheral movement disorders, which are conditions that affect the nerves controlling your muscles. Despite being called “hemifacial”, meaning “half of the face”, in some rare cases (about 2.6% of all HFS cases), it can affect both sides of the face.
While this condition does not lead to major physical disability, it can cause a lot of social discomfort and stress, leading to serious psychological issues in the patient.
What Causes Hemifacial Spasm?
Primary Hemifacial Spasm
Hemifacial Spasm (HFS) is primarily caused by pressure on a facial nerve, usually because of an unusually large or misshapen artery. The main arteries involved are branches of the anterior inferior cerebellar artery, the posterior inferior cerebellar artery, and the vestibular artery, among others.
The facial nerve, which is responsible for facial expressions, exits the brainstem at a point commonly known as the root-exit zone. This area is only covered by a thin covering (the arachnoid membrane) and lacks a protective layer (the epineurium). It’s also an area where central and peripheral myelin (the protective coverings on nerve fibers) meet, created by two different types of cells – oligodendrocytes and Schwann cells. Because of all this, the nerve here is very vulnerable to any stimulation, like compression or irritation.
Secondary Hemifacial Spasm
Hemifacial Spasm can also occur as a result of other conditions or causes, such as:
* Physical injuries
* A late complication of Bell’s palsy (a condition that causes sudden, temporary weakness in your facial muscles)
* Structural lesions along the course of the facial nerve, particularly a benign (non-cancerous) tumor pressing on the portion of the nerve inside the skull
* Unusual connections between arteries and veins, bulging of arterial walls (aneurysms), arteriovenous fistulas (abnormal connections between arteries and veins), or clusters of blood vessels (angiomas)
* Infections in the middle ear (otitis media) or a buildup of skin cells in the middle ear (cholesteatoma)
* Tumors of the salivary gland located below your ear (parotid gland)
* Chiari malformation (where brain tissue extends into your spinal canal) and other structural abnormalities of the back of the skull
* Lesions in the brainstem, like the plaque from multiple sclerosis that damages the protective coating on nerve fibers.
Risk Factors and Frequency for Hemifacial Spasm
Hemifacial spasm (HFS) is a rare condition that affects more women than men worldwide. Statistically, about 14.5 in every 100,000 women and 7.4 in every 100,000 men will develop HFS, indicating that women are twice as likely to have HFS as men. It’s interesting to note that, for reasons not yet known, the condition appears to be slightly more common among people of Asian descent than those of Caucasian descent. Most instances of HFS occur randomly, but there have been a few reports of familial cases-where multiple family members have the condition.
Usually, HFS begins in adulthood, typically between the ages of 40 and 60. It tends to affect the left side of the face more than the right, based on the majority of reported cases. Additionally, research suggests that 40% of those with HFS also have high blood pressure.
Signs and Symptoms of Hemifacial Spasm
Hemifacial spasm (HFS) is a condition where one side of the face experiences involuntary contractions. Normally, these contractions start around the eye, which results in the affected eye closing involuntarily. Other signs that can occur along with this are eyebrow twitching and raising, which is known as the “other Babinski sign”. This sign is a distinctive feature of HFS and helps doctors tell it apart from other conditions such as blepharospasm, where these characteristic eyebrow movements are not seen.
Over time, these scattered contractions can become more severe, affecting the lower facial muscles. In addition, blinking becomes forced. For secondary HFS, the contractions spread to the whole face, turning into steady spasms as the condition worsens. Uniquely, these involuntary contractions can persist during sleep, which can lead to disturbed sleep or insomnia for the person.
In advanced cases, one side of the face might appear to be different from the other due to muscle contractions, leading to a noticeable change in the individual’s facial symmetry. Rare symptoms can include ear clicking, ear pain, and hearing loss. Certain factors like stress, fatigue, and anxiety can worsen the symptoms. However, relaxation techniques or just touching the face can help to lessen the spasms or twitching.
After a severe case of Bell’s palsy, some patients may experience facial twitching similar to HFS. In these cases, when the eye blinks, other facial muscles might contract involuntarily. This happens because of irregular reconnection of the facial nerves.
Studies have shown that around 40% of individuals with HFS also have high blood pressure. Therefore, it is important to check for the presence of high blood pressure in patients with HFS.
Testing for Hemifacial Spasm
Diagnosing hemifacial spasm (HFS) is typically based on your detailed medical history, and an examination of your nervous system and the affected area. In most cases, electrophysiological tests aren’t crucial for the diagnosis. In simple terms, electrophysiological tests record the electrical activity in your muscles and nerves. However, these tests can be particularly useful in the early stages of HFS when it may be challenging to distinguish this condition from further similar ones.
Some common conditions that can be confused with HFS are facial muscle tremors (facial myokymia), abnormal blinking or spasming of the eyelids (blepharospasm), localized muscle contractions (motor tics), and certain types of seizures. Electrophysiological testing usually helps in making these distinctions.
Proper diagnosis is crucial because many different conditions can resemble HFS. For instance, if facial nerve compression is suspected, it is crucial to rule out any structural abnormalities, especially harmless brainstem tumors or issues near an area called the cerebellopontine angle. A brain magnetic resonance imaging (MRI) scan is considered the most effective way to rule out structural issues that may require surgery or could indicate conditions like multiple sclerosis.
In most cases, computerized tomography (CT) and magnetic resonance angiography (another type of MRI focused on blood vessels) aren’t typically needed. This is because these tests often won’t show anything abnormal in cases of primary HFS. They frequently show a loop of blood vessels close to the facial nerve, which can be found even in people without HFS. However, magnetic resonance angiography may be used in patients who are scheduled for certain types of surgery known as microvascular decompression. In such cases, a high-resolution T2-weighted images and 3D time-of-flight magnetic resonance angiography can be handy for evaluating the condition before the operation.
Treatment Options for Hemifacial Spasm
The main goal of treating hemifacial spasm (HFS), a condition where half of the face suddenly contracts, is to lessen these muscle contractions. This can be done through medication or surgery, depending on the severity and cause of the condition.
One well-known treatment for HFS is injections with a substance called botulinum neurotoxin, commonly known as botox. Botox has become a popular choice because it has been found to significantly improve symptoms in up to 95% of patients in some studies. Before starting botox, however, it’s crucial to rule out other potential causes of the spasms such as tumors or vascular malformations.
Botox injections are quite straightforward and are typically given in the muscles most affected by spasm, such as eyelid and various facial muscles. There can be side effects, like drooping or swelling, temporary bruising, or facial weakness. However, these are usually mild and temporary.
Botox works by blocking the transmission of nerve signals that cause muscle contraction, leading to a temporary paralysis of the muscles supplied. This effect tends to last between three and six months. Another benefit is that botox can reportedly alleviate depressive symptoms in patients with HFS, since it reduces nerve signals to parts of the brain associated with depression and anxiety.
The common botox dosage requires a repetition every three to six months, as its effects can vary. Relief from symptoms usually kicks in three to six days after the injection and peaks after two weeks.
Oral medications are another treatment option, often used in mild or early cases of HFS. These include anticonvulsants, benzodiazepines, and other substances that control muscle spasms. However, their results can be inconsistent and may come with side effects, especially over long-term use. Therefore, they are generally considered a first choice for those not willing to try botox or undergo surgery.
Surgery offers a permanent solution by addressing the underlying cause of HFS. It’s typically the preferred choice for severe cases. The procedure, called microvascular decompression, releases the nerve responsible for the spasms from the blood vessel putting pressure on it. Relieving this pressure often leads to the disappearance of the muscle spasms. Despite the high success rate of approximately 80%-88%, surgical treatment does come with potential risks, such as hearing loss, facial nerve paralysis, and symptoms may reoccur in rare cases.
What else can Hemifacial Spasm be?
Diagnosing Hemifacial Spasm (HFS) correctly is key to planning effective treatment. There are many conditions that can look like HFS, so physicians should be aware of this. In particular, if a patient under the age of 40 has HFS, the doctor should check for any signs of multiple sclerosis, although it’s rare for this to be the first sign of the disease. When multiple sclerosis affects the area of the brain stem, it can involve the roots of the facial nerves which can lead to irregular signals that result in HFS.
What to expect with Hemifacial Spasm
Hemifacial spasm is a condition that often gets worse over time. However, it’s notable that in rare cases, about 10% of people with this condition may see it improving on its own. This condition is generally harmless but can persist.
It is crucial for patients to know that the most effective and simple treatment for hemifacial spasm involves consistent botox injections every 3 to 6 months. If the condition doesn’t respond well to the botox injections or if the patient decides they no longer want these injections, they might consider a type of surgery called microvascular surgery.
Preventing Hemifacial Spasm
Hemifacial spasm (HFS) is a condition that can cause significant distress, embarrassment, and even lead to anxiety and depression due to the limitations it places on a person’s ability. In severe cases, it can even cause continuous eye closure, effectively mimicking blindness. This can pose serious dangers, especially while driving or working with heavy machinery.
One well-known way to manage HFS is through the use of botox injections, which are known to be quite effective. However, there are setbacks to this approach, such as the need for regular procedures and the hefty financial cost.
For those considering surgery, it’s important to be very well-informed about what the procedure will entail. Undertaking microvascular decompression surgery, which includes an operation called a craniotomy (surgery on the skull), is a complex and invasive option. It’s crucial for patients to fully understand the potential benefits and risks before deciding on this surgical procedure.
