It is a chronic, neuromuscular condition characterised by involuntary contractions of the facial muscles on one side (hemi). Although it is a relatively painless condition, it causes inconvenience to the affected person.
Associated Anatomy
Facial muscles
Hemifacial Spasm Causes
- Compression of facial nerves - An artery presses upon the facial nerve (specifically the 7th cranial nerve), at the point where it connects to the brain stem. This sends out faulty signals to the brain, causing involuntary twitches.
- Nerve injury - A head injury may cause damage to the nervous tissue, leading to post-traumatic hemifacial spasms.
- Tumours - A benign tumour may put pressure on the facial nerve, leading to convulsions.
- Mental stress - Anxiety, fatigue and psychological strain act as triggers.
- Infections or strokes - Though rare, these may cause compression of the facial nerves, inducing spasms.
- Congenital factors - Being born with blood vessel clusters, adjacent to facial nerves, increases the chance of developing hemifacial spasms.
- Side effects of other conditions - The spasms may develop as a result of complications, in individuals having Bell’s palsy and multiple sclerosis.
- Idiopathic - In some cases, the exact causes are unknown and are attributed to spontaneity.
Signs Or Symptoms of Hemifacial Spasm
- Continuous twitching of the eye muscles.
- Painless, involuntary convulsions on one side of the face.
- Ear discomfort, like ringing sensation or pain.
- Spasms slowly spread down the face, to the upper neck.
- Feeling of the mouth being pulled to one side.
Hemifacial Spasm Treatment
- Muscle relaxants: Commonly called Botox, Botulinum toxin is an injectable muscle relaxant used to ease the affected muscles, and reduce the spasms. It is the most effective therapy for this condition. The injections need to be taken every three to six months.
- Oral medication: Anticonvulsant drugs such as carbamazepine, gabapentin, and baclofen are prescribed as the initial line of treatment.
- Surgery: Microvascular decompression (MVD) surgery is considered the last resort. The blood vessel compressing the affected facial nerve is located by craniectomy (removing a piece of the skull). A tiny sponge or Teflon padding is inserted between the nerve and the vessel, preventing further compression.
Risk Factors
- Psychological strain: People under stress and anxiety are more likely to develop this condition.
- Lack of sleep and rest: Long spells of wakefulness and overworking without proper rest, are concerning factors.
- History of medical conditions: Individuals with a history of facial palsy and hormonal imbalance are susceptible.
- Hereditary: The genetic angle is under research, but there have been instances of familial connections.
Stages
- It starts with an involuntary quivering of the eyelids.
- It is followed by twitching of the ipsilateral (same side) facial muscles in the cheek and mouth region.
- The convulsions slowly progress to the upper neck.
- Very rarely, it affects both sides of the face, though not simultaneously.
Typical Tests
The diagnosis is conducted based on clinical history and symptoms. The affected individual undergoes a thorough physical and neurological examination. Electromyography (EMG) is done in the initial stages, to rule out possibilities of similar conditions. This is followed by advanced imaging tests like magnetic resonance imaging (MRI) scans. If surgery is being considered, a magnetic resonance (MR) angiogram is done to determine the exact location of the blood vessel that is compressing the affected nerve.
Primary Prevention
- Relief from strain: Avoid the triggers that may lead to stress and anxiety.
- Staying relaxed: Practice techniques of relaxation to prevent fatigue and calm the nerves.
- Managing the symptoms early: Timely diagnosis and management help in restricting the condition.
- Maintenance of fitness: Regular exercise releases endorphins or feel-good hormones, which serve to reduce stress.
Secondary Prevention
- Medicines: Take the prescribed medications on time.
- Adequate rest: Take frequent breaks and avoid getting overworked.
- Dietary restrictions: Limit caffeine intake.
- Diet must-haves: Include vitamin D, magnesium, and antioxidants in your diet.
- Awareness: Educating oneself regarding the expected symptoms and related hazards is important.
- Alternative therapies: Massage and Acupuncture techniques are viable options.
- Joining a support group: It helps to deal with social and emotional issues.
Additional Types
Hemifacial spasms can be classified as typical and atypical. Typical hemifacial spasms begin by twitching of the eyelids, gradually progressing to the cheeks and mouth. Atypical hemifacial spasms originate in the lower facial muscles and move upwards to the eyelids.
Alternate name
Tic Convulsif or Involuntary Facial Twitching
Differential Diagnosis
Accurate diagnosis of hemifacial spasm is important, as its symptoms mimic those of several other movement disorders, such as:
- Blepharospasm (affecting muscles controlling the eyelids)
- Oromandibular dystonia (affecting jaws, tongue and pharynx)
- Bell’s palsy (facial muscle paralysis)
- Hemimasticatory spasm (involuntary contractions of jaw muscles)
- Trigeminal neuralgia (painful sensations on one side of the face)
Epidemiology
- Prevalence: Worldwide, it has an estimated prevalence of 14.5 per 100,000 women and 7.4 per 100,000 men. In India, it affects nine people per 100,000.
- Age: 40 to 80 years.
- Gender: More common in women.
- Ethnicity: More frequent in individuals of Asian origin.
- Side affected: Left side, predominantly.
Expected Prognosis
In most cases, injection therapy is effective in warding off the symptoms. However, the treatment needs to be continued long-term. Some may require surgery. Around 85% of people recover well after treatment. Even though it is a chronic condition, it can be managed by regular medication, preventive measures and consistent follow-ups.
Natural Progression
If left untreated, it may end up affecting more facial muscles, which may permanently pull the mouth to one side. It may even develop into painful contractions, as in the case of trigeminal neuralgia.
Pathophysiology
Compression of the facial nerve by an aberrant blood vessel leads to ephaptic transmission (changes in the excitability of adjacent neurons by a specific neuron). It causes demyelination of the axons at the site of compression.
Possible Complications
The MVD surgery may cause complications like infections, breathlessness, paralysis, hearing problems, double vision, and difficulty in swallowing. The condition itself can develop into trigeminal neuralgia. If the associated tumours are left untreated, they may metastasize and lead to cancer.
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