Idiopathic blepharospasm is a bilateral involuntary spasm of the circular muscle of the eye, which can be accompanied by spontaneous clonic-tonic contractions of the sternocleidomastoid muscles. Clinical symptoms are represented by rapid blinking, spastic closing of the eye slit, increased lacrimation, a feeling of “sand” in the eyes, burning. MRI, rheoencephalography, biomicroscopy, visometry, electroencephalography are used for diagnosis. Conservative therapy includes injections of botulinum toxin, oral administration of benzodiazepines, cholinolytics, instillation of moisturizers. With low efficiency, blepharoplasty is indicated.
General information
Idiopathic blepharospasm is commonly considered in ophthalmology as one of the variants of cranial muscular dystonia. The prevalence of the primary form of the disease in the USA is 40:100,000 of the population, in European countries – 15:100,000. 45% of patients note that the severity of symptoms decreases briefly after taking alcoholic beverages. 93% of patients resort to the use of corrective gestures (closing the eye, squinting, compression of the eyelid) to stop or prevent the development of an attack. The first clinical manifestations occur in middle-aged and elderly people. In women, the disease is diagnosed 3 times more often than in men.
Causes
In most cases, the disease develops sporadically, but it has been established that primary blepharospasm can be inherited by an autosomal dominant type. It is based on a mutation of the genes 9q34, 18q. When the Xq13 Xp22 genes are affected, it is possible to establish an X-linked type of inheritance. Risk factors for the development of a secondary form of the disease are:
- Ischemic brain lesions. The most common causes are infarction (ischemic stroke) with localization in the left frontal lobe and bilateral damage to the thalamus.
- Medical effects. Long-term use of drugs from the group of neuroleptics, antidepressants, antiparkinsonian and antipsychotic drugs in some cases is complicated by blepharospasm.
- Cranial synkinesia. Eyelid spasm is often caused by perinatal pathology, hepatolenticular degeneration and even Arnold-Chiari malformation.
- Mitochondropathy. In this group of diseases, the process of oxidative phosphorylation is disrupted, which often leads to spastic twitching of muscle fibers.
Pathogenesis
The mechanism of development is based on hyperreactivity of the periocular muscles due to the cranial form of muscular dystonia. Scientists believe that this pathology affects the basal ganglia. In this case, the passage of the pulse from the nuclei to the structures of the brain stem, cerebellum and premotor cortex is disrupted. Dopaminergic and cholinergic systems are involved in the pathophysiological process. A violation in the work of the premotor cortex leads to dysfunction of integrative processes of motor control, which is manifested by insufficient reciprocal inhibition of antagonist muscles.
With a decrease in visual acuity, concomitant damage to the thalamus is often detected, leading to a slowdown in the passage of the pulse from the striopallidar complex to the cortex. Incorrect modulation of the motor program potentiates the development of the clinic of spastic eyelid contraction. It has been experimentally proved that an important role in the pathogenesis is played by a violation of glucose metabolism. According to the results of proton MR spectroscopy, patients have a decrease in N-acetylaspartate, creatine phosphokinase. Afferentation disorder is only a change in the primary link of pathogenesis. The progression of pathology is associated with the development of secondary complications.
Classification
Idiopathic blepharospasm is more often acquired in nature, a congenital variant is rarely observed. Regardless of the type of disease, the symptoms will debut after 40 years. The following forms are distinguished:
- Primary. Blepharospasm is a local manifestation of torsion muscular dystonia with the only symptom – spasm of the fibers of the circular muscle.
- Secondary. The appearance of tonic-clonic contractions is caused by an organic lesion of brain structures or a violation of blood supply.
- Eyelid opening apraxia syndrome. The difficult process of opening the eye slit is caused by hypofunction of the muscle lifting the upper eyelid.
Symptoms of idiopathic blepharospasm
The first manifestation of the disease is a mild twitching of the eyelids, which eventually gives way to involuntary closing of the eyes. The development of the clinical picture is often preceded by rapid blinking, squinting, spontaneous lowering of the eyelid without a spastic component. Sensory disturbances include discomfort, sensation of a foreign body in the eye socket, burning sensation. Persons suffering from this pathology do not seek help from a specialist for a long time, associating this symptom with photophobia. The progression of the disease leads to the appearance of stable tonic or tonic-clonic spasms. Patients complain of persistent closing of the eyelids. It is not possible to open the eye slit independently.
Patients cannot foresee when the next attack will occur. The average duration of spastic contraction is 3-5 minutes. During the inter-criminal period, the general condition is not violated. In the initial stages, pathology is amenable to volitional control. As a rule, both eyes are affected, but the severity of symptoms in the right and left eyes may vary slightly. Over time, the muscles of the lower half of the face and neck are involved in the process. There is increased lacrimation, dry eyes. There is no visual dysfunction. The pupils’ reaction to light is preserved.
In severe cases, the quality of life of the patient significantly decreases, sometimes up to the impossibility of independent movement. Patients note that the disease significantly complicates daily activity (reading books, sewing, working at the computer). Symptoms often occur at the most inconvenient moment (when driving a car, crossing the road), but are absent during sleep. The severity of clinical manifestations decreases after a long rest and increases when trying to fix the gaze, in stressful situations. There are no spontaneous remissions.
Complications
Muscle hypertrophy leads to the appearance of entropion, less often – ectropion. The lesion of the muscle fibers of the tongue, larynx, neck, facial and masticatory muscles is complicated by oromandibular dystonia. Due to a prolonged spasm, a tension headache develops. Increased dryness of the membranes of the anterior segment of the eyeball leads to xerophthalmia. In patients with this pathology, a history of hypertonicity of the sympathetic nervous system entails an increase in blood pressure, heart rate. The formation of erosive defects on the surface of the cornea leads to the attachment of bacterial or infectious keratitis.
Diagnostics
To verify the diagnosis, anamnesis is collected, physical and special ophthalmological examination is carried out. Harrison’s criteria are studied (features of childbirth and development, concomitant neurological symptoms, results of laboratory and instrumental studies). During the diagnosis, the following are used:
- MRI of the head. Magnetic resonance imaging is performed to visualize the structure of the meninges, intracranial vessels in patients with suspected arteriovenous malformations.
- Rheoencephalography. Diagnosis of blood filling of the vessels of the head and neck is informative for assessing the nature of venous outflow. With a decrease in REG indicators, it can be assumed that the disease is based on lesions of an ischemic nature.
- Electroencephalography. Registration of bioelectric signals that come from nerve cells allows us to assess the degree of functional activity of the brain.
- Biomicroscopy of the eye. The study makes it possible to identify secondary lesions of the cornea of the eye, manifested by degenerative-dystrophic changes, the formation of ulceration sites on the shell.
- Ophthalmoscopy. It is used to study the condition of the retina and the optic nerve disc (optic disc). A pronounced spasm can potentiate a violation of the outflow of blood, followed by stagnation and the formation of small-focal hemorrhages. The ZEN is unchanged.
- Visometry. Visual acuity is impaired only when the pathological process spreads to the thalamus, which is manifested by the clinic of cortical blindness.
Differential diagnosis is performed with hemifacial spasm, myocemia, Tourette syndrome. Unlike idiopathic blepharospasm, symptoms of hemifacial spasm can occur during sleep, often due to paralysis of the 7th pair of cranial nerves. With myokemia, convulsive twitching appears against the background of stress or mechanical irritation of the orbital conjunctiva. The process is one-sided, often affects the lower eyelid. Tourette’s syndrome is characterized by multiple involuntary motor tics, which are accompanied by the reproduction of strange sounds and offensive statements.
Treatment of idiopathic blepharospasm
The patient’s management tactics depend on the severity of symptoms and the frequency of seizures. In the early stages, it is possible to use psychotherapy, acupuncture. As a conservative therapy , it is used:
- Botulinum neurotoxin type A. The drug has a presynaptic blocking effect on cholinergic nerve endings. The effect of the injection persists for 3-4 months, after which repeated administration is required.
- Benzodiazepine-type drugs. This group of medicines is included in the basic treatment regimen. Due to the interaction of benzodiazepines with GABA receptors, the binding of gamma-aminobutyric acid to protein structures increases, which, in turn, reduces the excitability of neurons. If the effectiveness of medicines of this group is insufficient, neuroleptics, antidepressants, muscle relaxants or sedatives are additionally used.
- Holinolytics. Anticholinergic drugs block the mediator acetylcholine, reducing the rate of passage of the nerve impulse. Along with the relief of spastic contractions, pupil dilation and accommodation paralysis are noted.
- Moisturizers. Instillation of artificial tear preparations is prescribed with the development of xerophthalmia.
Surgical treatment is indicated for persistent blepharospasm and ineffectiveness of drug therapy. Plastic surgery of the upper, less often – lower eyelids is carried out. The use of this method of treatment is most appropriate for apraxia syndrome. In the absence of the effect of blepharoplasty, a bilateral intersection of the branches of the facial nerve is performed. Previously, thermolytic damage of nerve fibers innervating the eyelid was used in the treatment of patients with idiopathic blepharospasm.
Prognosis and prevention
The prognosis for life is favorable, however, frequent attacks of spastic contractions sharply complicate the social adaptation of the patient. With constant tonic contractions of the circular muscle with rare episodes of relaxation, the patient cannot move independently. Timely treatment makes it possible to compensate for the main clinical manifestations of pathology. Methods of disease prevention have not been developed. Patients with blepharospasm in combination with neurological manifestations need to examine the structures of the brain for the detection of organic lesions.
