Most patients present with intermittent blepharospasm. It is not uncommon to hear that any minor accident or pathological condition, e.g., eye irritation due to dust exposure, keratoconjunctivitis sicca, conjunctivitis or blepharitis, acted as initial triggers of blepharospasm. Rapid, forced blinking may precede the latter. Here, blink frequency and muscle tone exceed those observed in healthy individuals trying to eliminate a small foreign body from their eyes.
Similarly, a patient may report trauma to have caused oromandibular dystonia. Such trauma may consist in blunt facial trauma sustained during sports accidents, falls or even dental treatment. Dystonia of lower facial musculature usually manifests after blepharospasm, i.e., the disease tends to spread. However, spread of dystonia from lower facial or neck regions to the eye is less likely . Movement disorders may comprise masticatory, lingual, pharyngeal as well as laryngeal muscles . In this line, patients may present with involuntary masticatory movements, clench their jaws, thrust their mandibles forward, purse their lips or grimace.
In some cases, dystonia may spread further and affect neck muscles. Spread may occur even years after symptom onset. Although trauma may account for disease progress, it is not always possibly to identify its cause.
Diagnosis of MS is based on clinical examination and exclusion of secondary dystonias . Laboratory analyses of blood samples, diagnostic imaging and possibly genetic screens may be applied to rule out the following differential diagnoses:
In MS patients, the aforementioned analyses and screens are normal.
MS is generally treated with injection of botulinum toxin. Such treatment is merely symptomatic and aids to resolve muscle spasms. In order to mediate that effect, botulinum toxin has to be injected into the affected muscles. Doses ranging from 5 to 25 units have been recommended for distinct muscles . Decreased muscle tones are usually noted within three days after the injection and persist for several months. Effect duration varies from patient to patient - most patients are fine with four injections per year. Injection of botulinum toxin is considered a safe procedure that is rarely associated with adverse events .
A variety of other drugs has been applied to relieve MS-associated symptoms. However, only limited success was reported for antiepileptics, muscle relaxants, anticholinergics, benzodiazepines and related drugs as well as tetrabenazine . These drugs may pose alternative treatment options if botulinum toxin injections yield only unsatisfactory results. However, possible benefits have to be considered against side effects of those medications. High risks of side effects are associated with anticholinergic therapy.
As has been indicated above, deep brain stimulation of the internal globus pallidum has been gaining importance as a therapeutic approach to otherwise intractable MS. Although many patients worry about the risks of brain surgery, stereotactic placement of electrodes is safe and bears only low risks of stroke, infection or neurological sequelae.
Prognosis is favorable. Patients who don't respond to medication may benefit from deep brain stimulation of the internal globus pallidum. According to a recent study regarding long-term treatment response to this technique, most patients experience considerably improvement, i.e., severity of blepharospasm and oromandibular dystonia significantly decreases . If cervical dystonia is present, the likelihood of improvement for this particular symptom is lower. Spontaneous remission has been reported .
To date, MS is considered a primary dystonia, i.e., there is no underlying disease triggering disturbance of muscle tone in patients suffering from MS. In contrast, secondary dystonia may be observed in individuals suffering from Parkinson's disease or Huntington's disease or in those who sustained a trauma. Indeed, patients treated for Parkinson's disease are not unlikely to develop MS since antiparkinson drugs may trigger this facial dystonia by modulating dopamine receptors. Interaction with gamma-aminobutyric acid (GABA), serotonine and adrenergic receptors has also been proposed to contribute to MS. All these effects may be mediated by distinct psychotropic drugs . However, drug-induced MS is a rare side effect of such medication and additional factors either predispose certain patients for dystonia or trigger the disease while treated for other pathological conditions. Such additional factors are most likely genetic disorders or environmental influences. Nevertheless, most MS cases are deemed idiopathic.
Functional impairment of basal ganglia and possibly additional brain regions like the brain stem are assumed to account for facial dystonia, but little more is known about their causes.
The annual incidence of focal dystonia has been estimated to be about 12 per 100,000 people . With regards to that same study, one out of three patients presenting with focal dystonia suffered from blepharospasm. Due to inconsistent use of distinct designations, e.g. facial dystonia, orofacial dystonia, and craniocervical dystonia, multimorbidity and considerable overlap of symptoms, precise epidemiological data regarding MS cannot be provided here.
Regarding MS prevalence, there is a broad age peak between 30 and 70 years. Nevertheless, MS has been diagnosed in younger and older patients. Women are affected about twice as often as men, a phenomenon that can't currently be explained.
Functional impairment of basal ganglia is assumed to cause MS-associated symptoms. Basal ganglia is a rather general term that refers to a number of nuclei located at the base of the forebrain. They comprise brain regions like ventral and dorsal striatum, globus pallidum and substantia nigra, and form part of a complex neuronal network. Basal ganglia are connected to cortex and thalamus and are involved in regulatory circuits that account for a variety of motor, cognitive and limbic functions. In this context, regular, involuntary blinking may be dependent on basal ganglia function and disturbance of impulse generator or regulator, particularly abnormal excitation, may result in blepharospasm. However, further research is needed to shed more light on basal ganglia function - their involvement in determined movements is often based on little more than speculation.
However, both data regarding etiology as well as therapy of MS argue for the hypothesis of a basal ganglia-mediated disorder. As has been mentioned above, antiparkinson drugs have been reported to induce MS. Symptoms associated with Parkinson's disease are essentially caused by a shortage of dopamine and relative excess of acetylcholine. The former, in turn, results from neuronal cell death occurring in the substantia nigra. Antiparkinson drugs either aim at compensation for lack of dopamine, stimulation of dopamine receptors, reduction of dopamine degradation or decrease of acetylcholine effects. They mimic actions otherwise executed by the substantia nigra, i.e, by an anatomic structure forming part of the basal ganglia.
Another structure assumed to play a major role in control of subconscious and voluntary movements is the globus pallidum which is, as has been mentioned above, also part of the basal ganglia. Deep brain stimulation of the internal globus pallidum has been reported to relieve symptoms of movement disorders like dystonia . This technique basically consists in stereotactic insertion of electrodes in very close proximity to the internal globus pallidum and continuous stimulation of local neurons. This may eventually result in excitation or inhibition of those cells. The precise mechanisms underlying deep brain stimulation effects are not yet fully understood, but the fact that modulation of neuronal signalling in this anatomical structure improves MS-associated symptoms strongly implies a role of the globus pallidum in MS pathogenesis.
No preventive measures can be recommended at this time.
Meige syndrome (MS) pertains to a group of disorders referred to as focal dystonias. It is named in honor of the French neurologist Henri Meige who is generally ascribed the first description of the disease. He published his observations in 1910 . Its most characteristic symptoms are blepharospasm and oromandibular dystonia which manifest as repeated, forced blinking or the inability to open the affected eye and involuntary movements of lips, tongue, masticatory and mimic musculature, respectively. Basically any muscle contributing to lower face or neck movements may be affected. Contrary to generalized forms of dystonia, neither limbs nor trunk are involved.
MS is usually diagnosed in middle-aged persons and more often in females. Its etiology is largely unknown; some cases seem to be induced by administration of drugs. It is assumed that impairment of basal ganglia function accounts for the abovementioned symptoms. Patients often report certain environmental factors to trigger symptom onset, e.g., temperature, wind and light.
Due to knowledge gaps regarding causes and pathogenesis of MS, treatment can only be symptomatic except in cases of drug-induced pathology. Here, dose reduction may be sufficient to remedy the disease. Empiric evidence argues for injections of botulinum toxin as most effective measure to prevent muscle spasms. Muscle relaxants and anti-convulsants have been applied with less success. Deep brain stimulation of the internal globus pallidum may be an alternative therapeutic approach . Additionally, those patients who identified individual environmental triggers may avoid those as much as possible.
Of note, idiopathic orofacial dystonia, idiopathic orofacial dyskinesis, craniocervical dystonia or similar designations all refer to MS.
Meige syndrome (MS) is a rare disease pertaining to the group of focal dystonia. The term dystonia refers to disturbances in muscle tone, while the attribute focal distinguishes these disorders from generalized ones that affect the whole body. As it is, MS is a facial dystonia and is therefore also called idiopathic orofacial dystonia. If neck muscle involvement is detected, physicians may talk about craniocervical dystonia.
Voluntary and subconscious movements of eye and lower facial musculature are controlled by complex neuronal circuits that involve brain regions like basal ganglia, cortex and thalamus. MS-associated symptoms are assumed to be triggered by functional impairment of basal ganglia. Overexcitation of basal ganglia neurons may result in alterations of muscle tone impulse generators and regulators and thus provoke dystonia.
Little is known about etiologic factors inducing this malfunction of basal ganglia. Most cases are deemed idiopathic, i.e., no specific cause can be identified. Some MS patients receive treatment for comorbidities like Parkinson's disease and psychological disorders. And although drugs prescribed to this end may provoke facial dystonia, such side effects are observed in a minority of patients. This fact implies that additional factors play a role in MS pathogenesis.
Rhythmic, spastic or tremor-like muscle contractions affecting eye, lower facial and possibly neck musculature. In detail, the following may be observed:
Symptomatic episodes may be induced by air pollution, eye irritation, facial trauma or dental treatments. Some patients report certain postures, activities and environmental factors to exacerbate symptoms.
MS is an exclusion diagnosis. Thus, workup mainly aims at ruling out other diseases that may trigger similar symptoms. Laboratory analyses of blood samples and diagnostic imaging are applied to this end. Stroke, Parkinson's disease, Huntington's disease, brain tumors and multiple sclerosis shall serve as examples.
Muscle spasms are remedied by injecting botulinum toxin ("Botox") into affected muscles. This is considered a safe procedure that often provides relieve for several months. A variety of other drug therapies has been tested, but little success has been reported for administration of antiepileptics, muscle relaxants, anticholinergics, benzodiazepines and related drugs.
Otherwise intractable cases may be cured by means of deep brain stimulation of the internal globus pallidum. This procedure involves placement of electrodes in one of the basal ganglia involved in MS pathogenesis. Continuous excitation of local neurons yields significant improvement of symptoms. Contrary to general assumption, this minimally invasive brain surgery has not been related to major adverse events. It should seriously be considered if drug treatment does not provide sufficient relieve from facial dystonia.