Oromandibular dystonia is a paroxysmal dystonia accompanied by violent movements of the muscles of the oral and mandibular groups. The main symptoms include uncontrolled movements of the lower jaw and lips, trism, facial asymmetry, spontaneous smile, the use of corrective gestures. Diagnosis is based on the data of anamnesis and general clinical examination, the results of differential diagnosis. The treatment program includes muscle relaxants, anticonvulsants, valproates, neuroleptics, NSAIDs, botulinum therapy, physiotherapy procedures, rarely – neurosurgical interventions.
ICD 10
G24.1 Idiopathic familial dystonia
General information
Oromandibular, orobuccofacial or orofacial dystonia (OMD) refers to the most common variants of focal dystonic hyperkinesis. The latter, in turn, are the most frequent forms of motor disorders and are observed in 30-60 people per 100,000 population. Most often, the disease debuts at an older age, after 40-50 years, which causes another name for this pathology – late dystonia. The structure of morbidity is dominated by female representatives, the ratio of men and women is about 1:2. The incidence rate of drug-induced OMD in people receiving long-term treatment with neuroleptics is in the range of 5-20%.
Causes
Dystonia can be congenital or acquired, oromandibular hyperkinesis more often belongs to the second group. In some cases, its formation is associated with a mutation in the DYT1 locus on the 9th chromosome. Also, the genes DYT 4, DYT 6, DYT 7 can play a certain role, which can be transmitted both by autosomal dominant and autosomal recessive type. The acquired form of the disease is caused by the following factors:
- Vascular disorders. The development of orobuccofacial hyperkinesis may be associated with damage to the extrapyramidal system against the background of intracranial hemorrhages, arteriovenous malformations, cerebral artery aneurysms, strokes.
- Brain injuries. Damage to the strio-pallidar system and the formation of OMD cause severe perinatal and craniocerebral injuries, improper prosthetics. In some cases, dental treatment may be a provoking factor in predisposed patients.
- The effect of medications. The appearance of symptoms of pathology is often associated with prolonged use of pharmaceuticals, including dopamine antagonists, some neuroleptics, calcium channel blockers, antiepileptic drugs.
- Neoplastic processes. Violent movements can be a sign of the formation of malignant or benign brain tumors, encephalitis in paraneoplastic syndrome.
- Toxins. The formation of persistent hyperkinesis is provoked by chronic intoxication with industrial or household chemicals, in particular – methanol, disulfiram, cyanides, carbon disulfide, manganese, cobalt.
- Infectious diseases. Oromandibular dystonia can develop against the background of severe viral encephalitis, subacute sclerosing panencephalitis, CNS tissue damage in HIV infection.
Pathogenesis
The components of the pathogenesis of the disease have not been thoroughly studied. It is believed that the basis of OMD is a neurodynamic defect at the level of the basal ganglia – the striated and subthalamic nuclei, the substantia nigra, and the pediculate core of the tire. It is characterized by increased activity of cholinergic and dopaminergic systems. Also, with this pathology, it is likely that there is a violation of articular-muscular feeling, kinesthesia against the background of dysfunction of proprioreceptors (neuromuscular, neuromuscular tendon fibers) and sensorimotor disintegration caused by a violation of the conductive pathways between the motor zones of the precentral gyrus of the cerebral cortex, the structures of the extrapyramidal system and the cerebellum. As a result, spontaneous contractions of the chewing, chin muscles, tongue muscles, subcutaneous neck muscle, circular mouth muscle are formed.
Classification
Depending on the probable causes and the time of development, oromandibular dystonia is divided into several variants. The use of classification in clinical practice simplifies the process of diagnosis and differentiation between possible variants of hyperkinesis, as well as the selection of appropriate pharmacotherapy. It is customary to distinguish the following forms of the disease:
- Idiopathic or prussic. It is formed without clearly defined reasons among representatives of the older age group. It is also called spontaneous buccal-lingual-chewing dyskinesia of the elderly.
- Medicinal or neuroleptic. It develops with prolonged use of medications from the group of antiparkinsonian drugs and neuroleptics, most often phenothiazines, butyrophenones. This form of pathology is referred to as Kulenkampf-Turnov syndrome.
- Secondary or symptomatic. It unites all cases of OMD that arise as a result of violations of the limbic-reticular complex against the background of other pathological processes occurring in the body – intoxication, infections, etc.
Symptoms
Clinically, the disease manifests itself by forcibly closing and / or opening the mouth, clenching the jaws, lateral movements of the lower jaw. At the same time, there is a curvature of the lip line, an asymmetry of the cheeks. There is a deviation of the tongue, its protruding, twitching or other movements, an involuntary smile. Often the pathology is of an individual nature and is manifested by dystonia of only 1-2 muscle groups. The most common variant is dystonic trism. Symptoms increase with talking, chewing, emotional reactions.
A characteristic feature of oromandibular hyperkinesis is the use of various corrective gestures. Trying to fight spontaneous movements, patients can touch or press on various parts of the lower third of the face, bite the lower lip, chew or suck various objects, perform any other actions that reduce the severity of symptoms. Strong-willed control over violent movements of the facial muscles is rarely observed. In severe cases, dystonic hyperkinesis is accompanied by severe diffuse headaches and dysfunction of the temporomandibular joint.
Diagnostics
The diagnosis is established mainly on the basis of the clinical picture of the disease, anamnestic data, differentiation with other pathologies, laboratory tests and neuroimaging are rarely used. Differential diagnosis of OMD is carried out with other hyperkinesis of the facial region: bruxism, various variants of trism, neuromuscular tics, myofascial syndrome of masticatory muscles. The patient’s examination plan includes:
- Survey. The neurologist details the patient’s complaints, finds out the possible presence of such disorders in the closest blood relatives. The specialist clarifies the potential relationship between the development of existing symptoms and taking medications, previously suffered diseases or injuries of the central nervous system.
- Physical examination. When determining the neurological status, the function of the V and VII pairs of cranial nerves is evaluated, the nature of violent movements and their changes in response to the use of corrective techniques, speech activity are established.
- Genetic analysis. The search for mutations is carried out only after a preliminary diagnosis of OMD in atypical situations, for example, when the disease debuts at the age of 30 or manifests with dystonic hyperkinesis of the limb.
- Neuroimaging. Brain MRI is indicated in the presence of anamnestic information indicating secondary forms of pathology. CT of the brain is informative in case of suspicion of the formation of calcinates and iron accumulations in the central nervous system.
Treatment
In the early stages of treatment, medications of various groups are used. The main goal of therapy is to restore neurotransmitter balance in the subcortical ganglia. If pharmacotherapeutic drugs are ineffective, botulinum therapy is used, surgical interventions are performed. In general, the treatment program for OMD may consist of the following items:
- Pharmacotherapy. As a base, drugs from the groups of central-acting muscle relaxants, anticonvulsants or tranquilizers are prescribed. There is a paradox characteristic of this disease – the effectiveness of medications that can provoke it (neuroleptics and valproates) is noted. Because of this feature, funds from the listed groups are gradually being replaced by atypical analogues. NSAIDs are used symptomatically.
- Botulinum therapy. Due to the risk of dysphagia and dysarthria formation, it is carried out only with pronounced functional disorders. The place of local injection and the dose of drugs based on botulinum toxin A are selected individually based on the clinical features of OMD in a particular patient.
- Physical therapy. It is effective in combination with pharmacotherapeutic agents. Laser therapy, electrocontherapy, bioptron therapy, physiotherapy baths are used. Occlusal mouthguards are recommended to normalize the functions of the temporomandibular joint.
- Neurosurgical operations. Surgical treatment for orofacial dystonia is indicated only with resistance to all of the above methods, represented by implantation of electrodes in the area of the inner part of the pale globe for the purpose of deep stimulation of the central nervous system.
Prognosis and prevention
The prognosis for oromandibular dystonia depends on the effectiveness of the chosen therapy and compliance with the recommendations of the neurologist. In most cases, it is possible to completely rid the patient of violent movements. According to statistics, after treatment, relief of all symptoms is observed in 90% of patients. The risk of complications, even taking into account surgical interventions, is at the level of 1-2%. There is no specific prevention. Non-specific preventive measures are aimed at eliminating the causes of secondary and drug-induced forms of OMD, imply rational medication intake, early treatment of infectious diseases and organic pathologies of the brain, minimizing contact with neurotoxic substances.